Comparative analysis of the effect of bevacizumab maintenance regimens after first-line chemotherapy in patients with metastatic colorectal cancer (MCRC): A single institution experience.

Abstract

e15032 Background: The majority of patients with metastatic colorectal cancer (MCRC) will ultimately experience disease progression following initial therapy. Although phase III clinical trials show that continued maintenance therapy improves progression free and overall survival in MCRC, the optimal maintenance regimen with an acceptable safety profile is still undetermined. This study aimed to assess outcomes of bevacizumab-containing maintenance therapy after first line chemotherapy for MCRC. Methods: One hundred thirteen patients (46 males, 67 females) with MCRC diagnosed between 2005 and 2014 who received chemotherapy at Karmanos Cancer Institute were included in this retrospective analysis. Induction treatment for most patients consisted of either 5-FU or capecitabine-based chemotherapy with either oxaliplatin or irinotecan and with or without bevacizumab. Eighty percent of patients who received bevacizumab with induction also received it as part of maintenance therapy. Results: After stratifying for age (dichotomized at 65 years) and induction therapy bevacizumab, there was no difference in PFS for induction regimens with or without bevacizumab (p = 0.67). For patients who received capecitabine as maintenance chemotherapy, the addition of bevacizumab resulted in non-significant larger hazard of a PFS event (HR = 1.46, p = 0.36). Among those who received 5-FU maintenance, the addition of bevacizumab resulted in non-significant smaller hazard of a PFS event (HR = 0.48, p = 0.11). There was no difference in observed toxicities between patients who received bevacizumab and those who did not (p = 0.38), with further sub-set analysis showing no increased toxicities among those who received 5-FU (p = 0.76) and those who received capecitabine (p = 0.16). Conclusions: In patients with metastatic colorectal cancer, there was no difference in efficacy or safety when adding bevacizumab to either 5-FU or capecitabine for maintenance after first line chemotherapy. Based on our results, tolerability and compliance with oral capecitabine ought to be a key factor in determining the choice of maintenance in patients with MCRC.