Potent covalent irreversible inhibitor of KRAS G12C IBI351 in patients with advanced solid tumors: First-in-human phase I study

IBI351 is an irreversible and covalent inhibitor of KRAS G12C. Despite FDA approval of two KRAS G12C inhibitors, there are still significant unmet clinical needs in Chinese patients and ongoing concerns about the optimal dosage. Herein, we presented the phase Ia/Ib study of IBI351 monotherapy in Chinese patients with advanced solid tumors harboring KRAS G12C mutation. In phase Ia dose escalation, IBI351 at 250/450/700/900 mg once daily and 450/600/750 mg twice daily (BID) were evaluated. Potentially efficacious doses and optimal recommended phase 2 dose (RP2D) were further evaluated in patients with advanced non-small cell lung cancer (NSCLC) in phase Ia dose expansion and phase Ib. Safety, pharmacokinetics, and investigator-assessed tumor response were evaluated. As of June 13, 2023, 176 patients were enrolled. IBI351 was well tolerated with no dose-limiting toxicity reported across all evaluated doses. The RP2D was determined as 600 mg BID by considering safety, efficacy and pharmacokinetics. A total of 168 patients (95.5 %) had at least one treatment-related adverse event (TRAE), and 64 patients (36.4 %) had grade 3 or higher TRAEs, most commonly gamma-glutamyl transferase increased (10.2 %) and anemia (6.8 %). For patients with NSCLC, the confirmed objective response rate (ORR) was 45.5 % across all doses. At 600 mg BID, the confirmed ORR was 46.8 % and median progression-free survival was 9.6 months with a median follow-up of 6.9 months. IBI351 was well tolerated in patients with advanced solid tumors and showed promising antitumor activity in advanced NSCLC patients with KRAS G12C mutation. •IBI351 was well tolerated in advanced solid tumor patients harboring KRAS G12C.•IBI351 demonstrated promising efficacy in advanced NSCLC patients with KRAS G12C.•IBI351 might be a novel treatment option for advanced solid tumors with KRAS G12C.