Patent Application
20150064215
Disclosed herein is a targeted delivery and expression system of multiple therapeutic molecules. Therapeutic molecules include cellular components such as RNA, DNA, proteins or any combination of at least two of the cellular components. In an embodiment, the delivery and expression system is an inter-kingdom expression system. The system provided herein has great potential to overcome delivery limitations because of their biocompatibility, low toxicity, small size, stable plasmid maintenance, targeted delivery ability, efficient gene transfer, feasible cargoes and low costs. Provided herein are methods and compositions having preventive, diagnostic and therapeutic applications against cancer and infectious diseases. Described herein is a method of treatment of cancer or tumor using a modified bacteria or composition comprising the modified bacteria. In certain embodiments, the method of prevention or treatment of tumor/cancer or influenza or other infectious diseases is in combination with other treatment approaches. In certain embodiments, the treatment against cancer or tumor is chemotherapy, radiation therapy, gene therapy, surgery or a combination thereof. Described herein are vectors, cells comprising the vectors. Also described herein are therapeutic and prophylactic compositions comprising the modified bacteria. In certain embodiments, the therapeutic and prophylactic compositions contain a purified form of the modified bacteria. In certain embodiments, the therapeutic and prophylactic compositions do not contain other strains of microorganisms. In one aspect, the modified bacteria harboring therapeutic cargoes grow within a tumor/cancer, retarding its growth. In one aspect, the tumor/cancer is a solid tumor/cancer. In one aspect, the modified bacteria are rapidly eliminated from normal tissues. In another aspect, the modified bacteria are excellent carriers for vaccine antigens from other bacteria, viruses, parasites and tumors, being able to stimulate strong host immune responses against the corresponding antigens.
The low costs, fast production, diverse natural and modified tropism profiles, high packaging capacity, coupled with their immunological tolerance in target organs and relative ease of control in the case of adverse events, make bacterial-mediated delivery an attractive alternative to gastrointestinal, respiratory, urogenital tracts and solid tumors. Therapeutic benefits of bacteria including attenuated Salmonella spp., Shigella spp., Bacillus Calmette-Guerin (BCG), Y. enterocolitica, Lactobacillus spp. and non-pathogenic E. coli, have been observed in vaccination against infectious disease, gene therapy against cancer, and topical delivery of antibodies and immunomodulatory cytokines in inflammatory bowel disease. These encouraging but pre-clinical studies justify further development of bacteria as a therapeutic vector against many types of pathology.
In cancer therapy, reducing problems such as inadequate tumor targeting, inefficient penetration of a tumor by a drug, toxicity to normal cells and limited lifetimes of therapeutic agents is a major target of research (Minchinton and Tannock 2006). Microbial organisms, which can act as natural anti-cancer agents and can be modified to enhance their therapeutic capabilities, are useful in overcoming many of the problems of conventional treatments (Forbes 2010). Most studies use attenuated bacteria to decrease the virulence (Hoffman 2011) and augment their natural cytotoxicity with vectors designed to deliver an agent to the tumor. Strategies for bacteria-based treatment have included delivering pro-drugs that are activated in the tumor (Barbe, Van Mellaert et al. 2006), producing a cytotoxic protein in the bacteria (Zhang, Man et al. 2010), delivery of DNA expression vectors and short hairpin RNA (shRNA) (Xiang, Fruehauf et al. 2006).
Oncolytic bacteria have a long/checkered history in cancer therapy and are perceived as safe but ineffective. Many challenges remain in effectively utilizing bacteria as antitumor agents and, to date, clinical trials of bacterial mediated therapy have had modest results (Cunningham and Nemunaitis 2001). One factor relates to the virulence of the bacteria and the effects of the host immune response to their presence (Westphal, Leschner et al. 2008). Other factors are the efficiency of intracellular delivery of multiple agents to target cells, instability of the vector carrying plasmid leading to its loss in the bacteria, inefficient transport of expression plasmids to the tumor cell nucleus and ensuring an optimal dose level of therapeutic agents. Thus, new methods are needed for the development of a novel class of bacterial vectors to treat mammals.
In immunotherapy/vaccination, delivery of eukaryotic plasmid-encoded antigens into macrophages, T cells and/or dendritic cells by live attenuated bacteria is has been used to stimulate cellular and humoral immune responses against bacterial toxin, virus and tumor antigens, but not very successfully. As an adjuvant for recruitment of innate immunity, pathogen-associated molecular patterns of these vaccine strains can amplify the immune response. When using invasive recombinant bacterial vectors for delivery of DNA vaccines, at least five problems should be solved: (a) plasmid loss (b) low frequency of host internalization (c) bacteria-induced apoptosis/pyroptosis (d) low efficacy of gene transfer and (e) transient gene expression.
A better understanding of the mechanism of preferential tropism profiles and of host-vector interactions as well as the advent of modern techniques for genetic manipulation have accelerated the development of novel synthetic bacterial systems for clinical testing. A ‘long-homology arm’ strategy which is able to increase both accuracy and efficiency of genetic engineering technology in gram-negative strains has previously been reported. This robust and efficient method is powerful for multiple chromosome insertions or deletions to engineer bacteria for targeted delivery and expression of multiple therapeutic molecules and/or antigens in the target cells.
In view of the foregoing, it is an object of the present invention to provide modified bacteria to treat cancers and infectious diseases, thereby overcoming various deficiencies and shortcoming of the prior art, including those outlined above. Provided herein is a gene expression system that has an inter-kingdom dual expression (IKDE) of antitumor agents and recombinant antigens, in the nucleus or cytoplasm of eukaryotic cells, with priming and maintenance of the system in the bacteria. Also provided herein are modified bacteria comprising one or more of the following characteristics: (a) deletion of the amino acid biosynthesis-related gene and/or stress response gene for further attenuation; (b) mutation of the biofilm-producing gene to preclude biofilm formation; (c) placing essential genes with a tightly regulated control to program cell lysis; (d) development of a balanced-lethal host-vector system; (e) incorporation of cholesterol dependent cytolysin gene to enhance endosomal escape.
In an embodiment, the modified bacteria is a facultative anaerobic. In certain embodiment, the modified bacterium is a Gram-negative bacterium. In certain embodiments, the facultative anaerobic, includes, but not limited to Salmonella typhimurium. In certain embodiment, the essential gene is, for example, a gene for aspartate-semialdehyde dehydrogenase (“asd”). In certain embodiments, asd is operatively linked and is under the control of a hypoxia-conditioned promoter. In certain embodiments, the normal functions of the bacteria are not compromised by the deletion or mutation of any of its genes. In certain embodiments, the modified bacteria are Salmonella typhimurium, Salmonella choleraesuis, Salmonella enteritidis and S. typhimurium, Escherichia coli, Escherichia. coli K-12, Escherichia. coli O157:H7, Shigella, Shigella dysenteriae, Shigella flexneri, Shigella boydii, Shigella sonnei, Yersinia, Yersinia pestis, Yersinia pseudotuberculosis and Yersina enterocolitica.
Described herein is a method of enhancing the safety and tumor-targeted ability of bacterial pathogens by using recombinant DNA techniques. Provided herein is a method of making the modified bacterial vector. Examples of such genetic mutations include, but are not limited to: (a) deletion of the amino acid biosynthesis-related gene, such as aroA, gua, thy, leu and arg gene, to make the bacteria more susceptible to nutrient shortage, particularly in the intracellular compartment where they will die due to lack of nutrients; (b) mutation of the biofilm-producing gene, such as csgD (curli synthesis), adrA (cellulose synthesis) and gmd (colonic acid synthesis), to enhance intracellular gene transfer and make the bacteria more sensitive to antibiotics; (c) placing an essential gene “asd” (coding for aspartate-semialdehyde dehydrogenase) with a tightly regulated control to make the bacteria only survive in the necrotic/hypoxic core of solid tumors; (d) deletion of the stress response gene, such as htrA, recA and lisp gene; (e) relocating an essential gene “infA” (coding for translation initiation factor IF-1) to the therapeutic plasmid and (f) incorporation of the gene coding for Listeriolysin O to break the Salmonella-containing vesicles.
Described herein is a tumor-targeting bacterial vector for prokaryotic-eukaryotic delivery and expression with multiple genetic mutations and a method of making the vector. The obligate anaerobic Salmonella strain YB1 with hypoxia regulatory control can only survive within the tumor in animals (Yu, Yang et al. 2012). The naturally occurring antitumor activity of facultative anaerobic bacteria is further enhanced by genetic manipulations. In a preferred embodiment, an engineered strain ST1, was generated in the Salmonella 7207 strain background using the λ Red-mediated ‘long homology arm’ recombination technology. Firstly, T7 RNA polymerase (T7 RNAP) gene was integrated into the gmd chromosomal locus to provide an initial RNAPs source for activating the system and enable a high transcription of RNA or exogenous gene driven by PT7. Removal of gmd gene encoding GDP-D-mannose dehydratase precludes the synthesis of colonic acid, thereby interfering with the ability of Salmonella to produce biofilms and enhance intracellular presence in vivo. Secondly, an essential gene asd was replaced by a pore-forming listeriolysin O gene hlyA, which encodes a bacterial factor required for an efficient breakdown of lysosomal membrane after phagocytosis and then release the exogenous protein as well as DNA/mRNA. Subsequently, the asd gene with anaerobic control was cloned back at the htrA gene locus. Double mutation (asd and htrA) made bacteria to grow only under anaerobic conditions while being disabled for growth in normal tissues. The final step was to relocate a small essential gene infA (encoding for translation initiation factor 1) from chromosome to plasmid for stable plasmid maintenance. In certain embodiments, the modified bacteria include, but not limited to Salmonella spp., Escherichia coli, Shigella spp., Bacillus Calmette-Guerin (BCG), Listeria monocytogenes, Yersinia enterocolitica, Mycobacterium, Streptococcus spp., and Lactobacillus spp.
The modified tumor-targeted bacteria provided herein are not lethally toxic. The modified bacteria exclusively grow inside the tumor hypoxic/necrotic zone. In one embodiment, the modified bacterium is ST1. Controlled growth of ST1 lowers the risk for sepsis in the clinical setting. In mouse models, ST1 is replication-incompetent in normal organs and amplified within tumors to as high as 108 cfu per gram tissue. These high titers can enhance the therapeutic effects, as the high amount therapeutic molecules generated and delivered by bacteria. Furthermore, undesirable property of forming biofilms by bacteria at high concentrations poses a serious problem in the clinics and restricts the intracellular residence of the bacteria in tumors which may impair their potential to act as gene transfer vehicles {Crull, 2011 #954}. However, these problems are circumvented by the present disclosed system which allows more efficient and safe usage of bacterial vectors in the animals.
Provided herein is a bacterial vector that is superior to previous bacterial and viral systems in term of in vivo stability. In the previous studies, all the bacterial delivery systems used prokaryotic plasmids to express the helper proteins for invasion or cellular entry into the target host cells (Souders, Verch et al. 2006). In comparison, provided herein, the bacterial factors involved in tumor fitness, intracellular delivery and expression were integrated into the chromosome. It made some improvements in reducing metabolic burden, enhancing stability, safe concern, tight regulation of gene expression and high efficacy of gene transfer. Furthermore, due to the fact the efficiency and the duration of expression of nucleic acids-based products are mainly dependent on the amount of plasmid DNA or RNA delivered. A Salmonella infA+ vector/infA− host maintenance system was developed to maintain the therapeutic vectors at high copies in vivo. This adaptation helps to maintain the plasmid in suitable strains in the absence of selective antibiotics.
The modified bacterial vectors useful for practicing the method disclosed herein is capable of entering tumor cells and localizing to the cytoplasm. Such bacterial vectors are endocytosed and pass through the endocytic membrane and are ultimately processed by the targeted cells for generation of therapeutic factors. The non-virulent bacteria described herein have invasive properties (or are modified to have invasive properties) and enter a mammalian host cell through various mechanisms. In one embodiment, Salmonella can invade cells by a trigger behavior including massive membrane ruffling and actin cytoskeleton reorganization, which are stimulated by a series of bacterial effector proteins translocated by a type III secretion system (Murli, Watson et al. 2001). After adhesion and entry, the modified bacteria could escape from the host-cell vacuole and replicate in the cytoplasm by integrating a cytolysin expression cassette under an in vivo inducible promoter from Salmonella Pathogenicity Island 2. In some embodiments, the bacterium can stay alive for various times in the said cells and may continue to amplify protein or genetic materials. The exogenous molecules can then be released from the bacterium into the cell by leakage. In certain embodiments of the invention, the bacterium can also replicate in the eukaryotic cell. In a preferred embodiment, bacterial replication does not kill the said cell. In certain embodiments, the bacteria deliver therapeutic factors, which includes, but are not limited to, for example, functional protein, DNA, RNA or a combination of at least two factors.
Provided herein is a feasible shuttle for introducing multiple therapeutic factors including, but not limited to, proteins, DNA and translation-competent mRNA, into the mammalian cells. For the RNA delivery, in a preferred embodiment, the translation-competent mRNA with poly A tail adapted for eukaryotic translation by linking a viral ribosome entry site sequence before the encoding sequence, which is driven by T7 RNAPs in the bacterial carriers. Upon intracellular entry, the mRNAs are efficiently released from the disrupted bacteria and immediately translated in the eukaryotic cytoplasm. However, the exogenous gene expression level directly dependent on the amount of the released mRNA and RNAPs. One approach for enhancing gene expression is the use of an autocatalytic cytoplasmic expression system mediated by phage RNAPs, which is based on the previous observation that a plasmid-based gene expression system including T7 RNAP amplification circuit could increase the expression level (Finn, Lee et al. 2004). However, for the plasmid delivery system, it is more difficult due to the presence of nuclear barriers. Only a small proportion of intact plasmid DNA can be transported into the nucleus through the nuclear pore complex for transcription. To overcome this main barrier and facilitate gene expression, provided herein is a combined prokaryotic-eukaryotic (inter-kingdom) dual expression (IKDE) system, containing a T7 RNAP-based cytoplasmic expression system as well as a well-known nuclear system. Following in vitro infection, the expression efficiency of this dual expression with a T7 autogene-based positive feedback loop is more than two orders of magnitude higher than that of the standard nuclear expression system (cytomegalovirus (CMV)-based). Having established the feasibility of an inter-kingdom delivery and expression mediated by the modified bacteria as described in the Examples, the present disclosure addressed the issue of gain and loss-of-function genetics in a therapeutic scenario.
Using tumor-killing bacteria may the cheapest way of treating cancer. A more potent synergistic antitumor effect might be obtained by the intrinsic toxicity of bacteria plus the inter-kingdom expression of versatile tumor specific therapeutic factors. In one embodiment, the modified bacteria express one or more therapeutic bioactive polypeptide or protein, preferably oncolytic proteins, negative regulators of tumor angiogesis tumor-specific antigens and immune modulating factors (such as cytokines) in the extracellular environment and/or inside the target cells. In certain embodiments, the modified bacteria are effective in raising an anti-tumor response in mammals. Provided herein are methods comprising introducing at least one modified bacterium, comprising a prokaryotic vector, said vector comprising one or more DNA molecules encoding one or more proteins, and one infA locus, wherein said proteins include prodrug-converting enzymes, cytokines, bacterial toxins and angiogenic inhibitors with high oncolytic abilities. In a certain embodiment, as a protein delivery vehicle, Salmonella ST1 encoding the extracellular domain of TNF-related apoptosis-inducing ligand (TRAIL) expressed cytokines directly in the extracellular environment or in the tumor cells through a surface display or Salmonella type III secretion system without the requirement of bacterial lysis. The soluble domain of TRAIL can trigger rapid apoptosis in a board range of human cancer cells independent of their p53 status, but not in most normal cells. Unlike traditional chemotherapy drugs, TRAIL-expressing ST1 can selectively grow inside tumors and continuously release the biologically active cytokines in situ at high concentration, thereby achieving maximal killing effects while sparing systemic cytotoxicity. In an embodiment, the delivery of biologically active cytokines by ST1 led to strong inhibitions of tumor development in the MDA-MB-231 xenograft tumor model. Live attenuated ST1-mediated protein delivery is potentially superior to inactivated preparations owing to: (1) their ability to induce cell-mediated immunity in addition to cytokine response; (ii) effectiveness after single-dose administration; (iii) low production cost; (iv) the ease of manufacturing and (v) as carriers for the delivery of active proteins to the solid tumors.
In an embodiment, the modified bacteria are live attenuated. In an embodiment, the modified bacteria are used as a vector to transfer DNA encoding therapeutic proteins through an inter-kingdom dual expression system, wherein said proteins include bacterial toxins, cytokines, prodrug-converting enzymes, angiogenic inhibitors, tumor cell-expressed antigens and immunomodulatory mediators. In a preferred embodiment, the modified bacterium is ST1. ST1 transferred with one or more DNA molecules encoding therapeutic proteins delivers nucleic acids to achieve tumor-targeted expression. In an embodiment, DT-A gene, encoding the catalytic fragment of diphtheria toxin, was cloned to inter-kingdom expression plasmid pIKDE. In an embodiment, the inter-kingdom system (bacteria and plasmid vector) has been modified to include the deletion of the initiation factor 1 and GDP-mannose dehydrogenase encoding gene, replacement with a hypoxia-controlled asd gene expression cassette, integration of T7 RNAP and cytolysin expression cassette, carrying a plasmid pIKDE-DTA with one or more of the following characteristics: (i) a reasonably small size (9.7 kb); (ii) an origin of replication responding for a high copy number; (iii) E. coli infA locus allowing in vivo plasmid maintenance; (iv) T7 RNAP autogene cassette which can amplify the polymerases after cytoplasmic entry; (v) insertion of an excellent DNA nuclear targeting sequence—a 72-bp element of the SV40 enhancer for enhancing nuclear import; (vi) suicide gene expression driven by both PCMV (for nuclear expression) and PT7 (for cytoplasmic expression). It is the first report to date describing the design and use of such expression system. By taking advantage of the tumor-targeted and oncolytic effects of ST1 and the translation inhibition activity of DT A chain, a single dose of ST1/pIKDE-DTA induced remarkable shrinkage of solid tumors and greatly reduced the risk of death with no gross sign of toxicity in both immune deficient and competent mice models. In one embodiment, the pIKDE-DTA comprises the sequence as indicated in
In an embodiment, the bacterial vectors are used for RNA interference (RNAi) therapy. An inter-kingdom RNAi interference system has been developed by combining prokaryotic and eukaryotic transcription of shRNA. In certain embodiments, the system has one or more of the following improvements: (1) high tumor-targeting characteristics; (2) in vivo plasmid maintenance; (3) combination of prokaryotic and eukaryotic transcription of the shRNA. In a preferred embodiment, ST1-mediated inter-kingdom RNAi can transfer RNAi effectors between bacteria and mammals. The transcription of shRNA and microRNA precursor can be achieved in the bacterial cells as well as through eukaryotic transcription machinery in the cytosol of the infected tumor cells. Specifically, shRNA targets against oncogenes or tumor-related factors, such as vascular endothelial growth factor (VEGF), kinesin spindle protein (KSP), human epidermal growth factor receptor 2 (HER2), V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS), β-catenin, signal transducer and activator of transcription 3 (STAT3), transforming growth factor β-activated kinase 1 (TAK1), and polo-like kinase 1 (PLK1), can be transcribed from an RNAi plasmid pIKR-shRNA by T7 RNAPs inside the ST1 cells. Following phagosome disruption, these shRNAs will be released within the shRNA-encoding plasmids in the target host cells. Subsequent transcription of shRNAs by mammalian cells takes place in the cytoplasm. Then a series of RNAi processing steps will occur sequentially in mammals. In a certain embodiment, oligonucleotides encoding shRNA against no actual target tdTomato and a key mediator of Wnt/β-catenin pathway β-Catenin, cell cycle-associated protein (PLK1) genes were inserted into the multiple cloning sites, generating pIKR-shTom (vector control), pIKR-shCAT and pIKR-shPLK. In one embodiment, the pIKR-shCAT comprises the sequence as indicated in
In an embodiment, bacterially activated exosomes, and in particular naturally derived exosomes comprising therapeutic factors, which are prepared according to the methods disclosed herein. Cytotoxic exosomes which have been loaded by the bacterial cells described herein include, but are not limited to one or more protein or peptides, RNA species, DNA species or thereof. In certain embodiments, the RNA content includes one or more RNA species, such as, but not limited to, mRNA, microRNA, siRNA, shRNA, or a combination thereof.
The invention further provides methods of eliciting an effective immune response in a subject by administering an attenuated Salmonella or composition of the invention to a subject. By encapsulation of the DNA/mRNA/microRNA and shRNA vaccine expressing the hemagglutinin (HA) gene of H7N9 influenza virus in the modified nonreplicative Salmonella by intraperitoneal injection, it is sufficient to elicit immune response against HA. The vaccine strain constructed by the invention can be subcultured stably in vitro with selection pressure or not, which is proved by CFU tests. Furthermore, DNA vaccine delivery may benefit from the auto-amplified expression system, resulting in improved immunogenicity effect against the vectored antigens. The inventive vaccine is advantageous over current inactivated or live attenuated vaccines, as updating of the vaccine requires only the replacement of the encoding sequence with the new virus.
Provided herein is a modified bacterial vector. The modified bacterial vector is a tumor-targeted delivery vehicle of antitumor molecules and as a therapeutic ‘factory’ for feasible drug production to enhance tumor regression. More importantly, these engineered bacteria carrying different cargoes were well tolerated in animal models. In a preferred embodiment, Salmonella ST1 harboring inter-kingdom expression vectors, which are able to replicate within the tumors, and are useful for inhibiting the growth and/or reducing the tumor volume of sarcomas, carcinomas, lymphomas or other solid tumors, including, but not limited to, breast cancer, prostate cancer, cervical cancer, uterine cancer, lung cancer, ovarian cancer, testicular cancer, thyroid cancer, astrocytoma, glioma, pancreatic cancer, stomach cancer, liver cancer, colon cancer, and melanoma.
This invention provides multivalent bacterial vectors that can be used either prophylactically or therapeutically for the treatments of patients by using the bacteria harboring multiple cargoes generated by the methods described herein.
Also described herein are therapeutic and prophylactic compositions comprising the modified bacteria. Such a composition can be administered alone or as an adjunct to other therapy selected from gene therapy, chemotherapy, radiation, immunotherapy and/or other therapeutics or vaccines. In certain embodiments, the therapeutic and prophylactic compositions contain a purified form of the modified bacteria. In certain embodiments, the therapeutic and prophylactic compositions do not contain other strains of microorganisms. Also disclosed are methods of preventing and treating tumor and/or cancer and infectious diseases using the system provided herein.
Other features and advantages of the disclosure will be apparent from the following detailed description and claims.
Also described herein is a kit comprising the modified bacteria and a pharmaceutically acceptable carrier.
Since Salmonella is closely related to the Escherichia genus and has a broad host range, its genomic information is clear and share many common features with E. coli. Compared to gram-positive bacteria (e.g. Clostridium), Salmonella is easier to perform genetic manipulations. It survives and proliferates within cells; therefore it can deliver genetic materials in the targeted cells. For example, it may directly deliver ectopic mRNA and utilize the translation machinery of host cells to synthesize the corresponding exogenous proteins. On the other hand, since it is facultative anaerobic, it is easy to culture it in vitro and then send them to target hypoxic region within tumors. More important, genetically attenuated Salmonella vectors provide additional safety as they can be readily controlled or eliminated from the human body by the application of ciprofloxacin in case of serious sepsis and can avoid (random) genomic integration {Crull, 2011 #955}. Thus, Salmonella can serve as both bacterial “weapon” and “vector” in research and medication.
In the process of utilizing live attenuated Salmonella as a carrier in cancer therapy or DNA vaccination, safety, stability and delivery efficiency are the most important issue, which can be solved by deleting virulent genes and inserting functional genes. For example, by placing an essential gene asd under a hypoxia controlled genetic circuit, S. typhimurium strain SL7207 was engineered to an obligate anaerobic Salmonella strain YB1. YB1 could only survive inside the tumor, but were totally cleared from other normal tissues. However, its curative ability needs to be further improved. Description of YB1 is in pending U.S. patent application Ser. No. 13/871,716, filed Apr. 26, 2013, the content of which is incorporated by reference in its entirety.
Therefore, the present disclosure provides a superior modified bacterial strain that has improved curative ability. Provided herein is a modified bacteria comprising one or more of the following characteristics: (a) deletion of one amino acid biosynthesis-related gene aroA; (b) mutation of gmd gene to preclude the biofilm formation; (c) placing an essential gene aspartate-semialdehyde dehydrogenase (“asd”) with a tightly hypoxic control; (d) deletion of the stress response gene htrA; (e) introduction of an infA+ (cloned from E. coli MG1655 strain) plasmid in infA− mutant makes the bacterial strain plasmid-dependent and (f) integration of the hlyA gene coding for Listeriolysin O (LLO) under the regulation of Salmonella pathogenicity island II promoter into the genome. In certain embodiments, the modified bacteria comprise two, three, four or five of the above-identified characteristics. In one embodiment, the modified bacteria comprise all of the above-identified characteristics.
In one embodiment, the modified bacterium comprises a vector comprising T7 RNAP and an essential gene under a tightly hypoxic regulation. In one embodiment, the T7 RNAP is under the control of lac promoter. In one embodiment, the essential gene is asd. In one embodiment, the FNR related anaerobic capable promoter PpepT controls asd transcription while an aerobic promoter, PsodA, facilitates transcription of antisense asd that blocks any leakage of asd expression under aerobic conditions. In one embodiment, the modified bacterium is ST1.
In one embodiment, the modified bacterium comprises a vector comprising a transgene under the transcription regulation by PT7 and PCMV and a T7 RNAP autogene expression cassette. In one embodiment, the transgene and the T7 RNAP comprise a viral ribosome binding site (IRESEMCV). In one embodiment, the transgene expresses therapeutic molecules including RNA, DNA and proteins. In one embodiment, the transgene express cytokine. In one embodiment, the cytokine is cytokine sTRAIL. In one embodiment, the transgene expresses a fusion protein. In one embodiment, the transgene is a toxin. In one embodiment, the toxin is DT-A. In one embodiment, the transgene is an antigen. In one embodiment, the antigen is Influenza A virus (A/Shanghai/4664T/2013(H7N9)) hemagglutinin (HA). In one embodiment, the modified bacteria comprise a vector with chromosomal infA, aroA and gmd deletion and site-specific integration of T7 RNAP and hlyA gene. In certain embodiments, the vector comprises one or more of the following: (i) less than 10 kb of sequences; (ii) an origin of replication; (iii) E. coli infA locus; (iv) T7 RNAP autogene cassette; (v) a 72-bp element of the SV40 enhancer for enhancing nuclear entry and (vi) therapeutic gene expression driven by both PCMV and PT7. In one embodiment, the vector is ST1.
In one embodiment, the transgene expresses an oligonucleotide encoding a shRNA or a microRNA precursor. In one embodiment, the shRNA is against a cell cycle-associated protein polo-like kinase 1 (“PLK1”). In one embodiment, the shRNA is against a key intracellular signal transducer beta-catenin (“CTNNB1”) in the Wnt signaling pathway. In one embodiment, the microRNA precursor is tumor suppressor microRNA let-7.
Described herein is a method of making the modified bacteria. The method comprises one or more of the following steps: (a) deletion of the amino acid biosynthesis-related gene, such as aroA, gua, thy, leu and arg gene; (b) mutation of the genes required for biofilm formation on the surface of epithelial cells, such as csgD, adrA and gmd; (c) placing an essential gene asd with a tightly hypoxic control; (d) construction of a balanced-lethal system in which the infA gene of E. coli MG1655 strain was designed to be introduced in a plasmid that complements an infA mutation in the chromosome of the Salmonella strain; (e) deletion of the stress response gene, such as htrA, recA and hsp gene and (f) integration of a pore-forming cytolysin gene under the control of an in vivo-inducible promoter.
Described herein is a tumor-targeting vector for prokaryotic-eukaryotic delivery and expression and a method of making the vector. In a preferred embodiment, an engineered strain ST1, was generated in the Salmonella 7207 strain background using the λ Red-mediated ‘long homology arm’ recombination technology. In certain embodiments, the method comprises one or more of the following steps: (i) integration of a T7 RNA polymerase (T7 RNAP) gene into the gmd chromosomal locus; (ii) mutation or deletion of gmd gene encoding GDP-mannose 4,6-dehydratase; (iii) replacement of an essential gene, such as asd with a pore-forming listeriolysin O gene such as hlyA; (iv) the essential gene such as asd gene with anaerobic control, for example, an essential gene expression cassette comprising an essential gene cloned behind a hypoxia-inducible promoter in the sense orientation as well as a aerobic promoter in the antisense orientation is added at the htrA gene locus; (v) double mutation of asd and htrA; and (vi) relocate a small essential gene such as infA (encoding for translation initiation factor 1) from chromosome to plasmid.
In certain embodiments, the modified bacteria include, but not limited to Salmonella, Escherichia coli, Shigella, Bacillus Calmette-Guerin (BCG), Listeria monocytogenes, Yersinia, Mycobacterium, Streptococcus, and Lactobacillus. In certain embodiments, the modified bacteria are Salmonella typhimurium, Salmonella choleraesuis, Salmonella enteritidis and S. typhimurium, Escherichia coli, Escherichia. coli K-12, Escherichia. coli O157:H7, Shigella, Shigella dysenteriae, Shigella flexneri, Shigella boydii, Shigella sonnei, Yersinia, Yersinia pestis, Yersinia pseudotuberculosis and Yersina enterocolitica.
Provided herein is a method of producing exosomes comprising one or more protein or peptides, mRNA, shRNA, microRNA or a combination therefore. The method comprises the steps of infecting a host animal with ST1 that comprises a vector expressing a transgene; and isolating exosomes from said host animals.
ST1 strain was engineered from the auxotrophic S. typhimurium 7207 strain through a series of genetic manipulations (
ST1 can target the solid tumors and invade into the targeted cells (
S.
typhimurium
S.
typhimurium 2337-65 derivative hisG46,
ΔhtrA::cat-PpepT-asd-sodA
ΔhtrA::cat-PpepT-asd-sodA; ΔinfA::tetR
ΔinfA::cat
ΔinfA::cat
ΔhtrA::PpepT-asd-sodA; ΔinfA::tetR
E.coli MG1655 strain
Although ST1 is able to localize the cell cytoplasm and efficiently release genetic materials, one obstacle most likely still hindering DNA delivery is the nuclear trafficking. Here, a novel IKDE system is provided, including a T7 RNAP-based cytoplasmic expression system as well as the nuclear system. The activation of transgene expression was based on an inter-kingdom interaction of bacteria and host cells (
Next, kinetics of the reporter expression was tested after ST1-mediated delivery of an IKDE system versus that of plasmid DNA and/or translation-competent mRNA in the post-infection period (
We are capable of having far more effective in vitro and in vivo screening methods. Using our synthetic inter-kingdom expression platform, the intracellular expression of proteins and small interfering RNAs can be achieved by ST1-mediated gene transfer and RNAi. We sought to assess the therapeutic effects of promising candidates (Table. 2) on human cancers by in vitro screening. ST1 harboring different therapeutic candidates (e.g. protein, DNA or RNA, either individually or in combination) were added to the medium and released multiple cargos into the cells. The effects of the therapeutic factors were detected by measuring or monitoring physiological events such as cell death, proliferation or disturbances in signal transduction pathways. Here, cell viabilities and apoptosis rates were measured to rapidly evaluate anti-tumor factors, including protein, shRNA and microRNA on human breast cancer MDA-MB-231 cells. Polypeptide DT-A and shRNA against PLK1 were most effective in suppressing growth and killing abilities (
The present invention provides a method for plasmid maintenance, the method comprising: providing expression plasmids comprising the plasmid maintenance systems described herein and encoding for a protein of interest, said expression plasmids having copy numbers which vary from low copy number (1˜10 copies per cell) to medium copy number (15˜20 copies per cell) to high copy number (up to 100's of copies per cell); transforming bacterial live vectors with such expression plasmids; and testing for stabilities in vivo (
Provided herein is a method of delivery of active anti-tumor proteins. In accordance with this invention therapeutic proteins are introduced into tumor cells via a bacterial vector comprising a nucleic acid sequence encoding for a therapeutic gene. Unlike traditional chemotherapy drugs, as a carrier for generating heterogenous therapeutic proteins, ST1 can selectively grow inside solid tumors and continuously release the biologically active proteins in situ at high regional concentration, thereby achieving maximal killing effects while sparing systemic cytotoxicity. Special delivery systems in Salmonella carriers such as surface display or secretion of therapeutic proteins were shown to be advantageous for eliciting antitumor responses.
To examine whether the soluble TRAIL fusion protein could target to surface, the outer-membrane fraction of ST1/pLpp_ompA_sTRAIL bacterial cells was isolated by ultracentrifugation. One single band migrating at a molecular mass of the expected size of the monomeric form of the Lpp_ompA (46-159) fusion protein was detected by western blot (
After validation of protein expression, the tumor inhibitory effects were examined in a nude mouse model. Tumor volumes were monitored by a two-dimensional caliper measurement. As indicated in
In vitro results encourage us to determine whether ST1 could trigger a high level expression of therapeutic genes in vivo. In a certain embodiment, DT-A gene, encoding the catalytic fragment of diphtheria toxin, was cloned into plasmid pIKDE. The bacteria-vector system consists of the Salmonella ST1 with chromosomal infA and gmd deletion, integration of T7 RNAP and LLO expression cassette, and tightly anaerobic control of survival, carrying a plasmid pIKDE-DTA with the following features: (1) a reasonably small size (9.7 kb); (2) an origin of replication responding for a high copy number; (3) E. coli infA locus allowing in vivo plasmid maintenance; (4) T7 RNAP autogene cassette which can amplify the polymerases after cytoplasmic entry; (5) a 72-bp element of the SV40 enhancer and (6) the suicide gene was fused in frame with the Kozak sequence and inserted into down-stream of the CMV/T7 combinational promoter. It is the first report to date describing the design and use of such a T7 RNAP autogene-based nuclear/cytoplasmic dual expression system.
The therapeutic efficiency of ST1/pIKDE-DTA was tested in a metastatic breast cancer model. To do so, 4T1 mouse tumor cells were implanted into the mammary fat pad of immune-competent, syngeneic BALB/c hosts. The 4T1 tumors are highly malignant and often lead to death because of metastasis, rapid growth rate and limited treatment options. Biodistribution experiments in the immune-competent mice confirmed that the bacteria were specifically internalized by primary tumors and metastatic nodules (
In vivo antitumor effect of ST1-mediated expression of DT A chain was evaluated in terms of tumor growth and survival rate. Systemic delivery of ST1/pIKDE-DTA potently reduced growth of primary tumors (
ST1 packaged with shRNA-encoding plasmid DNA has knockdown effects in human cancer xenografts. The theoretic steps implemented for inter-kingdom RNAi were shown in
The incorporation of T7 RNAP autogene cassette is designed to maintain a high transcription level in the mammalian system, which was confirmed by quantitative RT-PCR (159.1±67.4 copies/ng RNA). To determine whether the T7 RNAP-based cytoplasmic expression system elicits vector specific shRNA transcription in the transformed Salmonella as well as in the bacterially infected host cells, the gene-silencing activity of ST1 harboring shRNA expression vector with or without the T7 RNAP locus were compared. As expected, the knockdown efficiency of ST1/pIKRΔT7P-shPLK (bacteria-mediated RNAi only) largely decreased compared to ST1/pIKR-shPLK (inter-kingdom RNAi) at a rather long time (
The enhanced therapeutic effect of bacteria plus ST1-mediated inter-kingdom RNAi led to a noticeable tumor growth reduction compared to that in controls (
In order to exclude any unspecific toxic effect responsible for the observed effects, preliminary acute toxicity experiments were conducted. Body weight of each mouse was recorded every other day. Total body weights of ST1 treated mice reduced at the beginning and then recovered to normal conditions (
Provided herein is a novel exosome-based delivery platform that transfers exogenous cargoes to selected tissues. Exosomes are membrane-bond vesicles of nanoparticle size (40-100 nm) of endocytotic origin and act as natural carriers of mRNA, small RNA and proteins. Accumulating evidences indicate the exosomes may play a critical role in cell-to-cell communication. Various bioactive molecules from one cell can be transferred to another cell via exosomes. By taking advantage of its natural carrier capability, the exosome with exogenous genetic cargoes can facilitate a long-distance delivery of therapeutic factors. In addition, one advantage of these natural nanoparticles is an immune evasion allowing for repeat administration.
Provided herein is a method to load exosomes with exogenous protein, mRNA and shRNA in viva by ST1 infection and isolated them from murine model. Exosome-like microvesicles were harvested from the tumors treated with ST1/pIKDE (empty vector) and ST1/pIKDE-DTA by ultracentrifugation or differential centrifugation and filtered through a 0.2 μm size filter to remove impurities. The pelleted exosomes were further dissolved in DEPC water for RNA isolation and Electron microscopy or lysis buffer for protein extraction. Electron microscopy and western blot analysis (
The mutant strains of the invention are highly suitable for use in a live attenuated vaccine, as a live vector and a DNA-mediated vaccine. DNA vaccines have been the subject of much promising research against influenza, but the high copy number plasmids required are notoriously unstable in Salmonella. To solve this problem, an expression plasmid is provided which encodes (1) a Plasmid Maintenance system and (2) a protein operaly linked to a dual promoter (3) a T7 RNAP autogene-based cassette. Therefore the stability and novel inter-kingdom dual expression platform enables the possibility of new vaccination strategies against H7N9.
Here, we used the hemagglutinin (HA) from the avian influenza H7N9 virus as a model antigen, which is the essential vaccine antigen, to evaluate the ability of our engineered strain to deliver an antigen encoded by the improved DNA vaccine vector to host tissues. A DNA fragment encoding Influenza A virus (A/Shanghai/4664T/2013(H7N9)) hemagglutinin (HA) with Kozak sequence was inserted downstream of the IRESEMCV in the improved DNA vaccine vector to obtain pIKDE-HA. BALB/c mice were immunized intraperitoneally with ST1/pIKDE-HA at the dosage of 107 CFU. In order to evaluate the humoral immune responses mounted against ST1/pIKDE-HA strain, ELISA assays were performed to test the anti-HA IgG responses using blood sera of vaccinated mice the 14th, 35th and 48th day after immunization. Results indicated that anti-HA responses of mice immunized with ST1/pIKDE-HA strain were moderate on the day 14 after immunization. After receiving three boosts on day 14, 21 and 28, the anti-HA IgG response in the mice were greatly increased. 100% mice (all 7 mice) had high anti-HA IgG responses on day 48 (
The modified bacteria containing the RNA and/or DNA molecules provided herein can be formulated for a variety of types of administration, including systemic and topical administration. For systemic administration, injection is preferred, including intravenous, intramuscular, intraperitoneal, intrarectal and subcutaneous routes. For injection, the composition can be formulated in liquid solutions, preferably in physiologically compatible buffers such as Hank's solution or Ringer's solution.
For oral administration, the pharmaceutical compositions may take the form of, for example, tablets or capsules prepared by mixing the effective amount of bacteria and the proper amount of additives according to known methods in pharmaceutical chemistry. Suitable formulations can be prepared by methods commonly employed using conventional, organicor inorganic additives, such as an excipient selected from fillers or diluents (e.g., sucrose, starch, mannitol, glucose, cellulose, calcium phosphate or calcium carbonate and the like), binders (e.g., cellulose, carboxymethylcellulose, gelatin, gum arabic, polyethlyeneglycol or starch and the like), disintegrants (e.g., sodium starch glycolate, croscarmellose sodium and the like), lubricants (e.g., magnesium stearate, light anhydrous silicic acid, sodium lauryl sulfate and the like), flavoring agents (e.g., citric acid, menthol and the like), preservatives (e.g., sodium benzoate, sodium bisulfate, methylparaben and the like), stabilizers (e.g., citric acid, sodium citrate, acetic acid and the like), suspending agents (e.g., methylcellulose, polyvinyl pyrrolidone or aluminum stearate and the like), dispersing agents (e.g., hydroxypropylmethylcellulose and the like), surfactants (e.g., sodium lauryl sulfate, polaxamer, polysorbates and the like), antioxidants (e.g., Ethylene diamine tetraacetic acid (EDTA), butylated hydroxyl toluene (BHT) and the like) or solubilizers (e.g., polyethylene glycols, SOLUTOL™, GELUCIRE™ and the like).
The modified bacteria provided herein can be administered to a patient in the conventional form of preparations, such as injections and suspensions. Suitable formulations can be prepared by methods commonly employed using conventional, organic or inorganic additives, such as an excipient selected from fillers or diluents, binders, disintegrants, lubricants, flavoring agents, preservatives, stabilizers, suspending agents, dispersing agents, surfactants, antioxidants or solubilizers.
Excipients that may be selected are known to those skilled in the art and include, but are not limited to fillers or diluents (e.g., sucrose, starch, mannitol, sorbitol, lactose, glucose, cellulose, talc, calcium phosphate or calcium carbonate and the like), a binder (e.g., cellulose, carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, hydroxypropylmethylcellulose, polypropylpyrrolidone, polyvinylpyrrolidone, gelatin, gum arabic, polyethyleneglycol or starch and the like), a disintegrants (e.g., sodium starch glycolate, croscarmellose sodium and the like), a lubricant (e.g., magnesium stearate, light anhydrous silicic acid, talc or sodium lauryl sulfate and the like), a flavoring agent (e.g., citric acid, or menthol and the like), a preservative (e.g., sodium benzoate, sodium bisulfate, methylparaben or propylparaben and the like), a stabilizer (e.g., citric acid, sodium citrate or acetic acid and the like), a suspending agent (e.g., methylcellulose, polyvinyl pyrrolidone or aluminum stearate and the like), a dispersing agent (e.g., hydroxypropylmethylcellulose and the like), surfactants (e.g., sodium lauryl sulfate, polaxamer, polysorbates and the like), antioxidants (e.g., ethylene diamine tetraacetic acid (EDTA), butylated hydroxyl toluene (BHT) and the like) and solubilizers (e.g., polyethylene glycols, SOLUTOL®, GELUCIRE® and the like). The effective amount of the modified bacteria provided herein in the pharmaceutical composition may be at a level that will exercise the desired effect.
In another embodiment, provided herein are compositions comprising an effective amount of modified bacteria provided herein and a pharmaceutically acceptable carrier or vehicle, wherein a pharmaceutically acceptable carrier or vehicle can comprise an excipient, diluent, or a mixture thereof. In one embodiment, the composition is a pharmaceutical composition.
Compositions can be formulated to contain a daily dose, or a convenient fraction of a daily dose, in a dosage unit. In general, the composition is prepared according to known methods in pharmaceutical chemistry. Capsules can be prepared by mixing the modified bacteria provided herein with a suitable carrier or diluent and filling the proper amount of the mixture in capsules.
Solid tumor cancers that can be treated by the methods provided herein include, but are not limited to, sarcomas, carcinomas, and lymphomas. In specific embodiments, cancers that can be treated in accordance with the methods described include, but are not limited to, cancer of the breast, liver, neuroblastoma, head, neck, eye, mouth, throat, esophagus, esophagus, chest, bone, lung, kidney, colon, rectum or other gastrointestinal tract organs, stomach, spleen, skeletal muscle, subcutaneous tissue, prostate, breast, ovaries, testicles or other reproductive organs, skin, thyroid, blood, lymph nodes, kidney, liver, pancreas, and brain or central nervous system. In certain embodiments, the solid tumors that can be treated by the methods provided herein include, but are not limited to, sarcomas, carcinomas, and lymphomas. In specific embodiments, a cancer that can be treated in accordance with the methods described include, but are not limited to, cancer of the breast, liver, colon, neuroblastoma, head, neck, eye, mouth, throat, esophagus, chest, bone, lung, kidney, rectum or other gastrointestinal tract organs, stomach, spleen, skeletal muscle, subcutaneous tissue, prostate, ovaries, testicles or other reproductive organs, skin, thyroid, blood, lymph nodes, pancreas and brain.
In particular embodiments, the methods for treating cancer provided herein inhibit, reduce, diminish, arrest, or stabilize a tumor associated with the cancer. In other embodiments, the methods for treating cancer provided herein inhibit, reduce, diminish, arrest, or stabilize the blood flow, metabolism, or edema in a tumor associated with the cancer or one or more symptoms thereof. In specific embodiments, the methods for treating cancer provided herein cause the regression of a tumor, tumor blood flow, tumor metabolism, or peritumor edema, and/or one or more symptoms associated with the cancer. In other embodiments, the methods for treating cancer provided herein maintain the size of the tumor so that it does not increase, or so that it increases by less than the increase of a tumor after administration of a standard therapy as measured by conventional methods available to one of skill in the art, such as digital rectal exam, ultrasound (e.g., transrectal ultrasound), CT Scan, MRI, dynamic contrast-enhanced MRI, or PET Scan. In specific embodiments, the methods for treating cancer provided herein decrease tumor size. In certain embodiments, the methods for treating cancer provided herein reduce the formation of a tumor. In certain embodiments, the methods for treating cancer provided herein eradicate, remove, or control primary, regional and/or metastatic tumors associated with the cancer. In some embodiments, the methods for treating cancer provided herein decrease the number or size of metastases associated with the cancer.
In certain embodiments, the methods for treating cancer provided herein reduce the tumor size (e.g., volume or diameter) in a subject by at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 80%, 85%, 90%, 95%, 99%, or 100%, relative to tumor size (e.g., volume or diameter) prior to administration of modified bacteria as assessed by methods well known in the art, e.g., CT Scan, MRI, DCE-MRI, or PET Scan. In particular embodiments, the methods for treating cancer provided herein reduce the tumor volume or tumor size (e.g., diameter) in a subject by an amount in the range of about 5% to 20%, 10% to 20%, 10% to 30%, 15% to 40%, 15% to 50%, 20% to 30%, 20% to 40%, 20% to 50%, 30% to 60%, 30% to 70%, 30% to 80%, 30% to 90%, 30% to 95%, 30% to 99%, 30% to 100%, or any range in between, relative to tumor size (e.g., diameter) in a subject prior to administration of modified bacteria as assessed by methods well known in the art, e.g., CT Scan, MRI, DCE-MRI, or PET Scan.
In certain embodiments, the methods for treating cancer provided herein reduce the tumor perfusion in a subject by at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 80%, 85%, 90%, 95%, 99%, or 100%, relative to tumor perfusion prior to administration of modified bacteria as assessed by methods well known in the art, e.g., MRI, DCE-MRI, or PET Scan. In particular embodiments, the methods for treating cancer provided herein reduce the tumor perfusion in a subject by an amount in the range of about 5% to 20%, 10% to 20%, 10% to 30%, 15% to 40%, 15% to 50%, 20% to 30%, 20% to 40%, 20% to 50%, 30% to 60%, 30% to 70%, 30% to 80%, 30% to 90%, 30% to 95%, 30% to 99%, 30% to 100%, or any range in between, relative to tumor perfusion prior to administration of modified bacteria, as assessed by methods well known in the art, e.g., MRI, DCE-MRI, or PET Scan.
In particular aspects, the methods for treating cancer provided herein inhibit or decrease tumor metabolism in a subject as assessed by methods well known in the art, e.g., PET scanning. In specific embodiments, the methods for treating cancer provided herein inhibit or decrease tumor metabolism in a subject by at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 80%, 85%, 90%, 95%, or 100%, relative to tumor metabolism prior to administration of modified bacteria, as assessed by methods well known in the art, e.g., PET scanning. In particular embodiments, the methods for treating cancer provided herein inhibit or decrease tumor metabolism in a subject in the range of about 5% to 20%, 10% to 20%, 10% to 30%, 15% to 40%, 15% to 50%, 20% to 30%, 20% to 40%, 20% to 50%, 30% to 60%, 30% to 70%, 30% to 80%, 30% to 90%, 30% to 95%, 30% to 99%, 30% to 100%, or any range in between, relative to tumor metabolism prior to administration of modified bacteria, as assessed by methods well known in the art, e.g., PET scan.
In some embodiments, a subject treated for cancer in accordance with the methods provided herein is a human who has or is diagnosed with cancer. In other embodiments, a subject treated for cancer in accordance with the methods provided herein is a human predisposed or susceptible to cancer. In some embodiments, a subject treated for cancer in accordance with the methods provided herein is a human at risk of developing cancer.
In one embodiment, a subject treated for cancer in accordance with the methods provided herein is a human infant. In another embodiment, a subject treated for cancer in accordance with the methods provided herein is a human toddler. In another embodiment, a subject treated for cancer in accordance with the methods provided herein is a human child. In another embodiment, a subject treated for cancer in accordance with the methods provided herein is a human adult. In another embodiment, a subject treated for cancer in accordance with the methods provided herein is a middle-aged human. In another embodiment, a subject treated for cancer in accordance with the methods provided herein is an elderly human.
In certain embodiments, a subject treated for cancer in accordance with the methods provided herein has a cancer that metastasized to other areas of the body, such as the bones, lung and liver. In certain embodiments, a subject treated for cancer in accordance with the methods provided herein is in remission from the cancer. In some embodiments, a subject treated for cancer in accordance with the methods provided herein that has a recurrence of the cancer. In certain embodiments, a subject treated in accordance with the methods provided herein is experiencing recurrence of one or more tumors associated with cancer.
In certain embodiments, a subject treated for cancer in accordance with the methods provided herein is a human that is about 1 to about 5 years old, about 5 to 10 years old, about 10 to about 18 years old, about 18 to about 30 years old, about 25 to about 35 years old, about 35 to about 45 years old, about 40 to about 55 years old, about 50 to about 65 years old, about 60 to about 75 years old, about 70 to about 85 years old, about 80 to about 90 years old, about 90 to about 95 years old or about 95 to about 100 years old, or any age in between. In a specific embodiment, a subject treated for cancer in accordance with the methods provided herein is a human that is 18 years old or older. In a particular embodiment, a subject treated for cancer in accordance with the methods provided herein is a human child that is between the age of 1 year old to 18 years old. In a certain embodiment, a subject treated for cancer in accordance with the methods provided herein is a human that is between the age of 12 years old and 18 years old. In a certain embodiment, the subject is a male human. In another embodiment, the subject is a female human. In one embodiment, the subject is a female human that is not pregnant or is not breastfeeding. In one embodiment, the subject is a female that is pregnant or will/might become pregnant, or is breast feeding.
In some embodiments, a subject treated for cancer in accordance with the methods provided herein is administered modified bacteria or a pharmaceutical composition thereof, or a combination therapy before any adverse effects or intolerance to therapies other than the modified bacteria develops. In some embodiments, a subject treated for cancer in accordance with the methods provided herein is a refractory patient. In a certain embodiment, a refractory patient is a patient refractory to a standard therapy (e.g., surgery, radiation, anti-androgen therapy and/or drug therapy such as chemotherapy). In certain embodiments, a patient with cancer is refractory to a therapy when the cancer has not significantly been eradicated and/or the one or more symptoms have not been significantly alleviated. The determination of whether a patient is refractory can be made either in vivo or in vitro by any method known in the art for assaying the effectiveness of a treatment of cancer, using art-accepted meanings of “refractory” in such a context. In various embodiments, a patient with cancer is refractory when one or more tumors associated with cancer, have not decreased or have increased. In various embodiments, a patient with cancer is refractory when one or more tumors metastasize and/or spread to another organ.
In some embodiments, a subject treated for cancer accordance with the methods provided herein is a human that has proven refractory to therapies other than treatment with modified bacteria, but is no longer on these therapies. In certain embodiments, a subject treated for cancer in accordance with the methods provided herein is a human already receiving one or more conventional anti-cancer therapies, such as surgery, drug therapy such as chemotherapy, anti-androgen therapy or radiation. Among these patients are refractory patients, patients who are too young for conventional therapies, and patients with recurring tumors despite treatment with existing therapies.
The effective amount of the modified bacteria provided herein to be administered to a subject will vary depending on the species of the subject, as well as the disease or condition that is being treated. Preferably, the dosage employed will be 107 to 1010 viable microorganisms per subject.
In one aspect, a method for treating cancer presented herein involves the administration of a unit dosage of modified bacteria thereof. The dosage may be administered as often as determined effective (e.g., once, twice or three times per day, every other day, once or twice per week, biweekly or monthly). In certain embodiments, a method for treating cancer presented herein involves the administration to a subject in need thereof of a unit dose of modified bacteria that can be determined by one skilled in the art.
In some embodiments, a unit dose of modified bacteria or a pharmaceutical composition thereof is administered to a subject once per day, twice per day, three times per day; once, twice or three times every other day (i.e., on alternate days); once, twice or three times every two days; once, twice or three times every three days; once, twice or three times every four days; once, twice or three times every five days; once, twice, or three times once a week, biweekly or monthly, and the dosage may be administered orally.
Presented herein are combination therapies for the treatment of cancer which involve the administration of modified bacteria in combination with one or more additional therapies to a subject in need thereof. In a specific embodiment, presented herein are combination therapies for the treatment of cancer which involve the administration of an effective amount of modified bacteria in combination with an effective amount of another therapy to a subject in need thereof.
As used herein, the term “in combination,” refers, in the context of the administration of modified bacteria, to the administration of modified bacteria prior to, concurrently with, or subsequent to the administration of one or more additional therapies (e.g., agents, surgery, or radiation) for use in treating cancer. The use of the term “in combination” does not restrict the order in which modified bacteria and one or more additional therapies are administered to a subject. In specific embodiments, the interval of time between the administration of modified bacteria and the administration of one or more additional therapies may be about 1-5 minutes, 1-30 minutes, 30 minutes to 60 minutes, 1 hour, 1-2 hours, 2-6 hours, 2-12 hours, 12-24 hours, 1-2 days, 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, 1 week, 2 weeks, 3 weeks, 4 weeks, 5 weeks, 6 weeks, 7 weeks, 8 weeks, 9 weeks, 10 weeks, 15 weeks, 20 weeks, 26 weeks, 52 weeks, 11-15 weeks, 15-20 weeks, 20-30 weeks, 30-40 weeks, 40-50 weeks, 1 month, 2 months, 3 months, 4 months 5 months, 6 months, 7 months, 8 months, 9 months, 10 months, 11 months, 12 months, 1 year, 2 years, or any period of time in between. In certain embodiments, modified bacteria and one or more additional therapies are administered less than 1 day, 1 week, 2 weeks, 3 weeks, 4 weeks, one month, 2 months, 3 months, 6 months, 1 year, 2 years, or 5 years apart.
In some embodiments, the combination therapies provided herein involve administering modified bacteria daily, and administering one or more additional therapies once a week, once every 2 weeks, once every 3 weeks, once every 4 weeks, once every month, once every 2 months (e.g., approximately 8 weeks), once every 3 months (e.g., approximately 12 weeks), or once every 4 months (e.g., approximately 16 weeks). In certain embodiments, modified bacteria and one or more additional therapies are cyclically administered to a subject. Cycling therapy involves the administration of modified bacteria for a period of time, followed by the administration of one or more additional therapies for a period of time, and repeating this sequential administration. In certain embodiments, cycling therapy may also include a period of rest where modified bacteria or the additional therapy is not administered for a period of time (e.g., 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, 1 week, 2 weeks, 3 weeks, 4 weeks, 5 weeks, 10 weeks, 20 weeks, 1 month, 2 months, 3 months, 4 months, 5 months, 6 months, 7 months, 8 months, 9 months, 10 months, 11 months, 12 months, 2 years, or 3 years). In an embodiment, the number of cycles administered is from 1 to 12 cycles, from 2 to 10 cycles, or from 2 to 8 cycles.
In some embodiments, the methods for treating cancer provided herein comprise administering modified bacteria as a single agent for a period of time prior to administering the modified bacteria in combination with an additional therapy. In certain embodiments, the methods for treating cancer provided herein comprise administering an additional therapy alone for a period of time prior to administering modified bacteria in combination with the additional therapy.
In some embodiments, the administration of modified bacteria and one or more additional therapies in accordance with the methods presented herein have an additive effect relative the administration of modified bacteria or said one or more additional therapies alone. In some embodiments, the administration of modified bacteria and one or more additional therapies in accordance with the methods presented herein have a synergistic effect relative to the administration of the Compound or said one or more additional therapies alone.
As used herein, the term “synergistic,” refers to the effect of the administration of modified bacteria in combination with one or more additional therapies (e.g., agents), which combination is more effective than the additive effects of any two or more single therapies (e.g., agents). In a specific embodiment, a synergistic effect of a combination therapy permits the use of lower dosages (e.g., sub-optimal doses) of modified bacteria or an additional therapy and/or less frequent administration of modified bacteria or an additional therapy to a subject. In certain embodiments, the ability to utilize lower dosages of modified bacteria or of an additional therapy and/or to administer modified bacteria or said additional therapy less frequently reduces the toxicity associated with the administration of modified bacteria or of said additional therapy, respectively, to a subject without reducing the efficacy of modified bacteria or of said additional therapy, respectively, in the treatment of cancer. In some embodiments, a synergistic effect results in improved efficacy of modified bacteria and each of said additional therapies in treating cancer. In some embodiments, a synergistic effect of a combination of modified bacteria and one or more additional therapies avoids or reduces adverse or unwanted side effects associated with the use of any single therapy.
The combination of modified bacteria and one or more additional therapies can be administered to a subject in the same pharmaceutical composition. Alternatively, modified bacteria and one or more additional therapies can be administered concurrently to a subject in separate pharmaceutical compositions. Modified bacteria and one or more additional therapies can be administered sequentially to a subject in separate pharmaceutical compositions. Modified bacteria and one or more additional therapies may also be administered to a subject by the same or different routes of administration.
The combination therapies provided herein involve administering to a subject to in need thereof modified bacteria in combination with conventional, or known, therapies for treating cancer. Other therapies for cancer or a condition associated therewith are aimed at controlling or relieving one or more symptoms. Accordingly, in some embodiments, the combination therapies provided herein involve administering to a subject to in need thereof a pain reliever, or other therapies aimed at alleviating or controlling one or more symptoms associated with or a condition associated therewith.
Specific examples of anti-cancer agents that may be used in combination with modified bacteria include: a hormonal agent (e.g., aromatase inhibitor, selective estrogen receptor modulator (SERM), and estrogen receptor antagonist), chemotherapeutic agent (e.g., microtubule dissembly blocker, antimetabolite, topisomerase inhibitor, and DNA crosslinker or damaging agent), anti-angiogenic agent (e.g., VEGF antagonist, receptor antagonist, integrin antagonist, vascular targeting agent (VTA)/vascular disrupting agent (VDA)), radiation therapy, and conventional surgery.
Non-limiting examples of hormonal agents that may be used in combination with modified bacteria include aromatase inhibitors, SERMs, and estrogen receptor antagonists. Hormonal agents that are aromatase inhibitors may be steroidal or nonsteroidal. Non-limiting examples of nonsteroidal hormonal agents include letrozole, anastrozole, aminoglutethimide, fadrozole, and vorozole. Non-limiting examples of steroidal hormonal agents include aromasin (exemestane), formestane, and testolactone. Non-limiting examples of hormonal agents that are SERMs include tamoxifen (branded/marketed as Nolvadex®), afimoxifene, arzoxifene, bazedoxifene, clomifene, femarelle, lasofoxifene, ormeloxifene, raloxifene, and toremifene. Non-limiting examples of hormonal agents that are estrogen receptor antagonists include fulvestrant. Other hormonal agents include but are not limited to abiraterone and lonaprisan.
Non-limiting examples of chemotherapeutic agents that may be used in combination with modified bacteria include microtubule disasssembly blocker, antimetabolite, topisomerase inhibitor, and DNA crosslinker or damaging agent. Chemotherapeutic agents that are microtubule dissemby blockers include, but are not limited to, taxenes (e.g., paclitaxel (branded/marketed as TAXOL®), docetaxel, abraxane, larotaxel, ortataxel, and tesetaxel); epothilones (e.g., ixabepilone); and vinca alkaloids (e.g., vinorelbine, vinblastine, vindesine, and vincristine (branded/marketed as ONCOVIN®)).
Chemotherapeutic agents that are antimetabolites include, but are not limited to, folate anitmetabolites (e.g., methotrexate, aminopterin, pemetrexed, raltitrexed); purine antimetabolites (e.g., cladribine, clofarabine, fludarabine, mercaptopurine, pentostatin, thioguanine); pyrimidine antimetabolites (e.g., 5-fluorouracil, capcitabine, gemcitabine (GEMZAR®), cytarabine, decitabine, floxuridine, tegafur); and deoxyribonucleotide antimetabolites (e.g., hydroxyurea).
Chemotherapeutic agents that are topoisomerase inhibitors include, but are not limited to, class I (camptotheca) topoisomerase inhibitors (e.g., topotecan (branded/marketed as HYCAMTIN®) irinotecan, rubitecan, and belotecan); class II (podophyllum) topoisomerase inhibitors (e.g., etoposide or VP-16, and teniposide); anthracyclines (e.g., doxorubicin, epirubicin, Doxil, aclarubicin, amrubicin, daunorubicin, idarubicin, pirarubicin, valrubicin, and zorubicin); and anthracenediones (e.g., mitoxantrone, and pixantrone).
Chemotherapeutic agents that are DNA crosslinkers (or DNA damaging agents) include, but are not limited to, alkylating agents (e.g., cyclophosphamide, mechlorethamine, ifosfamide (branded/marketed as IFEX®), trofosfamide, chlorambucil, melphalan, prednimustine, bendamustine, uramustine, estramustine, carmustine (branded/marketed as BiCNU®), lomustine, semustine, fotemustine, nimustine, ranimustine, streptozocin, busulfan, mannosulfan, treosulfan, carboquone, N,N′N′-triethylenethiophosphoramide, triaziquone, triethylenemelamine); alkylating-like agents (e.g., carboplatin (branded/marketed as PARAPLATIN®), cisplatin, oxaliplatin, nedaplatin, triplatin tetranitrate, satraplatin, picoplatin); nonclassical DNA crosslinkers (e.g., procarbazine, dacarbazine, temozolomide (branded/marketed as TEMODAR®), altretamine, mitobronitol); and intercalating agents (e.g., actinomycin, bleomycin, mitomycin, and plicamycin).
Non-limiting examples of other therapies that may be administered to a subject in combination with a Compound include:
(1) a statin such as lovostatin (e.g., branded/marketed as MEVACOR®);
(2) an mTOR inhibitor such as sirolimus which is also known as Rapamycin (e.g., branded/marketed as RAPAMUNE®), temsirolimus (e.g., branded/marketed as TORISEL®), evorolimus (e.g., branded/marketed as AFINITOR®), and deforolimus;
(3) a farnesyltransferase inhibitor agent such as tipifarnib;
(4) an antifibrotic agent such as pirfenidone;
(5) a pegylated interferon such as PEG-interferon alfa-2b;
(6) a CNS stimulant such as methylphenidate (branded/marketed as RITALIN®);
(7) a HER-2 antagonist such as anti-HER-2 antibody (e.g., trastuzumab) and kinase inhibitor (e.g., lapatinib);
(8) an IGF-1 antagonist such as an anti-IGF-1 antibody (e.g., AVE1642 and IMC-A11) or an IGF-1 kinase inhibitor;
(9) EGFR/HER-1 antagonist such as an anti-EGFR antibody (e.g., cetuximab, panitumamab) or EGFR kinase inhibitor (e.g., erlotinib; gefitinib);
(10) SRC antagonist such as bosutinib;
(11) cyclin dependent kinase (CDK) inhibitor such as seliciclib;
(12) Janus kinase 2 inhibitor such as lestaurtinib;
(13) proteasome inhibitor such as bortezomib;
(14) phosphodiesterase inhibitor such as anagrelide;
(15) inosine monophosphate dehydrogenase inhibitor such as tiazofurine;
(16) lipoxygenase inhibitor such as masoprocol;
(17) endothelin antagonist;
(18) retinoid receptor antagonist such as tretinoin or alitretinoin;
(19) immune modulator such as lenalidomide, pomalidomide, or thalidomide;
(20) kinase (e.g., tyrosine kinase) inhibitor such as imatinib, dasatinib, erlotinib, nilotinib, gefitinib, sorafenib, sunitinib, lapatinib, or TG100801;
(21) non-steroidal anti-inflammatory agent such as celecoxib (branded/marketed as CELEBREX®);
(22) human granulocyte colony-stimulating factor (G-CSF) such as filgrastim (branded/marketed as NEUPOGEN®);
(23) folinic acid or leucovorin calcium;
(24) integrin antagonist such as an integrin α5β1-antagonist (e.g., JSM6427);
(25) nuclear factor kappa beta (NF-κβ) antagonist such as OT-551, which is also an anti-oxidant.
(26) hedgehog inhibitor such as CUR61414, cyclopamine, GDC-0449, and anti-hedgehog antibody;
(27) histone deacetylase (HDAC) inhibitor such as SAHA (also known as vorinostat (branded/marketed as ZOLINZA)), PCI-24781, SB939, CHR-3996, CRA-024781, ITF2357, JNJ-26481585, or PCI-24781;
(28) retinoid such as isotretinoin (e.g., branded/marketed as ACCUTANE®)
(29) hepatocyte growth factor/scatter factor (HGF/SF) antagonist such as HGF/SF monoclonal antibody (e.g., AMG 102);
(30) synthetic chemical such as antineoplaston;
(31) anti-diabetic such as rosaiglitazone (e.g., branded/marketed as AVANDIA®)
(32) antimalarial and amebicidal drug such as chloroquine (e.g., branded/marketed as ARALEN®);
(33) synthetic bradykinin such as RMP-7;
(34) platelet-derived growth factor receptor inhibitor such as SU-101;
(35) receptor tyrosine kinase inhibitors of Flk-1/KDR/VEGFR2, FGFR1 and PDGFR beta such as SU5416 and SU6668;
(36) anti-inflammatory agent such as sulfasalazine (e.g., branded/marketed as AZULFIDINE®); and
(37) TGF-beta antisense therapy.
The following non-limiting examples are merely illustrative of the preferred embodiments of the present invention, and are not be construed as limiting the invention.
With careful genetic engineering, S. typhimurium was modified to target solid tumor and express multiple therapeutic molecules. The starting parental strain is the auxotrophic Salmonella enterica serovar typhimurium 7207 strain (S. typhimurium 2337-65 derivative hisG46, DEL407 [aroA::Tn 10{Tc-s}], made by λ-Red mediated recombineering, selecting for the appropriate antibiotic resistance markers. Strain SL001 was constructed by first replacing the gmd open reading frame by a RCR-amplified cassette containing a chloramphenicol resistance gene and a T7 RNAP gene (Δgmd::T7 RNAP-cat). Then the PCR product target gmd gene was electroporated into recombination-competent cells and selected on LB plates containing 25 μg/ml of chlormaphenicol. Then the excision of the antibiotic gene has been achieved here using plasmid p705cre to produce a recombinase that eliminates DNA fragment flanked by two loxP sites, generating the strain SL001.
For the integration of hlyA gene into the genome, first, pYB-asd (a pBSK derivate with 1 kb flanking regions of asd sites) has been generated to target the essential gene. Subsequently, an in vivo inducible promoter PsseA sequence was cloned from the Salmonella Pathogenicity Island 2 (SPI2) and ligated into plasmid pYB-asd through the NotI and HindIII cutting sites. PCR product loxp-cat-loxp was amplified from plasmid ploxp-cat-loxp and ligated into pYB-asd-PsseA at the XhoI site to create plasmid pYB-asd-PsseA-cat. A hlyA gene encoding LLO was PCR-amplified from Listeria genomic DNA and digested with HindIII and XhoI, then ligated into pYB-asd-PsseA-cat, to construct plasmid pYB-asd-hlyA (
Then the DNA-targeting cassette has been digested with KpnI and SacII from pYB-asd-hlyA. The fragment was purified and transformed into electro-competent SL001 cells induced for the phage λ Red-mediated recombineering system. After recombineering, the correct colonies were identified by colony PCR conformation, using a pair of primers: asd-test-f and PsseA-r. Chloramphenicol resistance gene was removed by site-specific Cre/loxP mediated recombination by transformation of plasmid p705cre-Km, generating the strain SL002. Similarly, an anti-stress related gene htrA was replaced by cat-PpepT-asd-sodA cassette. The essential gene with tightly anaerobic control was cloned back to develop strain SL003.
Furthermore, to maintain the therapeutic plasmids without antibiotic selections, a “precise” deletion of the entire structural gene of initiation factor 1 (encoded by infA) from SL003 chromosome has been performed, which is presented in Example 6.5. After a series of genetic manipulations (
These mutants are attracted to tumors, can penetrate into tumor tissue, but do not exclusively colonize tumor hypoxic cores. A series of ST1 mutants have been developed by a similar strategy.
To decrease the fitness of tumor-targeting Salmonella, a replication-incompetent strain SL006 (diaminopimelic acid auxotropy) has been engineered. SL006 has the following genotype: S. typhimurium 2337-65 derivative hisG46, ΔaroA::Tn10 (Tcs), Δgmd::T7 RNAP, Δasd::PsseA-hlyA, ΔinfA::cat, which was derived from SL002 strain by removing an essential gene. The infA::cat cassette generated using PCR with pYB-infA-cat was purified and transformed into electro-competent SL002 cells harboring plasmid pET28a-infA and psim6 for λ Red-recombination. Samples of the electroporation mixture were spread on LB plates supplemented with 25 m/ml chloramphenicol. PCR amplification of the new junctions between the drug marker and infA homology arm-flanking DNA was performed to confirm that the wild-type copy of infA was removed.
Because early metastases and viable tumor cells outside necrotic regions are well or partially oxygenated, they are inaccessible to obligate anaerobic bacteria. To increase the fitness in the non-hypoxic, outer rim of the solid tumor and metastases, replication-competent strains SL007 and SL008 have been developed. SL007 has the following genotype: S. typhimurium 2337-65 derivative hisG46, ΔaroA::Tn10 (Tcs), Δgmd::T7 RNAP, ΔhtrA::PsseA-hlyA, ΔinfA::cat, which was derived from SLOW strain through two procedures. In the first step, pYB-htrA (a pBSK derivate with 1 kb flanking regions of htrA locus) has been generated. The DNA sequence encoding PsseA-hlyA and loxp-cat-loxp were ligated into plasmid pYB-asd through multiple cutting sites to construct plasmid pYB-htrA-hlyA. Then the DNA-targeting cassette has been digested with KpnI and SacII from pYB-htrA-hlyA. The fragment was purified and transformed into electro-competent SL001 cells induced for the phage λ Red-mediated recombineering system. After overnight incubation, the correct colonies were identified by colony PCR conformation. Chloramphenicol resistance gene was removed by induction of Cre recombinase. In the second step, in the new mutant strain, the essential gene infA was replaced by cat cassette, generating SL007. ΔhtrA mutation causes low growth defects in growth at high or low temperatures and stationery phase further attenuating SL007 strain.
SL008 has the following genotype: S. typhimurium 2337-65 derivative hisG46, ΔaroA::Tn10(Tcs), Δgmd::T7 RNAP, Δasd::PsseA-hlyA, ΔhtrA::PpepT-asd-sodA, ΔinfA::tetR, which was derived from SL003 strain. Chloramphenicol resistance gene in SL003 was eliminated by induction of Cre recombinase. Once the loxp sites have been removed, the transcription of asd gene is controlled by the upstream htrA promoter, which resulted in a leaky expression under normal oxygen levels. Then the infA gene was replaced by tetR expression cassette via recombineering, generating SL008 strain. This mutant is attracted to tumors, can penetrate into tumor tissue and effectively colonize viable regions of tumors otherwise unaffected by standard cancer therapy (
Tight control of the expression of the essential gene asd under hypoxic conditions requires a precise genetic regulation. Based on the design of the “obligate” anaerobic S. typhimurium strain YB1, FNR regulated anaerobic capable promoter PpepT and aerobic promoter PsodA (antisense) were used to control asd transcription in ST1. If asd does not express, the bacteria will die in the absence of additional DAP. Survival of ST1 under normal and low oxygen conditions was tested. For anaerobic growth on LB agar plates, an ananerobic jar was applied to maintain low oxygen concentration (0.5% O2) by absorption of AnaeroPacks and monitored by an oxygen meter. ST1 showed the combination of growth under 0.5% oxygen concentration and repression in the aerobic environment without exogenous DAP supplement (
Three groups of six-week-old BALB/c mice were inoculated with CT26 colon cancer cells and, when tumor volumes reached 300˜500 mm3, a single dose (5×107) of ST1, SL007 or SL008 was injected via the tail vein. On day 14 post injections, mice were euthanized and most organs and tumor were collected, homogenized and cultured on LB agar plates with antibiotics. CFU/gram was used as a relative measure of the degree of colonization of the tissues with bacteria (
For SL007 inoculated mice, 103 to 105 CFU/gram of bacteria were found in normal organs. On day 14, SL007 levels in tumor reached 2.1×108 CFU/gram. In comparison, by 2 weeks following injections, ST1 and SL008 were totally eliminated from spleen, liver and kidney, which could prevent a risk for sepsis in the clinical setting. Tuning survival gene asd expression level in SL008 strain leads to migration throughout the tumor (in both viable and necrotic region) (
As live carriers, therapeutic efficacy of these bacteria is always related to the amount of protein presented or the dose of DNA delivered. Therefore, plasmid stability is the most critical parameter for the successful delivery of cargos. In this study, we describe the development of a balanced-lethal vector/host system based on an enzyme essential for protein synthesis in E. coli and S. typhimurium. In strain ST1, the exogenous plasmid is maintained, since it harbors a small essential gene infA, which has been removed from the chromosome. As a consequence, only plasmid-carrying infA− mutant cells can survive, making this strain totally dependent on the maintenance of the infA+ plasmids.
First, the plasmid pET28a-infA containing infA cassette clone from E. coli MG1655 strain has been constructed and co-transformed with psim6 into SL003 (
After 5-day growth in antibiotic free medium, all the infA− mutant cells carried the exogenous infA+ plasmids. However, more than 80% of the parental SL003 cells had lost the plasmid (
Since it has been shown that both ST1 and SL008 are capable of targeting and proliferating in tumor tissue, we assessed the plasmid stability of ST1 and SL008 harboring high-copy-number plasmid pcDNA3.1-infA (pUC origin, AmpR) or low-copy-number plasmid pET32-infA (pER322 origin, AmpR) in tumor tissues after systemic administration. A mouse tumor model was created by implanting CT26 mouse colon cancer cells in the right thigh of BALB/c mice. No statistic difference was detected in the total number of bacteria and total account of ST1 containing high or low-copy-number plasmids harboring infA gene. Validating by CFU test on ampicillin-rich plates indicated that the plasmids containing ampicillin resistance gene still remained in ST1 strains after 3 weeks following injections (
To confirm of the bacterial invasion of ST1, mouse colon cancer CT26 cell monolayer (80˜90% confluence) was incubated with ST1 (at an MOI of 200) for 3 h under 0.5% oxygen concentration. Subsequently, the culture medium was removed and replaced with fresh medium supplemented with gentamicin (50 μg/mL) to kill external bacteria. After 2 and 4 hours, cells were washed and treated with lysis buffer (1% Triton X-100 in PBS) for 30 min on ice. The amount of intracellular bacteria was measured by plating serial dilutions of cell lysates on LB plates with strepmycin and DAP. Invasion rate (%)=number of internalized Salmonella/number of mammalian cells per well×100.
At 2 h post infection, more than 80% of cells contained one or more bacteria. At a later time point (4 h) the number of infected cells kept unchanged, however, the amount of bacteria inside the infected cells increased approximately 2-fold, suggesting that ST1 can replicate within the tumor cells (
Furthermore, to ascertain the ability of ST1-mediated delivery of protein, GFP was used as a marker. Tumor cells were incubated with ST1 carrying a prokaryotic plasmid psgfp. After a 3 h-incubation, ST1/psgfp invaded nearly 80% of epithelial cells which was quantified by gentamicin protection assay, and elicit >50% fluorescent cells detected by flow cytometry using a FACScalibur cytometer (
Plasmid pLpp_ompA_GFP encodes a hybrid protein consisting of (a) a signal sequence and first nine N-terminal amino acids of the major E. coli lipoprotein Lpp, (b) amino acids 46-159 of the outer membrane protein A (ompA) and the GFP domain. Fluorescence visualization of ST1/pLpp_ompA_GFP indicated the insertion of GFP on the outer membrane (
Another plasmid pSspH2-GFP was constructed to fuse the marker protein with the secretion and translocation effectors SspH2 (1-142 aa domain) from the type III secretion system. Here, pGFP without the signal domain was constructed as control. Compared to the vector control, noticeably high fluorescence intensity and diffused location of reporter protein in the cytosol were detected in ST1/pSspH2-GFP infected cells, indicating that a more effective and efficient delivery of exogenous proteins can be achieved through the type III secretion system (
Endostatin, a 20-kDa carboxy-terminal fragment of collagen XVIII, is a potent anti-angiogenic agent currently being evaluated in clinical trials. However, a discrepancy remained unresolved: sustained tumor regression has only been observed with a non-soluble, precipitated form of recombinant endostatin produced in bacteria. To shed light on this question and establish a model of systemic anti-angiogenic gene therapy of cancer that may surmount obstacles in protein production and delivery, we transformed SL008 with a plasmid pSspH2-Endostatin encoding a seretable form of murine endostatin (
Furthermore, the ability of Salmonella SL008 to secrete biologically active antiangiogenic factors at therapeutically sufficient levels largely enhanced the antitumor effects. Taking advantage of the tumor-targeting characteristics of SL008, secretion expression of Endostatin by SL008 throughout the tumors avoided systemic toxicity and markedly stopped tumor growth in mice (
Beside exogenous proteins and eukaryotic plasmids, ST1 is capable of delivering of RNA. By integration of the T7 RNAP gene into the genome, ST1 is able to mediate a transcription of functional mRNA encoding proteins or shRNA. After adhesion and entry, ST1 could escape from the host-cell vacuole by equipping them with LLO and replicate in the cytoplasm of host cells. Some bacteria disrupt and release nucleic acids and proteins inside the cytosol. To investigate whether ST1 could deliver functional mRNA in host cells, EGFP was used as an indicator for monitoring target gene expression in our system. The released unmodified mRNAs without a 5′7-methylguanosine cap structure and a 3′ poly translation in mammals and block prokaryotic translation, Kozak consensus sequence as well as an IRES sequence of the encephalomyocarditis virus were cloned upstream of gene of interest.
For mRNA delivery, the inserted cassettes PT7-kozak-IRES-EGFP-pA20 fragment was amplified from pIRES-EGFP and digested by BglII and NotI. The stabilized vector backbone was generated from the plasmid pET32-infA. pET32a-infA was digested with BglII and NotI and the backbone was purified using agarose gel extraction. The backbone was ligated with PT7-kozak-IRES-EGFP-pA20 fragment and after transformation; the plasmid pT7-EGFP was confirmed by sequencing. Then the prokaryotic plasmid was transformed into engineered ST1 strain to yield ST1/pT7-EGFP (
RNA delivery of ST1/pT7-EGFP was examined. Infection of cultured mouse CT26 cells was performed using ST1/pT7-EGFP at an MOI of 200. At 48 h post infection, cells were detached by trypsinisation and EGFP expression was detected by western blot (
To monitor the ST1-mediated inter-kingdom expression in CT26 mouse colon cancer cells, EGFP was used as a marker. ST1/pIKDE-EGFP was co-cultured with a monolayer of CT26 mouse cancer cells at an MOI of 200 for 3 h. After removal of extracellular bacteria, cells were cultured in a hypoxic incubator containing 0.5% O2 and 5% CO2 at 37° C. for 48 h and then fixed. Fluorescence microscopy revealed fluorescence in the cytosol cells infected with ST1/pIKDE-EGFP and a lack of fluorescent signal from ST1/pIKDE treated cells (
CT26 colon tumors are highly malignant and often lead to death. To investigate the anti-tumor effects of ST1/pIKDE-DTA and SL008/pIKDE-DTA, a colon tumor model was established in the immunocompetent mice. CT26 tumor models were prepared by subcutaneous injection of 1×105 cells into the BALB/c inbred mice (6˜8 weeks of age). When the tumor reached 500 mm3 in size, the mice were received treatments. ST1 or SL008 harboring pIKDE-DTA (
The hemagglutinin protein (HA) gene of avian influenza virus was amplified by PCR from the cDNA of avian influenza H7N9 virus, and sub-cloned into eukaryotic expression vector pIKDE. The HA gene was identified by sequencing. The recombinant plasmid was transformed into asd mutant ST1 (replication-incompetent), and the recombinants were designed as ST1/pIKDE-HA (
To determine whether specific gene silencing can be achieved by ST1 harboring an inter-kingdom RNAi system after its intracellular entry, MDA-MB-231 cancer cells were infected with ST1 carrying plasmid pIKR-shCAT encoding shRNA against the gene of β-Catenin (
The MDA-MB-231 xenograft model was established in which 106 cells were injected into BALB/c female nude mice. Then the mice with established tumors (˜250 mm3) were intravenously injected with PBS, ST1/pIKR-shTom or ST1/pIKR-shCAT. The monitoring of tumor growth for 20 days showed a substantial reduction in ST1/pIKR-shCAT treated mice (
Subsequently, the bacterial distribution was analyzed for safety issues. On day 20 post infection, all the mice were sacrificed and tumor, liver, spleen, kidney, lymph node, lung and heart were removed and weighted. Organs were homogenized in 9 volumes of H2O and CFU tests of viable Salmonella in each organ were determined by plating serial dilutions on LB agar plates supplemented with streptomycin or the antibiotic corresponding to the construction plasmid as well as DAP. The mean number of ST1 per gram tumor exceeded 107˜108 (
Relative analysis was tested with two ST1/pIKR-shCAT colonies harboring pIKR-shCAT which were separated from tumors on day 20 post injections. The separate detection of pIKR-shCAT and host chromosomal DNA were achieved using two separate primer sets, specific for the plasmid β-lactamase gene (bla) and for the chromosomal D-1-deoxyxylulose 5-phosphate synthase gene (dxs). Since both bla and dxs gene are single-copy in the plasmid pIKR-shCAT and Salmonella chromosomal DNA, respectively. Thus the plasmid copy number can be determined as the copy ratio of bla to dxs. The result was consistent with the previously reported value of pUC copy number within bacterial host cells, 500˜700 (Table. 4).
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The invention is not to be limited in scope by the specific embodiments described herein. Indeed, various modifications of the invention in addition to those described will become apparent to those skilled in the art from the foregoing description and accompanying figures. Such modifications are intended to fall within the scope of the appended claims.
All references cited herein are incorporated herein by reference in their entirety and for all purposes to the same extent as if each individual publication or patent or patent application was specifically and individually indicated to be incorporated by reference in its entirety for all purposes.
