303 Non-functional T cell responses in non-small cell lung cancer are induced during tumor antigen-specific T cell priming in the mediastinal lymph node

Background In non-small cell lung cancer (NSCLC), response to checkpoint blockade therapy (CBT) is associated with tumor-infiltrating CD8+ T cells, but not all cell-infiltrated tumors respond CBT. The subgroup of CBT-resistant has been clinically described as containing ”non-functional” responses. Mechanisms governing the generation non-functional responses remain poorly understood, and treatment options for this are limited. Methods We utilized a transplantable, syngeneic murine NSCLC line derived from an autochthonous driven by Kras G12D expression p53 deletion (KP line) model To study antigen-specific responses, we engineered KP cells express antigen SIY certain experiments. CBT consisted combined anti-CTLA-4 anti-PD-L1 therapy. Results Orthotopic failed CBT, flank were controlled Lung contained activated providing platform compare functional in NSCLC. Single-cell RNA sequencing revealed that lacked effector exhaustion molecules despite clonal expansion. Analysis cancer-specific dysfunction was established during priming lung-draining mediastinal lymph nodes (mLN) robust proliferation. flow cytometry found primed mLN underwent blunted differentiation characterized lack CD25, Granzyme B, TIM-3, retention TCF-1. This phenotype persisted tumors, consistent our initial observations absent molecule expression. Many patients expressed analogous gene program distinct exhaustion. TCF-1+ did mediate tumor control differentiate into after investigate alternative therapeutic strategies reinvigorating tumor-reactive focused on IL-2 IL-12, their receptors reduced mLN-primed cells. Administering recombinant IL-12 sufficient restore differentiation, induce control, significantly extend survival tumor-bearing mice. Conclusions Our results suggest arise priming. Transient combination overcomes dysfunctional state protective tumors. Ethics Approval All mouse experiments approved MIT’s Committee Animal Care (CAC) - DHHS Welfare Assurance # D16-00078