688 RAS(ON) inhibitors induce immunogenic cell death, promote antitumor immunity, and synergize with anti-PD-1 immunotherapy in a RAS Mutant NSCLC model

Background While homeostatic cell death is largely immunologically silent, immunogenic cell death (ICD) triggers immune activation. Certain chemotherapies and radiation therapies have been shown to induce ICD and promote antitumor immunity, but whether targeted molecular therapies such as RAS inhibitors can similarly induce ICD in RAS-driven tumors remains unclear. Induction of ICD by targeted therapies could help broaden the benefit of immunotherapy, particularly in RAS-driven non-small cell lung cancer (NSCLC) where immunotherapy is standard of care.Methods Daraxonrasib, a RAS(ON) multi-selective inhibitor, and elironrasib, a RAS(ON) G12C-selective inhibitor, both drive cancer cell death resulting in tumor regressions in RAS-driven models. Here, we investigate whether RAS(ON) inhibitors trigger ICD in the immunocompetent KPAR1.3 NSCLC model and evaluate their combination with anti-PD-1 immunotherapy.Results We first show that RAS(ON) inhibition by either daraxonrasib or elironrasib in tumor cells induces hallmarks of ICD in vitro, including calreticulin externalization and HMGB-1 release. Next, we demonstrate that vaccination of immunocompetent mice with tumor cells pre-treated with RAS(ON) inhibitors in vitro confers protection against subsequent tumor challenge, providing further evidence of ICD induction. In mice vaccinated with tumor cells pre-treated with a RAS(ON) multi-selective inhibitor, we detect tumor antigen-specific T cells in the spleen, further confirming immune activation. Lastly, treatment of tumor-bearing mice with daraxonrasib or elironrasib promotes T cell infiltration in the tumor microenvironment and results in increased durability of response and complete tumor regressions when combined with anti-PD-1 immunotherapy.Conclusions Simultaneously inducing cancer cell death and activating antitumor immunity remains a central goal of cancer therapeutics. Collectively, our preclinical findings demonstrate that both RAS(ON) mutant-selective and RAS(ON) multi-selective inhibitors can induce ICD and their antitumor activity is enhanced by combination with T cell-directed immunotherapies. The clinical evaluation of daraxonrasib and elironrasib in combination with pembrolizumab is ongoing in RAS mutant advanced NSCLC ( NCT06162221).