PFS, OS, ORR, and R0 resection rates were analyzed according to treatment arm for the LLD and non-LLD subgroups.
Of the 367 patients with RAS wt tumors, 89 (24%) had LLD and 278 (76%) had non-LLD. Within the RAS wt LLD and non-LLD subpopulations, demographic and baseline characteristics were comparable between treatment arms. In patients with RAS wt LLD, adding cetuximab to FOLFIRI significantly improved PFS (hazard ratio [HR][95% CI] = 0.21[0.09–0.49]) and ORR (odds ratio [OR][95% CI] = 8.99[3.17–25.52]), and numerically improved OS (HR[95% CI] = 0.65[0.38–1.10]) and R0 resection rate (OR[95% CI] = 2.68[0.63–11.43]) relative to FOLFIRI alone. In patients with RAS wt non-LLD, adding cetuximab to FOLFIRI significantly improved PFS (HR[95% CI] = 0.65[0.46–0.93]), OS (HR[95% CI] = 0.71[0.54–0.93]), ORR (OR[95% CI] = 2.44[1.49–3.98]), and—numerically—R0 resection rate (OR[95% CI] = 5.94[0.79–44.88]). Similar results were obtained from the KRAS wt population.
Adding cetuximab to first-line FOLFIRI appears to improve clinical outcomes and R0 resection rates in KRAS wt and RAS wt mCRC patients with LLD as well as in those with non-LLD.