Protein vaccines have suffered from weak immunogenicity but we have begun to overcome this obstacle by targeting pancreatic cancer proteins within monoclonal antibodies to uptake receptors on dendritic cells (DC). We emphasize DCs active in cross presentation such as DEC-205+ DCs. From research in many labs including our own, CD70 -- the tumor necrosis factor family ligand for CD27 -- is now appreciated to be a major contributor for initiating T cell immunity, accumulation of T cells in te tumor, and long term T cell survival. The expression of CD70 on DCs is tightly controlled, but CD27 is always expressed on na?ve T cells. We hypothesize that agonistic anti-CD27 antibody will be a superior adjuvant to improve the efficacy of pancreatic cancer vaccines, by ensuring delivery of the CD70 signal. This can be approached with new available tools. We propose to explore a new fully human Mab against huCD27 as a more effective adjuvant for a DC-targeted pancreatic cancer protein vaccine. We will also use a human CD27 transgenic mouse model, with both of these new tools being developed by Celldex Therapeutics. To obtain proof-of-principle, we will first use anti-CD27 in combination with a xenogenic pancreatic antigen, human mesothelin, HuMSLN, targeted within anti-DEC-205 mAb. We will assess the quantity, quality and duration of T cell immunity. Anti-CD27 will also be compared to the combination of poly IC and agonistic anti-CD40, a combination that is the most powerful known inducer of CD70 expression on DCs. We will next assess the efficacy of anti-CD27 in both prophylactic and therapeutic protocols using the Panc02 pancreatic transplantable tumor that is stably transduced to express huMSLN. In a more challenging setting, we will test if human anti-huCD27 can efficiently instruct mice to overcome self-tolerance to self/mouse mesothelin. We mainly want to identify vaccine conditions that allow T cell immunity to enter and function in the tumor microenvironment. In summary, our research plan will open up a new field to improve vaccination to a pancreatic cancer antigen, mesothelin, expressed by most pancreatic cancers. The impact of this proposal is not only to open up the anti-CD27 approach for humans, and to bring a readily tolerated DC-targeted protein vaccine approach to pancreatic cancer, but also to expand the scope of pancreatic cancer immune evaluation, at the level of CD4+ and CD8+ T cell properties especially durability and entry into transplantable tumors. All components of these preclinical studies are designed to be brought into clinical testing quickly, within the 2 years of this proposal, if anti-CD27 as hypothesized proves to be a superior adjuvant for integrated and durable T cell immunity.
This proposal will open a new dimension to pancreatic cancer vaccines using a new fully human anti-human CD27 monoclonal antibody as an adjuvant or immune booster. The proposal will bring valuable new resources to the pivotal CD27 pathway that can improve resistance to cancer, but in addition the proposal uses a dendritic cell-targeting protein vaccine that can be expanded to include several antigens and importantly, is already showing immunogenicity in healthy volunteers. All components of these preclinical studies are designed to be brought into clinical testing quickly, witin the two years of this proposal, if anti-CD27 as hypothesized proves to be a superior adjuvant for integrated and durable T cell immunity.
