The early infiltration by leukocytes into the tumor microenvironment leads to neovascularization, enhanced tumor growth, metastasis and lethality of the host. Notably, leukocytes enable tumor establishment, as suggested early on by Virchow in 1826 and proven more recently by others (e.g. Manning et al, 2007 Clin Ca Res 13:3951;review Wasiuk/Noelle et al. 2009 Clin Exp Immunol 155:140). Our own preliminary data (Noelle et al.) show that if one interferes with the early infiltration of inhibitory leukocytes, one can greatly enhance the development of protective tumor immunity and survival of the host. Further, eradicating mast cells increases survival from 5% to over 80% of mice to immunogenic tumors. In lieu of eradicating mast cells, our studies have evaluated if anti-tumor immunity can be enhanced by blocking angiogenesis. The preliminary data show that the use of anti-VEGFR2 Ab, which is functionally equivalent to the eradication of mast cells, can similarly increase survival of the host to immunogenic tumors. The premise of this proposal is that tumor vaccines that induce immunity to a non-immunogenic tumor like B16 melanoma, require an anti-angiogenic/mast cell approach to ensure that tumor site inhibitory leukocytes do not inhibit otherwise highly effective tumor-specific cell mediated immunity (CMI), as well as a cytoreduction/chemotherapeutic agent to provide immunologic space for effective CMI to develop. While most anti-angiogenesis studies focus directly on tumor site vasculature, investigators have begun to evaluate the impact of blocking angiogenesis on host responses to tumors. Based on our studies and those published, we hypothesize that anti-angiogenic factors will greatly enhance the efficacy of our tumor vaccine to elicit superior protective, acquired, tumor-specific cell-mediated immunity.
In Aim 1 we propose to use our experience in developing melanoma vaccines to provide proof-of-concept for a combination vaccine that 1) uses our proprietary CD40/TLR agonist adjuvant vaccine to induce superior CMI against tumors relative to vaccine technologies currently used by others, and 2) broadly abrogates angiogenesis/mast cell-induced inhibition of CMI across several additional tumor models. Furthermore, in Aim 2, cytoreductive/chemotherapy methods, shown to be somewhat effective in the clinic, will be overlaid on this approach to test for additional efficacy.
The premise of this proposal is that tumor vaccines that induce immunity to poorly or non-immunogenic tumors like B16 melanoma, require an anti-angiogenic/mast cell approach plus cytoreductive chemotherapy to ensure that the tumor site does not inhibit otherwise highly effective anti-tumor leukocytes. The approach here, based on our preliminary results, is to develop a combination therapy using our proprietary anti-CD40/TLR adjuvant vaccine combined with blocking Ab to the angiogenesis factor VEGFR2 as well as the cytoreductive chemotherapeutic Cytoxan. We predict that we can improve anti-tumor immunity against a range of otherwise hard-to-treat tumor states.
