Changing monoclonal antibody keeping unaltered the chemotherapy regimen in metastatic colorectal cancer patients: is efficacy maintained?

Monoclonal antibodies bevacizumab and cetuximab both improve overall survival (OS), progression free survival (PFS) and overall response rate (ORR) when combined with irinotecan-containing regimens. The optimal sequence of these monoclonal antibodies in combination with chemotherapy is controversial. This study analysed the efficacy of cetuximab plus Folfiri after progression with the same regimen plus bevacizumab in patients with metastatic colorectal cancer (mCRC). Patients are eligible if progressive disease (PD) after Folfiri-bevacizumab; ECOG PS 0–1. Primary endpoint is the disease control rate (DCR:ORR plus stable disease > 6 months); secondary endpoints: ORR, PFS, duration of response, OS and toxicity. ORR and DCR were reported with their confidence interval at 95%. Kaplan-Meier method was used for PFS and OS evaluation. Results: 54 patients were enrolled to receive Folfiri-cetuximab after PD to Folfiri-bevacizumab treatment. Median age was 65 (43–80), M/F 31/23, ECOG PS 0/1 was 36/ 18, WT Kras 33(61%). The DCR was 64.8% (CI 95% 52.1-77.5). Among the group of patients with stable or progressive disease at first line treatment, 13.3% of them obtained a response at second line. For second line treatment median duration of response was 6 months and clinical benefit 7 months. The ORR was 22.2% (CI 95% 11.1-33.3). The median progression-free survival was 7 months (CI 95% 6–8). The median overall survival for second line treatment was 14 months (CI 95% 11–17). No grade 4 toxicity was observed. Data suggest that this sequential combination therapy is active and well tolerated. At disease progression to first line chemotherapy treatment the maintenance of the same chemotherapy regimen and the change of the monoclonal antibody showed efficacy in response and survival in patients with mCRC.