Project Summary Cancer is the second leading cause of death in the US and despite efforts to develop small molecule and biological therapies, several solid tumors still have 5-year survival rates of 10% or less. CAR-T therapies have recently been approved for use in B-cell malignancies and have provided a starting point for cell therapies to gain a foothold as standard of care. However, translation of that success into solid tumors has been slow, almost non-existent. The major underlying cause for this appears to be lack of persistence of the therapeutic cell whereby it succumbs to the toxic milieu produced by the tumor. Ares Immunotherapy has isolated a unique T cell subset that can overcome this issue by means of anti-apoptotic mechanisms and at a limited ability to self-renew. These, in combination with an elevated homing and migration capacity, the ability to secrete both Th1 and Th17 cytokines, and direct cytotoxicity via Granzyme B and CD107A create a cell that has the potential to eradicate even large entrenched tumor masses. In preclinical studies the Ares cells, when generated as a mesothelin specific CAR-T, have been able to ablate tumors in a mesothelioma mouse model and greatly reduce tumor burden in a pancreatic model. Our proposed research plan will A) improve manufacturing robustness; B) determine the optimal cell to be used based on a combination of clinical efficacy and a robust, scalable process; and C) reduce the time and cost of manufacture. We will characterize this through a host of in vitro assays and verify with an animal study. Following these studies, we will proceed to final optimizations and conduct a toxicity study in route to an IND for a first-in-man study.