Abstract Efforts to improve the anti-tumor response to KRAS G12C targeted therapy have benefited from leveraging combination approaches. Here, we compare the anti-tumor response induced by the SOS1-KRAS interaction inhibitor, BI-3406, combined with a KRAS G12C inhibitor (KRAS G12C i) to those induced by KRAS G12C i alone or combined with SHP2 or EGFR inhibitors. In lung cancer and colorectal cancer (CRC) models, BI-3406 plus KRAS G12C i induces an anti-tumor response stronger than that observed with KRAS G12C i alone and comparable to those by the other combinations. This enhanced anti-tumor response is associated with a stronger and extended suppression of RAS-MAPK signaling. Importantly, BI-3406 plus KRAS G12C i treatment delays the emergence of acquired adagrasib resistance in both CRC and lung cancer models and is associated with re-establishment of anti-proliferative activity in KRAS G12C i-resistant CRC models. Our findings position KRAS G12C plus SOS1 inhibition therapy as a promising strategy for treating both KRAS G12C -mutated tumors as well as for addressing acquired resistance to KRAS G12C i.

Combined KRAS<sup>G12C</sup>and SOS1 inhibition enhances and extends the anti-tumor response in KRAS<sup>G12C</sup>-driven cancers by addressing intrinsic and acquired resistance

Combined KRASG12Cand SOS1 inhibition enhances and extends the anti-tumor response in KRASG12C-driven cancers by addressing intrinsic and acquired resistance