Frequency of S492R mutations in the epidermal growth factor receptor: analysis of plasma DNA from patients with metastatic colorectal cancer treated with panitumumab or cetuximab monotherapy.

These results may support targeting treatment to small patient subgroups based on the presence of emerging EGFR mutations and provide a molecular rationale for rechallenging with a different anti-EGFR agent in patients who develop resistance. Prospective studies are needed to evaluate the efficacy of panitumumab in the EGFR p.S492R mutant population.