SBIR-STTR Award

Various cancer vaccines based on tumor associated antigens (TAAs) or tumor specific antigens (TSAs) have shown efficacy in preclinical models. However, their therapeutic efficacies have been rather limited in clinical trial settings. Although the reason for clinical inefficacy for these vaccines is not known, the lack of an adjuvant with potent immunostimulatory capacity, ineffective delivery of TAAs/TSAs into professional antigen presenting cells (APCs), and/or the presence of significant immune evasion mechanisms may contribute to this effect. The main objective of this proposal is to develop a novel cancer vaccine for cervical cancer which overcomes these problems. The vaccine, designated ApoVax104-HPV, is based on the use of a proprietary formulation of the costimulatory ligand, 4-1BBL, designed to specifically deliver TAAs/TSAs to APCs. This vaccine formulation also activates APCs for the generation of an effective anti-tumor immune response with therapeutic efficacy. This novel, proprietary molecule consists of 4-1BBL chimeric with core streptavidin and is based on the company's platform technology ProtEx(tm), invented by the co-investigator of this application, Dr. Haval Shirwan. The ApoVax104 technology has been shown in preliminary studies to have potent immunostimulatory activity for T effector cells and inhibitory activity for T regulatory cells that are implicated in tumor growth. A vaccine formulation consisting of ApoVax104 conjugated with the human papillomavirus (HPV)-16 viral oncoprotein E7 will be generated and tested for its efficacy to induce an immune response in C57BL/6 mice. Successful completion of the proposed experiments will be the first step along the critical path for the development of ApoVax104 as the second-generation platform technology for ApoImmune. If ApoVax104-HPV proves effective in these initial proof-of-concept experiments, the Company will apply for a Phase II SBIR grant to further develop ApoVax104-HPV into a lead commercial product to test in a Phase I clinical trial. In addition, ApoVax104 vaccines may not only protect against cancer but also against infectious diseases, leading to the development of an entire line of ApoVax104-based vaccines with significant potential in the millions of dollars. Immune system-based treatment of cancer represents an alternative therapeutic approach to classic chemotherapy and radiation treatment, and promises to yield a more definitive solution based on a true molecular approach to cancer. ApoImmune's novel immune system-based therapy, ApoVax104 vaccine, is a new, innovative approach to treating cancer and malignant neoplastic diseases

Cervical cancer is one of the most common cancers affecting women and is a worldwide health problem. Unlike most cancers, cervical cancer is caused by a virus - the human papillomavirus (HPV). Two preventative vaccines against HPV were recently licensed in the United States. Merck & Co. developed a vaccine called Gardasil(tm) and GlaxoSmithKline has developed the vaccine Cervarix(tm). Although both appear to be effective at preventing HPV infection in women, neither vaccine protects women already infected with HPV from developing cancer or afflicted with the disease. An estimated 20 million people are infected with HPV and worldwide, cervical cancer is the third leading cause of cancer death affecting an estimated 500,000 women each year. Consequently, a therapeutic approach is still necessary to combat already existing HPV infection and cervical cancer. Regardless of significant advances in vaccinology, the therapeutic potential of cancer vaccines remains to be realized, partly due to an array of evasive and immunosuppressive mechanisms employed by progressing tumors4. Therefore, the success of therapeutic vaccines is not only contingent upon their ability to generate new immune responses and/or boost the existing ones, but also to overcome immune evasion mechanisms. Therapeutic vaccines based on well-defined universal tumor associated antigens (TAAs) represent an attractive approach because of their practicality as well as targeting broad range of cancer types. However, the weak antigenic nature of TAAs combined with possible immune tolerance and evasion mechanisms in cancer patients present major hurdles that require potent adjuvants to achieve therapeutic efficacy. To overcome these obstacles, ApoImmune has developed a proprietary novel HPV vaccine, ApoVax104-HPV, that constitutes i) a chimeric molecule containing the extracellular domain of costimulatory 4-1BBL fused C-terminus to core streptavidin (ApoVax104), and ii) biotinylated HPV 16 E7 oncoprotein as a TAA conjugated to the chimeric protein via biotin/streptavidin interaction. In the Phase I SBIR application, we demonstrated that ApoVax104 component of the vaccine i) targets conjugated antigens into dendritic cells (DCs) constitutively expressing the 4-1BB receptor and activates DCs for antigen uptake and presentation, leading to initiation of adaptive immunity, ii) directly works on CD4+ and CD8+ T effector (Teff) cells further augmenting adaptive immunity, and most importantly iiii) overcomes the suppressive function of CD4+CD25+FoxP3+ T regulatory (Treg) cells. Therefore, the pleiotropic effects of 4-1BBL on innate, adaptive, and regulatory immunity provides a unique advantage over other vaccine approaches under development or in clinical settings. This notion is supported by our strong data obtained during Phase I SBIR studies demonstrating that vaccination with ApoVax104 with a synthetic peptide representing the dominant CD8+ T cell epitope for HPV E7 oncogene (E749-57) was more effective than 3 benchmark adjuvants (lipopolysaccharide, (LPS), Monophosphoryl Lipid A (MPL), and CpG oligonucleotide (CpG), in the generation of primary and long- term T cell memory as well as in the eradication of established E7-expressing TC-1 tumors. In addition, vaccination with ApoVax104 resulted in better efficacy and undetectable toxicity as compared an agonistic Ab against 4-1BB receptor, currently being pursued for cancer clinical trials. Building on these strong preclinical studies obtained from Phase I, the goal of this Phase II SBIR application is to develop a humanized ApoVax104-HPV vaccine containing full length HPV16 E6 and E7 oncoproteins to conform to the requirements of the Food and Drug Administration (FDA) for Phase I clinical trials.

Public Health Relevance:
Unlike most cancers, cervical cancer is caused by a virus - the human papillomavirus (HPV). Cervical cancer is one of the most common cancers affecting women and is a worldwide health problem. An estimated 20 million people are infected with HPV and worldwide, cervical cancer is the third leading cause of cancer death affecting an estimated 500,000 women each year. The overall goal of this project is to develop a therapeutic cervical cancer vaccine, ApoVax104-HPV, into a lead commercial product to test in a Phase I clinical trial.

Public Health Relevance:
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