Overall Survival Analysis of the Phase III CodeBreaK 300 Study of Sotorasib Plus Panitumumab Versus Investigator's Choice in Chemorefractory KRAS G12C Colorectal Cancer

In the phase III CodeBreaK 300 study, sotorasib 960 mg-panitumumab significantly prolonged progression-free survival (PFS) versus investigator's choice (trifluridine/tipiracil or regorafenib) in patients with KRAS G12C-mutated chemorefractory metastatic colorectal cancer (mCRC). One hundred sixty patients were randomly assigned 1:1:1 to receive sotorasib 960 mg-panitumumab (n = 53), sotorasib 240 mg-panitumumab (n = 53), or investigator's choice (n = 54; crossover permitted after primary analysis). Overall survival (OS) analysis, a key secondary end point, although not adequately powered, was prespecified at 50% maturity (after approximately 80 deaths). In this study, we report the OS, updated overall response rates (ORRs), and data for safety. After a median follow-up of 13.6 months, 24, 28, and 30 deaths occurred in the sotorasib 960 mg-panitumumab, sotorasib 240 mg-panitumumab, and investigator's choice arms, respectively; updated objective response rates (ORRs; 95% CI) were 30.2% (95% CI, 18.3 to 44.3), 7.5% (95% CI, 2.1 to 18.2), and 1.9% (95% CI, 0.0 to 9.9), respectively. Compared with investigator's choice, the hazard ratios (HRs [95% CI]) for OS were 0.70 (95% CI, 0.41 to 1.18; two-sided P = .20) with sotorasib 960 mg-panitumumab and 0.83 (95% CI, 0.49 to 1.39; two-sided P = .50) with sotorasib 240 mg-panitumumab. No new safety signals were observed. Although not statistically significant, the observed OS HR and ORR along with prior PFS and safety findings support sotorasib 960 mg-panitumumab as a standard of care in patients with chemorefractory KRAS G12C mCRC.