Abstract 3472: A tumor draining lymph node CD8 T cell memory response is pivotal for a decrease in recurrence after neoadjuvant anti PD-1 therapy for NSCLC

Abstract Background: Non-small cell lung cancer (NSCLC) is the leading cause of cancer death worldwide. Even at early stages, death rates remain disproportionately high due to metastatic recurrence. Recently, blockade of the PD-1/PD-L1 axis has shown impressive increases in recurrence-free survival in a subset of patients. While efforts to decrease relapse have focused on decreasing residual micrometastatic disease at the time of definitive treatment, PD-1 directed therapy may allow for an adaptive immune response and the establishment of anti-tumor immunosurveillance. Building on results from a clinically relevant murine model of metastatic relapse after tumor resection and robust assays on systematically characterized tumor, lymph node and blood samples of early-stage lung cancer patients, we posit that immunologic CD8 T cell memory may be a primary mechanism of metastatic protection. Methods: We utilized a syngeneic murine model of metastatic lung adenocarcinoma (344SQ) after resection of tumor, tumor draining lymph node (tdLN) and non-draining lymph nodes (ndLN). Using bioluminescent imaging (BLI) and flow cytometric analysis we monitored T cell kinetics and anti-tumor activity after administration of anti-PD-1 antibody and/or KD033, a fusion antibody combining a high affinity anti-PD-L1 IgG1 antibody with an IL-15Rα sushi binding domain. Tumor/tdLN and ndLN T cells were characterized for PD-1/TCF-1/CD62L/CD44/CXCR5 memory phenotypes. In parallel, we analyzed resected tumor, tdLN and ndLN from early-stage NSCLC patients. Results: tdLN from murine models and early-stage patients maintain robust PD-1+ CXCR5+ CD8 T cell memory phenotypes not significantly found in the primary tumor, ndLN and peripheral blood. Neoadjuvant treatment with PD-1 blockade alone had a heterogenous response, with robust proliferation of T cell central and stem cell memory populations (CM & SCM) at the tdLN in responders compared to non-responders (p<0.05). Combination therapy with IL-15Rα agonist (KD033) potentiated diverse PD-1+ CXCR5+ CD8 stem cell like memory subsets in the tdLN and subsequent response at the primary tumor (100%) as well as displayed superior protection against metastatic recurrence up to 200 days compared to PD-1 inhibition or KD033 alone (median survival undetermined vs. 120d, 161d respectively p<0.05). Removal of tdLN or blockade of lymph node migration with FTY720 prior to therapy decreased a population of SCM and CM CD8 T cells found in the primary tumor, decreased primary tumor response and altered systemic memory subpopulations in the ndLN (p<0.05). Conclusions: Our data strongly points to a T cell memory response within the tumor draining lymph node as a possible driver of protection from systemic cancer recurrence, laying the groundwork for a new therapeutic strategy aimed at establishing CD8 immunosurveillance for protection from cancer recurrence. Citation Format: Tatiana Delgado Cruz, Geoffrey J. Markowitz, Mitchell Martin, Arshdeep Singh, Shelley Yang Bai, Nasser Altorki, Timothy McGraw, Vivek Mittal, Jonathan Villena-Vargas. A tumor draining lymph node CD8 T cell memory response is pivotal for a decrease in recurrence after neoadjuvant anti PD-1 therapy for NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3472.