Abstract 5106: The addition of radiation therapy to simultaneous targeting of PD-1 and IL2Rβγ enhances antigen-specific CD8 T cell anti-tumor immunity in pancreatic cancer models

Abstract Although IL-2 has been shown to critically mediate NK and T cell effector functions, when used in clinical trials this cytokine has failed due to toxicity and severe side effects of the systemic treatment. Our lab has investigated the use of a next-generation IL-2 compound, murine PD1-IL2v, which consists of an anti-PD-1 antibody fused to a IL2-variant with abolished binding to IL2Rα. Previous work shows this molecule results in tumor-antigen specific T cell expansion and differentiation towards immune effectors. Here, we report for the first time that radiation therapy amplifies the anti-tumor effect observed with PD1-IL2v treatment of murine orthotopic models of local tumor growth and metastasis. This anti-tumor effect is correlated with increases in proliferative and polyfunctional CD8 T cells across tumor, lymph node, and blood compartments. Furthermore, using an OVA-antigen specific orthotopic model, we found that radiation in combination with PD1-IL2v treatment enhances infiltration and activation of antigen-specific CD8 T cells, which have been shown to be critical for immunotherapy clinical success. A portion of tumor-bearing mice treated with radiation and PD1-IL2v fully eradicated their primary tumors and tumor rechallenges, which we show correlates with increased markers of memory in CD8 T cells of these mice. To demonstrate the clinical relevance of these preclinical findings, we performed RNA sequencing on paired pancreatic adenocarcinoma (PDAC) patient tumor tissue samples prior to and following radiation. We observed enhanced IL2Rβ and IL2Rγ expression as well as IL2R signaling in PDAC-patient responders to radiation therapy compared to non-responders. In conclusion, the antigen-specific, lasting memory response to preclinical PDAC models demonstrated here provides rationale for the treatment of PDAC with a radiation and PD1-IL2v combination. Citation Format: Maureen Hoen, Miles Piper, Laurel B. Darragh, Diemmy Nugyen, Jacob Gadwa, Maria Amann, Greta Durini, Michael Knitz, Benjamin Van Court, Tiffany Pham, Ross Kedl, Pablo Umana, Laura Codarri-Deak, Christian Klein, Angelo D’Alessandro, Sana D. Karam. The addition of radiation therapy to simultaneous targeting of PD-1 and IL2Rβγ enhances antigen-specific CD8 T cell anti-tumor immunity in pancreatic cancer models. [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 5106.