Rates of overall grade 3 to 4 toxicity, diarrhoea, and rash were increased (moderate-quality evidence for all three outcomes), but there was no evidence for increased rates of neutropenia.For the extended RAS wild-type population (no mutations in KRAS or NRAS), addition of EGFR MAb improved progression-free survival (HR 0.60, 95% CI 0.48 to 0.75; moderate-quality evidence) and overall survival (HR 0.77, 95% CI 0.67 to 0.88; high-quality evidence).
Grade 3-4 neutropenia was higher in arm A (28%/7%), as was grade 3 fatigue (12%/3%), and grade 3 neuropathy (11%/< 1%), whereas acneiform rash was confined to arm B. Retrospective analysis of KRAS mutational status did not demonstrate KRAS as a meaningful determinant of activity, except in arm B patients with KRAS-mutated tumors, which resulted in inferior PFS.