Patent Application
20200164083
The invention is in the field of drug-delivery and sustained-release formulations. More particularly, it concerns sustained-release compositions that deliver stabilized forms of GLP-1 agonists over periods of one month or more.
Exenatide is a 39-amino acid peptide that is a potent agonist of the GLP-1 receptor, making it an insulin secretagogue with glucoregulatory effects. It is widely used in the treatment of type 2 diabetes as the free peptide, marketed as Byetta® (Astra-Zeneca), the peptide is injected twice-daily due to the short in vivo half-life of 2.5 hours. It is highly desirable to extend the half-life of exenatide and related GLP-1 agonist peptides so as to improve their efficacy, decrease side effects, and ease the treatment burden on patients.
Peptide half-life is traditionally extended by one or a combination of several methods: (i) chemical modification of the peptide to slow metabolism; (ii) encapsulation to provide a slow-release depot formulation; and (iii) conjugation with a macromolecule to slow clearance. See, for example, Cal, et al., Drug Design, Development, and Therapy (2013) 7:963-970.
Chemical modifications of the peptide to increase half-life have resulted in once-daily GLP-1 agonists, for example lixisenatide (Lyxumia®) and liraglutide (Victoza®). Encapsulation of the peptide into PLGA (poly lactic-coglycolic acid) microparticles has been used to produce a slow-release formulation, marketed as Bydureon® (Astra-Zeneca), that allows for once-weekly subcutaneous injection. Attempts to extend the duration of Bydureon to once-monthly administrations using triglyceride formulations have not yet proven successful. Conjugation of GLP-1 peptide agonists with Fc antibody domains or with random-sequence polypeptides (XTEN) has been able to extend the half-life only up to 5-6 days.
It is convenient to consider the plasma half-life, the time required to lose one half of the drug from the system, in understanding dosing requirements. Dosing frequency is determined by the need to maintain drug levels at or above a certain efficacious level. If dosing is to occur once every half-life, then the dose must be such as to give an initial drug level 2× the efficacious level; similarly, if dosing to occur once every 2 half-lives, then the dose must be such as to give an initial drug level 4× the efficacious level. In theory, dosing could be made as infrequent as desired regardless of the half-life simply by increasing the amount of drug given per dose. Many drugs show toxicities that are related to high initial concentrations, however, placing a practical limitation on dosing frequency as a function of half-life. Dosing intervals of approximately 1-2 half-lives are typical. While several preparations of GLP-1 agonist peptides having suitable effective half-lives for once-monthly administration have been disclosed, these suffer several disadvantages. Encapsulating microspheres and phase-transition lipid formulations may suffer from initial burst-phase release of the peptide, exposing the patient to an initial undesirably high drug level. Implantable pumps require surgery for implantation and removal.
Initial bursts of drug release can be avoided through the use of covalently linked conjugates. While soluble, circulating conjugates typically do not have a sufficient half-life themselves to support once-monthly drug administration (the maximal half-life of poly(ethylene glycol) in humans is about 1 week), insoluble conjugate implants such as hydrogels are suitable. Compositions wherein drugs such as exenatide are covalently linked to various matrices through linkers having controllable rates of drug release have been previously disclosed, for example in U.S. Pat. Nos. 8,680,315; 8,754,190; 8,703,907, including insoluble matrices as disclosed in U.S. Pat. No. 8,946,405 and from hydrogels as disclosed in US2014/0288190 ('190). In one embodiment in the '190 publication, exenatide is linked to a hydrogel matrix wherein upon injection into the subcutaneous space, the hydrogel provides a depot from which exenatide is released by beta-eliminative cleavage of the linker to provide a long-acting source of the drug. Such hydrogels are by definition composed primarily of water, and the exenatide is therefore exposed to an aqueous environment for the duration of the depot. While this aqueous environment is considered advantageous for maintaining the complex structure of proteins, certain peptide sequences may suffer instabilities under such long-term conditions.
It has been found that the rate of degradation of exenatide in hydrogels under physiological conditions makes once-monthly or even less frequent administration of such formulations impractical. Exenatide has been reported to show chemical instabilities under stressed conditions (pH 7.9, 40° C. for 6 days) resulting from oxidation at M14 and W25 and from side-chain amide hydrolysis at Q13 and N28 (US patent application 2006/0194719; Zealand). Detailed kinetics of the instability were not disclosed. While a detailed model for deamidation of Asn residues in peptides has been described (Geiger & Clarke, J. Biol. Chem. (1987) 262:785-794), the rate of deamidation of peptides and proteins under physiological conditions is known to be highly variable (Robinson & Robinson, Proc Natl Acad Sci (2010) 98:12409-12413). Exenatide itself is sufficiently stable for twice-daily administration (Byetta®), and for once-weekly administration via a PLGA implant (Bydureon®).
Stabilized forms of exenatide have been disclosed. For example, PCT application WO2008/116294 (Matregen) discloses stabilized exenatide analogs modified at three positions: Q13, M14 and N28. While multiple amino acid substitutions in the exenatide sequence can be tolerated, it has now been found that replacement of N28 by a more stable residue is sufficient for effective stabilization of the peptide at pH 7.4, 37° C. Several products of exenatide deamidation, for example N28D and N28-isoD, have been disclosed in the above-cited US patent application 2006/0194719 (Zealand) and found to maintain potency for GLP-1 receptor activation. These products form an interconverting system, however, and are unstable towards equilibration to the original mixture of products.
Detailed investigations of the fate of exenatide in aqueous buffers at pH 7.4, 37° C., (i.e., physiological pH and temperature) have shown that it undergoes deamidation at Asn28 (N28) with a half-life of between 8 and 14 days, depending on the buffer. A hydrogel conjugate designed for once-monthly administration would thus be releasing primarily degradation products of exenatide after 8-14 days. It is thus essential for the stabilized GLP-1 agonist to have a sufficient resistance toward chemical degradation to minimize the amount of degraded forms released by the end of the administration period. This is achieved when the GLP-1 agonist forms less than 10% degradation products after one month at pH 7.4, 37° C., preferably less than 5% degradation products after one month at pH 7.4, 37° C.
The present invention is directed to conjugates that provide extended release of stabilized GLP-1 agonist peptides that support once-monthly or even less frequent administration of these peptides and are useful in the treatment of metabolic diseases and conditions such as metabolic syndrome, diabetes and obesity. The conjugates combine the extended stability of the GLP-1 agonist with the controlled release time provided by a suitable linker to a reservoir matrix that serves as a depot for release.
In one aspect, the present invention provides extended release conjugates comprising an insoluble matrix with a multiplicity of covalently attached linker-peptides, wherein the linkers cleave under physiological conditions of pH and temperature to release the free peptide and wherein the peptide is a stabilized GLP-1 agonist which shows degradation of less than 10% over one month at pH 7.4, 37° C. The conjugates of the invention can be illustrated schematically as formula (1)
M-(L-E)x (1)
wherein M is an insoluble matrix connected to a multiplicity (x) of GLP-1 agonist peptides E through cleavable linker L. E is a GLP-1 agonist stabilized with respect to degradation that occurs under physiological conditions of pH and temperature to show degradation of less than 10% over one month. x is an integer that represents the number of L-E moieties that yield suitable concentrations in the volume of the matrix. Suitable concentrations are 1-1000 mg peptide per ml matrix. The linker L releases free peptide with a half-life suitable for the desired period of administration.
In a second aspect, the present invention provides linker-peptides L-E having the formula (4)
wherein at least one, or both R1 and R2 is independently CN; NO2;
wherein R1 and R2 may be joined to form a 3-8 membered ring; and
wherein one and only one of R1 and R2 may be H or alkyl, arylalkyl or heteroarylalkyl, each optionally substituted; and
wherein one of R5 is (CH2)yZ, (CH2CH2O)xCH2CH2Z or (CH2)yNH—CO—(CH2CH2O)xCH2CH2Z, wherein x is 1-100, y=1-6, and the other R5 is H, alkyl, alkenylalkyl, alkynylalkyl, aryl, arylalkyl, heteroaryl or heteroarylalkyl, each optionally substituted;
Z is a functional group for mediating coupling to the insoluble matrix, and NH is the residue of an amino group of GLP-1 agonist E.
In one embodiment, R1 is CN or R3SO2, wherein R3 is alkyl or R92N, wherein each R9 is H, alkyl or substituted alkyl, one R5 is H and the other R5 is (CH2)—Z wherein n=1-6 and Z is a functional group through which the linker-peptide can be attached to M.
In one embodiment, E is [N28Q]exenatide (SEQ ID NO:2). The invention also includes this peptide and any pharmaceutically acceptable salts and pharmaceutical compositions thereof, as well as a protocol for administering a GLP-1 agonist which comprises administering to a subject having a condition benefited by a GLP-1 agonist, a composition that employs this peptide on its salt.
In a third aspect, the invention is directed to protocols for administering the conjugates of formula (1). In one embodiment, the conjugates are prepared as hydrogel microspheres suitable for subcutaneous injection using a narrow-gauge needle. It is expected that the conjugates of the invention are useful for the treatment of metabolic diseases and conditions in both humans and animals. Extended dosages of 1-3 months are achieved.
In order to achieve once-monthly administration of a peptide, the peptide must be supplied in the form of an insoluble matrix that is not circulating, but that operates as a depot for release of the drug. Circulating macromolecule conjugates of drugs are unsatisfactory as the conjugates themselves are cleared from the system, e.g., plasma, per se. Therefore, the peptide must be supplied within a matrix that is on a macro scale and wherein the peptide (or other drug) is present in the volume of the matrix at a concentration of 1-1000 mg peptide/ml matrix, preferably 1-100 mg peptide/ml matrix and more preferably 1-50 mg peptide/ml matrix. Thus, the matrix is of discernible volume, and may conveniently and collectively be administered in the form of microspheres. (The “volume of the matrix” is the total volume of the dose however supplied, including a dose of microspheres.)
In order to put the nature of the structures involved in the invention into perspective, applicants supply
A depiction of a typical insoluble hydrogel matrix comprising a linked peptide according to the invention is shown in
A generic description of this alternative is provided in
Matrix M:
Matrix M is an insoluble support to which the linker-peptide L-E is attached that serves as the reservoir from which E is released over the duration of treatment. M must be suitable for the attachment of the linker-peptide L-E, or otherwise comprise functional groups that can be derivatized so as to allow for such attachment. M must allow for free diffusion of peptide E once released through cleavage of linker L. M must furthermore be biodegradable to soluble products, and degrade slowly enough to allow for release of E without formation of excessive quantities of soluble M-L-E fragments yet quickly enough to minimize the burden of drug-free M-L remaining after E release in a multiple-dosing scenario.
In one embodiment, M is a biodegradable hydrogel prepared as disclosed in PCT Patent Publication WO2013/036847 and US2014/0288190 both incorporated herein by reference for their description of such hydrogels. These hydrogels comprise beta-eliminative crosslinkers that provide control over the rate of degradation. Thus, in some embodiments, the crosslinkers are of Formula (1) or (2) as follows.
wherein m is 0 or 1; and
wherein X and one of R1, R2 and R5 each comprise a functional group for coupling to polymer, and
with the proviso that at least one of R1 and R2 is CN; NO2;
wherein R1 and R2 may be joined to form a 3-8 membered ring; and
wherein any remaining R1 and R2 is H or is alkyl, arylalkyl or heteroarylalkyl, each optionally substituted; and
any remaining R5 is independently H or is alkyl, alkenylalkyl, alkynylalkyl, (OCH2CH2)pO-alkyl wherein p=1-1000, aryl, arylalkyl, heteroaryl or heteroarylalkyl, each optionally substituted; or
said crosslinker is of formula (2)
wherein two of R1, R2 and R5 comprise a functional group for binding to polymer;
m is 0-1;
n is 1-1000;
s is 0-2;
t is 2, 4, 8, 16 or 32;
Q is a core group having the valency t;
wherein R6 is H, optionally substituted alkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted arylalkyl, or optionally substituted heteroarylalkyl; and
with the proviso that at least one of R1 and R2 is CN; NO2;
wherein R1 and R2 may be joined to form a 3-8 membered ring; and
wherein any remaining R1 and R2 is H or is alkyl, arylalkyl or heteroarylalkyl, each optionally substituted; and
any remaining R5 is independently H or is alkyl, alkenylalkyl, alkynylalkyl, (OCH2CH2)pO-alkyl wherein p=1-1000, aryl, arylalkyl, heteroaryl or heteroarylalkyl, each optionally substituted.
The functional groups used to couple these crosslinkers to the matrix include N3, NH2, NH—CO2tBu, SH, S tBu, maleimide, CO2H, CO2tBu, 1,3-diene, cyclopentadiene, furan, alkyne, cyclooctyne, acrylate, aminooxy, keto and acrylamide. The two functional groups on Formulas (1) and (2) are different from each other, but not cognates. For example, if one is azide, the other is not cyclooctyne or alkyne.
By choosing a beta-eliminative crosslinker that results in M degradation and solubilization at a rate several-fold slower than the rate of E release from cleavage of L-E, the formation of soluble M-L-E fragments is minimized while providing for effective solubilization and clearance of the matrix. In one embodiment of the invention, these hydrogels are prepared by crosslinking multi-arm poly(ethylene glycol)s. The invention further contemplates other useful matrices, including crosslinked dextrans and hyaluronic acids.
Such matrices may be advantageously made as a slurry of microspheres that is amenable to injection using a narrow-gauge needle. Such slurries may be prepared using known methods, for example either bulk-phase emulsification or more precisely by microfluidic droplet emulsification of prepolymer mixtures. Particle size distribution can be refined through known methods if necessary, for example through sieving.
Peptide E:
The peptides (E) that are delivered by the invention are GLP-1 agonists, by which is meant a peptide capable of binding to and activating the GLP-1 receptor. Examples of GLP-1 agonists include the naturally-occurring exendins, for example exenatide (exendin-4; SEQ ID NO:1), liraglutide (SEQ ID NO:13), lixisenatide (SEQ ID NO:7), taspoglutide (SEQ ID NO:12), and sequence variants thereof. Synthetic sequences that bind and activate the GLP-1 receptor are also contemplated, for example sequences derived by in vitro screening and/or selection (Zhang, et al., Nature Commun. (2015) 6:8918).
It is essential that the peptide agonist E be chemically stable under physiological conditions during the period of administration. While this may not be an issue for direct administration of peptides, given their rapid clearance and frequent administration, extended-release preparations place more stringent requirements on peptide stability. For example, a peptide that degrades under physiological conditions with a half-life of 14 days may be perfectly suitable for once-daily administration as only 5% of the peptide will have degraded in 1 day. The same peptide under extended-release conditions of 30 days (i.e., once-monthly administration) would be 80% degraded by the end of the dosing period, and thus would be unsuitable.
The mechanism of degradation of peptides that contain the sequence Asn-Gly, for example the N28-G29 dipeptide in exenatide is shown below. As shown, an initial L-succinimide is formed which results in conversion of the asparagine residue to aspartic or isoaspartic acid. Both the D and L forms of these modified amino acids are obtained.
Examination of sequence variants of exenatide itself has revealed that replacement of N28 with other amino acids can provide an agonist of sufficient stability to support once-monthly administration via an extended-release conjugate while having minimal effects on the potency of the peptide to band and activate the GLP-1 receptor. Thus, agonists having SEQ ID NOS:2-4 wherein N28 of SEQ ID NO:1 is replaced by Q, A or K, respectively, have been found to bind and activate the GLP-1 receptor with comparable affinity and potency as native exenatide, while showing <10% or <9% chemical degradation over a one-month period.
The present invention further contemplates the use of suitably stabilized GLP-1 agonists other than exenatide. The above-described instabilities are expected to occur with other GLP-1 agonists having the Asn-Gly dipeptide sequence, for example lixisenatide and other synthetic peptide sequences. These peptides would be expected to undergo the same sequence of degradation reactions as shown above. Suitably stabilized forms of these GLP-1 agonists useful in the present invention include SEQ ID NOS:8-11. Taspoglutide (SEQ ID NO:13) and liraglutide (SEQ ID NO:14) do not have the unstable Asn-Gly dipeptide and are suitable for use in the invention. Other causes of instability may also be corrected. For the agonist of the present invention the stabilized form produces less than 10% degradation products after one month at pH 7.4, 37° C., preferably less than 9% degradation products after one month at pH 7.4, 37° C.
Cleavable Linker L:
The cleavable linker connects the GLP-1 agonist E to the insoluble matrix M and is cleaved under physiological conditions to release free E. The rate of linker cleavage determines the effective half-life of the peptide and is selected based on the desired frequency of administration. It is further important that the degradation rate of the matrix and the release rate of the peptide be coordinated with the desired frequency of administration. Previously, no attempt has been made to balance these features which balance is necessary for the success of the compositions of the invention in permitting administration on a monthly or less-frequent basis. Any linker which results in achieving this balance will be satisfactory. While there are no hard and fast rules as to the relationship between the rate of release of the drug and the rate of degelation of the matrix, a convenient rule of thumb is that the degelation rate should be approximately three times the rate of release of the free peptide. If the peptide is released too rapidly before degelation occurs, the subject is left with a deposit of gel at the time of the subsequent dosing. If the release is too slow in comparison to the degelation rate, the peptide remains bound to portions of the gel that are freed into the circulation. Neither circumstance is desirable. This relationship is described by Reid, R., et al. Macromolecules (2015) 48:7359-7369. Structural features that dictate the degelation rate of various matrices depend on crosslinking moieties and structural correlations can be used to provide suitable degelation rate for the matrix.
The balance of degradation and release rates is visualized as follows:
Release of a relatively rapidly-cleared drug from a depot through cleavage of a covalent linker imparts the half-life of the linker cleavage to the half-life of the drug in the plasma. As the dosing frequency is dependent upon drug plasma half-life, there is thus also a relationship between the linker cleavage rate and the dosing frequency. It is typically desired to minimize the difference between the maximum (Cmax) and minimum (Cmin) plasma concentrations of drug to which a patient is exposed in order to reduce the potential for toxicities arising from excessively high drug concentrations while maintaining the amount required for efficacy between doses.
If the dosing frequency is set equal to the plasma half-life of the drug, for example, there will be a 2-fold difference between Cmax and Cmin, while if the drug is dosed once every 2 plasma half-lives the difference increases to 4-fold. It is thus usual to minimize the number of drug half-lives between doses to minimize Cmax. For an extended-release conjugate, this is achieved by decreasing the release rate.
For an extended-release conjugate, however, the steady-state level of drug from a depot is inversely proportional to the release rate. While the Cmax/Cmin ratio may be arbitrarily reduced by slowing the release rate of the drug from the conjugate, the need to maintain a certain value for Cmin while using an acceptable dosage places a limit on this approach. For a single administration, the dose can be calculated by
where CL=drug clearance rate, F=bioavailability, k1=the rate of drug release from the conjugate depot, and tmin=time to reach Cmin. From this it can be shown that the lowest dose required to maintain Cmin for a given tmin is achieved when k1=1/tmin. Alternatively stated, this is when the drug release half-life (=ln(2)/k1)=ln(2)*tmin. The optimal drug release half-life for a particular dosing frequency is thus given as ln(2)*(dosing interval). When the release half-life is shorter than optimal, the required dose increases due to the depot being depleted prior to reaching tmin.
Generally speaking, drug release rates that are slower than optimal are more tolerable than ones that are too fast. Thus, a conjugate with a drug release rate supporting once-monthly administration could also be useful for biweekly or once-weekly administration regimens. Further, the relationship between the drug release rate and the required dose to maintain Cmin is such that some deviation from ideal is tolerable. This is depicted in accordance with the parameters set forth above in
In detail as shown in
Similarly, the dose required to maintain the drug concentration above Cmin at steady-state in a repeat-dosing scenario is given as:
In a repeat-dosing scenario, there is no optimal dose as described above, but rather the required dose decreases with decreasing release rate since higher proportions of drug remain from previous doses, thus adding to the total drug depot present.
There are practical limits to the use of slower release rates to decrease dose, however, given a need to minimize the release of drug-bearing gel fragments from the biodegradable matrix, a desire to minimize the total depot burden on the patient, and an increased time to attain steady-state drug levels.
In one embodiment, the cleavable linker L has the formula (3)
wherein at least one, or both R1 and R2 is independently CN; NO2;
wherein R1 and R2 may be joined to form a 3-8 membered ring; and
wherein one and only one of R1 and R2 may be H or alkyl, arylalkyl or heteroarylalkyl, each optionally substituted; and
wherein one of R5 is (CH2)yZ, (CH2CH2O)xCH2CH2Z or (CH2)yNH—CO—(CH2CH2O)xCH2CH2Z, wherein x is 1-100, y=1-6, and the other R5 is H, alkyl, alkenylalkyl, alkynylalkyl, aryl, arylalkyl, heteroaryl or heteroarylalkyl, each optionally substituted; and
Z is a functional group for mediating coupling to the matrix.
Such linkers cleave by beta-elimination. In preferred embodiments of the invention, R1 is CN or R3SO2, wherein R3 is substituted or unsubstituted alkyl or (R9)2N, wherein each R9 is independently substituted or unsubstituted alkyl; R2 is H; one R5 is (CH2)yZ and the other R5 is H. Z is N3, SH, NH—C(═O)CH2ONH2, or O—NH2. In particularly preferred embodiments, R1 is CN or CH3SO2 and/or Z is N3.
Other types of cleavable linkers may be used, for example, linkers that cleave by enzymatic or non-enzymatic hydrolysis, such as those in PCT Publication WO2006/136586 incorporated herein by reference. The sole requirement is that the linker cleavage rate be appropriate for the required administration regimen as described above.
In one embodiment of the present invention, the linker cleaves and releases E with a half-life under physiological conditions suitable to support once-monthly administration, i.e., the linker cleaves and releases E with of half-life between 220 and 1440 hours. In a more preferred embodiment, the linker cleaves and releases E with a half-life between 280 and 1000 hours, more preferably between 320 and 800 hours. In other embodiments of the invention, the linker cleaves and releases E with a half-life under physiological conditions suitable to support administration once every 3 months or biweekly.
In a specific embodiment of the invention, linker L has the formula (5) wherein R1 is CN. As demonstrated in Example 5, this linker releases peptide from the hydrogel in the rat with a half-life of 760 h.
In another specific embodiment, linker L has the formula (5) wherein R1 is CH3SO2. As demonstrated in Example 5, this linker releases peptide from the hydrogel in the rat with a half-life of 350 h.
Linker L is connected to peptide E through formation of a carbamate linkage between the C═O group of L and an amino group of E. The amino group may be either the N-terminal alpha-amino group or an epsilon-amino group of a lysine side chain. Methods for preparing both are known in the art. In one embodiment, L is attached to the alpha-amino group of E during solid-phase synthesis of the peptide.
Linker L further comprises a group Z that allows for attachment of the linker-peptide L-E to matrix using chemistry that is compatible and selective in the presence of the functional groups on peptide E. Z may be azide, in which case L-E is connected to the matrix using either a 1,3-dipolar cycloaddition reaction to form a 1,2,3-triazole linkage, or a phosphine-mediated Staudinger ligation to form an amide; both reactions are well-documented in the art. The cycloaddition reaction may be either a copper-catalyzed addition to an alkyne-derivatized matrix or a strain-promoted addition to a cyclooctyne- or bicyclononyne-derivatized matrix. Z may also be an aminooxy or aminooxy-acetamido group, in which case L-E is connected to a keto-derivatized matrix using an oximation reaction. Or Z itself may be a keto group, connecting to an aminooxy group on the matrix. Z may also be a thiol group, in which case L-E is connected to a haloacetyl-derivatized, maleimide-derivatized, or epoxy-derivatized matrix through formation of a thioether.
Thus, the functional groups used to couple L to the matrix include N3, NH2, NH—CO2tBu, SH, StBu, maleimide, CO2H, CO2tBu, 1,3-diene, cyclopentadiene, furan, alkyne, cyclooctyne, acrylate, aminooxy, keto or acrylamide.
Preparation of the Conjugates:
The conjugates are prepared by connecting a peptide E, a cleavable linker L, and a matrix M. In one embodiment, the connections are made pairwise with the order of connection being flexible. Thus, peptide E may be first connected to linker L, and the resulting L-E connected to matrix M. Alternately, linker L may be connected to matrix M, and E then connected to M-L. When M is a matrix prepared by polymerization of monomer units, M-L or M-L-E may be the result of the polymerization process by using a crosslinkable monomer-L or monomer-L-E unit in the reaction.
For biological use, the conjugates must meet stringent criteria for sterility and endotoxin contamination. While in certain cases it may be possible to use a terminal sterilization process, in general the conjugates of the invention are not amenable to this. Insoluble hydrogels, for example, are also not amenable to sterile filtration. Thus, it may be desirable that the conjugates of the invention are prepared under aseptic conditions. The conjugates may be prepared either as injectable microsphere suspensions or they may be formed in situ by coinjection of the monomer units.
Formulations:
The conjugates may be formulated using standard pharmaceutically acceptable buffers and excipients to improve injectability and storage stability. Typical formulations include a buffer to maintain pH between 4 and 7, preferably between 5 and 6. Excipients may include stabilizing agents for the peptide drug, for example antibacterial and/or antioxidant agents such as meta-cresol, tonicity-adjusting agents such as a polyol like mannitol, and viscosity-reducing agents such as taurine, theanine, sarcosine, citrulline, and betaine.
Methods of Use:
The conjugates of the invention are useful in the treatment of metabolic conditions and diseases in both humans and animals in which the administration of a GLP-1 agonist is known to be effective, including but not limited to type-2 diabetes, metabolic syndrome, and obesity. The greatly increased effective half-life enables once-monthly dosing, thus improving patient compliance (obviating missed doses) and improving patient quality of life. Dosing is preferentially by subcutaneous injection, and may be performed using an autoinjector.
The following examples are offered to illustrate but not to limit the invention.
A solution of 2.4 mM exenatide (1 mL), 0.1% NaN3 and 200 uM Lys(DNP)OH as internal standard in 200 mM NaPi, pH 7.4, was kept at 37° C. At intervals, 50 uL aliquots were removed and frozen at −20° C. until assay. Various samples were thawed and analyzed a) by HPLC, b) for GLP1R agonist activity, and c) for protein isoaspartate methyl transferase activity. The sample incubated for 56 days was subjected to HPLC and samples at RV 9.9, 10.4 and 10.8 were collected and individually analyzed for purity by analytical RP-HPLC, GLP1R agonist and PIMT activities.
(a) HPLC profiles of the deamidation of exenatide vs. time are shown in
(b) Time points were analyzed for GLP-1 receptor activation by GLP1R cAMP Hunter™ bioassay (DiscoverX). The EC50 values are summarized below in Table 1.
The Asp peptide isolated from the deamidation mixture contained a small amount of potentially interfering isoAsp peptide, but synthetic [Asp28]exenatide showed agonist activity comparable to exenatide. The amount of D-isoAsp formed in the deamidation reaction at 56 days is so small (˜12%) it cannot contribute significantly to agonist activity of the mixture.
(c) To assay the presence of isoaspartate, protein isoaspartate methyl transferase (PIMT) assays were performed using the ISOQUANT® isoaspartate detection kit as recommended by the supplier (Promega). Sample mixtures at t=0 and t=56 days, as well as individual samples purified from the t=56 day mixture were assayed for isoAsp peptides.
The Ala, Asp, Gln and Lys substitutions for Asn28 of exenatide were prepared by SPPS. All [Xaa28]exenatides had EC50 values (17- to 41 pM) comparable to exenatide (17 pM) in a GLP-1RA assay. Upon extended incubation (˜3 months) of these [Xaa28]exenatides in 200 mM Pi, pH 7.4, 37° C., major new peaks were not observed, except for [Asp28]exenatide which slowly isomerized to [isoAsp28]exenatide. At low peptide concentrations (˜0.2 mM), small losses were observed in A280 consistent with non-specific adsorption to vessel surfaces. At 2 mM [Gln28]exenatide, the t1/2 for loss of peptide was estimate at >1=30 weeks. Hence, [Gln28]exenatide is very stable under physiological conditions. A t1/2 of 30 weeks would give a <9% loss in one month.
The ability of various exenatide analogs to activate the GLP-1 receptor was assayed using a cAMP assay (GLP1R cAMP Hunter™ bioassay (DiscoverX)). The N28D, N28A, N28K, and N28Q analogs were found to have comparable ability to exenatide.
When the mixture of degradation products (
Preparation of Macromonomer A
(a) A solution of 1-(bis-(2-methoxyethyl)aminosulfonyl)-7-azido-2-heptyl succinimidyl carbonate (prepared using the methods described in WO2013/036847; 1.12 mmol) in 5 mL of acetonitrile was added to a solution of H-Lys(Boc)-OH (300 mg, 1.22 mmol) and NaHCO3 (420 mg, 5.0 mmol) in 10 mL of water and 5 mL of acetonitrile. After 0.5 h, the solution was concentrated under vacuum to remove acetonitrile, acidified with 1 N HCl, and extracted with ethyl acetate. The extract was washed with water and brine, then dried over MgSO4, filtered, and evaporated to provide crude Na-[1-(bis-(2-methoxyethyl)aminosulfonyl)-7-azido-2-heptyloxy)carbonyl]-Ne-(BOC)-lysine (“azido-linker[mod]-Lys(Boc)-OH”).
Prepared according to this method were azido-linker[mod]-Lys(Boc)-OH wherein the modulator is bis(2-methoxyethyl)aminosulfonyl, dimethylaminosulfonyl, cyano, methylsulfonyl, 4-methylpiperidinylsulfonyl, morpholinosulfonyl or phenylsulfonyl.
(b) The above crude azido-linker[mod]-Lys(Boc)-OH was dissolved in 25 mL of CH2Cl2 and treated with N-hydroxysuccinimide (138 mg, 1.2 mmol) and dicyclohexylcarbodiimide (0.5 mL of a 60 wt % solution in xylenes) for 2 h. The mixture was filtered and chromatographed on SiO2 using a gradient of acetone in hexane to provide the succinimidyl ester azido-linker[mod]-Lys(Boc)-OSu.
Prepared according to this method were azido-linker[mod]-Lys(Boc)-OSu wherein the modulator is bis(2-methoxyethyl)aminosulfonyl, dimethylaminosulfonyl, cyano, methylsulfonyl, 4-methylpiperidinylsulfonyl, morpholinosulfonyl or phenylsulfonyl.
(c) A solution of 20-kDa 4-arm PEG-tetraamine in acetonitrile (10 mL, 200 mg/mL, 40 mM amine, 0.4 mmol, 1 equiv) containing N,N-diisopropylethylamine (80 mM, 0.8 mmol, 2 equiv), was treated with a solution of azido-linker[mod]-Lys(Boc)-OSu in acetonitrile (3.3 mL, 145.5 mM, 0.48 mmol, 1.2 equiv). The resulting mixture was kept at room temperature for 1 h, then a 0.010 mL sample was assessed for amine content by TNBS assay using the PEG-tetraamine as a standard; typically <1% of the starting amines remain. The reaction was then treated with acetic anhydride (40.8 mg, 0.0378 mL, 0.4 mmol, 1 equiv) for 15 minutes prior to concentration under vacuum to a viscous syrup (˜4 mL) that was slowly added to MTBE (350 mL). The resulting suspension was stirred for 1 h, then the precipitate was recovered by filtration, washed with MTBE (150 mL), and dried under vacuum to give macromonomer A as a white solid.
Prepared according to this method were macromonomer A wherein the modulator is bis(2-methoxyethyl)aminosulfonyl, dimethylaminosulfonyl, cyano, methylsulfonyl, 4-methylpiperidinylsulfonyl, morpholinosulfonyl or phenylsulfonyl.
Preparation of Macromonomer B
A 4-mL, screw top vial was charged with PEG20kDa-[NH2]4 (SunBright PTE-200PA; 150 mg, 7.6 μmol PEG, 30.2 μmol NH2, 1.0 equiv, 20 mM final amine concentration), MeCN (1.5 mL), and iPr2NEt (7 μL, 40 mol, 1.3 equiv, 27 mM final concentration). A solution of the activated ester cyclooctyne (39 mol, 1.3 equiv, 27 mM final concentration) was added and the reaction mixture was stirred at ambient temperature. Reactions were monitored by C18 HPLC (20-80% B over 11 min) by ELSD. When complete, Ac2O (3 μL, 30 μmol, 1 equiv per starting NH2) was added to the reaction mixture and the mixture was stirred for 30 min. The reaction mixture was then concentrated to a thick oil and suspended in MTBE (20 mL). The resulting suspension as vigorously stirred for 10 min. The resulting solids were triturated three times with MTBE (20 mL) by vigorously mixing, pelleting in a centrifuge (2800 rpm, 4° C., 10 min), and removal of the supernatant by pipette. The resulting solids were dried under vacuum at ambient temperature for no more than 30 min. Stock solutions were prepared in 20 mM NaOAc (pH 5) with a target amine concentration of 20 mM. Cyclooctyne concentration was then verified by treatment with PEG7-N3 (2 equiv) and back-titration of the unreacted PEG7-N3 with DBCO-CO2H.
Macromonomers prepared using this procedure include those wherein the cyclooctyne group is MFCO, 5-hydroxycyclooctyne, 3-hydroxycyclooctyne, BCN, DIBO, 3-(carboxymethoxy)cyclooctyne, and 3-(2-hydroxyethoxy)cyclooctyne, prepared using MFCO pentafluorophenyl ester, 5-((4-nitrophenoxy-carbonyl)oxy)cyclooctyne, 3-(4-nitrophenoxycarbonyl)oxycyclooctyne, BCN hydroxysuccinimidyl carbonate, DIBO 4-nitrophenyl carbonate, 3-(carboxymethoxy)cyclooctyne succinimidyl ester or 3-(hydroxyethoxy)cyclooctyne 4-nitrophenyl carbonate.
The derivatized 8-arm macromonomer P, is prepared as follows: Macromonomer P is an 8-arm PEG with each arm terminated with a cyclooctyne. A solution of 200 mg of 40-kDa 8-arm PEG-amine.HCl (JenKem Technologies; 40 umol NH2), 20 mg of BCN p-nitrophenyl carbonate (SynAffix; 63 umol), and 20 uL of N,N-diisopropylethylamine (115 umol) in 2 mL of DMF was stirred 16 h at ambient temperature. After quenching with 0.5 mL of 100 mM taurine in 0.1 M KPi, pH 7.5, for 1 h, the mixture was dialyzed sequentially against water, 1:1 methanol/water, and methanol using a 12-kDa membrane. After evaporation, the residue was dissolved in 2 mL of THF and precipitated with 10 mL of methyl tbutyl ether. The product was collected and dried (190 mg). Macromonomers P comprising other cyclooctynes may be prepared similarly by using the appropriate activated cyclooctyne.
The derivatized 4-arm macromonomer T is prepared as follows: T comprises a 4-arm PEG with each arm terminated with a releasable linker-azide. A solution of 25 umol of the azido-linker-succinimidyl carbonate (prepared using the methods described in WO2013/036847) in 1 mL of ACN was added to a mix of 5 umol (100 mg) of 20-kDa 4-arm PEG-amine hydrochloride (pentaerythritol core, JenKem Technologies) in 1 mL of water and 40 uL of 1.0 M NaHCO3 (40 umol). After 1 hr at ambient temperature the solution was dialyzed (12-14 k MWCO) against 1 L of 50% methanol followed by 1 L of methanol. After evaporation, the residue (109 mg) was dissolved in 2.12 mL of sterile-filtered 10 mM NaOAc, pH 5.0, and stored frozen at −20° C. The azide concentration determined by reaction with DBCO-acid was 9.5 mM. Macromonomers T comprising linker-azides having alternate modulators may be prepared similarly by using the appropriate azide-linker-succinimidyl carbonates.
The peptide-releasing hydrogels may be prepared from the derivatized macromonomers in at least two different ways.
(a) In one embodiment, linker-peptide is attached to macromonomer P prior to formation of the insoluble hydrogel matrix. An azido-linker-peptide of formula (4) such as that illustrated in Example 1 herein is mixed with macromonomer P in a stoichiometry such that some fraction of the arms of P are derivatized with linker-peptide. The resulting material is then crosslinked using sufficient macromonomer T to react the remaining arms of P with arms of T and thus form an insoluble matrix. Thus, n moles of azido-linker-peptide of formula (4) is mixed with n/(8f) moles of macromonomer P, where f=the desired fractional loading of arms with linker-peptide (i.e., for 50% loading of arms, f=0.5) in a suitable solvent, typically buffered aqueous media. After allowing sufficient time for the azido-linker-peptide to react, the resulting solution is mixed with n(1/f−1)/4 moles of macromonomer T to form the insoluble hydrogel matrix. Typically, f is chosen such that there are >3 crosslinked arms to each P residue in the hydrogel matrix (f<0.625). The crosslinking reaction to form the insoluble hydrogel matrix can be performed either as a bulk material or in a suspension or emulsion so as to form a finely-divided particulate polymer, for example microspheres as described in Example 2 herein.
(b) Alternatively, the insoluble hydrogel matrix can be prepared, followed by attachment of the linker-peptide. For a final hydrogel comprising 8f equivalents of linker-peptide for each P macromonomer residue in the matrix, an insoluble hydrogel matrix is formed by reaction of n/(8f) moles of macromonomer P with n(1/f−1)/4 moles of macromonomer T. The crosslinking reaction to form the insoluble hydrogel matrix can be performed either as a bulk material or in a suspension or emulsion so as to form a finely-divided particulate polymer, for example microspheres as described in Example 2 herein. The polymerized matrix is then allowed to react with a solution of at least n moles of azido-linker-peptide of formula (4), such that the linker-peptide is covalently attached to the matrix. Unreacted azido-linker-peptide is washed from the matrix to provide the peptide-releasing hydrogel.
Peptides were synthesized by standard solid-phase methodology using Chemmatrix® Rink amide resin (0.5 meq/g) on a Symphony® peptide synthesizer. Fmoc-amino acids (5 eq per coupling) were double-coupled to the N-terminus of the peptide chain using HCTU (4.9 eq per coupling) and N,N-diisopropylethylamine (10 eq per coupling) in DMF at ambient temperature. Fmoc groups were removed using 20% 4-methylpiperidine in DMF. [N28Q]exenatide was deprotected and cleaved from the resin using 95:2.5:2.5 trifluoroacetic acid/triisopropylsilane/dithiothreitol.
Crude [N28Q]exenatide (22 mg) was purified on a semi-preparative scale using a Shimadzulm LC-20AD system equipped with a Peak Scientific HiQ® 5μ C18 column (50×20 mm ID) eluting with a linear gradient of 30%-60% MeCN (0.1% TFA) in water (0.1% TFA). The purest fractions, as judged by analytical C18 HPLC, were combined, concentrated by ˜40% to remove MeCN, and lyophilized to provide [N28Q]exenatide (6.4 mg, 1.4 mmol) as a fluffy white solid. C18 HPLC purity determined at 280 nm: 86% pure (RV=9.4 min); [N28Q]exenatide; m/z=4200.
On-resin N-terminal carbamoylation of peptides was performed by a modification of a previously described method (Schneider, E. L. et al, Biocong. Chem (2016) 1 March on line prepublication) and is exemplified by the following.
In a septum-capped 125 mL Erlenmeyer flask, NH2[N28Q]exenatide (free α-amine) Chemmatrix® Rink amide resin (0.5 meq/g substitution, 0.48 mmol peptide/g peptide-resin, 4.00 g peptide-resin, 0.48 mmol peptide) was gently stirred in 40 mL of DMF for 30 min at ambient temperature under N2. The swollen resin was then treated with 8 mL of O-(7-azido-1-cyano-2-heptyl)-O′-succinimidyl carbonate (0.18 M in DMF, 1.44 mmol, 30 mM final) and 4-methyl-morpholine (158 μL, 1.44 mmol). The reaction mixture was gently stirred under N2 for 2 h then vacuum filtered. The resin was washed with successively DMF (3×30 mL) and CH2Cl2 (4×50 mL) then dried under high vacuum. Kaiser test was negative for free amines in intermediate linker-modified resin (3.84 g). The resin was then treated with 40 mL of 90:5:5 TFA:TIPS:H2O with stirring under N2. After 2.5 h, the resin was vacuum filtered and washed with TFA (2×10 mL). The filtrate was concentrated to −20 mL. The crude linker-peptide was precipitated by drop-wise addition of the TFA concentrate to ice-cold Et2O:hexane (2:1, 160 mL) in 4 tared 50 mL Falcon tubes. After incubating on ice for 30 min, the crude linker-peptide was pelleted by centrifugation (3 min at 2000×g), and the supernatant was decanted. The pellet was triturated/vortexed with ice-cold Et2O:hexane (2:1, 160 mL), incubated on ice, centrifuged, and decanted as above. After drying under high vacuum, the crude linker-peptide was isolated as an off-white solid (1.76 g) then dissolved in 5% AcOH. After heating at 40° C. for 1 h, the crude material was purified by preparative HPLC. MS: m/z=4408.
Nα-[1-(methylsulfonyl)-7-azido-2-heptyloxycarbonyl]-exenatide was similarly prepared using O-(7-azido-1-(methylsulfonyl)-2-heptyl)-0′-succinimidyl carbonate. MS: m/z=4461.
A 2-reagent Telos® hydrophobic flow-focusing microfluidic chip (Dolomite) with seven parallel 50 um drop forming channels was used. Fluid flow was controlled by a gas-pressure driven pump, similar in function to the Mitos Pressure Pumps manufactured by Dolomite Microfluidics. These pumps use pressurized gas to drive the flow of liquid through the microfluidic chip. The driving pressure is computer controlled using proportional pressure regulators (Proportion Air, MPV series) to maintain a stable flow rate by using a feedback loop from a liquid flow sensor (Sensirion, SLI-0430). This type of flow control is scalable to deliver liquid from multi-liter reservoirs, and produces flow rates with ˜1% standard deviation, superior to syringe pumps that often have up to a 20% oscillation in their flow rate. This system was used to deliver the two hydrogel prepolymer solutions and the continuous phase. Typical flow rates were 2.1 ml/h for each prepolymer solution and 14 mL/h for the continuous phase. The continuous phase was composed of decane containing 1% w/v Abil® EM90 (Evonik) and 1% w/v PGPR (Danisco). The outlet tube of the device was connected to a fraction collector (Gilson FC203B), and fractions were collected in 10 minute intervals. Quality control was performed by photographing the chip at 5× magnification with a high speed camera (UniBrain®, Fire-I 580b) attached to a microscope (Nikon™, EQ-51436) equipped with an automated stage to visualize the seven channels of the chip. Images of each channel were collected every 5 minutes. Fractions containing large particles resulting from device failure could be eliminated from the batch.
Microspheres washes were conducted in 50 mL Teflon® (FEP) centrifuge tubes (Oak Ridge, 3114-0050). After washing, the microspheres were recovered by centrifugation. Centrifugation is conducted for 5 min at 3000 g's for separation of organic phases, and 20 min for separation of aqueous phases. All solutions and wash solvents were filtered through 0.2 um Nylon-66 filters (Tisch, SPEC17984).
A suspension of microspheres from a microfluidics run (30 mL) in decane containing surfactant were allowed to cure at room temperature for 24 h. The decane layer was removed, and the microspheres were partitioned between 0.1% (w/v) aqueous NaN3 (15 mL) and pentane. The mixture was agitated for 30 min then the pentane phase was separated by centrifugation. The microsphere suspension was then treated with water (30 mL) and washed with five consecutive (39 mL) portions of pentane. After centrifugation, the excess aqueous phase was removed and the microsphere slurry was treated with an equal volume of 50% w/v TFA for 30 min for sterilization. The microspheres were recovered by centrifugation at 1000 g's (note: the spheres shrink in TFA and form a compact pellet, so excessive force should be avoided). The pellet was treated with 0.125 M Na2HPO4 (150 mL) to give a suspension of pH ˜6.5. After swelling for 18 h the spheres were recovered by centrifugation, then washed with five 100 mL portions of water and finally five 100 mL portions of 70% ethanol. The slurry was pelleted to final concentration at 3000 g's for 30 min. After aspiration of the supernatant, the microsphere slurry was transferred to a 60 mL syringe (BD No. 309653) that was connected by a Luer coupling to another 60 mL syringe and homogenized by several back-and-forth passages to disperse small clumps. The syringe containing the slurry was used to load individual 10 mL syringes through the Luer coupling that were stored at 4° C. until use.
Three 0.100 mL portions of amino-microsphere slurry in acetonitrile were weighed to determine their density (0.79±0.2 g/mL), then each portion was then treated with 0.900 mL of 50 mM NaOH for 18 h at room temperature to cleave crosslinks and form [H2N-Lys(NH2)—NH]4-PEG20kDa monomers. Each sample was assayed for total amine concentration by TNBS assay by diluting 0.030 mL to 0.120 mL with borate buffer (100 mM, pH 9.3) then treating with 0.150 mL of borate buffer containing 0.04% w/v sodium 2,4,6-trinitrobenzenesulfonate in a microtiter plate. The change in absorbance of the TNBS reactions at 420 nm was monitored for 3 h in a plate reader at 25° C. then the final absorbance at 420 nM was recorded. Equivalent reactions containing TNBS alone were used for background subtraction and reactions containing 40, 20, or 10 uM lysine were used for amine concentration standards. The total amine concentration/2 of the microsphere digests provides the free e-amine content of the gel.
The reaction is performed in the syringe reaction vessel as follows. For each 4 mL of a packed suspension of amino-microspheres in MeCN containing 2 μmol amine/mL gel slurry are added 32 μmol DIPEA (4 equivalents) in 1 mL MeCN, and 9.6 μmol (1.2 equivalents) of 1-fluoro-2-cyclooctyne-1-carboxylate pentafluorophenyl ester (MFCO-PFP) in 1 mL MeCN. After 1 h rocking at ambient temperature, a small amount (˜50 uL) of microspheres is expelled from the syringe outlet and treated with 0.5 mL of 0.04% w/v TNBS in 0.1 M sodium borate, pH ˜9.3 (1) for 30 min; complete reaction is indicated by a microsphere color matching the TNBS solution compared to starting amino-microspheres which stain an intense orange. After reaction, the microspheres are capped by the addition of 8 μmol (1 equivalent) of Ac2O in 1 mL MeCN for 10 min. After removal of the supernatant, ˜2 mL of the microspheres is transferred to a second 10 mL syringe, each slurry is washed with 4×3 volumes MeCN per packed slurry volume and the slurries combined.
The coupling of the azido-linker-[N28Q]exenatides prepared in Example 1 was performed in the syringe reaction vessel described in (Schneider, et al, supra). To a suspension of 2.4 g of a slurry of MFCO-derivatized microsphere of Example 3 (11.2 μmol MFCO) in 30% MeCN in a 10 mL syringe was added a solution of 46 mg (10.4 μmol) of Nα-[1-(methylsulfonyl)-7-azido-2-heptyloxycarbonyl]-[N28Q]exenatide in 2 mL 30% MeCN. The mixture was slowly rotated until the OD280 of an aliquot was constant at −24 hr. About 50% of the slurry was transferred to a second syringe, and both samples were washed with 4×2 mL of 30% MeCN and then 5×5 mL of 10 mM NaPi, 0.04% Tween® 20, pH 6.2. The [N28Q]exenatide-loaded microspheres were then syringe-to-syringe transferred to several 1.0 mL dosing syringes. The total loading of the microsphere was 1.9 μmol peptide gm−1 of slurry as determined by the total peptide released at pH 8.4.
Release of free [N28Q]exenatide from the microspheres was measured in vitro by suspending a sample of the conjugate in 0.1 M borate, pH 9.4, and following the solubilization by the increase in OD280 at 37° C. (
Microspheres comprising [N28Q]exenatide attached via a linker wherein R1=CN and R2=H were prepared similarly, using Nα-[1-cyano-7-azido-2-heptyloxycarbonyl]-[N28Q]exenatide (Example 1). The final preparation comprised 2.2 μmol peptide gm−1 in isotonic acetate buffer (10 mM acetate, 120 mM NaCl, pH 5.0) with 0.05% Tween® 20.
The contents of tared 1 mL dosing syringes containing the microsphere slurries prepared in Example 4 were administered through a 27 gauge needle s.c. into the flank of cannulated male Sprague Dawley rats, ˜350 g. Each syringe contained 0.45 or 0.98 μmol peptide at 1.9 μmol peptide g−1 slurry. The syringes were weighed prior to and after dosing to verify the mass delivered to each rat. Blood samples (300 μL) were drawn and the serum was frozen at −80° C. until analysis.
Exenatide concentrations were measured by ELISA according to the manufacturer's protocol (Peninsula Laboratories Inc., # S-1311). Frozen serum samples were thawed on ice and diluted between 5 and 20-fold in the provided rat serum. The standard exenatide showed an EC50=0.22 nM (reported 0.19 nM). Data replicates were averaged and fitted to appropriate pharmacokinetic models. [N28Q]Exenatide concentrations in sera were measured by LC-MS/MS.
The results are shown in
The ability of [N28Q]exenatide to provide tolerance to a bolus of oral glucose relative to exenatide was determined in mice. A total of 54 male, 8-week old C57BL/6J mice (JanVier France) were acclimatized for 2 weeks then stratified into 9 groups (n=6). On day 0, mice were fasted for 4 h then dosed with test article by subcutaneous injection at t=−15 minutes followed by glucose at 0 minutes. Blood glucose was measured at −60, −15, 0, 15, 30, 60, and 120 minutes. Blood samples for insulin measurements were taken at 0 and 15 minutes. Results are shown in
A total of 55 male Zucker diabetic fatty rats (ZDF-Leprfa/Crl) 6 weeks of age, and 180-200 gram (Charles River, USA) were single-housed and blood glucose and body weight were monitored bi-weekly for 2-4 weeks. Based on morning-fed blood glucose, outliers were excluded and 40 diabetic rats (average weight 340 g, blood glucose 9.7 to 22.5 mM, average 16.2 mM) were stratified into 4 groups of n=10.
At t=0:
Group I received vehicle in an Alzet® pump (2ML4);
Group II received exenatide Alzet® pump (30 μg/kg/day, in AcOH, pH 4.5);
Group III received s.c. hydrogel microsphere-[N28Q]exenatide having drug-release modulator R1=CN described in Example 4, 0.37 mg peptide) plus vehicle pump;
Group IV received s.c. hydrogel microsphere-[N28Q]exenatide (3.7 mg peptide) plus vehicle pump.
On day 29, two days after the 4 week OGTT, pumps were replaced and the hydrogel microsphere-[N28Q]exenatide was re-dosed s.c. at the same levels. On day 56, the pumps were removed and animals were allowed to recover for 4 wks. Six rats that became diabetic at a later age received [N28Q]exenatide in osmotic pumps (30 μg/kg/day, in AcOH, pH 4.5) on day 28 that were discontinued on day 56, after which animals were allowed to recover for 4 weeks.
Body-weights were monitored daily from day −3 throughout the study. Food and water intake were monitored on day −3 and daily for the first 11 days after the first dose then bi-weekly for the rest of the study period. Blood sampling was performed for pharmacokinetic studies 2 days after the first dose and then once weekly. HbA1c was measured day −3, and days 26 and 55 before OGTT, and the gastric emptying test was performed on day 26. For the OGTT, rats were semi-fasted overnight (60%) then PO glucose (2 g/kg in 10 mL) was administered at t=0. Blood glucose and insulin were measured at t=−60, −15, 0, 15, 30, 60 and 120 minutes after the glucose challenge. Gastric emptying was measured by administration of acetaminophen (100 mg/kg) with the OGTT on day 26, and blood levels were measured at 15, 30, 60 and 120 min.
The results are shown in
A single dose of a hydrogel microsphere preparation comprising [N28Q]exenatide was effective at controlling blood glucose for at least one month.
A. Syringes (0.5 mL U-100 insulin syringe with fixed 29 g×½″ needle, BD) were filled under sterile conditions with the [N28Q]exenatide-microsphere slurry prepared in Example 4 in isotonic acetate (10 mM Na Acetate, 143 mM NaCl) pH 5.0 0.05% Tween® 20. Microspheres using drug-release modulator R1=MeSO2 contained 1.3 μmol peptide/g slurry, and microspheres using drug-release modulator R1=CN contained 1.4 μmol peptide/g slurry. The content of each syringe was administered SC in the flank of six cannulated male Sprague Dawley rats (average weight 270 g).
The needle assembly was purged of air and weighed prior to and following dosing to determine the mass of the slurry delivered to each rat; with the MeSO2 modulator 130 mg slurry containing 0.7 mg peptide (170 nmol) was administered to each rat, and with the CN modulator 400 mg slurry containing 2.5 mg peptide (580 nmol) was administered.
Blood samples (300 μL) were drawn at 0, 1, 2, 4, 8, 24, 48, 72, 120, 168, 240, 336, 432, 504, 600, 672 hours for both linkers and additional samples were obtained at 840, 1008, 1176, 1344, 1512, 1680, 1848, and 2016 hours for the linker with the CN modulator. Serum was prepared and frozen at −80° C. until analysis. Serum [N28Q]exenatide was analyzed by LC/MS/MS.
The results are shown in
B. The small amounts of microspheres needed in the mouse required a diluent to allow accurate dosing. Using a dual syringe-based reaction vessel {Schneider, 2016 #24} the buffer of a [N28Q]exenatide-microsphere slurry (˜1 mL for drug-release modulator R1=MeSO2, 4 mL for R1=CN) was aseptically exchanged for a solution of isotonic acetate pH 5.0 (10 mM NaOAc, 143 mM NaCl), 25% glycerol and 0.05% Tween® 20. This diluent served to keep the microspheres in a homogeneous suspension prior to and during administration and allowed dosing of convenient volumes. The slurry was then diluted with the same mixture to give 264 nmol peptide/mg slurry (R1=MeSO2) or 720 nmol peptide/mg slurry [R1=CN). Syringes (0.5 mL U-100 insulin syringe with fixed 29 g×½″ needle, BD) were filled with the suspended microspheres under aseptic conditions. The needle assembly of each syringe was purged of air and weighed prior to and following dosing to determine the average mass of slurry delivered to each mouse.
For R1=MeSO2, 120 mg of slurry containing 130 ug peptide (30 nmol) was administered SC in the flank of each of 18 CD-1 mice (average weight 30 g). Blood samples (100 μL) were drawn from the orbital sinus at 8, 24, 48, 72, 96, 120, 168, 240, 336, 408, 504, 576 and 672 hours on a staggered schedule to give 6 replicates at each time-point, and sera of each were prepared. For R1=CN, 200 mg slurry containing 605 μg peptide (144 nmol) was likewise administered SC to 24 CD-1 mice. Blood samples (100 μL) were drawn from the orbital sinus at the same times as above, and also at 840, 1008, 1176, 1344, 1512, 1680, 1848, and 2016 hours on a staggered schedule to give 6 replicates at each time-point. Serum was prepared and frozen at −80° C. until analysis. Serum [N28Q]exenatide was analyzed by LC/MS/MS.
Serum samples were treated with 3 vol of ACN and centrifuged. The supernatant was dried, reconstituted and applied to a HPLC MS/MS system. The sample was eluted by a water/ACN gradient containing 0.1% formic acid. The calibration curve for [N28Q]exenatide was linear over the range of 0.25-100 ng/mL. HPLC-MS/MS analyses were carried out on a Sciex 5500 QTrap® mass spectrometer coupled with a Shimadzu HPLC system. The Shimadzu HPLC system consisted of two LC-30AD HPLC pumps and a SIL-30AC autosampler with a 100-μL loop installed. The chromatographic separations were achieved on a 3-μm C18, 2.1×50 mm HPLC column, with mobile phase gradients. The mass spectrometer was operated in positive electrospray ionization mode and the resolution setting used was the unit for both Q1 and Q3. The multiple-reactions monitoring (MRM) transition was m/z=841.1->396.3 for [N28Q]exenatide. Peak-area integrations were performed using Analyst software (version 1.5.2) from Sciex.
The results are shown in
C vs. t curves (text) were analyzed using GraphPad Prism by non-linear regression of eq X (text) with weighting by 1/SD2; since ka>>k1 we modeled the single exponential phase of the terminal half-life using data points later than the first few days.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US17/22791 | 3/16/2017 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62309330 | Mar 2016 | US | |
| 62416058 | Nov 2016 | US |
