Patent Application
20240417738
Immunotherapy agents, such as anti-PD1 antibodies, have made a significant impact in cancer treatment. However, the response rates of such agents are still limited to ˜20%. Intratumoral toll-like receptor (TLR) agonists have been shown to be effective as monotherapy and to enhance response to anti-PD1. However, the intratumoral route is difficult to implement in the clinic. Improved compositions and methods for administering such agents are needed to improve cancer therapies.
Provided herein are compositions and methods for the treatment of cancer.
For example, provided herein are compositions for the co-administration of TLR agonists (e.g., a TLR7/8 and TLR9 agonist). In these compositions, the TLR7/8 agonist can be formulated in an injectable liposome or nanoemulsion formulation. For example, in some embodiments, the composition can include resiquimod formulated in liposomes at 10% wt/wt combined with SD-101, a TLR9 agonist, to achieve high degree of synergy. The composition can be administered systemically and has been shown to elicit excellent tumor growth inhibition in a MC38 murine tumor model. The composition can exhibit much higher activity than either agent (resiquimod, SD-101) alone. Administration of this composition can induce a high level of type I cytokines, upregulate PD-L1 in splenocytes, or any combination thereof. Optionally, this therapy can be further be combined with a PD-1 and/or PD-L1 inhibitors to achieve an even greater therapeutic response. Unlike many existing TLR agonists, these compositions do not require intratumoral administration. These compositions can be administered (e.g., systemically via infusion) to treat cancer.
Also provided are compositions for the co-administration of one or more TLR agonists (e.g., a a TLR7/8 agonist) and anti-PD-L1 (LNAASO/siRNA). These compositions can generate a higher level of dendritic cell activation and maturation, which induces potent T cell activation and anti-tumor activities. In addition, by co-delivering TLR agonists with an anti-PDL1 antisense oligonucleotide, the overall immuno-suppressive environment could be skewed back to immuno-permissive conditions, which is associated with regulatory T cell population reduction and macrophage repolarization.
The composition can comprise a pH-sensitive lipid nanoemulsion formulation (PSNE) that includes both the one or more TLR agonists (e.g., a CpG oligonucleotide-based TLR agonist) and one or more antisense oligonucleotised that reduce the expression of PD-L1. The PSNE lipid nanoparticles can have an average particle size of less than 250 nm (e.g., less than 200 nm, less than 150 nm, or less than 100 nm). In some cases, the PSNE lipid nanoparticles can have an average particle size of from 50 nm to 100 nm (e.g., from 85-95 nm), which was ideal for delivery into the tumor microenvironment (TME) through enhanced permeation and retention (EPR) effect. These compositions can exhibit much higher activity than either agent alone. For example, in an MC-38 syngeneic murine tumor model, single agents of either oligonucleotide-based TLR agonist (class-C CpG) or anti-PDL1 LNA ASO in PSNE can elicit ˜45% of tumor growth inhibition (TGI), whereas co-encapsulation of both CpG and ASO into a single particle lead to a higher TGI at ˜73%. Flow cytometry analysis showed that inhibitory regulatory T lymphocytes (Treg) population frequency in the spleen was reduced in single-agent groups and further reduced in the combination group, indicating the reversal of immune-suppressive environment. Furthermore, PD-L1 expression was assessed on splenic macrophages, T lymphocytes as well as overall splenocytes by flow cytometry and RT-qPCR. The results showed that PD-L1 expression was downregulated in macrophages in all treatment groups, but not in splenic T lymphocytes. In addition, PD-L1 mRNA levels were reduced by ˜60% in groups treated with anti-PDL1 ASO, in both single-agent and combination groups, illustrating that the PSNE lipid nanoparticles were taken up by phagocytes and overcame PD-L1 upregulation by TLR activation.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Methods and materials are described herein for use in the present invention; other, suitable methods and materials known in the art can also be used. The materials, methods, and examples are illustrative only and not intended to be limiting. All publications, patent applications, patents, sequences, database entries, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control.
“Aqueous solution” refers to a composition comprising in whole, or in part, water.
“Organic lipid solution” refers to a composition comprising in whole, or in part, an organic solvent having a lipid. In some embodiments, the organic lipid solution can comprise an alkanol, most preferably ethanol. In certain embodiments, the compositions described herein can be free of organic solvents, such as ethanol.
“Lipid” refers to a group of organic compounds that are esters of fatty acids and are characterized by being insoluble in water but soluble in many organic solvents, e.g, fats, oils, waxes, phospholipids, glycolipids, and steroids.
“Amphipathic lipid” comprises a lipid in which hydrophilic characteristics derive from the presence of polar or charged groups such as carbohydrates, phosphato, carboxylic, sulfato, amino, sulfhydryl, nitro, hydroxy and other like groups, and hydrophobic characteristics can be conferred by the inclusion of a polar groups that include, but are not limited to, long chain saturated and unsaturated aliphatic hydrocarbon groups and such groups substituted by one or more aromatic, cycloaliphatic or heterocyclic group(s).
Examples include phospholipids, aminolipids and sphingolipids. Phospholipids include phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, phosphatidic acid, palmitoyloleoyl phosphatidylcholine, lysophosphatidylcholine, lysophosphatidylethanolamine, dipalmitoylphosphatidylcholine, dioleoylphosphatidylcholine, distearoylphosphatidylcholine or dilinoleoylphosphatidylcholine. Amphipathic lipids also can lack phosphorus, such as sphingolipid, glycosphingolipid families, diacylglycerols and b-acyloxyacids.
“Anionic lipid” is any lipid that is negatively charged at physiological pH, including phosphatidylglycerol, cardiolipin, diacylphosphatidylserine, diacylphosphatidic acid, N-dodecanoyl phosphatidylethanolamines, N-succinyl phosphatidylethanolamines, N-glutarylphosphatidylethanolamines, lysylphosphatidylglycerols, and other anionic modifying groups joined to neutral lipids.
“Cationic lipid” carry a net positive charge at a selective pH, such as physiological pH, including N,N-dioleyl-N,N-dimethylammonium chloride (“DODAC”); N-(2,3-dioleyloxy)propyl)-N,N,N-trimethylammonium chloride (“DOTMA”); N,N-distearyl-N,N-dimethylammonium bromide (“DDAB”); N-(2,3-dioleoyloxy)propyl)-N,N,N-trimethylammonium chloride (“DOTAP”); and N-(1,2-dimyristyloxyprop-3-yl)-N,N-dimethyl-N-hydroxyethyl ammonium bromide (“DMRIE”). Additionally, a number of commercial preparations of cationic lipids are available which can be used in the present invention. These include, for example, LIPOFECTIN®, LIPOFECT AMINE®, and TRANSFECTAM®.
Provided herein are pharmaceutical composition that comprise a lipid particle encapsulating a first TLR agonist and a second TLR agonist. Optionally, the lipid particle can further comprise an additional active agent, such as a PD-L1 antagonist (e.g., an anti-PD-L1 antisense oligonucleotide). In some embodiments, the first TLR agonist and the second TLR agonist target different TLRs. In some embodiments, the first TLR agonist comprises a TLR7 agonist, a TLR8 agonist, or a TLR7/8 agonist. In certain embodiments, the first TLR agonist comprises resiquimod. In some embodiments, the second TLR agonist comprises a TLR9 agonist. In certain embodiments, the second TLR comprises SD-101.
Also provided are pharmaceutical compositions that comprise a lipid particle encapsulating a TLR agonist and an antisense oligonucleotide capable of reducing expression of PD-L1 in a target cell. In some of these embodiments, the TLR agonist comprises a TLR9 agonist, such as SD-101.
In the compositions described above, the lipid particles can comprise a pH-sensitive lipid nanoemulsion formulation. The lipid particles can comprise one or more ionizable lipids; one or more neutral lipids; one or more PEGylated lipids; and one or more fusogenic oils, as discussed in more detail below.
These compositions can optionally be buffered at an acidic pH (e.g., a pH of less than 6.5, such as a pH of from 4 to 6.5, or a pH of from 5.0 to 6.5). In some embodiments, these compositions can be buffered at a pH for from 6.5 to less than 6.8, or from 6.5 to less than 7. By buffering at an acidic pH, the delivery efficiency of the compositions can be enhanced as compared to otherwise identical compositions buffered at a pH of 7 or more. In other embodiments, these compositions can be buffered at a pH of from 7 to 7.4.
The lipid particles can have an average diameter of less than 1 micron, such as from from 50 nm to 750 nm, 50 nm to 250 nm, from 50 nm to 200 nm, from 50 nm to 150 nm, or from 50 nm to 100 nm. The lipid particles can have a polydispersity index (PDI) of less than 0.4.
The components of these compositions are described in more detail below.
As described above, the compositions described herein can comprise one or more ionizable lipids. An“ionizable lipid” is a lipid that carries a charge that is pH-dependent. The one or more ionizable lipids in the composition described herein can comprise ionizable cationic lipids which carry a positive or neutral carge depending on pH.
Generally, in lipid-based formulations for nucleic acid delivery, either a cationic lipid or an ionizable lipid is used to enable electrostatic interaction with the negatively charged cargo. A cationic lipid is typically defined as a lipid that carries a permanent positive charge(s) that typically comes from a quaternary amine. Examples of a cationic lipids include DOTAP, DOTMA, DDAB, and DODAC. In contrast, ionizable lipids include a chemical moiety, such as a tertiary amine(s), which is positively charged at acidic pH but becomes uncharged at neutral to basic pH. Ionizable lipids can have a pKa value in a biologically relevant range. However, the pKa value of such a lipid is highly dependent on the method used to measure it, resulting in up to 3 units of difference in numerical values for the same lipid. This has been documented in a recent article by Carrasco et al. Communications Biology volume 4, Article number: 956 (2021).
Examples of ionizable lipids are DODMA (N,N-dimethyl-2,3-dioleyloxypropylamine), DODAP, DLinDMA (1,2-dilinoleyloxy-3-dimethylaminopropane), DLinMC3DMA (dilinoleylmethyl-4-dimethylaminobutyrate), DLinKC2DMA (2-dilinoleyl-4-dimethylaminoethyl-[1,3]-dioxolane), ALC-0315 ([(4-hydroxybutyl)azanediyl]di(hexane-6,1-diyl)bis(2-hexyldecanoate)), SM-102 (9-heptadecanyl 8-{(2-hydroxyethyl)[6-oxo-6-(undecyloxy)hexyl]amino}octanoate), Merck-32 (see e.g., WO 2012/018754), Acuitas-5 (see e.g., WO 2015/199952), KL-10 (see e.g., U.S. Patent Application Publication 2012/0295832), C12-200 (see e.g., Love, K T et al., PNAS, 107: 1864 (2009)), 3-(N—(N′,N′-dimethylaminoethane)-carbamoyljcholesterol (“DC-Chol”) and the like. Ionizable lipids also include those disclosed in U.S. Pat. Nos. 8,158,601, 9,593,077, 9,365,610, 9,567,296, 9,580,711, and 9,670,152, International Publication Nos. WO 2012/018754, WO 2015/199952, WO 2019/191780, and U.S. Patent Application Publication Nos. 2012/0295832, 2017/0190661 and 2017/0114010, each of which is incorporated herein by reference in its entirety.
In some embodiments, the one or more ionizable lipids can comprise a lipid headgroup comprising a tertiary amine. In certain embodiments, the one or more ionizable lipids can comprise N,N-dimethyl-2,3-dioleyloxypropylamine (DODMA), [(4-hydroxybutyl)azanediyl]di(hexane-6,1-diyl)bis(2-hexyldecanoate) (ALC-0315); 9-heptadecanyl 8-{(2-hydroxyethyl)[6-oxo-6-(undecyloxy)hexyl]amino}octanoate (SM-102), DLin-MC3-DMA; DLin-KC2-DMA; or any combination thereof.
In some embodiments, the one or more ionizable lipids comprise at least 20 mol % (e.g., at least 25 mol %, at least 30 mol %, at least 35 mol %, at least 40 mol %, at least 45 mol %, at least 50 mol %, at least 55 mol %, or at least 60 mol %) of the total components forming the lipid particle. In some embodiments, the one or more ionizable lipids comprise 65 mol % or less (e.g., 60 mol % or less, 55 mol % or less, 50 mol % or less, 45 mol % or less, 40 mol % or less, 35 mol % or less, 30 mol % or less, or 25 mol % or less) of the total components forming the lipid particle
The one or more ionizable lipids are present in the lipid particle in an amount ranging from any of the minimum values described above to any of the maximum values described above. For example, in some embodiments, the one or more ionizable lipids are present in the lipid particle in an amount of from 20 mol % to 65 mol % (e.g., from 30 mol % to 50 mol %) of the total components forming the lipid particle.
As described above, the compositions described herein can comprise one or more neutral lipids.
Examples of neutral lipids include phospholipids such as lecithin, phosphatidylethanolamine, lysolecithin, lysophosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, sphingomyelin, egg sphingomyelin (ESM), cephalin, cardiolipin, phosphatidic acid, cerebrosides, dicetylphosphate, distearoylphosphatidylcholine (DSPC), dioleoylphosphatidylcholine (DOPC), dipalmitoylphosphatidylcholine (DPPC), dioleoylphosphatidylglycerol (DOPG), dipalmitoylphosphatidylglycerol (DPPG), dioleoylphosphatidylethanolamine (DOPE), palmitoyloleoyl-phosphatidylcholine (POPC), palmitoyloleoyl-phosphatidylethanolamine (POPE), palmitoyloleyol-phosphatidylglycerol (POPG), dioleoylphosphatidylethanolamine 4-(N-maleimidomethyl)-cyclohexane-1-carboxylate (DOPE-mal), dipalmitoyl-phosphatidylethanolamine (DPPE), dimyristoyl-phosphatidylethanolamine (DMPE), distearoyl-phosphatidylethanolamine (DSPE), monomethyl-phosphatidylethanolamine, dimethyl-phosphatidylethanolamine, dielaidoyl-phosphatidylethanolamine (DEPE), stearoyloleoyl-phosphatidylethanolamine (SOPE), lysophosphatidylcholine, dilinoleoylphosphatidylcholine, and mixtures thereof. Other diacylphosphatidylcholine and diacylphosphatidylethanolamine phospholipids can also be used. The acyl groups in these lipids are preferably acyl groups derived from fatty acids having Cio-C24 carbon chains, e.g., lauroyl, myristoyl, palmitoyl, stearoyl, or oleoyl.
Additional examples of neutral lipids include sterols such as cholesterol and derivatives thereof. Non-limiting examples of cholesterol derivatives include polar analogues such as 5a-cholestanol, 5a-coprostanol, cholesteryl-(2′-hydroxy)-ethyl ether, cholesteryl-(4′-hydroxy)-butyl ether, and 6-ketocholestanol; non-polar analogues such as 5a-cholestane, cholestenone, 5a-cholestanone, 5a-cholestanone, and cholesteryl decanoate; and mixtures thereof. In preferred embodiments, the cholesterol derivative is a polar analogue such as cholesteryl-(4′-hydroxy)-butyl ether. Other examples of neutral lipids include nonphosphorous containing lipids such as, e.g, stearylamine, dodecylamine, hexadecylamine, acetyl palmitate, glycerol ricinoleate, hexadecyl stearate, isopropyl myristate, amphoteric acrylic polymers, triethanolamine-lauryl sulfate, alkyl-aryl sulfate polyethyloxylated fatty acid amides, dioctadecyldimethyl ammonium bromide, ceramide, and sphingomyelin.
In some embodiments, the one or more neutral lipids can comprise dipalmitoylphosphatidylcholine (DPPC), dioleoylphosphatidylethanolamine (DOPE), palmitoyloleoylphosphatidylcholine (POPC), egg phosphatidylcholine (EPC), distearoylphosphatidylcholine (DSPC), cholesterol, or any combination thereof.
In some embodiments, the one or more neutral lipids comprise at least 35 mol % (e.g., at least 40 mol %, at least 45 mol %, at least 50 mol %, at least 55 mol %, at least 60 mol %, at least 65 mol %, at least 70 mol %, or at least 75 mol %) of the total components forming the lipid particle. In some embodiments, the one or more neutral lipids comprise 80 mol % or less (e.g., 75 mol % or less, 70 mol % or less, 65 mol % or less, 60 mol % or less, 55 mol % or less, 50 mol % or less, 45 mol % or less, or 40 mol % or less) of the total components forming the lipid particle
The one or more neutral lipids are present in the lipid particle in an amount ranging from any of the minimum values described above to any of the maximum values described above. For example, in some embodiments, the one or more neutral lipids are present in the lipid particle in an amount of from 35 mol % to 80 mol % (30 mol % to 50 mol %) of the total components forming the lipid particle.
As described above, the compositions described herein can comprise one or more PEGylated lipids. The one or more PEGylated lipids are useful in that they can reduce or prevent the aggregation of lipid particles.
PEG is a linear, water-soluble polymer of ethylene PEG repeating units with two terminal hydroxyl groups. PEGs are classified by their molecular weights; and include the following: monomethoxypolyethylene glycol (MePEG-OH), monomethoxypolyethylene glycol-succinate (MePEG-S), monomethoxypolyethylene glycol-succinimidyl succinate (MePEG-S-NHS), monomethoxypolyethylene glycol-amine (MePEG-NEh), monomethoxypolyethylene glycol-tresylate (MePEG-TRES), monomethoxypolyethylene glycol-imidazolyl-carbonyl (MePEG-IM), as well as such compounds containing a terminal hydroxyl group instead of a terminal methoxy group (e.g., HO-PEG-S, HO-PEG-S-NHS, HO-PEG-NH2).
Examples of PEG-lipids include, but are not limited to, PEG coupled to dialkyloxypropyls (PEG-DAA), PEG coupled to diacylglycerol (PEG-DAG), PEG coupled to phospholipids such as phosphatidylethanolamine (PEG-PE), PEG conjugated to glycerides forming a glycol, e.g., 1,2-dimyristoyl-sn-glycerol, methoxy-PEG glycol (PEG-DMG), PEG conjugated to ceramides, PEG conjugated to cholesterol, or a derivative thereof, and mixtures thereof. In some examples, the one or more PEGylated lipids can comprise, for example, a PEG-ditetradecylacetamide, a PEG-myristoyl diglyceride, a PEG-diacylglycerol, a PEG dialkyloxypropyl, a PEG-phospholipid, a PEG-ceramide, or any combinations thereof.
The PEG moiety of the PEG-lipid conjugates described herein may comprise an average molecular weight ranging from 550 Daltons to 10,000 Daltons. In certain instances, the PEG moiety has an average molecular weight of from 750 Daltons to 5,000 Daltons (e.g, from 1,000 Daltons to 5,000 Daltons, from 1,500 Daltons to 3,000 Daltons, from 750 Daltons to 3,000 Daltons, from 750 Daltons to 2,000 Daltons). In some embodiments, the PEG moiety has an average molecular weight of 2,000 Daltons or 750 Daltons.
In certain instances, the PEG can be optionally substituted by an alkyl, alkoxy, acyl, or aryl group. The PEG can be conjugated directly to the lipid or may be linked to the lipid via a linker moiety. Any linker moiety suitable for coupling the PEG to a lipid can be used including, e.g., non-ester-containing linker moieties and ester-containing linker moieties. In one embodiment, the linker moiety is a non-ester-containing linker moiety. Suitable non-ester-containing linker moieties include, but are not limited to, amido (—C(O)NH—), amino (—NR—), carbonyl (—C(O)—), carbamate (—NHC(O)O—), urea (—NHC(O)NH—), disulphide (—S—S—), ether (—O—), succinyl (—(O)CCH2CH2C(O)—), succinamidyl (—NHC(O)CH2CH2C(O)NH—), ether, disulphide, as well as combinations thereof (such as a linker containing both a carbamate linker moiety and an amido linker moiety). In some embodiments, a carbamate linker is used to couple the PEG to the lipid. In other embodiments, an ester-containing linker moiety can be used to couple the PEG to the lipid. Suitable ester-containing linker moieties include, e.g., carbonate (—OC(O)O—), succinoyl, phosphate esters (—O—(O)POH—O—), sulfonate esters, and combinations thereof.
The term “diacylglycerol” or “DAG” includes a compound having 2 fatty acyl chains, R1 and R2, both of which have independently between 2 and 30 carbons bonded to the 1- and 2-position of glycerol by ester linkages. The acyl groups can be saturated or have varying degrees of unsaturation. Suitable acyl groups include, but are not limited to, lauroyl (C12), myristoyl (Ci4), palmitoyl (Ci6), stearoyl (Cis), and icosoyl (C20). In preferred embodiments, R1 and R2 are the same, i.e., R1 and R2 are both myristoyl (i.e., dimyristoyl), R1 and R2 are both stearoyl (i.e., distearoyl).
The term “dialkyloxyalkyl” or “DAA” includes a compound having 2 alkyl chains, R and R′, both of which have independently between 2 and 30 carbons. The alkyl groups can be saturated or have varying degrees of unsaturation.
Examples of PEG-DAA conjugates include PEG-didecyloxypropyl (C10), a PEG-dilauryloxypropyl (C12), a PEG-dimyristyloxypropyl (C14), a PEG-dipalmityloxypropyl (C16), and PEG-distearyloxypropyl (C18). In some of these embodiments, the PEG can have an average molecular weight of 750 or 2,000 Daltons. In certain embodiments, the terminal hydroxyl group of the PEG can be substituted with a methyl group.
In addition to the foregoing, other hydrophilic polymers can be used in place of PEG. Examples of suitable polymers that can be used in place of PEG include, but are not limited to, polyvinylpyrrolidone, polymethyloxazoline, polyethyloxazoline, polyhydroxypropyl methacrylamide, polymethacrylamide and polydimethylacrylamide, polylactic acid, polyglycolic acid, and derivatized celluloses such as hydroxymethylcellulose or hydroxyethylcellulose.
In some embodiments, the one or more PEGylated lipids comprise greater than 0 mol % (e.g., at least 0.5 mol %, at least 1 mol %, at least 1.5 mol %, at least 2 mol %, at least 2.5 mol %, at least 3 mol %, at least 3.5 mol %, at least 4 mol %, or at least 4.5 mol %) of the total components forming the lipid particle. In some embodiments, the one or more PEGylated lipids comprise 5 mol % or less (e.g., 4.5 mol % or less, 4 mol % or less, 3.5 mol % or less, 3 mol % or less, 2.5 mol % or less, 2 mol % or less, 1.5 mol % or less, 1 mol % or less, or 0.5 mol % or less) of the total components forming the lipid particle
The one or more PEGylated lipids are present in the lipid particle in an amount ranging from any of the minimum values described above to any of the maximum values described above. For example, in some embodiments, the one or more PEGylated lipids are present in the lipid particle in an amount of from greater than 0 mol % to 5 mol % of the total components forming the lipid particle.
The compositions described herein can comprise one or more fusogenic oils.
In some embodiments, the fusogenic oil can comprise a C12-C40 hydrocarbon (e.g., a C12 hydrocarbon, a C13 hydrocarbon, a C14 hydrocarbon, a C15 hydrocarbon, a C16 hydrocarbon, a C17 hydrocarbon, a C18 hydrocarbon, a C19 hydrocarbon, a C20 hydrocarbon, a C21 hydrocarbon, a C22 hydrocarbon, a C23 hydrocarbon, a C24 hydrocarbon, a C25 hydrocarbon, a C26 hydrocarbon, a C27 hydrocarbon, a C28 hydrocarbon, a C29 hydrocarbon, a C30 hydrocarbon, a C31 hydrocarbon, a C32 hydrocarbon, a C33 hydrocarbon, a C34 hydrocarbon, a C35 hydrocarbon, a C36 hydrocarbon, a C37 hydrocarbon, a C38 hydrocarbon, a C39 hydrocarbon, or a C40 hydrocarbon). In some cases, the C12-C40 hydrocarbon can comprise an alkyl or alkylene chain. Alkylene chains can include one or more double bonds (e.g., from one to five double bonds, or from one to three double bonds). In some embodiments, the C12-C40 hydrocarbon can comprise an alkylene chain, optionally comprising a least one cis-double bond. In some embodiments, the fusogenic oil can comprise fewer than three rings (e.g., fewer than two rings, or no rings).
In some examples, the fusogenic oil can comprise squalene, squalane, pristane, pristene, farnesene, farnesane, retinol, phytol, a carotene, a tocopherol, a tocotrienol, phytomenadione, menaquinone, where valence permits esters thereof, or a combination thereof. In certain embodiments, the fusogenic oil can comprise squalene.
In some embodiments, the one or more fusogenic oils comprise at least 10 mol % (e.g., at least 15 mol %, at least 20 mol %, at least 25 mol %, at least 30 mol %, or at least 35 mol %) of the total components forming the lipid particle. In some embodiments, the one or more fusogenic oils comprise 40 mol % or less (e.g., 35 mol % or less, 30 mol % or less, 25 mol % or less, 20 mol % or less, or 15 mol % or less) of the total components forming the lipid particle
The one or more fusogenic oils are present in the lipid particle in an amount ranging from any of the minimum values described above to any of the maximum values described above. For example, in some embodiments, the one or more fusogenic oils can be present in the lipid particle in an amount of from 10 mol % to 40 mol % of the total components forming the lipid particle.
In some embodiments, the fusogenic oil and the one or more PEGylated lipids can be present in the lipid particles at a molar ratio of at least 5:1 (e.g., at least 10:1, or at least 15:1). In some embodiments, the fusogenic oil and the one or more PEGylated lipids can be present in the lipid particles at a molar ratio of 20:1 or less (e.g., 15:1 or less, or 10:1 or less).
The fusogenic oil and the one or more PEGylated lipids can be present in the lipid particles at a molar ratio ranging from any of the minimum values described above to any of the maximum values described above. For example, in some embodiments, the fusogenic oil and the one or more PEGylated lipids can be present in the lipid particles at a molar ratio of from 5:1 to 20:1.
In some embodiments, the fusogenic oil and the one or more ionizable lipids can be present in the lipid particles at a molar ratio of at least 0.25:1 (e.g., at least 0.5:1, or at least 0.75:1). In some embodiments, the fusogenic oil and the one or more ionizable lipids can be present in the lipid particles at a molar ratio of 1:1 or less (e.g., 0.75:1 or less, or 0.5:1 or less).
The fusogenic oil and the one or more ionizable lipids can be present in the lipid particles at a molar ratio ranging from any of the minimum values described above to any of the maximum values described above. For example, in some embodiments, the fusogenic oil and the one or more ionizable lipids can be present in the lipid particles at a molar ratio of from 0.25:1 to 1:1.
Toll-like receptors (TLRs) are highly conserved transmembrane proteins, consisting of an ectodomain with multiple leucine-rich repeats for pattern recognition, a membrane-spanning α-helix, and a Toll/interleukin-1 receptor (TIR) domain for intracellular signaling. At least 13 mammalian TLRs have been identified, each specifically localizing to either the plasma membrane or endosomal membranes, and each detects a unique complement of PAMPs. Upon PAMP recognition, signal transduction occurs via TLR-specific recruitment of cytosolic TIR adaptor protein combinations. In concert with one or more of the four other adaptors, the TIR adaptor protein MyD88 is required for signaling from most TLRs. The MyD88-independent signaling events observed from TLR3 and TLR4 require TIR adaptor TRIF (also known as TICAM-1), with or without participation of TRAM (Yamamoto et al., 2003). The TLR-specific TIR adaptor signaling cascade activates receptor-specific transcription factors, such as NF-κB, activating protein-1 and interferon regulatory factors (IRFs), leading to expression of inflammatory and antimicrobial genes.
The compositions described herein can comprise one or more TLR agonists. A TLR agonist is any compound or substance that functions to activate a TLR, e.g., to induce a signaling event mediated by a TLR signal transduction pathway. Suitable TLR agonists include TLR1 agonists, TLR2 agonists, TLR3 agonists, TLR4 agonists, TLR5 agonists, TLR6 agonists, TLR7 agonists, TLR8 agonists, and TLR9 agonists.
It is now widely recognized that the generation of protective immunity depends not only on exposure to antigen, but also the context in which the antigen is encountered. Numerous examples exist in which introduction of a novel antigen into a host in an inflammatory context generates immunological tolerance rather than long-term immunity whereas exposure to antigen in the presence of an inflammatory agent (adjuvant) induces immunity. Since it can mean the difference between tolerance and immunity, much effort has gone into discovering the “adjuvants” present within infectious agents that stimulate the molecular pathways involved in creating the appropriate immunogenic context of antigen presentation. It is now known that a good deal of the adjuvant activity is due to interactions of microbial and viral products with different members of the Toll Like Receptors (TLRs) expressed on immune cells. The TLRs are named for their homology to a molecule in the Drosophila, called Toll, which functions in the development thereof and is involved in anti-microbial immunity.
Early work showed the mammalian homologues to Toll and Toll pathway molecules were critical to the ability of cells of the innate immune system to respond to microbial challenges and microbial byproducts. Since the identification of LPS as a TLR4 agonist numerous other TLR agonists have been described such as tri-acyl multitype HPV polypeptides (TLR1), peptidoglycan, lipoteichoic acid and Pam3Cys (TLR2), dsRNA (TLM), flagellin (TLR5), diacyl multitype HPV polypeptides such as Malp-2 (TLR6), imidazoquinolines and single stranded RNA (TLR7,8), bacterial DNA, unmethylated CpG DNA sequences, and even human genomic DNA antibody complexes (TLR9).
The term “agonist,” as used herein, refers to a compound that can combine with a receptor (e.g., a TLR) to produce a cellular activity. An agonist may be a ligand that directly binds to the receptor. Alternatively, an agonist may combine with a receptor indirectly by, for example, (a) forming a complex with another molecule that directly binds to the receptor, or (b) otherwise results in the modification of another compound so that the other compound directly binds to the receptor. An agonist may be referred to as an agonist of a particular TLR (e.g., a TLR7 agonist) or a particular combination of TLRs (e.g., a TLR 7/8 agonist—an agonist of both TLR7 and TLR8).
The terms “CpG-ODN,” “CpG nucleic acid,” “CpG polynucleotide,” and “CpG oligonucleotide,” used interchangeably herein, refer to a polynucleotide that comprises at least one 5′-CG-3′ moiety, and in many embodiments comprises an unmethylated 5′-CG-3′ moiety. In general, a CpG nucleic acid is a single- or double-stranded DNA or RNA polynucleotide having at least six nucleotide bases that may comprise, or consist of, a modified nucleotide or a sequence of modified nucleosides. In some embodiments, the 5′-CG-3′ moiety of the CpG nucleic acid is part of a palindromic nucleotide sequence. In some embodiments, the 5′-CG-3′ moiety of the CpG nucleic acid is part of a non-palindromic nucleotide sequence.
Suitable TLR agonists include isolated, naturally-occurring TLR agonists; and synthetic TLR agonists. TLR agonists isolated from a naturally-occurring source of TLR agonist are generally purified, e.g., the purified TLR agonist is at least about 80% pure, at least about 90% pure, at least about 95% pure, at least about 98% pure, at least about 99% pure, or more than 99% pure. Synthetic TLR agonists are prepared by standard methods, and are generally at least about 80% pure, at least about 90% pure, at least about 95% pure, at least about 98% pure, at least about 99% pure, or more than 99% pure.
Suitable TLR agonists include TLR agonists that are not attached to any other compound. Suitable TLR agonists include TLR agonists that are attached, covalently or non-covalently, to a second compound. In some embodiments, a TLR agonist is attached to another compound directly. In other embodiments, a TLR agonist is attached to another compound through a linker. The compound to which a TLR agonist is attached includes a carrier, a scaffold, an insoluble support, a microparticle, a microsphere, and the like. Carriers include therapeutic polypeptides; polypeptides that provide for increased solubility; polypeptides that increase the half-life of the TLR agonist in a physiological medium (e.g., serum or other bodily fluid); and the like. In some embodiments, a TLR agonist will be conjugated, directly or via a linker, to a second TLR agonist.
In some embodiments, the TLR agonist is a prodrug version of a TLR agonist. Prodrugs are composed of a prodrug portion covalently linked to an active therapeutic agent. Prodrugs are capable of being converted to drugs (active therapeutic agents) in vivo by certain chemical or enzymatic modifications of their structure. Examples of prodrug portions are well-known in the art and can be found in the following references. Biological Approaches to the Controlled Delivery of Drugs, R. L. Juliano, New York Academy of Sciences, (1988): Hydrolysis in Drug and Prodrug Metabolism: Chemistry, Biochemistry, and Enzymology, Bernard Testa, Vch Verlagsgesellschaft Mbh, (2003); and Prodrugs: Topical and Ocular Drug Delivery, Kenneth Sloan, Marcel Dekker; (1992). Examples of prodrug portions are peptides, e.g., peptides that direct the TLR ligand to the site of action, and a peptide which possesses two or more free and uncoupled carboxylic acids at its amino terminus. Other exemplary cleaveable prodrug portions include ester groups, ether groups, acyl groups, alkyl groups, phosphate groups, sulfonate groups, N-oxides, and tert-butoxy carbonyl groups.
In some embodiments, the TLR agonist is a monomeric TLR agonist. In other embodiments, the TLR agonist is multimerized, e.g., the TLR agonist is polymeric. In some embodiments, a multimerized TLR agonist is homofunctional, e.g., is composed of one type of TLR agonist. In other embodiments, the multimerized TLR agonist is a heterofunctional TLR agonist.
In some embodiments, a TLR ligand is a chimeric TLR ligand (also referred to herein as a “heterofunctional” TLR ligand). In some embodiments, a chimeric TLR agonist comprises a TLR9 agonist moiety, and a TLR2 agonist moiety. The following are non-limiting examples of heterofunctional TLR agonists.
In some embodiments, a chimeric TLR ligand has the following formula: (X)n-(Y)m, where X is a TLR1 agonist, TLR2 agonist, TLR3 agonist, TLR4 agonist, TLR5 agonist, TLR6 agonist, TLR7 agonist, TLR8 agonist, and TLR9 agonist, and where Y is a TLR2 agonist, TLR3 agonist, TLR4 agonist, TLR5 agonist, TLR6 agonist, TLR7 agonist, TLR8 agonist, and TLR9 agonist, and n and m are independently an integer from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more including all values and ranges there between. In certain embodiments, X or Y is TLR9 and X or Y is TLR2/6.
TLR2 agonists. TLR2 agonists include isolated, naturally-occurring TLR2 agonists; and synthetic TLR2 agonists. TLR2 agonists isolated from a naturally-occurring source of TLR2 agonist are generally purified, e.g., the purified TLR2 agonist is at least about 80% pure, at least about 90% pure, at least about 95% pure, at least about 98% pure, at least about 99% pure, or more than 99% pure. Synthetic TLR2 agonists are prepared by standard means, and are generally at least about 80% pure, at least about 90% pure, at least about 95% pure, at least about 98% pure, at least about 99% pure, or more than 99% pure. TLR2 agonists include TLR2 agonists that are not attached to any other compound. TLR2 agonists include TLR2 agonists that are attached, covalently or non-covalently, to a second compound. In some embodiments, a TLR2 agonist is attached to another compound directly. In other embodiments, a TLR2 agonist is attached to another compound through a linker.
TLR2 agonists include synthetic triacylated and diacylated lipopeptides. A non-limiting example of a TLR2 ligand is FSL-1 (a synthetic lipoprotein derived from Mycoplasma salivarium 1), Pam3Cys (tripalmitoyl-S-glyceryl cysteine) or S-[2,3-bis(palmitoyloxy)-(2RS)-propyl]-N-palmitoyl-(R)-cysteine, where “Pam3” is “tripalmitoyl-S-glyceryl”) (Aliprantis et al., 1999). Derivatives of Pam3Cys are also suitable TLR2 agonists, where derivatives include, but are not limited to, S-[2,3-bis(palmitoyloxy)-(2-R,S)-propyl]-N-palmitoyl-(R)-Cys-(S)-Ser-(Lys)4-hydroxytrihydrochloride; Pam3Cys-Ser-Ser-Asn-Ala; PaM3Cys-Ser-(Lys)4; Pam3Cys-Ala-Gly; Pam3Cys-Ser-Gly; Pam3Cys-Ser; PaM3Cys-OMe; Pam3Cys-OH; PamCAG, palmitoyl-Cys((RS)-2,3-di(palmitoyloxy)-propyl)-Ala-Gly-OH; and the like. Another non-limiting example of a suitable TLR2 agonist is Pam2CSK4 PaM2CSK4 (dipalmitoyl-S-glyceryl cysteine-serine-(lysine)4; or Pam2Cys-Ser-(Lys)4) is a synthetic diacylated lipopeptide. Synthetic TLRs agonists have been described in the literature. See, e.g., Kellner et al. (1992); Seifer et al. (1990); Lee et al. (2003).
TLR3 Agonists. TLR3 agonists include isolated, naturally-occurring TLR3 agonists; and synthetic TLR3 agonists. TLR3 agonists isolated from a naturally-occurring source of TLR3 agonist are generally purified, e.g., the purified TLR3 agonist is at least about 80% pure, at least about 90% pure, at least about 95% pure, at least about 98% pure, at least about 99% pure, or more than 99% pure. Synthetic TLR3 agonists are prepared by standard methods, and are generally at least about 80% pure, at least about 90% pure, at least about 95% pure, at least about 98% pure, at least about 99% pure, or more than 99% pure.
TLR3 agonists include TLR3 agonists that are not attached to any other compound. TLR3 agonists include TLR3 agonists that are attached, covalently or non-covalently, to a second compound. In some embodiments, a TLR3 agonist is attached to another compound directly. In other embodiments, a TLR3 agonist is attached to another compound through a linker.
TLR3 agonists include naturally-occurring double-stranded RNA (dsRNA); synthetic ds RNA; and synthetic dsRNA analogs; and the like (Alexopoulou et al., 2001). An exemplary, non-limiting example of a synthetic ds RNA analog is poly(I:C).
TLR4 Agonists. Suitable TLR4 agonists include isolated, naturally-occurring TLR4 agonists; and synthetic TLR4 agonists. TLR4 agonists isolated from a naturally-occurring source of TLR4 agonist are generally purified, e.g., the purified TLR4 agonist is at least about 80% pure, at least about 90% pure, at least about 95% pure, at least about 98% pure, at least about 99% pure, or more than 99% pure. Synthetic TLR4 agonists are prepared by standard methods, and are generally at least about 80% pure, at least about 90% pure, at least about 95% pure, at least about 98% pure, at least about 99% pure, or more than 99% pure.
TLR4 agonists include TLR4 agonists that are not attached to any other compound. Suitable TLR4 agonists include TLR4 agonists that are attached, covalently or non-covalently, to a second compound. In some embodiments, a TLR4 agonist is attached to another compound directly. In other embodiments, a TLR4 agonist is attached to another compound through a linker. Suitable compounds to which a TLR4 agonist is attached include a carrier, a scaffold, and the like.
TLR4 agonists include naturally-occurring lipopolysaccharides (LPS), e.g., LPS from a wide variety of Gram negative bacteria; derivatives of naturally-occurring LPS; synthetic LPS; bacteria heat shock protein-60 (Hsp60); mannuronic acid polymers; flavolipins; teichuronic acids; S. pneumoniae pneumolysin; bacterial fimbriae, respiratory syncytial virus coat protein; and the like. TLR4 agonist also include monophosphoryl lipid A-synthetic (MPLAs, Invivogen) and Phosphorylated HexaAcyl Disaccharide (PHAD, Avanti Polar Lipids), as well as other synthetic TLR4 agonists.
TLR 5 Agonists. Suitable TLR5 agonists include isolated, naturally-occurring TLR5 agonists; and synthetic TLR5 agonists. TLR5 agonists isolated from a naturally-occurring source of TLR5 agonist are generally purified, e.g., the purified TLR4 agonist is at least about 80% pure, at least about 90% pure, at least about 95% pure, at least about 98% pure, at least about 99% pure, or more than 99% pure. Synthetic TLR5 agonists are prepared by standard methods, and are generally at least about 80% pure, at least about 90% pure, at least about 95% pure, at least about 98% pure, at least about 99% pure, or more than 99% pure.
TLR5 agonists include TLR5 agonists that are not attached to any other compound. Suitable TLR5 agonists include TLR5 agonists that are attached, covalently or non-covalently, to a second compound. In some embodiments, a TLR5 agonist is attached to another compound directly. In other embodiments, a TLR5 agonist is attached to another compound through a linker. Suitable compounds to which a TLR5 agonist is attached include a carrier, a scaffold, and the like.
TLR5 agonists include a highly conserved 22 amino acid segment of flagellin as well as full length flagellin and other segments thereof.
TLR7 Agonists. Suitable TLR7 agonists include isolated, naturally-occurring TLR7 agonists; and synthetic TLR7 agonists. TLR7 agonists isolated from a naturally-occurring source of TLR7 agonist are generally purified, e.g., the purified TLR7 agonist is at least about 80% pure, at least about 90% pure, at least about 95% pure, at least about 98% pure, at least about 99% pure, or more than 99% pure. Synthetic TLR7 agonists are prepared by standard means, and are generally at least about 80% pure, at least about 90% pure, at least about 95% pure, at least about 98% pure, at least about 99% pure, or more than 99% pure.
TLR7 agonists include TLR7 agonists that are not attached to any other compound. Suitable TLR7 agonists include TLR7 agonists that are attached, covalently or non-covalently, to a second compound. In some embodiments, a TLR7 agonist is attached to another compound directly. In other embodiments, a TLR7 agonist is attached to another compound through a linker.
TLR7 ligands include imidazoquinoline compounds; guanosine analogs; pyrimidinone compounds such as bropirimine and bropirimine analogs; and the like. Imidazoquinoline compounds that function as TLR7 ligands include, but are not limited to, imiquimod, (also known as Aldara, R-837, S-26308), and R-848 (also known as resiquimod, S-28463; having the chemical structure: 4-amino-2-ethoxymethyl-α, α-dimethyl-1H-imidazol[4,5-c]quinoli-ne-1-ethanol). Suitable imidazoquinoline agents include imidazoquinoline amines, imidazopyridine amines, 6,7-fused cycloalkylimidazopyridine amines, and 1,2 bridged imidazoquinoline amines. These compounds have been described in U.S. Pat. Nos. 4,689,338, 4,929,624, 5,238,944, 5,266,575, 5,268,376, 5,346,905, 5,352,784, 5,389,640, 5,395,937, 5,494,916, 5,482,936, 5,525,612, 6,039,969 and 6,110,929. Particular species of imidazoquinoline agents that are suitable for use in a subject method include R-848 (S-28463); 4-amino-2ethoxymethyl-α, α-dimethyl-1H-imidazo[4,5-c]quinoline-s-i-ethanol; and 1-(2-methylpropyl)-1H-imidazo[4,5-c]quinolin-4-amine (R-837 or Imiquimod). Also suitable for use is the compound 4-amino-2-(ethoxymethyl)-α, α-dimethyl-6,7,8,9-tetrahydro-1H-imidazo[4,5-c]quinoline-1-ethanol hydrate (see, e.g., BM-003 in Gorden et al. (2005).
Suitable compounds include those having a 2-aminopyridine fused to a five membered nitrogen-containing heterocyclic ring. Such compounds include, for example, imidazoquinoline amines including but not limited to substituted imidazoquinoline amines such as, for example, amide substituted imidazoquinoline amines, sulfonamide substituted imidazoquinoline amines, urea substituted imidazoquinoline amines, aryl ether substituted imidazoquinoline amines, heterocyclic ether substituted imidazoquinoline amines, amido ether substituted imidazoquinoline amines, sulfonamido ether substituted imidazoquinoline amines, urea substituted imidazoquinoline ethers, thioether substituted imidazoquinoline amines, and 6-, 7-, 8-, or 9-aryl or heteroaryl substituted imidazoquinoline amines; tetrahydroimidazoquinoline amines including but not limited to amide substituted tetrahydroimidazoquinoline amines, sulfonamide substituted tetrahydroimidazoquinoline amines, urea substituted tetrahydroimidazoquinoline amines, aryl ether substituted tetrahydroimidazoquinoline amines, heterocyclic ether substituted tetrahydroimidazoquinoline amines, amido ether substituted tetrahydroimidazoquinoline amines, sulfonamido ether substituted tetrahydroimidazoquinoline amines, urea substituted tetrahydroimidazoquinoline ethers, and thioether substituted tetrahydroimidazoquinoline amines; imidazopyridine amines including but not limited to amide substituted imidazopyridine amines, sulfonamido substituted imidazopyridine amines, urea substituted imidazopyridine amines, aryl ether substituted imidazopyridine amines, heterocyclic ether substituted imidazopyridine amines, amido ether substituted imidazopyridine amines, sulfonamido ether substituted imidazopyridine amines, urea substituted imidazopyridine ethers, and thioether substituted imidazopyridine amines; 1,2-bridged imidazoquinoline amines; 6,7-fused cycloalkylimidazopyridine amines; imidazonaphthyridine amines; tetrahydroimidazonaphthyridine amines; oxazoloquinoline amines; thiazoloquinoline amines; oxazolopyridine amines; thiazolopyridine amines; oxazolonaphthyridine amines; thiazolonaphthyridine amines; and 1H-imidazo dimers fused to pyridine amines, quinoline amines, tetrahydroquinoline amines, naphthyridine amines, and tetrahydronaphthyridine amines.
Compounds include a substituted imidazoquinoline amine, a tetrahydroimidazoquinoline amine, an imidazopyridine amine, a 1,2-bridged imidazoquinoline amine, a 6,7-fused cycloalkylimidazopyridine amine, an imidazonaphthyridine amine, a tetrahydroimidazonaphthyridine amine, an oxazoloquinoline amine, a thiazoloquinoline amine, an oxazolopyridine amine, a thiazolopyridine amine, an oxazolonaphthyridine amine, and a thiazolonaphthyridine amine.
As used herein, a substituted imidazoquinoline amine refers to an amide substituted imidazoquinoline amine, a sulfonamide substituted imidazoquinoline amine, a urea substituted imidazoquinoline amine, an aryl ether substituted imidazoquinoline amine, a heterocyclic ether substituted imidazoquinoline amine, an amido ether substituted imidazoquinoline amine, a sulfonamido ether substituted imidazoquinoline amine, a urea substituted imidazoquinoline ether, a thioether substituted imidazoquinoline amines, or a 6-, 7-, 8-, or 9-aryl or heteroaryl substituted imidazoquinoline amine.
Guanosine analogs that function as TLR7 ligands include certain C8-substituted and N7,C8-disubstituted guanine ribonucleotides and deoxyribonucleotides, including, but not limited to, Loxoribine (7-allyl-8-oxoguanosine), 7-thia-8-oxo-guanosine (TOG), 7-deazaguanosine, and 7-deazadeoxyguanosine (Lee et al., 2003). Bropirimine (PNU-54461), a 5-halo-6-phenyl-pyrimidinone, and bropirimine analogs are described in the literature and are also suitable for use. See, e.g., Vroegop et al. (1999). Additional examples of suitable C8-substituted guanosines include but are not limited to 8-mercaptoguanosine, 8-bromoguanosine, 8-methylguanosine, 8-oxo-7,8-dihydroguanosine, C8-arylamino-2′-deoxyguanosine, C8-propynyl-guanosine, C8- and N7-substituted guanine ribonucleosides such as 7-allyl-8-oxoguanosine (loxoribine) and 7-methyl-8-oxoguanosine, 8-aminoguanosine, 8-hydroxy-2′-deoxyguanosine, and 8-hydroxyguanosine.
In some embodiments a substituted guanine TLR7 ligand is monomeric. In other embodiments, a substituted guanine TLR7 ligand is multimeric. Thus, in some embodiments, a TLR7 ligand has the formula: (B)q, where B is a substituted guanine TLR7 ligand, and q is 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10. The individual TLR7 ligand monomers in a multimeric TLR7 ligand are linked, covalently or non-covalently, either directly to one another or through a linker. Suitable TLR7 agonists include a TLR7 ligand as described in U.S. Patent Publication 2004/0162309.
In some embodiments, a TLR7 agonist is a selective TLR7 agonist, e.g., the agonist modulates cellular activity through TLR7, but does not modulate cellular activity through TLR8. TLR7-selective agonists include those shown in U.S. Patent Publication 2004/0171086. Such TLR7 selective agonist compounds include, but are not limited to, N1-{4-[4-amino-2-(2-methoxyethyl)-6,7,8,9-tetrahydro-1H-imidazo[4,5-c]quinolin-1-yl]butyl}-4-fluoro-1-benzenesulfonamide, N1-[4-(4-amino-2-(2-methoxyethyl)-1H-imidazo[4,5-c]quinolin-1-yl)butyl]-4-fluoro-1-benzenesulfonamide, N-[4-(4-amino-2-propyl-1H-imidazo[4,5-c]quinolin-1-yl)butyl]methanesulfonamide, N-{3-[4-amino-2-(2-methoxyethyl)-1H-imidazo[4,5-c]quinolin-1-yl]-2,2-dimethylpropyl}benzamide, N-(2-{2-[4-amino-2-(2-methoxyethyl)-1H-imidazo[4,5-c]quinolin-1-yl]ethoxy)ethyl)-N-methylmethanesulfonamide, N-(2-{2-[4-amino-2-(2-methoxyethyl)-6,7,8,9-tetrahydro-1H-imidazo[4,5-c]quinolin-1-yl]ethoxy}ethyl)benzamide, N-[4-(4-amino-2-methyl-1H-imidazo[4,5-c]quinolin-1-yl)butyl]cyclopentanecarboxamide, 1-[4-(1,1-dioxidoisothiazolidin-2-yl)butyl]-2-(2-methoxyethyl)-1H-imidazo[4,5-c]quinolin-4-amine, 2-methyl-1-[5-methylsulfonyl)pentyl-6,7,8,9-tetrahydro-1H-imidazo[4,5-c]quinolin-4-amine, N-(2-[4-amino-2-(ethoxymethyl)-6,7-dimethyl-1H-imidazo[4,5-c]pyridin-1-yl]-1,1-dimethylethyl}-N-cyclohexylurea, N-[2-(4-amino-2-ethyl-1H-imidazo[4,5-c]quinolin-1-yl)-1,1-dimethylethyl]benzamide, N-[3-(4-amino-2-butyl-1H-imidazo[4,5-c]quinolin-1-yl)-2,2-dimethylpropyl]methanesulfonamide, 1-[6-(methanesulfonyl)hexyl]-6,7-dimethyl-2-propyl-1H-imidazo[4,5-c]pyridin-4-amine, 6-(6-amino-2-propyl-1H-imidazo[4,5-c]quinolin-1-yl)-N-methoxy-N-methylhexamide, 1-[2,2-dimethyl-3-(methylsulfonyl)propyl]-2-(ethoxymethyl)-1H-imidazo[4,5-c]quinolin-4-amine, N-[4-(4-amino-2-methyl-1H-imidazo[4,5-c]quinolin-1-yl)butyl]-N-methyl-N-phenylurea, 1-{3-[4-amino-1-(2-methylpropyl)-1H-imidazo[4,5-c]quinolin-8-yl]phenyl}ethanone, 7-(4-amino-2-propyl-1H-imidazo[4,5-c]quinolin-1-yl)-2-methylheptan-2-ol, N-methyl-4-(4-amino-2-ethyl-1H-imidazo[4,5-c]quinolin-1-yl)butane-1-sulfonamide, N-(4-methoxybenzyl)-4-(4-amino-2-ethyl-1H-imidazo[4,5-c]quinolin-1-yl)butane-1-sulfonamide, N-{2-[4-amino-3-(ethoxymethyl)-6,7-dimethyl-1H-imidazo[4,5-c]pyridin-1-yl]-1,1-dimethylethyl}methanesulfonamide, 2-ethoxymethyl-1-(3-methoxypropyl)-7-(5-hydroxymethylpyridin-3-yl)-1H-imidazo[4,5-c]quinolin-4-amine, 1-[(2,2-dimethyl-1,3-dioxolan-4-yl)methyl]-2-(ethoxymethyl)-7-(pyridin-3-yl)-1H-imidazo[4,5-c]quinolin-4-amine, 4-[3-(4-amino-6,7-dimethyl-2-propyl-1H-imithizo[4,5-c]pyridin-1-yl)propane-1-sulfonyl]-benzoic acid ethyl ester, 2-butyl-1-{2-[2-(methylsulfonyl)ethoxy]ethyl}-1H-imidazo[4,5-c]quinolin-4-amine, N-(2-{4-amino-2-ethoxymethyl-7-[6-(methanesulfonylamino)hexyloxy]-1H-imidazo[4,5-c]quinolin-1-yl}-1,1-dimethylethyl)methanesulfonamide, N-(6-{[4-amino-2-ethoxymethyl-1-(2-methanesulfonylamino-2-methylpropyl)-1H-imidazo[4,5-c]quinolin-7-yl]oxy}hexyl)acetamide, 1-[4-(1,1-dioxidoisothiazolidin-2-yl)butyl]-2-ethoxymethyl-7-(pyridin-3-yl)-1H-imidazo[4,5-c]quinolin-4-amine, 1-[4-(1,1-dioxidoisothiazolidin-2-yl)butyl]-2-ethoxymethyl-7-(pyridin-4-yl)-1H-imidazo[4,5-c]quinolin-4-amine, 1-[4-(1,1-dioxidoisothiazolidin-2-yl)butyl]-2-ethoxymethyl-7-phenyl-1H-imidazo[4,5-c]quinolin-4-amine, 2-(ethoxymethyl)-1-{[1-(methylsulfonyl)piperidin-4-yl]methyl}-7-(pyridin-3-yl)-1H-imidazo[4,5-c]quinolin-4-amine, 2-(ethoxymethyl)-1-[(1-isobutyrylpiperidin-4-yl)methyl]-7-(pyridin-3-yl)-1H-imidazo[4,5-c]quinolin-4-amine, 2-(ethoxymethyl)-1-{[1-(morpholic-4-ylcarbonyl)piperidin-4-yl]methyl}-7-(pyridin-3-yl)-1H-imidazo[4,5-c]quinolin-4-amine, Cyclopropanecarboxylic acid [3-(4-amino-2-propyl-1H-imidazo[4,5-c]quinolin-1-yl)propoxy]amide, Isopropylcarbamic acid 4-amino-2-(2-methoxyethyl)-1-propyl-1H-imidazo[4,5-c]quinolin-7-yl ester, Ethyl 4-(4-amino-2-propyl-1H-imidazo[4,5-c]quinolin-1-yl)butyrate, 1-[4-amino-2-ethyl-7-(pyridin-3-yl)-1H-imidazo[4,5-c]quinolin-1-yl]-2-methylpropan-2-ol, 1-(4-amino-2-ethyl-7-[5-{hydroxymethyl)pyridin-3-yl]-1H-imidazo[4,5-c]quinolin-1-yl}-2-methylpropan-2-ol, 1-(3-[4-amino-2-(2-methoxyethyl)-8-(pyridin-3-yl)-1H-imidazo[4,5-c]quinolin-1-yl]propyl]pyrolidin-2-one, N-(2-{4-amino-2-ethoxymethyl-7-[6-(methanesulfonylamino)hexyloxy]-1H-imidazo[4,5-c]quinolin-1-yl}-1,1-dimethylethyl)acetamide, 1-{3-[4-amino-7-(3-hydroxymethylphenyl)-2-(2-methoxyethyl)-1H-imidazo[4,5-c]quinolin-1-yl]propyl}pyrrolidin-2-one, N-(4-[4-amino-2-ethoxymethyl-7-(pyridin-3-yl)-1H-imidazo[4,5-c]quinolin-1-yl]butyl)-N′-propylurea, N-{4-[4-amino-2-ethoxymethyl-7-(pyridin-3-yl)-1H-imidazo[4,5-c]quinolin-1-yl]butyl}butyramide, 5-(4-amino-2-propyl-1H-imidazo[4,5-c]quinolin-1-yl)-4,4-dimethylpentan-2-one, 1-cyclohexylmethyl-2-ethoxymethyl-7-(5-hydroxymethylpyridin-3-yl)-1H-imidazo[4,5-c]quinolin-4-amine, N,N-dimethyl-5-(4-amino-2-ethoxymethyl-1H-imidazo[4,5-c]quinolin-1-yl)pentane-1-sulfonamide, N-{3-[(4-amino-2-ethoxymethyl-1H-imidazo[4,5-c]quinolin-1-yl)amino]propyl}methanesulfonamide, and/or N,N-dimethyl-4-(4-amino-2-ethoxymethyl-1H-imidazo[4,5-c]quinolin-1-yl)butane-1-sulfonamide. Additional suitable TLR7 selective agonists include, but are not limited to, 2-(ethoxymethyl)-1-(2-methylpropyl)-1H-imidazo[4,5-c]quinolin-4-amine (U.S. Pat. No. 5,389,640); 2-methyl-1-[2-(3-pyridin-3-ylpropoxy)ethyl]-1H-imidazo[4,5-c]quinolin-4-amine (WO 02/46193); N-(2-{2-[4-amino-2-(2-methoxyethyl)-1H-imidazo[4,5-c]quinolin-1-yl]ethoxy}ethyl)-N-methylcyclohexanecarboxamide (U.S. Patent Publication 2004/0171086); 1-[2-(benzyloxy)ethyl]-2-methyl-1H-imidazo[4,5-c]quinolin-4-amine (WO 02/46189); N-{8-[4-amino-2-(2-methyoxyethyl)-1H-imidazo[4,5-c]quinolin-1-yl]octyl}-N-phenylurea (U.S. Patent Publication 2004/0171086 (IRMS)); 2-butyl-1-[5-(methylsulfonyl)pentyl]-1H-imidazo[4,5-c]quinolin-4-amine (WO 02/46192); N-{3-[4-amino-2-(2-methoxyethyl)-1H-imidazo[4,5-c]quinolin-1-yl]propyl}-4-methylbenzenesulfonamide (U.S. Pat. No. 6,331,539); and N-[4-(4-amino-2-ethyl-1H-imidazo[4,5-c]quinolin-1-yl)butyl]cyclohexanecar-boxamide (U.S. Patent Publication 2004/0171086 (IRM8)). Also suitable for use is the TLR7-selective agonist N-[4-(4-amino-2-ethyl-1H-imidazo[4,5-c]quinolin-1-yl)butyl-]methanesulfon-amide (Gorden et al., 2005).
TLR8 Agonists. Suitable TLR8 agonists include isolated, naturally-occurring TLR8 agonists; and synthetic TLR8 agonists. TLR8 agonists isolated from a naturally-occurring source of TLR8 agonist are generally purified, e.g., the purified TLR8 agonist is at least about 80% pure, at least about 90% pure, at least about 95% pure, at least about 98% pure, at least about 99% pure, or more than 99% pure. Synthetic TLR8 agonists are prepared by standard methods, and are generally at least about 80% pure, at least about 90% pure, at least about 95% pure, at least about 98% pure, at least about 99% pure, or more than 99% pure.
TLR8 agonists include TLR8 agonists that are not attached to any other compound.
TLR8 agonists include TLR8 agonists that are attached, covalently or non-covalently, to a second compound. In some embodiments, a TLR8 agonist is attached to another compound directly. In other embodiments, a TLR8 agonist is attached to another compound through a linker.
TLR8 agonists include, but are not limited to, compounds such as R-848, and derivatives and analogs thereof. Suitable TLR8 agonists include compounds having a 2-aminopyridine fused to a five membered nitrogen-containing heterocyclic ring. Such compounds include, for example, imidazoquinoline amines including but not limited to substituted imidazoquinoline amines such as, for example, amide substituted imidazoquinoline amines, sulfonamide substituted imidazoquinoline amines, urea substituted imidazoquinoline amines, aryl ether substituted imidazoquinoline amines, heterocyclic ether substituted imidazoquinoline amines, amido ether substituted imidazoquinoline amines, sulfonamido ether substituted imidazoquinoline amines, urea substituted imidazoquinoline ethers, thioether substituted imidazoquinoline amines, and 6-, 7-, 8-, or 9-aryl or heteroaryl substituted imidazoquinoline amines; tetrahydroimidazoquinoline amines including but not limited to amide substituted tetrahydroimidazoquinoline amines, sulfonamide substituted tetrahydroimidazoquinoline amines, urea substituted tetrahydroimidazoquinoline amines, aryl ether substituted tetrahydroimidazoquinoline amines, heterocyclic ether substituted tetrahydroimidazoquinoline amines, amido ether substituted tetrahydroimidazoquinoline amines, sulfonamido ether substituted tetrahydroimidazoquinoline amines, urea substituted tetrahydroimidazoquinoline ethers, and thioether substituted tetrahydroimidazoquinoline amines; imidazopyridine amines including but not limited to amide substituted imidazopyridine amines, sulfonamide substituted imidazopyridine amines, urea substituted imidazopyridine amines, aryl ether substituted imidazopyridine amines, heterocyclic ether substituted imidazopyridine amines, amido ether substituted imidazopyridine amines, sulfonamido ether substituted imidazopyridine amines, urea substituted imidazopyridine ethers, and thioether substituted imidazopyridine amines; 1,2-bridged imidazoquinoline amines; 6,7-fused cycloalkylimidazopyridine amines; imidazonaphthyridine amines; tetrahydroimidazonaphthyridine amines; oxazoloquinoline amines; thiazoloquinoline amines; oxazolopyridine amines; thiazolopyridine amines; oxazolonaphthyridine amines; thiazolonaphthyridine amines; and 1H-imidazo dimers fused to pyridine amines, quinoline amines, tetrahydroquinoline amines, naphthyridine amines, or tetrahydronaphthyridine amines.
In one particular embodiment, the TLR8 agonist is an amide substituted imidazoquinoline amine. In an alternative embodiment, the TLR8 agonist is a sulfonamide substituted imidazoquinoline amine. In another alternative embodiment, the TLR8 agonist is a urea substituted imidazoquinoline amine. In another alternative embodiment, the TLR8 agonist is an aryl ether substituted imidazoquinoline amine. In another alternative embodiment, the TLR8 agonist is a heterocyclic ether substituted imidazoquinoline amine. In another alternative embodiment, the TLR8 agonist is an amido ether substituted imidazoquinoline amine. In another alternative embodiment, the TLR8 agonist is a sulfonamido ether substituted imidazoquinoline amine. In another alternative embodiment, the TLR8 agonist is a urea substituted imidazoquinoline ether. In another alternative embodiment, the TLR8 agonist is a thioether substituted imidazoquinoline amine. In another alternative embodiment, the TLR8 agonist is a 6-, 7-, 8-, or 9-aryl or heteroaryl substituted imidazoquinoline amine.
In another alternative embodiment, the TLR8 agonist is an amide substituted tetrahydroimidazoquinoline amine. In another alternative embodiment, the TLR8 agonist is a sulfonamide substituted tetrahydroimidazoquinoline amine. In another alternative embodiment, the TLR8 agonist is a urea substituted tetrahydroimidazoquinoline amine. In another alternative embodiment, the TLR8 agonist is an aryl ether substituted tetrahydroimidazoquinoline amine. In another alternative embodiment, the TLR8 agonist is a heterocyclic ether substituted tetrahydroimidazoquinoline amine. In another alternative embodiment, the TLR8 agonist is an amido ether substituted tetrahydroimidazoquinoline amine. In another alternative embodiment, the TLR8 agonist is a sulfonamido ether substituted tetrahydroimidazoquinoline amine. In another alternative embodiment, the TLR8 agonist is a urea substituted tetrahydroimidazoquinoline ether. In another alternative embodiment, the TLR8 agonist is a thioether substituted tetrahydroimidazoquinoline amine.
In another alternative embodiment, the TLR8 agonist is an amide substituted imidazopyridine amines. In another alternative embodiment, the TLR8 agonist is a sulfonamide substituted imidazopyridine amine. In another alternative embodiment, the TLR8 agonist is a urea substituted imidazopyridine amine. In another alternative embodiment, the TLR8 agonist is an aryl ether substituted imidazopyridine amine. In another alternative embodiment, the TLR8 agonist is a heterocyclic ether substituted imidazopyridine amine. In another alternative embodiment, the TLR8 agonist is an amido ether substituted imidazopyridine amine. In another alternative embodiment, the TLR8 agonist is a sulfonamido ether substituted imidazopyridine amine. In another alternative embodiment, the TLR8 agonist is a urea substituted imidazopyridine ether. In another alternative embodiment, the TLR8 agonist is a thioether substituted imidazopyridine amine.
In another alternative embodiment, the TLR8 agonist is a 1,2-bridged imidazoquinoline amine. In another alternative embodiment, the TLR8 agonist is a 6,7-fused cycloalkylimidazopyridine amine.
In another alternative embodiment, the TLR8 agonist is an imidazonaphthyridine amine. In another alternative embodiment, the TLR8 agonist is a tetrahydroimidazonaphthyridine amine. In another alternative embodiment, the TLR8 agonist is an oxazoloquinoline amine. In another alternative embodiment, the TLR8 agonist is a thiazoloquinoline amine. In another alternative embodiment, the TLR8 agonist is an oxazolopyridine amine. In another alternative embodiment, the TLR8 agonist is a thiazolopyridine amine. In another alternative embodiment, the TLR8 agonist is an oxazolonaphthyridine amine. In another alternative embodiment, the TLR8 agonist is a thiazolonaphthyridine amine.
In yet another alternative embodiment, the TLR8 agonist is a 1H-imidazo dimer fused to a pyridine amine, quinoline amine, tetrahydroquinoline amine, naphthyridine amine, or a tetrahydronaphthyridine amine.
In some embodiments, the TLR8 agonist is a selective TLR8 agonist, e.g., the agonist modulates cellular activity through TLR8, but does not modulate cellular activity through TLR7. TLR8-selective agonists include those in U.S. Patent Publication 2004/0171086. Such TLR8 selective agonist compounds include, but are not limited to, the compounds shown in U.S. Patent Publication No. 2004/0171086 that include N-{4-[4-amino-2-(2-methoxyethyl)-1H-imidazo[4,5-c]quinolin-1-yl]butyl}quinolin-3-carboxamide, N-{4-[4-amino-2-(2-methoxyethyl)-1H-imidazo[4,5-c]quinolin-1-yl]butyl}quinoxoline-2-carboxamide, and N-[4-(4-amino-2-propyl-1H-imidazo[4,5-c]quinolin-1-yl)butyl]morpholine-4-carboxamide.
Other suitable TLR8-selective agonists include, but are not limited to, 2-propylthiazolo[4,5-c]quinolin-4-amine (U.S. Pat. No. 6,110,929); N1-[2-(4-amino-2-butyl-1H-imidazo[4,5-c][1,5]naphthridin-1-yl)ethyl]-2-amino-4-methylpentanamide (U.S. Pat. No. 6,194,425); N′-[4-(4-amino-1H-imidazo[4,5-c]quinolin-1-yl)butyl]-2-phenoxy-benzamide (U.S. Pat. No. 6,451,810); N′-[2-(4-amino-2-butyl-1H-imidazo[4,5-c]quinolin-1-yl)ethyl]-1-propa-nesulfonamide (U.S. Pat. No. 6,331,539); N-{2-[2-(4-amino-2-ethyl-1H-imidazo[4,5-c]quinolin-1-yl)ethyoxy]ethyl}-N′-phenylurea (U.S. Patent Publication 2004/0171086); 1-{4-[3,5-dichlorophenyl)thio]butyl}-2-ethyl-1H-imidazo[4,5-c]quinolin-4-amine (U.S. Patent Publication 2004/0171086); N-{2-[4-amino-2-(ethoxymethyl)-1H-imidazo[4,5-c]quinolin-1-yl]ethyl}-N′-(3-cyanophenyl)urea (WO 00/76518 and U.S. Patent Publication No. 2004/0171086); and 4-amino-α,α-dimethyl-2-methoxyethyl-1H-imidazo[4,5-c]quinoli-ne-1-ethanol (U.S. Pat. No. 5,389,640). Included for use as TLR8-selective agonists are the compounds in U.S. Patent Publication No. 2004/0171086. Also suitable for use is the compound 2-propylthiazolo-4,5-c]quinolin-4-amine (Gorden et al., 2005 supra).
TLR9 Agonists. Suitable TLR9 agonists include isolated, naturally-occurring TLR9 agonists; and synthetic TLR9 agonists. TLR9 agonists isolated from a naturally-occurring source of TLR9 agonist are generally purified, e.g., the purified TLR9 agonist is at least about 80% pure, at least about 90% pure, at least about 95% pure, at least about 98% pure, at least about 99% pure, or more than 99% pure. Synthetic TLR9 agonists are prepared by standard methods, and are generally at least about 80% pure, at least about 90% pure, at least about 95% pure, at least about 98% pure, at least about 99% pure, or more than 99% pure.
TLR9 agonists include TLR9 agonists that are not attached to any other compound.
TLR9 agonists include TLR9 agonists that are attached, covalently or non-covalently, to a second compound. In some embodiments, a TLR9 agonist is attached to another compound directly. In other embodiments, a TLR9 agonist is attached to another compound through a linker.
Examples of TLR9 agonists (also referred to herein as “TLR9 ligands”) include nucleic acids comprising the sequence 5′-CG-3′ (a “CpG nucleic acid”), in certain aspects C is unmethylated. The terms “polynucleotide,” and “nucleic acid,” as used interchangeably herein in the context of TLR9 ligand molecules, refer to a polynucleotide of any length, and encompasses, inter alia, single- and double-stranded oligonucleotides (including deoxyribonucleotides, ribonucleotides, or both), modified oligonucleotides, and oligonucleosides, alone or as part of a larger nucleic acid construct, or as part of a conjugate with a non-nucleic acid molecule such as a polypeptide. Thus, a TLR9 ligand may be, for example, single-stranded DNA (ssDNA), double-stranded DNA (dsDNA), single-stranded RNA (ssRNA) or double-stranded RNA (dsRNA). TLR9 ligands also encompasses crude, detoxified bacterial (e.g., mycobacterial) RNA or DNA, as well as enriched plasmids enriched for a TLR9 ligand. In some embodiments, a “TLR9 ligand-enriched plasmid” refers to a linear or circular plasmid that comprises or is engineered to comprise a greater number of CpG motifs than normally found in mammalian DNA.
Examples of non-limiting TLR9 ligand-enriched plasmids are described in Roman et al. (1997). Modifications of oligonucleotides include, but are not limited to, modifications of the 3′OH or 5′OH group, modifications of the nucleotide base, modifications of the sugar component, and modifications of the phosphate group.
A TLR9 ligand may comprise at least one nucleoside comprising an L-sugar. The L-sugar may be deoxyribose, ribose, pentose, deoxypentose, hexose, deoxyhexose, glucose, galactose, arabinose, xylose, lyxose, or a sugar “analog” cyclopentyl group. The L-sugar may be in pyranosyl or furanosyl form.
TLR9 ligands generally do not provide for, nor is there any requirement that they provide for, expression of any amino acid sequence encoded by the polynucleotide, and thus the sequence of a TLR9 ligand may be, and generally is, non-coding. TLR9 ligands may comprise a linear double or single-stranded molecule, a circular molecule, or can comprise both linear and circular segments. TLR9 ligands may be single-stranded, or may be completely or partially double-stranded.
In some embodiments, a TLR9 ligand for use in a subject method is an oligonucleotide, e.g., consists of a sequence of from about 5 nucleotides to about 200 nucleotides, from about 10 nucleotides to about 100 nucleotides, from about 12 nucleotides to about 50 nucleotides, from about 15 nucleotides to about 25 nucleotides, from 20 nucleotides to about 30 nucleotides, from about 5 nucleotides to about 15 nucleotides, from about 5 nucleotides to about 10 nucleotides, or from about 5 nucleotides to about 7 nucleotides in length. In some embodiments, a TLR9 ligand that is less than about 15 nucleotides, less than about 12 nucleotides, less than about 10 nucleotides, or less than about 8 nucleotides in length is associated with a larger molecule.
In some embodiments, a TLR9 ligand does not provide for expression of a peptide or polypeptide in a eukaryotic cell, e.g., introduction of a TLR9 ligand into a eukaryotic cell does not result in production of a peptide or polypeptide, because the TLR9 ligand does not provide for transcription of an mRNA encoding a peptide or polypeptide. In these embodiments, a TLR9 ligand lacks promoter regions and other control elements necessary for transcription in a eukaryotic cell.
A TLR9 ligand can be isolated from a bacterium, e.g., separated from a bacterial source; produced by synthetic methods (e.g., produced by standard methods for chemical synthesis of polynucleotides); produced by standard recombinant methods, then isolated from a bacterial source: or a combination of the foregoing. In many embodiments, a TLR9 ligand is purified, e.g., is at least about 80%, at least about 90%, at least about 95%, at least about 98%, at least about 99%, or more, e.g., 99.5%, 99.9%, or more, pure. In many embodiments, the TLR9 ligand is chemically synthesized, then purified.
In other embodiments, a TLR9 ligand is part of a larger nucleotide construct (e.g., a plasmid vector, a viral vector, or other such construct). A wide variety of plasmid and viral vector are known in the art, and need not be elaborated upon here. A large number of such vectors have been described in various publications, including, e.g., Current Protocols in Molecular Biology, (1987, and updates).
In general, a TLR9 ligand used in a subject composition comprises at least one unmethylated CpG motif. The relative position of any CpG sequence in a polynucleotide in certain mammalian species (e.g., rodents) is 5′-CG-3′(i.e., the C is in the 5′ position with respect to the G in the 3′ position).
In some embodiments, a TLR9 ligand comprises a central palindromic core sequence comprising at least one CpG sequence, where the central palindromic core sequence contains a phosphodiester backbone, and where the central palindromic core sequence is flanked on one or both sides by phosphorothioate backbone-containing polyguanosine sequences.
In other embodiments, a TLR9 ligand comprises one or more TCG sequences at or near the 5′ end of the nucleic acid; and at least two additional CG dinucleotides. In some of these embodiments, the at least two additional CG dinucleotides are spaced three nucleotides, two nucleotides, or one nucleotide apart. In some of these embodiments, the at least two additional CG dinucleotides are contiguous with one another. In some of these embodiments, the TLR9 ligand comprises (TCG)n, where n=1 to 3, at the 5′ end of the nucleic acid. In other embodiments, the TLR9 ligand comprises (TCG)n, where n=1 to 3, and where the (TCG)n sequence is flanked by one nucleotide, two nucleotides, three nucleotides, four nucleotides, or five nucleotides, on the 5′ end of the (TCG)n sequence.
Exemplary consensus CpG motifs of TLR9 ligands useful in the invention include, but are not necessarily limited to: 5′-Purine-Purine-(C)-(G)-Pyrimidine-Pyrimidine-3′, in which the TLR9 ligand comprises a CpG motif flanked by at least two purine nucleotides (e.g., GG, GA, AG, AA, II, etc.) and at least two pyrimidine nucleotides (CC, TT, CT, TC, UU, etc.); 5′-Purine-TCG-Pyrimidine-Pyrimidine-3′; 5′-TCG-N-N-3′; where N is any base; 5′-Nx(CG)nNy, where N is any base, where x and y are independently any integer from 0 to 200, e.g., 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11-15, 16-20, 21-25, 25-30, 30-50, 50-75, 75-100, 100-150, or 150-200; and n is any integer that is 1 or greater, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or greater. 5′-Nx(TCG)nNy, where N is any base, where x and y are independently any integer from 0 to 200, e.g., 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11-15, 16-20, 21-25, 25-30, 30-50, 50-75, 75-100, 100-150, or 150-200; and n is any integer that is 1 or greater, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or greater. 5′-(TCG)n-3′, where n is any integer that is 1 or greater, e.g., to provide a TCG-based TLR9 ligand (e.g., where n=3, the polynucleotide comprises the sequence 5′-TCGNNTCGNNTCG-3′; SEQ ID NO:3); 5′Nm-(TCG)n-Np-3′, where N is any nucleotide, where m is zero, one, two, or three, where n is any integer that is 1 or greater, and where p is one, two, three, or four; 5′Nm-(TCG)n-Np-3′, where N is any nucleotide, where m is zero to 5, and where n is any integer that is 1 or greater, where p is four or greater, and where the sequence N-N-N-N comprises at least two CG dinucleotides that are either contiguous with each other or are separated by one nucleotide, two nucleotides, or three nucleotides; and 5′-Purine-Purine-CG-Pyrimidine-TCG-3′.
Where a nucleic acid TLR9 ligand comprises a sequence of the formula: 5′-Nm-(TCG)n-Np-3′, where N is any nucleotide, where m is zero to 5, and where n is any integer that is 1 or greater, where p is four or greater, and where the sequence N-N-N-N comprises at least two CG dinucleotides that are either contiguous with each other or are separated by one nucleotide, two nucleotides, or three nucleotides, exemplary TLR9 ligands useful in the invention include, but are not necessarily limited to: (1) a sequence of the formula in which n=2, and Np is NNCGNNCG (SEQ ID NO:4); (2) a sequence of the formula in which n=2, and Np is AACGTTCG (SEQ ID NO:5); (3) a sequence of the formula in which n=2, and Np is TTCGAACG (SEQ ID NO:6); (4) a sequence of the formula in which n=2, and Np is TACGTACG (SEQ ID NO:7); (5) a sequence of the formula in which n=2, and Np is ATCGATCG (SEQ ID NO:8); (6) a sequence of the formula in which n=2, and Np is CGCGCGCG (SEQ ID NO:9); (7) a sequence of the formula in which n=2, and Np is GCCGGCCG (SEQ ID NO:10); (8) a sequence of the formula in which n=2, and Np is CCCGGGCG (SEQ ID NO: 11); (9) a sequence of the formula in which n=2, and Np is GGCGCCCG (SEQ ID NO:12); (10) a sequence of the formula in which n=2, and Np is CCCGTTCG (SEQ ID NO:13); (11) a sequence of the formula in which n=2, and Np is GGCGTTCG (SEQ ID NO:14); (12) a sequence of the formula in which n=2, and Np is TTCGCCCG (SEQ ID NO:15); (13) a sequence of the formula in which n=2, and Np is TTCGGGCG (SEQ ID NO:101); (14) a sequence of the formula in which n=2, and Np is AACGCCCG (SEQ ID NO:16); (15) a sequence of the formula in which n=2, and Np is AACGGGCG (SEQ ID NO:17); (16) a sequence of the formula in which n=2, and Np is CCCGAACG (SEQ ID NO:18); and (17) a sequence of the formula in which n=2, and Np is GGCGAACG (SEQ ID NO:19); and where, in any of 1-17, m=zero, one, two, or three.
Where a nucleic acid TLR9 ligand comprises a sequence of the formula: 5′Nm-(TCG)n-Np-3′, where N is any nucleotide, where m is zero, one, two, or three, where n is any integer that is 1 or greater, and where p is one, two, three, or four, exemplary TLR9 ligands useful in the invention include, but are not necessarily limited to: (1) a sequence of the formula where m=zero, n=1, and Np is T-T-T; (2) a sequence of the formula where m=zero, n=1, and Np is T-T-T-T; (3) a sequence of the formula where m=zero, n=1, and Np is C-C-C-C; (4) a sequence of the formula where m=zero, n=1, and Np is A-A-A-A; (5) a sequence of the formula where m=zero, n=1, and Np is A-G-A-T; (6) a sequence of the formula where Nm is T, n=1, and Np is T-T-T; (7) a sequence of the formula where Nm is A, n=1, and Np is T-T-T; (8) a sequence of the formula where Nm is C, n=1, and Np is T-T-T; (9) a sequence of the formula where Nm is G, n=1, and Np is T-T-T; (10) a sequence of the formula where Nm is T, n=1, and Np is A-T-T; (11) a sequence of the formula where Nm is A, n=1, and Np is A-T-T; and (12) a sequence of the formula where Nm is C, n=1, and Np is A-T-T.
The core structure of a TLR9 ligand useful in the invention may be flanked upstream and/or downstream by any number or composition of nucleotides or nucleosides. In some embodiments, the core sequence of a TLR9 ligand is at least 6 bases or 8 bases in length, and the complete TLR9 ligand (core sequences plus flanking sequences 5′, 3′ or both) is usually between 6 bases or 8 bases, and up to about 200 bases in length.
DNA-based TLR9 ligands useful in the invention include, but are not necessarily limited to, polynucleotides comprising one or more of the following nucleotide sequences:
Additional TLR9 ligands useful in the invention include, but are not necessarily limited to, polynucleotides comprising one or more of the following nucleotide sequences:
DNA-based TLR9 ligands useful in the invention include, but are not necessarily limited to, polynucleotides comprising the following octameric nucleotide sequences:
A TLR9 ligand useful in carrying out a subject method can comprise one or more of any of the above CpG motifs. For example, a TLR9 ligand useful in the invention can comprise a single instance or multiple instances (e.g., 2, 3, 4, 5 or more) of the same CpG motif. Alternatively, a TLR9 ligand can comprise multiple CpG motifs (e.g., 2, 3, 4, 5 or more) where at least two of the multiple CpG motifs have different consensus sequences, or where all CpG motifs in the TLR9 ligand have different consensus sequences.
A TLR9 ligand useful in the invention may or may not include palindromic regions. If present, a palindrome may extend only to a CpG motif, if present, in the core hexamer or octamer sequence, or may encompass more of the hexamer or octamer sequence as well as flanking nucleotide sequences.
Multimeric TLR9 Ligands. In some embodiments, a TLR9 ligand is multimeric. A multimeric TLR9 ligand comprises two, three, four, five, six, seven, eight, nine, ten, or more individual (monomeric) nucleic acid TLR9 ligands, as described above, linked via non-covalent bonds, linked via covalent bonds, and either linked directly to one another, or linked via one or more spacers. Suitable spacers include nucleic acid and non-nucleic acid molecules, as long as they are biocompatible. In some embodiments, multimeric TLR9 ligand comprises a linear array of monomeric TLR9 ligands. In other embodiments, a multimeric TLR9 ligand is a branched, or dendrimeric, array of monomeric TLR9 ligands.
In some embodiments, a multimeric TLR9 ligand has the general structure (X1)n(X2)n where X is a nucleic acid TLR9 ligand as described above, and having a length of from about 6 nucleotides to about 200 nucleotides, e.g., from about 6 nucleotides to about 8 nucleotides, from about 8 nucleotides to about 10 nucleotides, from about 10 nucleotides to about 12 nucleotides, from about 12 nucleotides to about 15 nucleotides, from about 15 nucleotides to about 20 nucleotides, from about 20 nucleotides to about 25 nucleotides, from about 25 nucleotides to about 30 nucleotides, from about 30 nucleotides to about 40 nucleotides, from about 40 nucleotides to about 50 nucleotides, from about 50 nucleotides to about 60 nucleotides, from about 60 nucleotides to about 70 nucleotides, from about 70 nucleotides to about 80 nucleotides, from about 80 nucleotides to about 90 nucleotides, from about 90 nucleotides to about 100 nucleotides, from about 100 nucleotides to about 125 nucleotides, from about 125 nucleotides to about 150 nucleotides, from about 150 nucleotides to about 175 nucleotides, or from about 175 nucleotides to about 200 nucleotides; and where n is any number from one to about 100, e.g., n=1, 2, 3, 4, 5, 6, 7, 8, 9, 10, from 10 to about 15, from 15 to about 20, from 20 to about 25, from 25 to about 30, from 30 to about 40, from 40 to about 50, from 50 to about 60, from 60 to about 70, from 70 to about 80, from 80 to about 90, or from 90 to about 100. In these embodiments, X and X2 differ in nucleotide sequence from one another by at least one nucleotide, and may differ in nucleotide sequence from one another by two, three, four, five, six, seven, eight, nine, ten, or more bases.
As noted above, in some embodiments, a subject multimeric TLR9 ligand comprises a TLR9 ligand separated from an adjacent TLR9 ligand by a spacer. In some embodiments, a spacer is a non-TLR9 ligand nucleic acid. In other embodiments, a spacer is a non-nucleic acid moiety. Suitable spacers include those described in U.S. Patent Publication 20030225016. A TLR9 ligand is multimerized using any known method.
TLR9 Ligand Modifications. A TLR9 ligand suitable for use in a subject composition can be modified in a variety of ways. For example, a TLR9 ligand can comprise backbone phosphate group modifications (e.g., methylphosphonate, phosphorothioate, phosphoroamidate and phosphorodithioate internucleotide linkages), which modifications can, for example, enhance their stability in vivo, making them particularly useful in therapeutic applications. A particularly useful phosphate group modification is the conversion to the phosphorothioate or phosphorodithioate forms of a nucleic acid TLR9 ligand. Phosphorothioates and phosphorodithioates are more resistant to degradation in vivo than their unmodified oligonucleotide counterparts, increasing the half-lives of the TLR9 ligands and making them more available to the subject being treated.
Other modified TLR9 ligands encompassed by the present invention include TLR9 ligands having modifications at the 5′ end, the 3′ end, or both the 5′ and 3′ ends. For example, the 5′ and/or 3′ end can be covalently or non-covalently associated with a molecule (either nucleic acid, non-nucleic acid, or both) to, for example, increase the bio-availability of the TLR9 ligand, increase the efficiency of uptake where desirable, facilitate delivery to cells of interest, and the like. Molecules for conjugation to a TLR9 ligand include, but are not necessarily limited to, cholesterol, phospholipids, fatty acids, sterols, oligosaccharides, polypeptides (e.g., immunoglobulins), peptides, antigens (e.g., peptides, small molecules, etc.), linear or circular nucleic acid molecules (e.g., a plasmid), insoluble supports, therapeutic polypeptides, and the like. Therapeutic polypeptides that are suitable for attachment to a TLR9 agonist include, but are not limited to, a dendritic cell growth factor (e.g., GM-CSF); a cytokine; an interferon (e.g., an IFN-α, an IFN-β, etc.); a TNF-α antagonist; and the like.
A TLR9 ligand is in some embodiments linked (e.g., conjugated, covalently linked, non-covalently associated with, or adsorbed onto) an insoluble support. An exemplary, non-limiting example of an insoluble support is cationic poly(D,L-lactide-co-glycolide). Additional TLR9 ligand conjugates, and methods for making same, are known in the art and described in, for example, WO 98/16427 and WO 98/55495. Thus, the term TLR9 ligand” includes conjugates comprising a nucleic acid TLR9 ligand.
A polypeptide, e.g., a therapeutic polypeptide, may be conjugated directly or indirectly, e.g., via a linker molecule, to a TLR9 ligand. A wide variety of linker molecules are known in the art and can be used in the conjugates. The linkage from the peptide to the oligonucleotide may be through a peptide reactive side chain, or the N- or C-terminus of the peptide. Linkage from the oligonucleotide to the peptide may be at either the 3′ or 5′ terminus, or internal. A linker may be an organic, inorganic, or semi-organic molecule, and may be a polymer of an organic molecule, an inorganic molecule, or a co-polymer comprising both inorganic and organic molecules.
If present, the linker molecules are generally of sufficient length to permit oligonucleotides and/or polynucleotides and a linked polypeptide to allow some flexible movement between the oligonucleotide and the polypeptide. The linker molecules are generally about 6-50 atoms long. The linker molecules may also be, for example, aryl acetylene, ethylene glycol oligomers containing 2-10 monomer units, diamines, diacids, amino acids, or combinations thereof. Other linker molecules which can bind to oligonucleotides may be used in light of this disclosure.
Human PD-L1 is a Type I membrane protein of 272 amino acids (precursor=290 amino acids) comprising an extracellular portion (from about residues 19 to 238) that includes an IgV domain (from about residues 18 to 130), a transmembrane domain (from about residues 239 to 261 and a short intracellular tail (from about residues 262 to 290). The amino acid and nucleotide sequences of human PD-L1 are shown in
The compositions described herein can include one or more antisense molecules that are capable of reducing expression of PD-L1 in a target cell (e.g., oligonucleotides that hybridize to PD-L1 mRNA).
As used herein “antisense molecule” is meant to refer to an oligomeric molecule, particularly an antisense oligonucleotide for use in modulating the activity or function of nucleic acid molecules encoding a PD-L1 (e.g., the polypeptide of SEQ ID NOs: 1), ultimately modulating the amount of PD-L1 produced in cells (e.g., immune cells, latently HIV-infected cells). This is accomplished by providing oligonucleotide molecules which specifically hybridize with one or more nucleic acids encoding PD-L1.
As used herein, the term “nucleic acid encoding a PD-L1 polypeptide” encompasses DNA encoding said polypeptide, RNA (including pre-mRNA and mRNA) transcribed from such DNA, and also cDNA derived from such RNA (e.g., a nucleic acid comprising the coding sequence of the nucleotide sequence set forth in SEQ ID NO: 2). The specific hybridization of an oligomeric compound with its target nucleic acid interferes with the normal function of the nucleic acid. The overall effect of such interference with target nucleic acid function is modulation of the expression of PD-L1.
“Hybridization” means hydrogen bonding between complementary nucleoside or nucleotide bases. Terms “specifically hybridizable” and “complementary” are the terms which are used to indicate a sufficient degree of complementarity or precise pairing such that stable and specific binding occurs between the oligonucleotide and the DNA or RNA target. It is understood in the art that the sequence of an antisense compound need not be 100% complementary to that of its target nucleic acid to be specifically hybridizable. An antisense compound is specifically hybridizable when binding of the compound to the target DNA or RNA molecule interferes with the normal function of the target DNA or RNA to cause a loss of utility, and there is a sufficient degree of complementarity to avoid non-specific binding of the antisense compound to non-target sequences under conditions in which specific binding is desired, i.e., under physiological conditions in the case of in vivo assays or therapeutic treatment, and in the case of in vitro assays, under conditions in which the assays are performed. Such conditions may comprise, for example, 400 mM NaCl, 40 mM PIPES pH 6.4, 1 mM EDTA, at 50 to 70° C. for 12 to 16 hours, followed by washing. The skilled person will be able to determine the set of conditions most appropriate for a test of complementarity of two sequences in accordance with the ultimate application of the hybridized nucleotides.
The term “oligonucleotide” refers to an oligomer or polymer of ribonucleic acid (RNA) or deoxyribonucleic acid (DNA) or mimetics thereof. This term includes oligonucleotides composed of naturally-occurring nucleobases, sugars and covalent internucleoside (backbone) linkages as well as oligonucleotides having non-naturally-occurring portions which function similarly. Such modified or substituted oligonucleotides are often preferred over native forms because of desirable properties such as, for example, enhanced cellular uptake, enhanced affinity for nucleic acid target and increased stability in the presence of nucleases. Examples of modified nucleotides include a 2′-O-methyl modified nucleotide, a nucleotide comprising a 5′-phosphorothioate group, a terminal nucleotide linked to a cholesteryl derivative, a 2′-deoxy-2′-fluoro modified nucleotide, a 2′-deoxy-modified nucleotide, a locked nucleotide, an abasic nucleotide, a 2′-amino-modified nucleotide, a 2′-alkyl-modified nucleotide, a morpholino nucleotide, a phosphoramidate and a non-natural base comprising nucleotide.
Methods to produce antisense molecules directed against a nucleic acid are well known in the art. The antisense molecules of the invention may be synthesized in vitro or in vivo.
The antisense molecule may be expressed from recombinant viral vectors, such as vectors derived from adenoviruses, adeno-associated viruses, retroviruses, herpesviruses, and the like. Such vectors typically comprise a sequence encoding an antisense molecule of interest (e.g., a dsRNA specific for PD-L1) and a suitable promoter operatively linked to the antisense molecule for expressing the antisense molecule. The vector may also comprise other sequences, such as regulatory sequences, to allow, for example, expression in a specific cell/tissue/organ, or in a particular intracellular environment/compartment. Methods for generating, selecting and using viral vectors are well known in the art.
Examples of antisense oligonucleotides that are capable of reducing expression of PD-L1 in a target cell are well known in the art. Examples include anti-PD-L1 ASOs described, for example, in International Publication No. WO 2017/157899 A1, which is hereby incorporated by reference in its entirety. Antisense molecules (siRNA and shRNA) inhibiting the expression of human PD-L1 are commercially available, for example from Santa Cruz Biotechnology Inc. (Cat. Nos. sc-39699). PD-L1 siRNA are described in Breton et al., J Clin Immunol. 2009 29(5): 637-45. Epub 2009 Jun. 27; Hobo et al., Blood, 2010, 116(22):4501-4511.
These compositions can be prepared as described herein or elsewhere, and can be administered by a variety of routes, depending upon whether local or systemic treatment is desired and upon the area to be treated. Administration may be topical (including transdermal, epidermal, ophthalmic and to mucous membranes including intranasal, vaginal and rectal delivery), pulmonary (e.g., by inhalation or insufflation of powders or aerosols, including by nebulizer; intratracheal or intranasal), oral, or parenteral. Parenteral administration includes intravenous, intraarterial, subcutaneous, intraperitoneal intramuscular or injection or infusion; or intracranial, (e.g., intrathecal or intraventricular, administration). Parenteral administration can be in the form of a single bolus dose, or may be, for example, by a continuous perfusion pump. In some embodiments, the compounds provided herein, or a pharmaceutically acceptable salt thereof, are suitable for parenteral administration. In some embodiments, the compounds provided herein are suitable for intravenous administration. In some embodiments, the compounds provided herein are suitable for oral administration. In some embodiments, the compounds provided herein are suitable for topical administration.
Pharmaceutical compositions and formulations for topical administration may include, but are not limited to, transdermal patches, ointments, lotions, creams, gels, drops, suppositories, sprays, liquids and powders. Conventional pharmaceutical carriers, aqueous, powder or oily bases, thickeners and the like may be necessary or desirable. In some embodiments, the pharmaceutical compositions provided herein are suitable for parenteral administration. In some embodiments, the pharmaceutical compositions provided herein are suitable for intravenous administration. In some embodiments, the pharmaceutical compositions provided herein are suitable for oral administration. In some embodiments, the pharmaceutical compositions provided herein are suitable for topical administration.
The compositions and methods described herein may be used to treat a variety of types of cancer. For example, the cancer can comprise adrenocortical tumors, adrenal cancer, anal cancer, bile duct cancer, bladder cancer, bone cancer, brain cancer, breast cancer, central nervous system cancer, cervical cancer, chest cancer, colon cancer, colorectal cancer, endometrial cancer, epidermoid carcinoma, esophageal cancer, eye cancer, glioblastoma, glioma, gallbladder cancer, gastrointestinal carcinoid tumors, gastrointestinal stromal tumor, gestational trophoblastic disease, head and neck, Hodgkin disease, Kaposi sarcoma, kidney cancer, laryngeal and hypopharyngeal cancer, leukemia, liver cancer (such as hepatocellular carcinoma), lung cancer (including non-small cell, small cell, and lung carcinoid tumors), lymph node cancer, lymphoma, lymphoma of the skin, melanoma, mesothelioma, mouth cancer, multiple myeloma, nasal cavity and paranasal sinus cancer, nasopharyngeal cancer, neuroblastoma, non-Hodgkin lymphoma, oral cavity and oropharyngeal cancer, osteosarcoma, ovarian cancer, pancreatic cancer, penile cancer, pituitary cancer, prostate cancer, pediatric malignancies, rectal cancer, retinoblastoma, rhabdomyosarcoma, salivary gland, sarcoma, skin cancer, small intestine cancer, stomach cancer, testicular cancer, thymus cancer, throat cancer, thyroid cancer, uterine cancer, vaginal cancer, and/or vulvar cancers.
Reference will now be made in detail to the present exemplary embodiments, examples of which are illustrated in the accompanying drawings. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice disclosed herein. The embodiments are further explained in the following examples. These examples do not limit the scope of the claims, but merely serve to clarify certain embodiments. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit being indicated by the following claims.
The invention will be described in greater detail by way of specific examples. The following examples are offered for illustrative purposes, and are not intended to limit the invention in any manner. Those of skill in the art will readily recognize a variety of non-critical parameters which can be changed or modified to yield essentially the same results.
Agonists for toll-like receptors (TLRs) have shown promising activities against cancer. In this example, a squalene-based nanoemulsion was loaded with resiquimod, a TLR7/8 agonist for therapeutic delivery. When combined with SD-101, a CpG-containing TLR9 agonist, strong anti-tumor activity was observed in MC38 murine colon carcinoma model. The treatment induced PD-L1 upregulation in tumors, suggesting a potential therapeutic synergy with immune checkpoint inhibitors.
Toll-like receptors (TLRs) play critical roles in immune responses by recognizing pathogen-associated molecule patterns (PAMP) followed by inducing cytokine production and activating adaptive immunity. TLRs are expressed either on the plasma membrane (TLR1/2/4/5/6/10) or in endosomes (TLR3/7/8/9) in antigen-presenting cells (APCs) such as dendritic cells and macrophages. TLR activation leads to the MyD88/NF-κB pathway induction and naïve T cell repertoires activation in adaptive immune responses[1]. Studies have shown that endosomal TLR agonists worked effectively as adjuvants in cancer vaccines due to their strong immunostimulatory activities [2]. Endosomal TLR agonists have been shown to activate plasmacytoid dendritic cells (pDCs) and cytotoxic T lymphocytes (CTLs), enhancing T cell-mediated immunity. Three agents with TLR agonist activity have been approved by FDA for cancer treatments including bacillus Calmette-Guerin (TLR2&4 agonists mixture), monophosphoryl lipid A (TLR2/4 agonists mixture), and imiquimod (TLR7 agonist)[2]. Overall the clinical efficacy of TLR agonists has been mixed [3-4]. Intra-tumoral injection has been investigated in recent CpG TLR9 agonists. However, this mode of administration is difficult in clinical practice for most solid tumors.
Strong innate and adaptive immune system activation and promising antitumor efficacy can be achieved using TLR7/8 and TLR9 combinations [5-7]. Synergistic cytokine release and antibody productions were observed using a Schistosoma japonicum DNA vaccine, containing a combination of TLR 7/8 and TLR9 agonists [6]. Another study has shown significant tumor suppression and synergistic IFN-7 secretion by TLR7/8/9 combination treatments[5-8]. However, these results on duo-TLR activation lacked an efficient platform for the delivery of TLR agonists.
Resiquimod (R848) is a TLR7/8 agonist that has shown antitumor activity in murine tumor models[9-12]. However, due to its limited solubility, an injectable formulation is needed for the clinical application of R848. Oil-in-water nanoemulsions (NE) are effective delivery systems for hydrophobic drugs[13-16]. NE consists of an oil core stabilized by surfactants, where the oil core could work as an efficient reservoir for poorly water-soluble drugs [17]. In addition, squalene-based NE has been shown as an efficient vaccine adjuvant by adaptive immunity activation[18]. Squalene-based NE vaccine adjuvants MF59 and AddaVax have been administered to more than 100 million people in more than 30 countries, in both seasonal and pandemic influenza vaccines. It is also noticed that the squalene core in NE, which was originally derived from shark liver oil, has been reported to potentiate both immune responses and antitumor efficacy[19].
In this study, we developed a squalene-based NE using 1,2-dioleoyl-s?n-glycero-3-phosphocholine (DOPC) and polysorbate 80 (Tween 80) as surfactants to encapsulate R848 (
Besides R848, we incorporated SD-101 as the other component to boost immunity activation. SD-101 is a second-generation TLR9 agonist containing cytidine-phospho-guanosine (CpG) dinucleotides. This class-C oligonucleotide stimulates TLR9, majorly expressed on pDCs and potentiates both innate and adaptive immune responses[20]. Furthermore, SD-101 has been shown to have promising antitumor efficacy in combination with immune checkpoint inhibitors or radiation therapies in clinical trials[20-22]. Our study demonstrated the synergistic antitumor activity through adaptive immune stimulation by R848-loaded NE and SD-101. The combination treatment of R848-loaded NE and SD-101 also showed upregulation of Pdl1 mRNA level in a mouse model, suggesting a therapeutic strategy based on combining TLR activation and PDL1 targeting.
Materials. Squalene was obtained from Sigma-Aldrich (St. Louis, MO, USA). 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) was purchased from Avanti Polar Lipids (Birmingham, AL). Resiquimod (R848) was purchased from MedChemExpress (Monmouth Junction, NJ), and SD-101 was synthesized by Alpha DNA (Montreal, Quebec, Canada). TNF-α, IL-6, and IL-12p70 mouse uncoated ELISA kits and high-capacity cDNA reverse transcription kit were purchased from Invitrogen (Waltham, MA). SsoAdvanced™ Universal SYBR® Green Supermix was purchased from Bio-Rad Laboratories (Hercules, CA). Real-time PCR pre-designed primers for murine Akt1, Bcl2, Hif1a, Pdl1 (Cd274), Calreticulin, Hmgb1, and Actb were obtained from Sigma-Aldrich (St. Louis, MO). Primers for murine Cd3e, CD4, CD8a, Foxp3 and Ifng were designed and were synthesized by ThermoFisher Scientific (Waltham, MA). Polysorbate 80 (Tween 80) and all other chemicals and buffers otherwise stated were purchased from Fisher Scientific (Hampton, NH).
R848-NE Formulation and Characterization. Squalene-based NE were prepared by hand-rapid injection of oil-lipid mixture into phosphate buffered saline (PBS). Squalene, DOPC, and Tween 80 were prepared at a molar ratio of 1/1/1 in ethanol. R848 was then added to the lipid-ethanol solution, maintaining lipid to R848 ratio at 10:1 (w/w). The final total lipid concentration of the nanoemulsion was 8 mg/mL, and the final R848 concentration was 0.8 mg/mL. R848-loaded NE (R848 NE) with lipid to R848 weight ratio of 20.1, 15:1, 10:1, 5:1, and 2:1 were developed to optimize R848 loading capacity in squalene-based nanoemulsion based on particle sizes and R848 solubility. Particle sizes were measured by dynamic light scattering (DLS) using a NICOMP NANO ZLS Z3000 (Entegris, Billerica, MA). Empty nanoemulsion (empty NE) was generated using similar procedures without adding R848. Empty NE and R848 NE were stored at 4° C. prior to characterization and long-term stability.
Sepharose CL-4B size exclusion chromatography was performed to examine the encapsulation efficiency of R848 within the squalene nanoemulsions. R848 concentrations were determined by UV-Vis spectrometry at 320 nm using a NanoDrop 2000 spectrophotometer [23]. Resiquimod loading efficiency was determined by the formula:
Cell Culture. RAW 264.7 murine macrophage cell line and MC38 murine colorectal carcinoma cell line were kind gifts given by Dr. Peixuan Guo and Dr. Christopher Coss at The Ohio State University College of Pharmacy, respectively. RAW 264.7 and MC38 were grown in DMEM supplemented with 10% FBS and 1× antibiotic-antimycotic and maintained at 37° C. under a humidified atmosphere containing 5% CO2.
In Vitro Macrophage Stimulation Imaging. RAW 264.7 cells were seeded at a density of 1.5×105 cells/well in 24-well plates 24 hours prior to treatments. Cells were treated with empty NE, R848, SD-101, R848 NE, or R848 NE/SD-101 combination for 24 hours. R848 was treated at 50 μM either independently, in nanoemulsion, or in combination with SD-101. SD-101 was treated at 300 nM individually or in combination. The morphological changes of RAW 264.7 cells were visualized under 200× brightfield by a Nikon Eclipse Ti—S microscope (Nikon, Tokyo, Japan) after 24-hour incubation.
In Vitro Cytokine Induction Evaluation by Enzyme-linked Immunosorbent Assay (ELISA). RAW 264.7 cells were seeded at a density of 3×10′ cells/well in 6-well plates 24 hours prior to treatments. Cells were treated with empty NE, R848, SD-101, R848 NE, or R848 NE/SD-101 combination for 24 hours. R848 was treated at 50 μM either individually, in nanoemulsion or in combination. SD-101 was treated at 300 nM either individually or in combination. Supernatant was collected and stored at −80° C. prior to cytokine quantification by ELISA. Supernatants were 6-fold pre-diluted by PBS, and TNF-α, IL-6, and IL-12p70 concentrations were measured by mouse uncoated ELISA kits per manufacturer's protocol.
In Vivo Antitumor Efficacy. MC38 murine colorectal syngeneic model was generated by subcutaneously inoculating C57BL/6N mice (obtained from Charles River Labortories) with 0.5×106 cells per mouse on the right flack. Treatments were initiated once tumors reached approximately ˜100 mm3. Mice (n=5) were intraperitoneally treated with saline, 4 mg/kg R848 NE, 2 mg/kg SD-101, or R848 NE/SD-101 combination (4 mg/kg R848 NE and 2 mg/kg SD-101). All treatment solutions were prepared in PBS. Mice were dosed every 3 days for 4 doses. Tumor growth and body weight were monitored and the tumor volumes were calculated according to the formula:
All animal studies were reviewed and approved by The Ohio State University Institutional Laboratory Animal Care and Use Committee (IACUC). All mice were euthanized on day 10, 6 hours after the fourth dose to peak the serum cytokine concentrations. Whole blood was collected through cardiac puncture. Tumor and spleen tissues were harvested and weighed for comparison. Spleen weights were normalized to individual body weights for comparison between treatment groups. Tissues and sera were stored at −80° C. prior to in vivo cytokine and gene regulation studies. Tumor growth inhibition (% TGI) on day 10 was determined by the formula:
Where T10 stands for average tumor volume of treatment group at day 10, To stands for average tumor volume of treatment group at day 0, C10 stands for average tumor volume of control group at day 10, and Co stands for average tumor volume of control group at day 0. % TGI>50% was considered meaningful.
In Vivo Cytokine Measurement. Mouse sera were collected by placing whole blood at room temperature for 30 minutes followed by 2000× g centrifugation for 20 minutes. Samples were collected and stored at −80° C. prior to cytokine quantification. Murine TNF-α, IL-6, and IL 12p70 cytokine concentrations were determined by ELISA per manufacturer's protocol.
In Vivo Gene Regulation by Real-time qPCR. Tumor and spleen tissues were homogenized in TRI reagent using probe sonication, and total RNA was extracted per manufacturer's protocol. cDNA was prepared using High-Capacity cDNA Reverse Transcription Kit per manufacturer's protocol. Real-time PCR was conducted on a QuantStudio 7 Flex Real-Time PCR System with target genes Akt1, Bc12, and Pdl1 in spleen tissue samples, and Akt1, Bc12, Hif1a, Pdl1, Calreticulin, Hmgb1 in tumor tissue samples. All genes were normalized to Actb as the housekeeping gene. The relative amount of RNA level was calculated and compared according to the 2−ΔΔCt method[24,25].
Statistical Analysis. All studies were done in triplicate. Data are presented as means±standard deviations unless otherwise indicated. Statistical analysis will be conducted using Microsoft Excel. One-way ANOVA will be used to determine variances in means between two or more treatment groups. A p-value of 0.05 was selected as the cutoff for statistical significance.
Particle Characterization. As a TLR7/8 agonist, resiquimod has been demonstrated to have great potency for cancer immunotherapy compared with other imidazoquinoline-analogs[26]. However, the tolerance induction and adverse effects limit its development as a strong candidate for a market drug. Several studies utilized polymer-based nanoparticles such as polylactic acid (PLA) or β-cyclodextrin to carry R848 to overcome these limitations[27-29]. Nonetheless, the disadvantages of polymeric nanoparticles include an toxic degradation for polymer materials and self-aggregation[30]. In our study, we utilized a squalene-based oil-in-water nanoemulsion as a carrier for R848 (
In Vitro Macrophage Stimulation. Morphological changes of macrophages upon activation can be visualized under microscopes, which can further be utilized to study the factors modulating pro-inflammatory (M1) and anti-inflammatory (M2) activation[33,34]. TLR7, 8, and 9 are expressed majorly on pDCs and macrophages[26,35-39], which further polarizing naïve macrophages to M1 activation[40,41]. We utilized RAW 264.7 murine macrophage cells to examine the immune stimulation carried out by R848 NE treatments as well as addition with SD-101 treatment. Our result showed that untreated RAW 264.7 generally exhibited a round form whereas empty NE-treated RAW 264.7 exhibited round form but became forming filopodia (
TNF-α is a pro-inflammatory cytokine which is indispensable for early immune response generation. We showed that all R848 and SD-101 treatments produced significant level of TNF-α inductions compared to the untreated group. Empty NE also induced moderate level of TNF-α due to the immune stimulation property carried out by squalene (
Both TLR7/8 and TLR9 stimulate IL-6 production, which acts as both pro-inflammatory and anti-inflammatory cytokine[44-47]. Here we reported that R848 NE treatment promoted production of IL-6 compared with R848 treatment, whereas empty NE did not show significant IL-6 production (
Lastly, IL-12p70 production biases Th1 activation resulting cellular immune responses[48,49]. There were moderate IL-12p70 production in both R848 NE and SD-101 treatment individually or in combination (
In Vivo Antitumor Efficacy. Research indicated that TLR7 and TLR9 agonists generate the highest immunogenicity compared with other endosomal TLR agonists by intranasal or oral administration[53]. In addition, intratumoral combination treatment of TLR7/8 and TLR9 agonists was also demonstrated to induce the highest tumor-specific immunity compared with each agent alone[5]. However, intraperitoneal administration is easy, quick, and minimally stressful for both animal studies and patients with metastasis-stage cancer in practice. In the present study, we utilized 4 mg/kg R848 and 2 mg/kg SD-101 individually or in combination to show a synergized antitumor efficacy through intraperitoneal administration. The moderate antitumor efficacies by R848 NE and SD-101 individual treatments were observed (
Although individual treatments of R848 NE or SD-101 showed significant tumor growth inhibition (50.72%±16.83% and 65.65%±12.88%), R848 NE/SD-101 combination treatment reached approximately 84.62%±28.05% total tumor growth inhibition at the end of study (Table 1) with the median tumor growth inhibition of 98.05%, suggesting the synergistic antitumor efficacy carried out by R848 NE/SD-101 combination treatment. No significant differences in body weight indicated mice treated with R848 NE and SD-101 individually or in combination had minor systemic toxicity. Among individual mouse treated with R848 NE/SD-101 combination, one mouse was observed with initial tumor size over 200 mm3 which had slightly higher tumor growth rate compared with other individuals within the same group (
Splenomegaly indicates T cell activation and natural killer cell (NK cell) expansion[56]. Besides the significant tumor inhibition in R848 NE/SD-101 combination treatment group, we also observed a remarkable splenomegaly in R848 NE/SD-101 combination treatment group compared with individual R848 NE or SD-101-only treatment group as well as the saline control (
In Vivo Cytokine Production. The presence of TNF-α indicates a strong pro-inflammatory cytokine release which further potentiate the tumor cell apoptosis[57]. In mouse sera, we observed a significant increase of TNF-α level among mice treated with R848 NE/SD-101 combination (
In Vivo Gene Regulation. Antitumor immunity carried out by R848 NE/SD-101 combination can be attributed to cellular-mediated cytotoxicity such as CTLs or NK cells activation in concordance with immunogenic cell death (ICD) processes[58,59]. Cd8a mRNA was significantly upregulated in tumor tissues from mice treated with R848 NE/SD-101 combination along with elevated Calreticulin and Cd3e (
Calreticulin mRNA upregulation (
TLR7/8 and TLR9 activation in cancer cells, lymphocytes, and pDCs are also associated with PD-L1 upregulation, which is an immune checkpoint for tumor immune escape[70-73]. Mice treated with R848 NE/SD-101 combination exhibited the highest level of Pdl1 mRNA in both spleen and tumor tissue compared with mice treated with individual treatments or saline control (
Our study presented a R848-loaded squalene-based nanoemulsion formulation that had better encapsulation efficiency compared with reported liposomal formulations. We also showed that R848 NE is highly stable during long-term storage at 4° C. Elevated TNF-α level in vitro demonstrated the strong immune activation by R848 NE and SD-101 individually. Brightfield images and cytokine levels in vitro and in vivo further illustrated a synergistic immune activation when R848 NE and SD-101 were treated in combination. Ultimately, we demonstrated that R848 NE/SD-101 combination treatment strongly enhanced the antitumor efficacy in vivo by greatly suppressed tumor growth over 80%. Our work indicated that intraperitoneal administration of R848 NE and SD-101 in combination could be a strong approach for CTLs and NK cells-dependent systemic antitumor treatment. Furthermore, the synergized PD-L1 upregulation in vivo by R848 NE/SD-101 combination implied greater antitumor potential while incorporating R848 NE/SD-101 treatment with anti-PD-L1 therapeutics.
Cancer vaccines are designed to trigger a specific and long-lasting immune response against tumor antigens. A well-designed vaccine should trigger dendritic cell (DC) activation by defined tumor antigens and include adjuvants that stimulate the expansion of naïve T cell repertoire into effector T cells. It has been shown that a combination of toll-like receptor (TLR) agonists with tumor-associated antigens (TAAs) triggers DC maturation, cytotoxic T cell (CTL) activation, and tumor regression. However, TLR activation induces PD-L1 expression on monocytes and dendritic cells, and even cancer cells, which protect them from CTL attack. The elevation of PD-L1 on cancer cells or monocytes can lead to CTL exhaustion and dysfunction. Here, we hypothesize that co-delivery of TLR agonists and anti-PD-L1 (LNA ASO/siRNA) leads to a higher level of dendritic cell activation and maturation, which induces potent T cell activation and anti-tumor activities. In addition, by co-delivering TLR agonists with anti-PDL1 ASO, the overall immuno-suppressive environment could be skewed back to immuno-permissive conditions, which is associated with regulatory T cell population reduction and macrophage repolarization. A novel pH-sensitive lipid nanoemulsion formulation, or PSNE, was developed to co-deliver CpG oligonucleotide-based TLR agonists as well as anti-PDL1 LNA ASO in a single particle. The PSNE lipid nanoparticles had particle sizes of ˜85-95 nm, which was ideal for delivery into the tumor microenvironment (TME) through enhanced permeation and retention (EPR) effect. In an MC-38 syngeneic murine tumor model, single agents of either oligonucleotide-based TLR agonist (class-C CpG) or anti-PDL1 LNA ASO in PSNE could lead to ˜45% of tumor growth inhibition (TGI), whereas co-encapsulation of both CpG and ASO into a single particle lead to a higher TGI at ˜73%. Flow cytometry analysis showed that inhibitory regulatory T lymphocytes (Treg) population frequency in the spleen was reduced in single-agent groups and further reduced in the combination group, indicating the reversal of immune-suppressive environment. Furthermore, PD-L1 expression was assessed on splenic macrophages, T lymphocytes as well as overall splenocytes by flow cytometry and RT-qPCR. The results showed that PD-L1 expression was downregulated in macrophages in all treatment groups, but not in splenic T lymphocytes. In addition, PD-L1 mRNA levels were reduced by ˜60% in groups treated with anti-PDL1 ASO, in both single-agent and combination groups, illustrating that the PSNE lipid nanoparticles were taken up by phagocytes and overcame PD-L1 upregulation by TLR activation.
In summary, we demonstrated that co-encapsulation of CpG-oligonucleotide-based TLR agonist and anti-PDL1 ASO in the PSNE formulation enhanced the delivery of both agents to the tumor and the spleen and was more effective in activating the immune system against the tumor.
Squalene was purchased from Sigma-Aldrich (St. Louis, MO). DOPC and DOPE were purchased from Avanti Polar Lipids (Alabaster, AL). DODMA and DMG-PEG2000 were purchased from NOF America (White Plains, NY). Any chemicals or buffers unless otherwise stated were purchased from Fisher Scientific (Hampton, NH).
DOPC, DOPE, Squalene, DODMA and DMG-PEG2000 were dissolved in ethanol as a mixture at a molar ratio of 15:28:10:45:2. Next, the lipid ethanol solution was rapidly injected into an acidic buffer to form empty pH-sensitive nanoemulsions (PSNEs) at a lipid concentration of 8 mg/mL. In the meantime, nucleic acid cargos, including SD-101 and anti-PDL1 locked nucleic acid (LNA) antisense oligonucleotides (ASO), were dissolved in nuclease-free water at 0.4 mg/mL. Empty PSNEs and nucleic acid cargos were warmed up to 60° C. prior to the mixing. Then, the cargo was added dropwise to the empty PSNEs on slow vortex at a weight ratio of 1 to 20 until nucleic acid-encapsulated PSNEs were formed. The products were incubated at 37° C. for 10 minutes and stored at 4° C. before use. The particle sizes and zeta potential (ζ) of nucleic acid-loaded PSNEs were analyzed by dynamic light scattering on a NICOMP Z3000 Nano DLS/ZLS System (Entegris, Billerica, MA).
Animal models. C57BL/6 mice were purchased from Charles River Laboratory. Animals were housed in a temperature-controlled room under a 12 hr light/12 hr dark cycle and fed normal chow diet. All animal studies were reviewed and approved by the Ohio State University Institutional Laboratory Animal Care and Use Committee. Both male and female mice were used for experiments.
MC-38 murine colorectal cancer cell line was a kind gift obtained from Dr. Christopher Coss at The Ohio State University College of Pharmacy. MC-38 syngeneic subcutaneous murine colorectal cancer model was developed by injecting 1 million MC-38 cells suspended in PBS into the right flank of each mouse subcutaneously. Tumor sizes and body weights were monitored daily using a digital caliper and a lab scale, respectively.
The treatments were started when the average tumor sizes reached 80 mm3. Mice were randomized into 6 groups of 5 mice per group. The treatments, including normal saline control, SD-101 oligonucleotides, SD-101 in PSNE, anti-PDL1 LNA in PSNE, SD-101 and anti-PDL1 LNA in PSNE, and Resiquimod and SD-101 in PSNE, were given once every three days with a total of 5 doses. Mice were sacrificed 6 hours after the final dose and organs as well as whole blood samples were collected for further analysis.
Serum samples were obtained from whole blood samples by incubating blood at RT for 30 minutes, followed by 2,000×g centrifugation for 20 minutes. The samples were stored at −80° C. prior to analysis. Cytokine concentrations were measured by uncoated ELISA kits purchased from Invitrogen per manufacturer's protocols.
Single cell splenocyte suspensions were harvested from spleens by the following procedures. Spleens were gently meshed through 70 um nylon meshes (Thermo Scientific) using a sterile 5-mL syringe plunge and washed with cold RPMI medium twice into six-well plates. Crude splenocyte suspensions were then centrifuged at 500×g for 5 minutes at 4° C. to obtain cell pellets. Cell pellets were resuspended in 1×RBC lysis buffer to lyse red blood cells for 5 minutes at RT and 10-fold volume of PBS was added to stop the reaction. After 500× g centrifugation for 5 minutes, the cell pellets were then resuspended in FACS staining buffer to form single cell splenocyte suspensions.
Antibodies were purchased from Biolegend (San Diego, CA), and surface cell staining was done per manufacturer's protocol. Intracellular staining was done by using Biolegend True-Nuclear™ Transcription Factor Buffer Set per manufacture protocol. The stained cells were analyzed on a BD LSRForetessa Flow Cytometer at the Flow Cytometry Shared Resources at The Ohio State University Comprehensive Cancer Center.
Splenocyte messenger RNA for gene expression analysis was extracted from splenocyte suspensions using TRI reagent per manufacturer's protocol. cDNA was prepared using High-Capacity cDNA Reverse Transcription Kit (Invitrogen). Real-time PCR was conducted on a QuantStudio 7 Flex Real-Time PCR System. The relative amount of RNA level was calculated and compared according to the 2-‘C’ method.
PSNEs encapsulating oligonucleotides and small molecules were successfully formulated with high colloidal stability. Particle sizes ˜80-100 nm were obtained for both empty PSNEs and PSNEs loaded with either SD-101 CpG ODNs or anti-PDL1 LNA ASOs. The polydispersity indexes (PdI) were ˜0.15-0.25, indicating narrowly distributed particle sizes were obtained in all samples (
Next, the encapsulations of ODN and small hydrophobic molecule cargos in PSNEs were analyzed by gel retardation assay and size exclusion chromatography, respectively. The gel image showed that ODNs were highly encapsulated in PSNEs, with a small amount of SD-101 adsorbed onto the PSNE surface while Resiquimod was added to the formulation. The percentage encapsulation of Resiquimod in PSNEs was ˜53.8% by calculating the ratios of two peaks on the chromatogram obtained by OD327 using a NanoDrop spectrophotometer (
The combination of SD-101 CpG ODNs and anti-PDL1 LNA ASOs in PSNEs showed a good antitumor effect in MC-38 murine syngeneic colon cancer model with a mean tumor growth inhibition (TGI) ˜73%. Two groups of mice treated with single agent in PSNE (either SD-101 ODNs or anti-PDL1 LNA ASOs) both showed TGIs of ˜46%, while mice treated with PSNE encapsulating SD-101 and Resiquimod had a mean TGI of 57% (
The spleen index (spleen weight presented in the percentage of body weight,
In a flow cytometry analysis (
Surface PD-L1 markers on both lymphocytes and myeloid cells were examined by flow cytometry to investigate the PD-L1 protein expressions on immune cells after treatments (
By doing splenocyte mRNA analysis, we assessed the cytokine secretion profile as well as overall PD-L1 levels after treating with TLR agonists and/or anti-PDL1 LNA. The results demonstrated an excellent activity for LNA in downregulating PD-L1 mRNA among splenocytes (
Based on the cytokine ELISA results (
In conclusion, this study showed that PSNEs were effective delivery vehicles of anti-PD-L1 LNA ASOs for antitumor therapy and was able to co-deliver ASOs with resiquimod. It showed that Anti-PD-L1 acted synergistically with TLR activation, therefore, the combination of anti-PD-L1 oligo (also siRNA) therapy and TLR agonists are highly synergistic. It was further shown that PSNE-delivered resiquimod was very effective, and was synergistic with CpG ODN SD-101, providing a novel approach to delivery TLR combinations for therapeutic purposes. Triple combination of dual TLR agonists and anti-PD-L1 produced the best overall therapeutic response.
Traditional cancer therapies, including surgery, radiation therapy, and chemotherapeutics have been practiced for decades to abolish tumor tissues, but those treatments have significant side effects. To reduce side effects, next-generation medications, including targeted therapy and immunotherapy, came into clinics after the first-approved monoclonal antibody rituximab in 1997. Compared to the targeted therapy targeting cancer cell itself, immunotherapy opens a new battlefield by targeting the immune system. Well-known immunotherapies, including immune checkpoint blockade (ICB), chimeric antigen receptor (CAR) T cell therapy, oncolytic viruses, and cancer vaccines have drawn increasing attention in treating cancer patients.
Cancer vaccines establish a promising strategy to trigger a specific and long-lasting immune response against tumor antigens. A well-designed cancer vaccine should trigger dendritic cell (DC) activation by defined tumor antigens and proper adjuvants, which stimulates the enlargement of naïve T cell repertoire into effector T cells. Many research groups have shown that combining toll-like receptor (TLR) agonists with tumor-associated antigens (TAAs) could initiate DC maturation, cytotoxic T cell (CTL) activation, and tumor shrinkage.
Tumor progression can be described by immunosurveillance with three stages: elimination of cancer cells by the immune system, cancer equilibrium, and tumor escape. The tumor escape evolves in genetic alternations of tumor antigens that avoid immune recognition as well as the tumor-extrinsic mechanisms with active immune suppression. Low expression level of major histocompatibility complex (MHC) class I on cancer cell surface reduces the recognition and eradication of CD8+ T cells. The tumor also produces immunosuppressive cytokines such as transforming growth factor β (TGF-β) or soluble Fas ligand to mediate regulatory T cells (Trgs) response on suppressing antitumor effector T cells. To overcome the immunosuppressive barrier built by TME or reduced-function CTL, immunomodulating agents are introduced to the clinics. Immune checkpoint blockade (ICB) agents can help to resume CTL functions by inhibiting negative regulator signals on the T cell surface. Typical targets are cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) or programmed cell death 1 (PD-1). Blocking the CTLA-4 or the PD-1 with monoclonal antibodies showed enhancement in effector T cell activation and proliferation.
An alternative pathway to upregulate immune system is to activate T cell functions by stimulating dendritic cells. Dendritic cells are the most potent and efficient antigen-presenting cells (APCs) of the innate immune system that can present exogenous antigens to CD4+ T cells and CD8+ T cells through MHC class II and I, respectively. DC cell maturation and activation are initiated through the antigen uptake and recognition by pattern recognition receptors (PRRs) such as toll-like receptors (TLRs). Matured DCs migrate to draining lymph nodes with high expression of MHCs and antigen-presenting ability. In draining lymph nodes, DCs meet with naïve T cells and instigate T cell activation. T cell activation requires three signals: antigen-associated MHC interaction with T cell receptor (TCR), co-stimulatory ligand (CD80, CD86, CD40) recognition and pro-inflammatory cytokines. All those signals facilitate CD4+ naïve T cells to differentiate into Th1 cells and enhance the cytotoxic response of CTLs. Therefore, the basic principle behind DC vaccines entails the incubation of DCs with tumor antigens/stimulator cocktail to produce DC maturation and the boost of T cell activation after injecting into patients. However, the objective response rate (ORRs) to DC vaccines in cancer patients rarely passed 15%.
To enhance the DC maturation, antigen uptake, and T cell activation, TLR agonists are introduced as stand-alone antitumor agents or as adjuvants combined with TAAs. TLR signal transduction cascades induce the production of type-1 interferons and inflammatory modulators, which facilitate the further T lymphocyte activities. Previously published research suggested injecting either free-form CpG ODNs or CpG-ODN nanoparticles with tumor antigens showed potent antitumor response in vivo. Besides CpG ODNs, synthetic TLR3 agonist poly(I:C) was used in several studies to show the facilitated induction of DC maturation and T cell-related antitumor activity.
CpG oligonucleotides are well-known for their TLR9 activation ability with type-1 interferon production, triggering the downstream processes of both innate and adaptive immunity activation. Many studies have been done using different subclasses of CpG ODNs as vaccine adjuvants to stimulate dendritic cell maturation and initiate T-cell (either Th1 or Th2) mediated immunity. In a research study, the researchers indicated that applying CpG ODN 2006 (a class-B CpG ODN) could increase the infiltrated T cells and activated DCs within draining lymph nodes, suggesting CpG ODN 2006 has the ability to stimulate DC activation as a vaccine adjuvant. Also, administering cell lysate together as the antigen source could facilitate not only the DC maturation process but also CTL generation. Besides, they demonstrated that applying CpG ODN 2006/lysate combination could significantly prolong the tumor-burden mice survival, compared to CpG ODN 2006 single treatment, indicating the supporting role of CpG ODNs in the vaccine construct, working as adjuvants.
CpG ODNs are ligands for TLR9, which is primarily expressed in human plasmacytoid dendritic cells specializing in secreting type-1 interferons. However, different subclasses of CpG ODNs have distinct abilities in stimulating type-1 interferon production due to the oligonucleotide structures. Class-A CpG ODNs include poly-G motifs at both 5′ and 3′ ends and a self-complementary palindrome containing one or more CpG motifs. Class-A CpG ODNs are strong IFN-α inducer. On the other hand, class-B CpG ODNs have complete phosphorothioate backbones but without high level structures, giving weak ability to induce IFN-α production but strong ability to stimulate B cell TLR9. It is reported that class-A CpG is more active in supporting natural killer cells (NK cells) and CTL function and granzyme-B content in CTLs, which is mediated mainly by type-1 interferons. Besides, IFN-α is an essential cytokine in activating NK cells and in partial activation and proliferation of memory CD8+ T cells. Interferon-γ (IFN-γ) secreted by activated NK cells also triggers Th1 cell-mediated immunity in combination with IL-12 secreted by activated DCs. As a result, applying class-A CpG ODNs instead of class-B CpG ODNs should initiate substantial innate and adaptive immunity as well as pro-inflammatory Th1 and CTL response.
In this example, we develop a series of highly fusogenic nanoemulsion-based lipid nanoparticle constructs to co-encapsulate negative-charged ODNs with different immune system booster factors, such as anti-PDL1 antisense oligonucleotides or tumor antigen peptides, at high loading amount as well as using a TLR agonist cocktail (CpG ODNs, poly(I:C), or Resiquimod) as the vaccine adjuvant to react on different DC subpopulations for the antigen-presenting enhancement. We also evaluated a TLR agonist combination to demonstrate the synergism over single agonist. The co-encapsulated TLR agonists give higher pro-inflammatory cytokine secretion and more intensive T cell activation. These strategies have the potential to overcome the current barrier of low stimulating effect on the immune system in vivo due to the delivery deficiency to APCs.
Materials. Squalene, polyinosinic:polycytidylic acid (polyI:C), monophosphoryl lipid A (MPLA) and D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) were purchased from Sigma-Aldrich (St. Louis, MO, USA). DSPC, DOPC, DOPE, and cholesterol were purchased from Avanti Polar Lipids (Alabaster, AL, USA). DODMA and DMG-mPEG2000 were purchased from NOF America (White Plains, NY, USA). DLin-MC3-DMA was purchased from DC Chemical (Shanghai, China). Resiquimod (R848), imiquimod (R837), and amphotericin B were purchased from MedChemExpress (Monmouth Junction, NJ, USA). Tocopherol succinate (TS) and didodecyldimethylammonium bromide (DDAB) were purchased from TCI America (Tokyo, JP). SD-101 CpG oligodeoxynucleotides (SD-101), CpG 2216 oligodeoxynucleotides, and 2′-OMethyl-modified murine anti-PDL1 antisense oligodeoxynucleotide gapmer (2′-OMe anti-PDL1 ASO) were synthesized by Alpha DNA (Montreal, CA). Locked nucleic acid-modified murine anti-PDL1 antisense oligodeoxynucleotide gapmer (anti-PDL1 LNA ASO) was synthesized by Integrated DNA Technologies (IDT, Coralville, IA, USA). Any chemicals or buffers otherwise stated were purchased from Fisher Scientific (Hampton, NH, USA).
Preparation of Cationic Nanoemulsion Incorporating TLR Agonists. For CpG 2216 and poly(I:C) cationic nanoemulsion, squalene, DDAB and TPGS were mixed into a lipid ethanol mixture at a molar ratio of 50:35:15. Next, the lipid-ethanol solution was rapidly injected into 20 mM HEPES buffer at pH 7.4, forming empty cationic nanoemulsions at a lipid concentration of 25.0 mg/mL. To produce oligonucleotide-encapsulated cationic nanoemlusions, CpG 2216 or poly(I:C) oligonucleotide solution (in DEPC water) at 2.0 mg/mL was added dropwise to the empty lipid nanoemulsions on slow vortex at a weight ratio of 1 to 12.5 until nucleic acid-encapsulated cationic nanoemulsions were formed. For imiquimod nanoemulsions, squalene, TS and TPGS were mixed into a lipid-ethanol mixture at a molar ratio of 75:15:10. Imiquimod (in DMSO) was added to the lipid-ethanol mixture to form homogeneous solution prior to ethanol diffusion. Next, the lipid-ethanol solution was rapidly injected into 20 mM Acetate buffer at pH 4.0, forming imiquimod-incorporated nanoemulsions at a lipid concentration of 30.0 mg/mL and an imiquimod concentration of 1.5 mg/mL. The particle sizes and zeta potential of nucleic acid-loaded pH-sensitive nanoemulsion were analyzed by dynamic light scattering with a NICOMP Z3000 Nano DLS/ZLS Systems (Entegris, Billerica, MA).
Squalene, DOTAP and TPGS were mixed into a lipid ethanol mixture at a molar ratio of 68:30:2. Next, the synthetic peptide PIA (LPYLGWLVF, SEQ ID NO:100) dissolved in DMSO, Resiquimod or MPLA was added to the lipid mixture to form homogeneous solution followed by the rapid injection of lipid/peptide/TLRa mixture into 20 mM phosphate buffer, pH 7.4 with 10% sucrose, to form peptide/TLRa loaded cationic nanoemulsions at a lipid concentration of 10.0 mg/mL. To form oligonucleotide-encapsulated cationic nanoemulsions, the SD-101 oligonucleotide solution (in DEPC water) was added dropwise to the empty lipid nanoparticles on slow vortex at a weight ratio of 1 to 10 until nucleic acid-encapsulated cationic nanoemulsions were formed. The final concentrations of P1A peptides, MPLA, Resiquimod, and SD-101 were 1.0, 0.2, 0.2, and 0.2 mg/mL, respectively (or according to the formulation table). The control for each group was performed at the same formulation but without PIA peptides. The products were stored in −20° C. before use. The particle sizes and zeta potential of nucleic acid-loaded pH-sensitive nanoemulsion were analyzed by dynamic light scattering with a NICOMP Z3000 Nano DLS/ZLS Systems.
Preparation of Standard Lipid Nanoparticles Incorporating CpG Oligonucleotides and Anti-PDL1 LNA Gapmers. DSPC, cholesterol, DLin-MC3-DMA and DMG-mPEG2000 were mixed into a lipid ethanol mixture at a molar ratio of 10:38.5:50:1.5. Next, the lipid ethanol mixture was rapidly injected into an acidic phosphate buffer to form empty lipid nanoparticles at a lipid concentration of 10.0 mg/mL. To form oligonucleotide-encapsulated lipid nanoparticles, the oligonucleotide solution (in DEPC water) was added dropwise to the empty lipid nanoparticles on slow vortex at a weight ratio of 1 to 10 until nucleic acid-encapsulated lipid nanoparticles were formed. The products were incubated at 37° C. for 10 minutes and stored in 4° C. before use. The particle sizes and zeta potential of nucleic acid-loaded pH-sensitive nanoemulsions were analyzed by dynamic light scattering with a NICOMP Z3000 Nano DLS/ZLS Systems.
Preparation of pH-sensitive Nanoemulsion (PSNE) Lipid Nanoparticles. DOPC, DOPE, Squalene, DODMA and DMG-mPEG2000 were mixed into a lipid-ethanol mixture at a molar ratio of 15:28:10:45:2. Next, the lipid ethanol mixture was rapidly injected into an acidic phosphate buffer to form empty pH-sensitive nanoemulsion at a lipid concentration of 8.0 mg/mL. In the meanwhile, nucleic acid cargos, including SD-101 and anti-PDL1 lucked nucleic acid (LNA) antisense oligonucleotides (ASO), were dissolved in DEPC water at 0.4 mg/mL. Empty pH-sensitive nanoemulsions and nucleic acid cargos were heated up to 60° C. prior to the mixing. Then, the cargo was added dropwise to the empty pH-sensitive nanoemulsion on slow vortex at a weight ratio of 1 to 20 until nucleic acid-encapsulated lipid nanoparticles were formed. The products were incubated at 37° C. for 10 minutes and stored in 4° C. before use. The particle sizes and zeta potential of nucleic acid-loaded pH-sensitive nanoemulsion were analyzed by dynamic light scattering with a NICOMP Z3000 Nano DLS/ZLS Systems.
Preparation of Next Generation pH-sensitive Nanoemulsion (PSNE-Chol) Lipid Nanoparticles. DOPE, cholesterol, squalene, DLin-MC3-DMA and DMG-mPEG2000 were mixed into a lipid-ethanol mixture at a molar ratio of 7:38:5:48:2. Next, the lipid-ethanol mixture was rapidly injected into an acidic phosphate buffer/tris buffer to form empty pH-sensitive nanoemulsions at a lipid concentration of 8.0 mg/mL. In the meanwhile, nucleic acid cargos, including SD-101, anti-PDL1 lucked nucleic acid (LNA) antisense oligonucleotides (ASO) or the mixture of both, were dissolved in DEPC water at 0.4 mg/mL. Empty pH-sensitive nanoemulsions and nucleic acid cargos were heated up to 60° C. prior to the mixing. Then, the cargo was added dropwise to the empty pH-sensitive nanoemulsions on quick vortex at a weight ratio of 1 to 20 until nucleic acid-encapsulated lipid nanoparticles were formed. The products were titrated to pH 7 by 0.1N NaOH, incubated at 37° C. for 10 minutes, and stored at 4° C. before use. The particle sizes and zeta potential of nucleic acid-loaded pH-sensitive nanoemulsions were analyzed by dynamic light scattering with a NICOMP Z3000 Nano DLS/ZLS.
Cell Culture. Hepa1-6, MC-38 and RAW264.7 were kind gifts obtained from Drs. Kalpana Ghoshal at The Ohio State University College of Medicine, Christopher Coss and Peixuan Guo at The Ohio State University College of Pharmacy, respectively, and were cultured in DMEM (Millipore Sigma) supplemented with 10% FBS (Millipore Sigma) and antibiotics-antimycotics (Invitrogen) under 37° C. humidified atmosphere with 5% CO2.
in vitro Gene Regulation Evaluation by RT-qPCR. Cells were seeded at a density of 0.25-0.5 million per well in 6-well plates 24 hours prior to the LNP treatments. Next, cells were treated with the LNPs in complete media and were incubated for 24 hours before harvest. Total RNA in the cells was extracted using TRI reagent (Zymo Research) per manufacturer's protocol. cDNA was prepared by High-Capacity cDNA Reverse Transcription Kit (Invitrogen). Real-time PCR was conducted on a QuantStudio™ 7 Flex Real-Time PCR System using SsoAdvanced® Universal SYBR Green Supermix (Bio-Rad). The relative amount of RNA level was calculated and compared according to the 2−ΔΔCt method.
in vitro Surface Protein Expression Evaluation by Flow Cytometry. Cells were seeded at a density of 0.5-0.7 million cells per well in 60 mm cell culture dishes 24 hours prior to the LNP treatments. Next, cells were treated with the LNPs, murine interferon gamma, or LPS at various concentrations in complete media. Cells were washed with PBS twice followed by harvested using enzyme free cell dissociation solution, hank's based (Millipore Sigma). Cell suspensions were spun down at 500× g at 4° C. and the pellets were washed with PBS once followed by the resuspension in FACS staining buffer. Single cell suspensions were fixed in 1% PFA in PBS for 45 minutes at room temperature before stained with two biomarkers: mCd86-BV650 and mCD274-PE (Biolegend, San Diego, CA, USA) per manufacturer's protocol. The stained cells were analyzed on a BD LSRForetessa Flow Cytometer in the Flow Cytometry Shared Resource Core at The Ohio State University Comprehensive Cancer Center. Data were analyzed in FlowJo.
Cytotoxicity under Macrophage Condition Media. RAW264.7 cells were seeded at a density of 0.5 million per well in 6-wells plates 24 hours prior to the LNP treatments. Next, RAW cells were treated with next generation PSNE (PSNE-Chol) LNPs incorporating SD-101 CpG ODN or anti-PDL1 LNA, LPS, or combinations. Cultured condition media were harvested, spun down to remove cell debris, and stored at −80° C. before use. MC-38 and Hepa1-6 were seeded at a density of 3000-5000 cells per well in 96-well plates 24 hours prior to the condition media treatments. Cells were treated with 100 μL of the condition media in quadruplets and were incubated for 72 hours. The cell viability was examined by CellTiter Glo (Promega) utilizing a Biotek Synergy Hi Plate Reader.
Mice Study and MC-38/Hepa1-6 Syngeneic Tumor Models. CD-1 Swiss mice and C57BL/6N mice were purchased from Charles River Laboratory. Animals were housed in a temperature-controlled room under a 12 hr light/12 hr dark cycle and fed normal chow diet. All animal studies were reviewed and approved by The Ohio State University Institutional Laboratory Animal Care and Use Committee (IACUC). Both male and female mice were used for experiments.
MC-38 murine colorectal cancer cell line MC-38 syngeneic subcutaneous murine colorectal cancer model was developed by injecting one million MC-38 cells in PBS onto the right flank of each C57 mouse subcutaneously. Hepa1-6 syngeneic subcutaneous murine liver cancer model was developed by injecting one million Hepa1-6 cells in FBS onto the right flank of each C57 mouse subcutaneously. Tumor sizes and mice weights were monitored daily using a digital caliper and analytical scale, respectively.
in vivo Antitumor Activity Evaluation of Cationic Nanoemulsion Incorporating TLR Agonists on Hepa1-6 Murine HCC Syngeneic Model. The treatments were started when the average tumor sizes reached 80-100 mm3. Mice were randomized into 4 groups with 5 mice per group. The treatments, including normal saline, TLR9a CNE (CpG 2216), TLR3a CNE (poly(I:C)), and TLR7a NE at a dose of 50, 50, and 100 μg per injection, were given twice a week with a total of 8 doses. Mice were sacrificed upon the tumor sizes reached the early removal criteria and tumors were collected for further analysis.
in vivo Vaccine Efficacy Evaluation and Tumor Challenge on J558 Murine Myeloid Syngeneic Model. Wild type (WT) Balb/c mice (2 mice/control group and 3 mice/peptide-containing group) were treated with 100 μL of the peptide-included/control vaccines subcutaneously for 7 days. Mice were bled for P1-CTL (cytotoxic T lymphocytes, CD8+ T lymphocytes) detection 7 days after immunization, and mice were challenged with J558 murine myeloma cells on the 10th day. Mice were sacrificed 40 days after immunization and spleens and tumors examined for activated P1-CTL using flow cytometry.
in vivo Antitumor Activity Evaluation of Standard Lipid Nanoparticles Incorporating CpG Oligonucleotides and Anti-PDL1 LNA Gapmers on MC-38 Murine Colon Cancer Syngeneic Model. The treatments were started when the average tumor sizes reached 80-100 mm3. Mice were randomized into 6 groups with 5 mice per group. The treatments, including normal saline control, anti-PDL1 2′-OMe ASO gapmer in PBS, doxorubicin in PBS solution, SD-101 in LNP, anti-PDL1 ASO in LNP, SD-101 in LNP and anti-PDL1 ASO in LNP combination, and anti-PDL1 ASO in LNP with doxorubicin combination, were given once every three days with a total of 5 doses. Mice were sacrificed upon the tumor sizes reached the early removal criteria and tumors were collected for further analysis.
in vivo Antitumor Activity Evaluation of pH-sensitive Nanoemulsion (PSNE) Lipid Nanoparticles on MC-38 Murine Colon Cancer Syngeneic Model. The treatments were started when the average tumor sizes reached 80-100 mm3. Mice were randomized into 6 groups with 5 mice per group. The treatments, including normal saline control, SD-101 oligonucleotides, SD-101 in PSNE, anti-PDL1 LNA in PSNE, SD-101 and anti-PDL1 LNA in PSNE, and Resiquimod and SD-101 in PSNE, were given once every three days with a total of 5 doses. Mice were sacrificed 6 hours after the final dose and various organs as well as whole blood samples were collected for further analysis.
in vivo Antitumor Activity Evaluation of Next Generation pH-sensitive Nanoemulsion (PSNE-Chol) Lipid Nanoparticles on MC-38 Murine Colon Cancer Syngeneic Model. The treatments were started when the average tumor sizes reached 80-100 mm3. Mice were randomized into 5 groups with 6 mice per group. The treatments, including normal saline control, SD-101 in PSNE-Chol, anti-PDL1 LNA in PSNE-Chol, SD-101 and anti-PDL1 LNA in PSNE-Chol, and the mixture of SD-101 in PSNE-Chol and anti-PDL1 LNA in PSNE-Chol, were given once every three days with a total of 5 doses. Mice were sacrificed upon the tumor sizes reached the early removal criteria and various organs as well as whole blood samples were collected for further analysis.
Splenocyte and Tumor Tissue Messenger RNA Quantification by RT-qPCR. Splenocyte messenger RNA for gene expression analysis was extracted from splenocyte suspensions using TRI reagent per manufacturer's protocol. cDNA was prepared using High-Capacity cDNA Reverse Transcription Kit (Invitrogen). Real-time PCR was conducted on a QuantStudio 7 Flex Real-Time PCR System. The relative amount of RNA level was calculated and compared according to the 2-ΔΔCt method.
Splenocytes and Tumor Infiltrated Immune Cells Population Examination by Flow Cytometry. Single cell splenocyte suspensions were harvested from spleens by the following procedures. Spleens were gently meshed through 70 um nylon meshes (Thermo Scientific) using a sterile 5-mL syringe plunge and washed with cold RPMI medium twice into six-well plates. Crude splenocyte suspensions were then centrifuged at 500×g for 5 minutes at 4° C. to obtain cell pellets. Cell pellets were resuspended in 1×RBC lysis buffer to lyse red blood cells for 5 minutes at RT and 10-fold volume of PBS was added to stop the reaction. After 500×g centrifugation for 5 minutes, the cell pellets were then resuspended in FACS staining buffer to form single cell splenocyte suspensions.
Antibodies were purchased from Biolegend (San Diego, CA), and surface cell staining was done per manufacturer's protocol. Intracellular staining was done by using Biolegend True-Nuclear™ Transcription Factor Buffer Set per manufacture protocol. The stained cells were analyzed on a BD LSRForetessa Flow Cytometer in the low Cytometry Shared Resource Core at The Ohio State University Comprehensive Cancer Center.
Cytokine ELISA. Serum samples were obtained from whole blood samples by incubating blood at RT for 30 minutes, followed by 2,000×g centrifugation for 20 minutes. Sera were collected and stored at −80° C. prior to cytokine analysis. Cytokine concentrations were measured by uncoated ELISA kits purchased from Invitrogen per manufacturer's protocols.
Statistical Analysis. Statistical analyses were performed with GraphPad PRISM software version 9 (GraphPad Software, San Diego, CA, USA). P-values≤0.05 were considered significant.
In the first preliminary study, several different toll-like receptor agonists were examined utilizing squalene-based nanoemulsions and intratumoral injections. Toll-like receptors are known to initiate immune responses as different receptors are responsible for sensing different kinds of PAMPs. Here, TLR3 agonist poly(I:C), TLR7 agonist imiquimod and TLR9 agonist CpG 2216 were selected and were encapsulated into the nanoemulsions either through hydrophobic interactions (imiquimod) or electrostatic interactions (poly(I:C) or CpG 2216). The drug nanoparticles were stable without forming aggregates while stored at 4° C. Due to the limited cavities in the tumor tissues, the injection volumes were limited to 50-100 μL per injection. The administrations were done by directly injecting the nanoemulsions into the tumor center cavities with careful monitoring. In
In the first preliminary study, only TLR agonists were supplied utilizing nanoparticle carriers. The tumor-associated antigens were supplied endogenously within the tumor microenvironment. During the intratumoral injection, dendritic cells and other phagocytes could uptake both TLR agonist nanoparticles and/or tumor-associated antigens to initiate inflammatory responses and dendritic cell activation or maturation. Antigen presentation in dendritic cells is a highly specified and regulated process that requires degraded pathogen proteins (antigens) and activation signals (TLR agonists). Plasmacytoid dendritic cells (pDC) activated by CpG TLR9 agonists are professional antigen-presenting cells (APC) to CD8+ T lymphocytes through cross antigen presentation. However, a successful antigen presentation procedure requires the simultaneous occurrence of PAMP (here, TLR agonists) and antigen proteins in APCs. Therefore, to develop a well-defined cancer vaccine against a specific cancer subtype, a specific, well-defined antigen peptide was added to the squalene nanoemulsion, along with the combinations of TLR agonists in the second preliminary study.
Since the single TLR activation did not give substantial responses, dual or triple TLR agonist combinations were considered. Poly(I:C) was abandoned due to its low potency. MPLA, which is a TLR4 agonist working similarly to lipopolysaccharide (LPS) by mimicking bacterial infections, was selected as one of the components. Besides, imiquimod was substituted by the modified version, Resiquimod, which is a TLR7/8 agonist, to enhance the drug solubility and improve the process manipulation. Furthermore, SD-101 CpG oligonucleotide, a type-C CpG oligonucleotide, was added to the portfolio along with CpG 2216, a type-A CpG oligonucleotide. The evaluation of the potency of each combination (Table 2) was done by immunizing the mice with peptide-incorporated TLR agonist nanoemulsions subcutaneously, followed by tumor challenge.
PIA is a well-defined antigen peptide for murine myeloma cells J558. The peptide can be synthesized by solid-state peptide synthesis with high purity and high precision. The sequence of the P1A peptide is LPYLGWLVF (SEQ ID:100), with over half of the residues being hydrophobic or aromatic amino acids (highlighted bold). The high lipophilicity of PIA antigen peptide was be dissolved in the squalene core and formed cationic nanoemulsions by adding permanently charged DOTAP to the formulations. DOTAP was used as the electrostatic charge source to pair with oligonucleotides to form stable cationic nanoparticles or nano-lipoplex.
Worked as the cancer vaccine candidate, the mice were immunized once to illustrate the immune system stimulation potency, and a tumor challenge was done to demonstrate the protective ability after immunization. In
In a third study, SD-101 was combined with anti-PDL1 antisense oligonucleotides (anti-PDL1 ASO) to examine the antitumor efficacy by not only stimulating immune responses but also downregulating the checkpoint molecule PD-L1, or programmed cell death-ligand 1. PD-L1, also known as cluster of differentiation 274 (CD274), is a protein that acts as a brake to stop the immune responses by binding to its receptor PD-1 and inducing inhibitory signals. By downregulating the PD-L1 expression in either immune cells or cancer cells, T lymphocyte responses would not be diminished by the signaling pathways triggered by PD-1/PD-L1 interactions. To demonstrate the activity of both SD-101 CpG ODN and anti-PDL1 ASO, both oligonucleotides were fully encapsulated in standard lipid nanoparticles with the golden standard ionizable lipid DLin-MC3-DMA at a golden composition of DSPC/cholesterol/DLin-MC3-DMA/DMG-mPEG2000=10/38.5/50/1.5 (m/m). Mice bearing with MC-38 tumors were treated once every three days for five doses. The results (
Besides the tumor burden analysis, the weight analysis during the treatment period was an important parameter to evaluate the overall systemic toxicity caused by the therapeutic agents. In
The anti-PDL1 gapmer ASO was originally designed by Roche in locked nucleic acid (LNA) modifications at two ends and tagged with a GalNac moiety for liver targeting. In our study, the GalNac moiety was removed to obtain a single-stranded, 16-mer anti-murine PD-L1 gapmer antisense oligonucleotide. In the initial testing, 2′-OMe modified nucleotides were used at two ends to protect the antisense oligonucleotides from nuclease degradation. However, studies have shown that 2′-OMe modification had minor improvement over the original deoxynucleotides, with minor enhancement in messenger RNA binding. The newer version of nucleotide modification is the locked nucleic acid (LNA), in which the 2′-O on the ribose is linked with the 4′-C through the methylene bridge. The binding affinity of the LNA modified ASO is significantly stronger than 2′-OMe modified ASO, and the former can increase RNase H binding to the complementary sequences after binding with target messenger RNA for mRNA degradation. Therefore, the target gene downregulation of the original design of the LNA-modified anti-murine PD-L1 gapmer ASO was examined against the 2′-OMe modified ASO through different transfection methods on different murine cell lines in vitro. In
In Vivo Antitumor Activity Evaluation of pH-Sensitive Nanoemulsion (PSNE) Lipid Nanoparticles on MC-38 Murine Colon Cancer Syngeneic Model.
To evaluate the anticancer activity of the PSNE lipid nanoparticles encapsulating SD-101 CpG ODN, anti-PDL1 LNA ASO, and Resiquimod in vivo, mice were treated with the single agents or combinations at doses of 2.0 mg/kg each once every three days for five doses. In
In the second trial, different parameters and characterizations of PSNE lipid nanoparticles were examined and evaluated. PSNE lipid nanoparticles encapsulating oligonucleotides and small molecules were successfully formulated with high colloidal stability. Small particle sizes ˜80-100 nm were achieved for both empty PSNE LNP and encapsulated LNP with either SD-101 CpG ODNs or anti-PDL1 LNA ASOs. The polydispersity indexes (Pd1) were ˜0.15-0.25, indicating uniformly distributed particle sizes were obtained in all samples (
Next, the encapsulations of ODN and small hydrophobic molecule cargos in PSNE LNP were analyzed by gel retardation assay (
The combination of SD-101 CpG ODNs and anti-PDL1 LNA ASOs in PSNE lipid nanoparticles showed a good tumor growth inhibition outcome on the MC-38 murine syngeneic colon cancer model (
The spleen index (spleen weight presented in the percentage of body weight,
In flow cytometry analysis (
Surface PD-L1 markers on both lymphocytes and myeloid cells were examined by flow cytometry to investigate the PD-L1 protein expressions on immune cells after treatments (
The PSNE was further developed by applying the knowledge from the COVID-19 vaccines in lipid nanoparticle delivery. The next-generation PSNE was composited of DOPE, squalene, DLin-MC3-DMA, cholesterol, and DMG-mPEG2000. The evaluation of the gene delivery (antisense oligonucleotides, siRNAs, mRNAs) was done by RT-qPCR in vitro and Luciferase bioluminescence in vivo (data not shown). The compositions were fine-tuned, and 11 different formulations were examined and presented as a series of next-generation PSNE for different applications. Based on the evaluation results (data not shown), there were several candidates that had high in vivo expression administered systemically, such as PSNE-Chol/M5. Additionally, PSNE-Chol/M9-M11 were tested in vitro along with M5 as M9, M10, and M11 showed high mRNA delivery efficiency in vitro on various cell lines (HEK293T, A549, Hepa1-6, and HepG2).
In the gene delivery evaluation study, three different signature murine cell lines were used, including Hepa1-6 HCC cell line, MC-38 colon cancer cell line, and RAW264.7 macrophage cell line. The former two represented the tumor burden while the latter represented the immune cell populations. All the gene expression levels were normalized to the PBS control group, giving us a clear comparison among each treatment group. As shown in
On the other hand, the result on RAW cells suggested that immune cells were not susceptible to anti-PDL1 LNA ASO gene regulation using next-gen PSNEs. The expression level of the murine PD-L1 had no significant changes while treated with control oligonucleotides or anti-PDL1 LNA ASO. The murine PD-L1 expressions were slightly upregulated in each treatment groups indicating that the next gen PSNE platforms might have the ability to activate RAW cells, such as cytokine release, which was reported for most lipid nanoparticle formulations.
Next, the next-gen PSNE, specifically PSNE-Chol/M5, was tested in both Hepa1-6 and MC-38 in vitro to evaluate the murine PD-L1 downregulation efficiency under the stimulation of cytokines. Cancer cells are highly sensitive to the surrounding cytokines and chemokines and will respond to the environmental stimulations accordingly. It is well-known that pro-inflammatory cytokine interferon gamma (IFN-γ) would induce surface PD-L1 expression on cancer cells in response to the pro-inflammation status and activation of adaptive immune systems. In
In the previous section, the gene regulation of murine PD-L1 mRNA by IFN-γ and/or PSNE-Chol/M5-anti-PDL1 LNA ASO was confirmed by RT-qPCR, and the result demonstrated the promising outcome of using PSNE-Chol/M5-anti-PDL1 LNA ASO as an agent to decrease the expression level of mRNA at mRNA stage. However, the protein expression level of the surface PD-L1 must be confirmed to further demonstrate the correlation of using PSNE-Chol/M5-anti-PDL1 LNA ASO as an anticancer agent in regulating immune checkpoint expression. To investigate the surface PD-L1 expression on cancer cells and immune cells, Hepa1-6 and MC-38 cells treated with IFN-7 and PSNE-Chol/M5-anti-PDL1 LNA ASO were scanned using flow cytometry to quantify the surface immune checkpoint expression. Moreover, RAW264.7 cells treated with PSNE-Chol/M5-SD-101 were examined for the surface activation marker CD86 as well as surface PD-L1 expression. In
RAW264.7 cell surface markers were examined after the treatments to investigate the immune activation effect of each agent and combination. As a positive control of macrophage activation, LPS, a TLR4 agonist, showed a significant increase in CD86 expression as well as PD-L1 expression after the overnight treatment. However, the cells treated with free SD-101 oligonucleotides, a TLR9 agonist, did not exhibit strong activation (increase in surface CD86 expression) as LPS at the 5 μg/mL level. On the other hand, RAW cells treated with LPS and PSNE-Chol/M5-anti-PDL1 LNA ASO showed a decrease in PD-L1 expression compared with LPS only group but were still significantly induced in PD-L1 expression by LPS (
Cytotoxicity under Macrophage Condition Media.
After verifying the direct effect of PSNE-Chol/M5-SD-101 LNP and PSNE-Chol/M5-anti-PDL1 LNA ASO LNP formulations on cancer cells and macrophages through RT-qPCR and flow cytometry, the indirect effects of PSNE-Chol/M5-SD-101 and PSNE-Chol/M5-anti-PDL1 LNA ASO LNP formulations on cancer cells were determined by examining the cancer cell viability after incubated with macrophage condition media. Condition media were prepared by harvesting the cytokine-containing media from macrophages treated with next-gen PSNE formulations overnight. The short-lived cytokines secreted by macrophages were preserved and directly interacted with cancer cells. Cancer cells, both Hepa1-6 and MC-38, were treated with RAW264.7 macrophage cytokine-containing condition media, and the viability was taken after 72 hours. Interestingly, Hepa1-6 (data not shown) has no significant cytotoxic effect on drug-treated condition media compared with normal condition media (PBS control). The morphology of Hepa1-6 cells was found to no change, or unaffected, under a bright-view microscope. On the other hand, MC-38 cells (
In Vivo Antitumor Activity Evaluation of Next Generation pH-Sensitive Nanoemulsion (PSNE-Chol) Lipid Nanoparticles on MC-38 Murine Colon Cancer Syngeneic Model.
The in vitro validation of next-gen PSNE LNPs in cancer cell lines and macrophage cell lines gave us some insight into the therapeutic effects in vivo. Therefore, next-gen PSNE LNPs incorporating SD-101 and anti-PDL1 LNA ASO were tested on the MC-38 syngeneic model as single agents or as combinations. Based on the hypothesis, the anticancer efficacy of the next-gen PSNE should be higher than the previous generation PSNE without cholesterol. The delivery efficiency of anti-PDL1 LNA ASO to cancer cells and splenocytes should be higher than that using previous generation PSNE as well. The mice were treated with either saline control, PSNE-Chol/M5-SD-101 LNPs, PSNE-Chol/M5-anti-PDL1 LNA ASO LNPs, the 1:1 mixture of both LNPs, or the co-loading LNPs with the oligonucleotides at a weight ratio of 1:1. In
However, the toxicity of the LNP agents was monitored by the body weight loss and the early-stage viability during the treatment period. The body weight curves (
After the treatments were finished and the mice were sacrificed, several important parameters were measured and examined (
Next, splenocyte populations were examined to elucidate the effects of next-gen PSNE delivery platform on the immune cells. As shown in
Not only the splenocyte mRNA expressions, but also the tumor single-cell mRNA expressions were examined as well. Tumor single-cell suspensions were obtained by dissociating the tumor tissues using proteases to remove the extracellular matrixes. The RT-qPCR results from tumor single-cell suspensions illustrated that there were no significant differences in Pdl1 expression, though PSNE-Chol/M5-anti-PDL1 LNA ASO LNP single-agent group showed lower Pdl1 expression (
Furthermore, based on the nature of nanoparticle biodistribution, anatomy of the liver, and the biodistribution assay utilizing DiR lipid near-infrared fluorescence dye-decorated PSNE-Chol/M5, the majority of lipid nanoparticles administered systemically accumulated in the liver with a minor (3% FL intensity of that at the liver, data not shown) in the spleen, livers of the PSNE-Chol/M5-anti-PDL1 LNA ASO LNP treatment group were analyzed for Pdl1 mRNA level using RT-qPCR. The RT-qPCR results (
In this Example, several strategies were tested to stimulate the immune system to fight against cancers. We selected the activation of dendritic cells through toll-like receptor activation as the central concept, and multiple strategies and combinations were tested utilizing different lipid nanoparticle formulations. In the early stage of the project, cationic nanoemulsions were used to encapsulate both hydrophobic agents, such as lipophilic TLR agonists or antigen peptides, and oligonucleotides into a single particle for delivery. In the late stage of the project, a newly developed pH-sensitive nanoemulsion lipid nanoparticle delivery platform was used to enhance the delivery of antisense oligonucleotides and CpG oligonucleotides.
To enhance the immune system activation, tumor associated antigens and toll-like receptor agonists are needed. In our first series of constructs, different TLR agonists were encapsulated into cationic nanoemulsions and were injected intratumorally. The antigen sources for dendritic cell activation were defined as the tumor cell debris from necrotic tumor cells, released proteins/fragments in exosomes or the phagocytosed dead cancer cells. While the tumor microenvironment was full of useful antigens, the internal environment was anti-inflammatory, and the cytotoxic immune cell functions were inhibited by the released anti-inflammatory cytokines, such as TGF-β. Therefore, TLR agonists were needed to reactivate the immune cells, and the agonists were supplemented by nanoemulsions carrying imiquimod, CpG 2216, or poly(I:C). The preliminary study did not show significance in tumor growth inhibition, but some of the mice did have complete regression after the treatment, both in imiquimod (TLR7 agonist) and CpG 2216 (TLR9 agonist) treatment groups. Also, the tumor model selection was an important factor for evaluation, as Hepa1-6 syngeneic tumor model tend to generate larger ulcers and necrosis at the center of the tumor tissue, which was a good key factor for tumor associated antigen generation but would also lead to early removal as the illness and unhealthy ulcers could affect the overall animal health. The bleeding ulcers generated by Hepa1-6 model caused the early removal of mice in saline control group, generating bias against the treatment groups. Furthermore, mice in the treatment groups were removed due to the bleeding ulcer at the early stage of tumor progression, and that led to the bias in judging the therapeutic effect of the cancer vaccine. Overall, the preliminary experiment still gave us some useful information including the potency of different TLR agonists delivering intratumorally in vivo.
Next, we evaluated an alternative strategy in which defined tumor antigens along with TLR agonists or in combinations as a series of comprehensive cancer vaccine constructs were encapsulated. PIA peptide is a well-defined peptide antigen for murine J558 myeloma and has been reported to be successful to trigger protective response against J558 myeloma. Since P1A is a hydrophobic peptide, it can be successfully dissolved in squalene oil core as a solvate. Besides adding P1A to the nanoemulsion constructs, several TLR agonist combinations were tested, including MPLA (TLR4), Resiquimod (TLR7/8) and CpG 2216 or SD-101 (TLR9). MPLA and Resiquimod are lipophilic substances and can be dissolved in the squalene core as well. One the other hand, CpG 2216 and SD-101 are oligonucleotide-based cargos and have to be encapsulated into lipid nanoparticles through electrostatic interactions. The combination protective therapy, or the cancer vaccines, did show some promising results while co-loading three different TLR agonists together in a single particle instead of two or one of them. The result was interesting since the cancer vaccines were given subcutaneously and might have to boost the response as the general concept suggested to reactivate memory immune cells. The data suggested that a single shot of cancer vaccines might not be useful for generating anticancer immunity or other routes of administration might be needed.
Besides applying tumor associated antigens along with TLR agonists, we further considered delivering anti-PDL1 antisense oligonucleotides to downregulate PD-L1 surface expressions on tumor cells to enhance the immune response as what was achieved by anti-PDL1 or anti-PD1 antibodies as immune checkpoint blockade therapies. The immune checkpoint signaling required the interaction between PD-L1 and PD-1 or PD-1 and CTLA-4 to inhibit the immune activation response on CD4+ and CD8+ T lymphocytes, which are the two of the main populations for anticancer immunity. Therefore, SD-101, the TLR9 agonist, and anti-PDL1 antisense oligonucleotides were encapsulated separately in standard lipid nanoparticles to enhance the delivery of oligonucleotides to cells and increase the circulation time. However, the overall outcome was not favorable for using anti-PDL1 ASO LNP as single therapy, while SD-101 LNP worked efficiently as a single agent. As the matter of fact, lipid nanoparticles were intended to deliver the cargos to liver, as liver is the major organ for foreign substance elimination. The sinusoids and capillaries in the liver could entrap the nanoparticles as the sizes were similar. The majority of the nanoparticles went to the liver, which was the nature of the lipid nanoparticle physiology. Further, we found that the modification on the ASO affected the efficacy significantly, as previously reported and as the in vitro evaluation done in-house by comparing 2′-OMe modified ASO with LNA modified ASO. The result also indicated that the failure of the anti-PDL1 ASO LNP single therapy could be resulted from the inefficient cargo carried in the lipid nanoparticles, as the standard lipid nanoparticle with DLin-MC3-DMA being a golden standard from delivery with high delivery efficiency.
To figure out a solution and develop a delivery platform for immune system activation therapy against cancer, a pH-sensitive nanoemulsion-based lipid nanoparticle delivery platform was developed to accommodate both hydrophobic substances and nucleic acid substances in a single construct. Several combinations were evaluated including TLR agonist combinations or combinations of TLR agonists with anti-PDL1 LNA ASO. The preliminary results presented in this Example were promising, with a high TGI ˜70%.
Endosomal TLR agonists worked effectively as anticancer agents by facilitating antigen-presenting processes in dendritic cells (DCs) and augmenting CD8+ T lymphocyte (or cytotoxic T lymphocyte, CTL) maturation, which could rapidly recognize and kill cancer cells by T cell-mediated immunity. In the present study, a squalene-based nanoemulsion (NE) formulation was developed to co-deliver resiquimod (R848), a TLR7/8 agonist, and ivermectin (IVM), an anti-parasitic drug used worldwide since 1975. R848-IVM co-loaded NE was developed and characterized for stability. Antitumor activity of R848-IVM NE was also evaluated in vitro and in vivo. In vivo studies demonstrated that IVM could augment the immunogenic cell death induced by R848 and showed strong antitumor activity with over 80% tumor growth inhibition. Significant HMGB1 release into the tumor microenvironment was observed in mice treated with R848-IVM co-loaded NE. Over 3-fold increase in Cd8a expression was also observed in tumor tissues. The results suggested a potential combination therapy of systemic co-delivering IVM with other immune stimulation agents against solid cancer.
Toll-like receptors (TLRs) play critical roles in immune responses by recognizing pathogen-associated molecule patterns (PAMP) followed by inducing cytokine production and activating adaptive immunity. TLRs are expressed either on cellular surfaces (TLR1/2/4/5/6/10) or on endosomal surfaces (TLR3/7/8/9) of antigen-presenting cells (APCs) such as dendritic cells (DCs) or macrophages. TLRs are poised to recognize foreign molecular patterns, initiate MyD88/NF-κB transduction pathway, and activate naive T cell repertoires in the adaptive immune systems. Studies have demonstrated that endosomal TLR agonists worked effectively as adjuvants in cancer vaccines due to their strong immunostimulatory abilities and antitumor efficacies. Endosomal TLR agonists have been shown to facilitate antigen-presenting processes in DCs and augment CD8+ T lymphocyte (or cytotoxic T lymphocytes, CTL) maturation, which could eventually suppress cancer cell growth through T cell-mediated immunity. The antitumor activity carried out by endosomal TLR agonists suggests that cell-mediated immunity derived from TLR activations could be beneficial for anticancer therapies while combining with personalized antigen-based therapies, immune checkpoint blockades, chemotherapeutics, or radiotherapies. Three TLR agonists have been approved by FDA for cancer treatments, including bacillus Calmette-Guerin (TLR2&4 agonists mixture), monophosphoryl lipid A (TLR2/4 agonist), and imiquimod (TLR7 agonist). Overall, the clinical outcomes of TLR agonists were mixed. Intra-tumoral or intradermal injection of TLR agonists has been investigated recently. However, these routes of administration are difficult to access during clinical practice for most solid tumors
During the treatment of TLR agonists against cancer, immunogenic cell death (ICD) plays an important role in antitumor immunity by rapidly inducing surface exposure of high-mobility group box 1 protein (HMGB1), calreticulin, as well as tumor antigens release to immune cells. Chronic exposure of these damage-associated molecular patterns (DAMPs) will recruit DCs and facilitate CTL activation through antigen presentation. The activated DCs and CTLs will accelerate the pace of engulfment of antigenic components in the tumor microenvironment (TME) and result in long-term antitumor immunity. Patients treated with traditional chemotherapies exhibited ICD-mediated antitumor immunity with an increased ratio of CTLs to regulatory T cells (Tregs) in their TMEs. The ICD-mediated antitumor response could also be augmented by immune checkpoint blockade which impedes immune escape between tumor cells and immune cells. However, chemotherapies are often associated with high cytotoxicity which causes dose-dependent damage to normal cells even if been administered locally to lower the systemic side effects. On the other hand, immune checkpoint blockade became a revolutionary approach to activate patients' immune systems to treat cancer. However, anticancer efficacy by immune checkpoint inhibitors is limited to “hot tumors” with abundant tumor-infiltrating immune cells, whereas “cold tumors” with limited immune cell infiltration showed minor responses to immune checkpoint inhibitors. Therefore, an immunomodulating therapy with enhanced systemic immune activation, rapid induction of ICD, and low toxicity would be an ideal approach for systemic anticancer treatment.
Resiquimod (R848) is a TLR7/8 agonist that has been shown to have ideal antitumor activities in murine tumor models. However, a single treatment of R848 was insufficient to induce systemic immune responses against tumors. Ivermectin (IVM) is an anti-parasitic drug used worldwide since 1975. Research has shown that IVM had the potential to alter the release of HMGB1 and calreticulin in TME, making it an ideal candidate to induce ICD in addition to R848 treatment. Nonetheless, due to the limited solubility of R848 and IVM, an injectable formulation is needed for clinical translation. Oil-in-water nanoemulsions (NE) have been proposed as promising non-viral delivery systems for hydrophobic drugs. NE consists of an oil core encapsulated by surfactants, where the oil core could work as an efficient reservoir to solubilize poor water-soluble drugs. Our work above demonstrated a squalene-based NE to encapsulate R848, a TLR7/8 agonist, which showed moderate antitumor activity through systemic administration.
In this Example, squalene-based NE was developed to co-encapsulate R848 and IVM. The squalene NE greatly increased the solubility of R848 and IVM in an aqueous solution, which turned the hydrophobic drugs feasible for systemic administration. The squalene-based NE eliminated the autophagy-associated cytotoxicity from IVM but maintained its ability to promote ICD. The R848-IVM co-loaded NE showed high stability when stored at 4° C. and −20° C. IVM NE treatment successfully induce HMGB1 releasement out from TMEs and increase Cd8a mRNA expression in tumor tissues. The antitumor efficacy of R848-IVM co-loaded NE (R848-IVM NE) was superior to R848 NE or IVM NE, suggesting the potential of combination therapies using TLR agonists along with IVM.
Materials. Squalene was obtained from Sigma-Aldrich (St. Louis, MO, USA). 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) was purchased from Avanti Polar Lipids (Birmingham, AL, USA). Polysorbate 80 (Tween 80) was purchased from Fisher Scientific (Hampton, NH, USA). R848 and IVM were purchased from MedChemExpress (Monmouth Junction, NJ, USA) and Sigma-Aldrich, respectively. Any other reagents, including but not limited to buffers, were all obtained from Fisher Scientific.
R848-IVM NE Formulation and Characterization. Squalene-based NE was prepared by hand-rapid injection of oil-lipid mixture into phosphate-buffered saline (PBS). Squalene, DOPC, and Tween 80 were prepared at a molar ratio of 1/1/1 in ethanol. R848 and IVM were then added to the lipid-ethanol solution individually or in combination, maintaining lipid to R848/IVM at 10:1 (w/w). The final lipid concentration of the NE was 8 mg/mL, and the final drug concentrations were 0.8 mg/mL for both. Particle sizes were measured by dynamic light scattering (DLS) using a NICOMP NANO ZLS Z3000 (Entegris, Billerica, MA, USA). Empty NE was generated using the same procedures without R848 or IVM. Empty NE and R848-IVM NE were stored at 4° C. before characterization, and at −20° C. for long-term stability test. Sepharose CL-4B size exclusion chromatography was performed to examine the encapsulation efficiency of R848 or IVM within the squalene nanoemulsions. Drug concentrations were determined by UV-Vis spectrometry at 320 nm (R848) or 245 nm (IVM) using a NanoDrop 2000 spectrophotometer. The loading efficiency was determined by the equation below:
In the saturated solubility study, R848 or IVM were dissolved in PBS or formulated in NE at 2 mg/ml and incubated at room temperature for 24 hours. Insoluble solid drugs were pelleted down by centrifugation. Supernatants were collected for concentration analysis. R848 concentrations were quantified by UV-Vis spectrometry at 320 nm using a NanoDrop 2000 spectrophotometer. IVM concentrations were quantified by high-performance liquid chromatography (HPLC) using an isocratic mobile phase composed of water/methanol/acetonitrile (8:36:56, v/v/v), an C18 column (Kromasil 150-C-18, 4.6×150 mm), and PDA detection at 230 nm.
Cell Culture. RAW 264.7 murine macrophage cell line and MC38 murine colorectal carcinoma cell line were kind gifts given by Dr. Peixuan Guo and Dr. Christopher Coss at The Ohio State University College of Pharmacy, respectively. RAW 264.7 and MC38 were grown in DMEM supplemented with 10% FBS and 1× antibiotic-antimycotic. Cells were maintained at 37° C. and grown under a humidified atmosphere containing 5% CO2.
Cell Viability Assay. MC38 cells were seeded at 3000 cells/well in 96-well plates 24 hours before treatments. Cells were treated with R848, IVM, R848 NE, or IVM NE with escalated concentrations from 1 μM to 400 μM. A separate experiment was set up to evaluate the potential cytotoxicity of empty NE. Empty NE was treated with concentrations ranging from 10 μg/mL to 4000 μg/mL. After 72 hour-treatment, cell viability was examined by CellTiter 96R AQueous One Solution (Promega, Madison, WI) per manufacturer protocol. The IC50 for R848 or IVM was determined by R programming.
In Vitro Gene Regulation by R848 NE, IVM NE, and R848-IVM NE. MC38 cells were seeded at 3×105 cells/well in 6-well plates 24 hours before treatments. Cells were treated with R848, IVM, R848 NE, IVM NE, or R848-IVM NE in complete media and incubated for 24 hours. R848 and IVM were both treated at 8 μM, either as free drug solution or in squalene NE. Total RNA was extracted using TRI reagent (Zymo Research) per manufacturer protocol. cDNA was prepared by high-capacity cDNA reverse transcription kit (Invitrogen, Waltham, MA, USA), and real-time qPCR (RT-qPCR) was done using SsoAdvanced™ Universal SYBRR Green Supermix (Bio-Rad Laboratories, Hercules, CA) on a QuantStudio 7 Flex Real-time PCR System. RT-qPCR primers for murine Calreticulin, Hmgb1, Lc3b, and Actb were purchased from Sigma-Aldrich. Actb was selected as the housekeeping gene control. The relative amount of RNA level was calculated and compared according to the 2-ΔΔCt method.
In Vitro Tumor Cell Migration Assay. A scratch wound healing model was conducted to examine the migratory ability of MC38 cells following treatment. MC38 cells were seeded at a density of 5×105 cells/well in 6-well plates 24 hours before treatments. A scratch wound across the well was made using a 10 ul pipet tip immediately before treatment. Cells were washed by PBS and incubated with complete media containing 8 μM of R848, IVM, R848 NE, IVM NE, or R848-IVM NE. Cells were allowed to proliferate at 37° C. for 24 hours. Distances between edges of the wound were measured by Nikon Eclipse Ti—S microscope (Nikon, Tokyo, Japan).
In Vivo Antitumor Activity. MC38 murine syngeneic colorectal cancer model was generated by inoculating 1×106 cells/mouse in PBS on the right flanks of C57BL/6N mice (Charles River Laboratories). Treatments were initiated once tumor sizes reached approximately 100 mm3. Mice (n=5) were intraperitoneally treated with saline, 4 mg/kg R848 NE, 4 mg/kg IVM NE, or R848-IVM NE (4 mg/kg R848 and 4 mg/kg IVM) every 3 days for 3 doses. Tumor growth and body weight were monitored, and the tumor volumes were calculated according to the equation below:
All mice were maintained and treated according to the guidelines from the Institutional Animal Care and Use Committee (IACUC) at The Ohio State University. All groups were euthanized on day 9, and whole-blood samples were collected through cardiac puncture. Mouse sera were collected by placing whole-blood samples at room temperature for 30 minutes followed by 2000× g centrifugation for 20 minutes at RT. Samples were stored at ˜80° C. before cytokine quantification. Murine TNF-α and IL-6 concentrations were determined by TNF-α and IL-6 mouse uncoated ELISA kits (Invitrogen, Waltham, MA, USA) per manufacturer protocol. Tumor and spleen tissues were harvested and weighed for comparison. Spleen weight was normalized to individual bodyweight for comparison between treatment groups. Tumor growth inhibition (% TGI) on day 10 was determined by the equation below:
where T10 stands for average tumor volume of the treatment group at day 10, To stands for average tumor volume of the treatment group at day 0, C10 stands for average tumor volume of the control group at day 10, and Co stands for average tumor volume of the control group at day 0. % TGI>50% was considered meaningful.
In Vivo Gene Regulation by R848 NE, IVM NE, and R848-IVM NE. Tumor and spleen tissues were immediately harvested at the end of treatment. Spleens were homogenized into single-cell suspensions by pressing through 70 μm cell strainers with syringe plungers. Splenocytes were washed and resuspended in FACS staining buffer at 2×107 cells/mL. 1×106 cells of splenocytes were saved for flow cytometry analysis. The remaining splenocytes were lysed in TRI reagent for total RNA extraction. Tumor tissues were homogenized directly in TRI reagent through probe sonication. Total RNAs were isolated per manufacturer protocol. RT-qPCR was completed according to the procedures stated in section 2.5. The sequences of real-time qPCR assay primers for murine Cd3e, Cd4, and Cd8a were listed below.
In vivo Protein Expression Analysis by Western Blot. Tumors were harvested and homogenized in Pierce RIPA buffer (Thermo Fisher Scientific) using a handheld homogenizer. Total proteins were extracted after incubating on ice for 30 minutes and centrifuged at 14000×g for 30 minutes at 4° C. Protein samples were denatured, quantified, and equal amounts of proteins were loaded and electrophoresed on 10% SDS-polyacrylamide gels and transferred onto nitrocellulose membranes. The transferred membranes were blocked with 5% nonfat milk in Tris-buffered saline (TBS). HMGB1 rabbit monoclonal antibody and anti-rabbit HRP conjugated secondary antibody were purchased from Cell Signaling (Danvers, MA, USA). Ki-67 rabbit monoclonal antibody was purchased from Thermo Fisher Scientific. Specific target protein bands were developed with enhanced chemiluminescence (ECL) detection system and total proteins were detected by Ponceau S as control.
Flow Cytometry. APC/Cyanine7 anti-mouse CD3e (145-2C11), FITC anti-mouse CD4 (RM4-5), PE/Cyanine7 anti-mouse CD8a (53-6.7), PE anti-mouse FOXP3 (MF-14), and True-Nuclear Transcription Factor Buffer Set for FOXP3 staining were purchased from Bio-Legend (San Diego, CA, USA). Single-cell suspensions of splenocytes in FACS staining buffer were stained per manufacturer protocol. Stained cells were analyzed using an LSR II flow cytometer in Flow Cytometry Shared Resources (FCSR) at The Ohio State University Comprehensive Cancer Center.
Statistical Analysis. All studies were done in triplicate. Data are presented as means±standard deviations unless otherwise indicated. Statistical analysis will be conducted using Microsoft Excel. One-way ANOVA was used to determine variances in means between two or more treatment groups. Student's t test was used as a post-hoc analysis to determine statistically significant differences between any two groups. A p-value of 0.05 was selected as the cutoff for statistical significance.
Particle Characterization and Solubility. IVM is a broad-spectrum antiparasitic agent against many endo- and ecto-para-sites. Recent studies suggested that IVM exhibited certain antitumor activities through multiple pathways in many types of tumors. However, severe side effects have been reported when high doses of IVM were administered. Previous research has introduced different lipid-based nanoparticles to deliver IVM against parasites. However, a systemic delivery platform for IVM against cancers has not been well established. In our previous Examples, a squalene-based NE was capable to encapsulate R848 and achieved great potential of eliminating tumor growth through systemic administration in tumor-bearing mice when combined with other TLR agonists. Herein, squalene-based NE was capable of co-encapsulating IVM and R848. R848-IVM NE was approximately 140-160 nm in size,
which was larger than IVM NE or R848 NE (
In Vitro Cell Viability. Although most TLR7/8 agonists, such as R848, have no direct cytotoxic effects in vitro or in vivo, many reports have shown that IVM confers significant toxicity through autophagy and DNA damages. Treatments with empty NE in MC38 cells showed no significant cytotoxicity at the highest dose of 4000 μg/ml. Likewise, treatments with free R848 and R848 NE did not result in significant cytotoxicity (IC50>100 μM), analyzed by MTS assay (
In Vitro Gene Regulation by Free Drugs and NE Formulation. The process of immunogenic cell death in tumors is mainly mediated by DAMPs released from cancer cells, which includes surface exposure of calreticulin, releasement of HMGB1 and type I interferons (IFNs). DAMPs are further recognized by APCs and CTLs to induce antitumor immunity. Many studies have shown that calreticulin translocation and exposure were two important components as ICD checkpoints, and knockdown of calreticulin completely abolished the immunogenicity in tumors during the ICD process. In addition, HMGB1 has been shown to facilitate ICD from the extracellular compartment including triggering tumor necrosis factor-alpha (TNFa) releasement, APC maturation, and CTLs recruitment. However, endogenous calreticulin and HMGB1 exhibit controversial roles in cancer progression. Endogenous HMGB1 was demonstrated to promote cancer cell proliferation and CRT has pro-angiogenic functions due to its ability to promote the expression of vascular endothelial growth factor (VEGF) which leads to cancer cell proliferation and migration as well.
In MC38 cells, Calreticulin mRNA level was slightly decreased after R848 NE treatment, indicating the potential of cell growth inhibition (
IVM has been demonstrated to trigger autophagy-mediated cell death by blocking PAK1/Akt axis and generating LC3-II in autophagosomes, where LC3 is a key protein participating in initiating autophagy. In the present study, squalene-based NE mitigated the autophagy-mediated cell death from IVM, which can be identified by reduced Lc3b mRNA expression to normal level in IVM NE treatment compared with free IVM treatment (
Wound Healing. Wound healing studies were performed to monitor the relative mobility of MC38 following treatment with R848 NE, IVM NE, or R848-IVM NE (
In Vivo Antitumor Activity. In the animal study to evaluate the antitumor efficacy for R848-IVM NE, 4 mg/kg R848 NE and IVM NE were administered individually or as R848-IVM NE to show a combined antitumor efficacy through intraperitoneal administration. Moderate antitumor efficacy by R848 NE treatment was observed compared with saline control and was consistent with our previous results. Studies have shown that IVM potentiated ICD processes and promoted antitumor immunity for immune checkpoint inhibitors. However, no significant antitumor effect has been observed in mice treated with IVM NE compared with saline control, which corresponds with previous research on the IVM (
R848-IVM NE has reached 88.66%±14.91% in tumor growth inhibition (TGI %) at the end of the study, which was superior to R848 NE and IVM NE treatments (Table 4). No significant weight loss was observed during the treatment regimen, suggesting minor systemic toxicity of R848-IVM NE treatment. Mice treated with R848 NE or R848-IVM NE exhibited slight splenomegaly. The increase in spleen weights was caused by the immune activation carried out by R848. No significant changes in spleen weight were observed in mice treated with IVM NE. No significant changes in serum cytokine level were observed.
Effects of R848 and IVM on Gene Regulation and Immune Cell Population in vivo. Although no significant cytokine increase in serum was observed in mice treated 359 with R848 NE, IVM NE, or R848-IVM NE, RT-qPCR results of tumor tissues suggested that IVM NE and R848-IVM NE significantly induce significant Hmgb1 mRNA upregulation (
Flow cytometry data indicated that CTL populations in mouse spleens were reduced after treatment with R848 NE and R848-IVM NE (
Although ICD-mediated antitumor immunity has been demonstrated to facilitate the antitumor response by both traditional chemotherapies and immune checkpoint blockades in many cancer patients, chemotherapies are often correlated with unwanted side effects and toxicity, which causes dose-dependent damage to normal cells even being administered locally to lower drug concentrations within systemic circulation. On the other hand, the anticancer efficacy by immune checkpoint inhibitors is limited to tumors that have already been infiltrated by T cells, whereas tumors with less T cell infiltration showed minor responses to immune checkpoint inhibitors. The present study showed a promising strategy to achieve systemic antitumor activity through augmenting the process of ICD by using combination therapy of R848 and IVM co-encapsulated squalene-based NE. R848-IVM NE is highly stable during long-term storage at 4° C. and −20° C. The squalene-based NE greatly reduced the cytotoxicity carried out by IVM. Ultimately, R848-IVM NE strongly enhanced the antitumor activity in vivo by greatly suppressing tumor growth over 80%. The results indicated that intraperitoneal administration of R848-IVM NE could be a promising strategy to induce ICD and recruit CTLs and NK cells to TME, suggesting a broader application of IVM in inducing ICD while combining with TLR agonists or other immunotherapeutic against cancer.
The compositions and methods of the appended claims are not limited in scope by the specific compostions and methods described herein, which are intended as illustrations of a few aspects of the claims. Any compositions and methods that are functionally equivalent are intended to fall within the scope of the claims. Various modifications of the compositions and methods in addition to those shown and described herein are intended to fall within the scope of the appended claims. Further, while only certain representative compounds, components, compositions, and method steps disclosed herein are specifically described, other combinations of the compounds, components, compositions, and method steps also are intended to fall within the scope of the appended claims, even if not specifically recited. Thus, a combination of steps, elements, components, or constituents may be explicitly mentioned herein or less, however, other combinations of steps, elements, components, and constituents are included, even though not explicitly stated.
The term “comprising” and variations thereof as used herein is used synonymously with the term “including” and variations thereof and are open, non-limiting terms. Although the terms “comprising” and “including” have been used herein to describe various embodiments, the terms “consisting essentially of” and “consisting of” can be used in place of “comprising” and “including” to provide for more specific embodiments of the invention and are also disclosed. Other than where noted, all numbers expressing geometries, dimensions, and so forth used in the specification and claims are to be understood at the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, to be construed in light of the number of significant digits and ordinary rounding approaches.
Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of skill in the art to which the disclosed invention belongs. Publications cited herein and the materials for which they are cited are specifically incorporated by reference.
This application claims benefit of U.S. Provisional Application No. 63/270,719, filed Oct. 22, 2021, and U.S. Provisional Application No. 63/288,152, filed Dec. 10, 2021, each of which is hereby incorporated herein by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US22/78611 | 10/24/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63270719 | Oct 2021 | US | |
| 63288152 | Dec 2021 | US |
