A randomised,open-label phase II trial of afatinib versus cetuximab in patients with metastatic colorectal cancer

PurposeThis randomised phase II trial aimed to compare efficacy of the irreversible ErbB family blocker, afatinib, with cetuximab in patients with KRAS wild-type metastatic colorectal adenocarcinoma (mCRC) with progression following oxaliplatin- and irinotecan-based regimens. Efficacy in patients with KRAS mutations was also evaluated.Patients and methodsPatients with KRAS wild-type tumours were randomised 2:1 to afatinib (40 mg/day, increasing to 50 mg/day if minimal toxicity) or cetuximab weekly (400 mg/m² loading dose, then 250 mg/m²/week) according to number of previous chemotherapy lines. All patients with KRAS-mutated tumours received afatinib. Primary end-points were objective response (OR) for the wild-type group and disease control for the KRAS-mutated group. Secondary end-points were progression-free survival (PFS) and overall survival (OS).ResultsPatients with KRAS wild-type tumours (n = 50) received afatinib (n = 36) or cetuximab (n = 14). Unconfirmed and confirmed ORs were 3% and 0% for afatinib versus 20% and 13% for cetuximab (odds ratio: 0.122 [P = 0.0735] and <0.001, respectively). Median PFS was 46.0 and 144.5 days for afatinib and cetuximab, respectively. Median OS was 355 days with afatinib but not reached for cetuximab. In the KRAS-mutated group (n = 41), five (12%) patients achieved confirmed disease control (stable disease; P = 0.6394 [comparison versus 10%]); no ORs were reported. Median PFS and OS were 41.0 and 173 days, respectively. Most frequent treatment-related adverse events were diarrhoea and rash across groups.ConclusionsThe efficacy of afatinib was inferior to cetuximab in patients with KRAS wild-type mCRC. In patients with KRAS-mutated tumours, disease control was modest with afatinib. Afatinib had a manageable safety profile.