Abstract A012: Combined AXL and KRAS inhibition synergize and drive immune recruitment in KRAS-mutant NSCLC

Abstract KRAS mutations occur in 20-30% of NSCLC. Allele-specific KRAS inhibitors yield responses in a minority of patients which are relatively short-lived, largely due to the rapid reactivation of MAPK signaling. This highlights the importance of identifying combinatorial treatments that extend MAPK suppression and enhance anti-tumor activity. AXL is a TAM-family RTK that is implicated in progression, immune evasion and resistance, and is targetable by the clinical-stage inhibitor bemcentinib. In this study, we performed in vivo CRISPRa screening for mediators of resistance to KRAS-targeted therapy and evaluated whether simultaneous KRAS and AXL inhibition enhance MAPK suppression and augment anti-tumor immunity in KRAS-mutant NSCLC. MethodsWe conducted autochthonous in vivo CRISPRa screening in a Kras-G12D; P53 model of NSCLC using a pooled sgRNA library targeting 442 frequently altered genes under selection with MRTX1133 (KRAS-G12D inhibitor). Candidate hits were validated in mouse and human cell lines using immunoblotting, RBD pull-down, bulk RNA-seq, clonogenic assays, and synergy analyses. Therapeutic activity was tested in a syngeneic subcutaneous model, and effects on the immune microenvironment were assessed. ResultsIn our in vivo CRISPRa screen, AXL was the top hit in mice treated with MRTX1133. We found that AXL phosphorylation increased concurrently with MAPK reactivation in vitro and in cells with acquired resistance. Combined KRAS and AXL inhibition (MRTX1133 + bemcentinib) prolonged MAPK suppression, as indicated by reduced phospho-ERK, DUSP6, and MYC expression, and downregulation of MAPK-responsive transcripts. Pulldown of active RAS showed that the combination further suppressed KRAS reactivation. Transcriptomic profiling showed stronger pathway suppression with combination therapy, with significantly lower MAPK Pathway Activity Scores. In vitro, the combination displayed robust synergy and reduction of clonogenic potential in the majority of KRAS-mutant NSCLC cell lines. In vivo, combined therapy significantly restricted tumor growth without added toxicity and maintained MAPK suppression in most tumors, whereas all MRTX1133-only tumors exhibited phospho-ERK staining. We found enhanced interferon signaling, increased CXCL9/10 expression, greater infiltration of T-cells, and elevated Fas/FasL expression in combination-treated tumors, collectively supporting enhanced T-cell recruitment and Fas-mediated cytotoxicity. DiscussionThese data identify AXL as a critical mediator of adaptive resistance to KRAS inhibition and demonstrate that combining KRAS and AXL inhibition yields sustained MAPK pathway suppression alongside tumor growth restriction and immune modulation. Although MRTX1133 is no longer in development, similar synergy with G12C-targeting and emerging pan-KRAS inhibitors suggests broad applicability. This work highlights KRAS/AXL targeting as a promising therapeutic strategy and illustrates the utility of in vivo CRISPRa screening for discovering actionable combinations. AI was used to improve the clarity of this abstract. Citation Format: Fredrik I. Thege, Annaliese Kramer, Amber Hoskins, Ashwath Seetharaman, Yuki Makino, Kimal Rajapakshe, Sonja M. Woermann, Anirban Maitra. Combined AXL and KRAS inhibition synergize and drive immune recruitment in KRAS-mutant NSCLC abstract. In: Proceedings of the AACR Special Conference in Cancer Research: RAS Oncogenesis and Therapeutics; 2026 Mar 5-8; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Res 2026;86 (5Suppl₁): Abstract nr A012.