Magnitude of progression-free survival (PFS) improvement and treatment (Tx) duration in metastatic colorectal cancer (mCRC) for bevacizumab (BV) in combination with oxaliplatin-containing regimens: An analysis of two phase III studies

4073 Background: In trials of BV with FOLFOX (fluorouracil, leucovorin, oxaliplatin) for mCRC, variability in the magnitude of PFS improvement has been reported [HR=0.61 in E3200 vs HR= 0.83 (FOLFOX or CAPOX (capecitabine and oxaliplatin)) in NO16966]. We propose that differences in rates of treatment discontinuation (D/C) for adverse events (AE) between these studies may have resulted in differences in the observed benefits associated with BV. We explored Tx duration (proportion of patients on Tx) and Tx D/C data at median PFS for the BV containing arms of each study. Methods: ECOG study E3200 randomized previously treated patients with mCRC to FOLFOX ± BV (10 mg/kg). NO16966 employed a 2x2 design that randomized previously untreated patients with mCRC to CAPOX vs FOLFOX and to BV (5 mg/kg) or placebo. In both trials, study Tx was defined as any component of the prescribed regimen. PFS was estimated from Kaplan-Meier curves, and hazard ratios (HR) for PFS were estimated by Cox regression. Results: Median...