A phase II study alternating erlotinib with second-line mFOLFOX6 or FOLFIRI for metastatic colorectal cancer

Background: Based on our pre-clinical data, we hypothesized that sequencing chemotherapy with erlotinib would increase the tumor response rate in patients with metastatic colorectal cancer. Patients and Methods: A phase II trial (planned n=58) using second-line therapy for metastatic colorectal cancer with either oxaliplatin-based (mFOLFOX6) or irinotecan-based (FOLFIRI) combination chemotherapy and 100 mg erlotinib daily on days 3-8 after each infusion (days 1 and 2) every 14 days. The primary endpoint was the response rate compared to the historical response rate. Results: The FOLFIRI/erlotinib arm met the pre-specified response rate criteria of at least 10% to expand accrual to the intended sample size. The trial was halted after an interim safety analysis (n=11) due to excess grade 3 neutropenia, dose reductions and treatment delays. Grade 3 or 4 neutropenia was observed in 64% of patients. The response rate was 18%. Conclusion: In second-line treatment for metastatic colorectal cancer, mFOLFOX6 or FOLFIRI with erlotinib in a sequence-dependent fashion is not feasible despite potential promising activity.