KRAS G12C–Targeted Therapy in Non-Small Cell Lung Cancer: From Resistant Salvage to Potential First-Line Backbone

KRAS G12C, long considered an undruggable oncogenic driver, has become one of the most consequential therapeutic targets in non-small cell lung cancer (NSCLC). The discovery of a cryptic binding pocket accessible in the GDP-bound state enabled covalent inhibitors—sotorasib and adagrasib—that have received regulatory approval for previously treated KRAS G12C-mutant NSCLC, with sotorasib demonstrating PFS and OS superiority over docetaxel in CodeBreaK 200 and adagrasib showing meaningful intracranial activity and a progression-free survival benefit over docetaxel in KRYSTAL-12. Yet response durability is limited by on-target switch-II pocket mutations, upstream RTK and SHP2-mediated bypass signaling, downstream MAPK and PI3K-AKT reactivation, phenotypic plasticity, and adverse modulation by co-occurring STK11, KEAP1, and TP53 alterations. Next-generation covalent inhibitors (divarasib, glecirasib, olomorasib), tri-complex RAS(ON) inhibitors (RMC-6291), pan-KRAS agents, and rationally designed combinations with EGFR, SHP2, SOS1, and PD-1 inhibitors are repositioning KRAS-directed therapy toward earlier lines of treatment. This review integrates the structural, signaling, and clinical biology of KRAS G12C with contemporary trial and real-world evidence to examine the emerging case for first-line KRAS G12C inhibition in genomically defined subsets of NSCLC. First-line use nonetheless remains investigational; platinum-based chemoimmunotherapy remains the standard of care outside of clinical trials, and a frontline indication will require confirmation from randomized phase III trials.