Abstract 5836: Suppression of TNFα and IFNγ signaling are key molecular events in KRASG12C mutant cancer cells to confer therapeutic resistance to Sotorasib and promote immune evasion

Abstract The groundbreaking development and FDA approval of the mutant and cancer selective KRASG12Cis Sotorasib and Adagrasib to treat NSCLC and CRC patients have revolutionized the field of cancer biology. While these inhibitors demonstrated efficacy in patients with KRASG12C mutation, their response was limited and short lived due to rapid and frequent emergence of therapeutic resistance. Multiple genetic alterations in KRASG12C cancer cells (mainly in RTK and MAPK pathways) have been reported to contribute to their acquired resistance to Sotorasib. However, there is unmet need to fully understand how cancer cells manipulate the immune regulatory signals in the TME to acquire therapeutic resistance and evade antitumor immunity. To this end, we utilized single cell profiling technology to delineate the intricate transcriptomic landscape of tumor cells and tumor infiltrated immune cells in the tumor microenvironment of Sotorasib-resistant tumors. Our single cell RNA seq analysis demonstrated that Sotorasib generated hot TME dominated by effector/cytotoxic T cells and inflammatory macrophages in Sotorasib-responsive CT26G12C colon tumors. Importantly, these Sotorasib-responsive tumors are enriched with immune active tumor populations with highly upregulated TNFα and IFNγ signals. Conversely, these immune-sensitive tumor clusters (with high TNFα and IFNγ signals) were strikingly contracted in Sotorasib-resistant tumors. Furthermore, Sotorasib-resistant tumors exhibited non-inflamed TME dominated by immune suppressive neutrophils and monocytes populations. Intriguingly, Sotorasib failed to suppress or delay tumor growth of resistant tumors even when combined with anti-PD1 immune checkpoint blockade, indicating that KRASi-resistant tumors are in nature less vulnerable to antitumor T cell immunity. In vitro, single-cell imaging flow cytometry revealed that Sotorasib-tolerant cancer cells displayed remarkable reduction in nuclear translocation of NFkB and STAT1 as compared to parental cells, highlighting the importance of TNFα and IFNγ signaling to maintain optimum immune modulatory response of KRASG12C mutant cancer cells to KRAS inhibition. Collectively, our findings uncovered cancer cell-intrinsic and extrinsic molecular mechanisms underlying clinical resistance to Sotorasib and provide a comprehensive profiling of tumor/immune microenvironment ecosystem in refractory tumors to lay the groundwork for developing promising treatment platforms to overcome this inevitable resistance and achieve optimum clinical outcome. Citation Format: Mohammed L. Ibrahim, Xiaoqing Yu, Dana Foresman, Zheng Hong, Eric Haura, Amer Beg. Suppression of TNFα and IFNγ signaling are key molecular events in KRAS mutant cancer cells to confer therapeutic resistance to Sotorasib and promote immune evasion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5836.