Abstract 4153: SETD2 loss and ATR inhibition synergistically promote cGAS signaling and immunotherapy response in renal cell carcinoma

Abstract Rationale: Immune checkpoint blockade (ICB) demonstrates durable clinical benefit only in a minority of renal cell carcinoma (RCC) patients. Identifying molecular features that determine response and developing approaches to enhance the response remain an urgent clinical need. Targeting S phase DNA damage repair (S-DDR) network has been reported to activate cGAS signaling and convert a non-immunogenic tumor microenvironment to an immunogenic tumor microenvironment, thus improving immunotherapy response in breast cancer and small cell lung cancer. SETD2 has been known to be required for ATM-mediated DNA damage response, and we hypothesize that SETD2 loss confers greater dependence on ATR activity and provides vulnerability to ATR inhibitors, which may further potentiate the response to immunotherapy. Methods: Applying molecular, cellular, and bioinformatic approaches, we comprehensively investigated the effects of SEDT2/Setd2 loss on the cytosolic DNA damage response pathway, the cGAS-mediated cytosolic DNA sensing pathway, the tumor immune microenvironment, and immunotherapy response in RCC cell lines, in the Renca-BALB/c immune competent murine model, and in RCC patients cohorts with or without ICB therapy. Results: We found that, in multiple RCC cell lines, pharmacological inhibition of the ATR-CHK1 axis activated the cGAS-IRF3-dependent cytosolic DNA sensing pathway, resulting in inflammatory cytokine expression. SETD2 mutated RCC cell lines or tumor samples were associated with preferential ATR-CHK1 activation over ATM-CHK2 activation. SETD2 knockdown promoted the cytosolic DNA sensing pathway and conferred greater sensitivity to ATR inhibition. In murine Renca tumors, Setd2 knockdown and the ATR inhibitor VE822 synergistically activated the cytosolic DNA sensing pathway, immune cell infiltration, and immune checkpoint protein expression. Setd2 deficient Renca tumors demonstrated greater vulnerability to ICB monotherapy or in combination with ATRi than Setd2 proficient tumors. SETD2 mutations were associated with a higher response rate and prolonged overall survival in ICB-treated RCC patients, but not in non-ICB-treated RCC patients. Conclusion: This study reveals that SETD2/Setd2 loss and ATR inhibitor synergize to enhance cGAS signaling and RCC tumor immune responsiveness, and provides mechanism-based guidance to develop more personalized combination therapy regimens for RCC patients with SETD2 mutations. Citation Format: Xiande Liu, Yanting Zhang, Xuesong Zhang, Daniel McGrail, Truong Lam, Anh Hoang, Elshad Hasanov, Ganiraju Manyam, Christine B. Peterson, Haifeng Zhu, Shwetha V. Kumar, Rehan Akbani, Nizar M. Tannir, Guang Peng, Eric Jonasch. SETD2 loss and ATR inhibition synergistically promote cGAS signaling and immunotherapy response in renal cell carcinoma. [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 4153.