Immunogenicity of a lambda phage-based anti-cancer vaccine targeting HAAH

We have designed, developed and produced a lambdaphage based anti-cancer vaccine (nano-particle) targeting human aspartyl (asparaginyl) b-hydroxylase (HAAH). This follows accumulated evidence that HAAH meets requirements of a good target for anti-cancer immunotherapy. The protein is over-expressed on the surface of cancer cells and plays a central role in cancer etiology that effects cancer cell growth, motility and invasiveness. Overexpression of HAAH in transfected normal cells is sufficient to induce cellular transformation, and suppression of HAAH expression (siRNA) or neutralized activity (mAb) returns cancer cells to a normal phenotype. Moreover, tumor growth in xenograft models of human liver and lung cancer is significantly (>80%) inhibited by administration of anti-HAAH monoclonal antibodies. Therefore, it is expected that a patient polyclonal antibody response against HAAH should result in a significant therapeutic effect. HAAH is an embryonic protein and as such is a self antigen. Moreover, it has been observed that the HAAH gene is well conserved and mouse AAH has very high homology in the N-terminal portion of HAAH and complete homology in the mid and C-terminal portion. Historically, recombinant HAAH protein administered with adjuvants has not proven to be very immunogenic in mice. Here we have used immunocompetent mice to test immunogenicity of three phage-based vaccine candidates, encompassing the N-terminal, mid and C-terminal portions of the HAAH extracellular domain. All three entities display highly significant, dose-dependent immunogenicity. Animals were injected with 5x10-5x10 pfus on days 0, 7 and 14. Animals were bled on day 21 and immunogenicity was screened using recombinant HAAH in an ELISA format. Cell-based ELISAs using liver (FOCUS) and lung (H460) cancer cell lines as well as FACS analysis on these lines were performed. The immunized mice sera had clear anti-HAAH (or anti-cancer cell) activity in all tests. Immunogenicity was dose and construct dependent. This work demonstrates that a nano-particle, phage-based vaccine can break immune tolerance to the native HAAH protein and elicit a specific antibody response; indicating that such vaccines may have significant therapeutic value. Indeed preliminary data from an ongoing animal study testing this vaccine in a mouse tumor model has demonstrated a quick and very significant anti-tumor activity, slowing the growth of subcutaneously implanted mouse liver cancer tumors. Thus, this strategy of expressing portions of the HAAH protein on the surface of lambda-phage has resulted in overcoming tolerance to self antigen and promises to be an effective anti-cancer vaccine.