Treatment patterns and clinical outcomes in patients with metastatic colorectal cancer initially treated with FOLFOX-bevacizumab or FOLFIRI-bevacizumab: results from ARIES, a bevacizumab observational cohort study.

Background: The Avastin Registry: Investigation of Effectiveness and Safety (ARIES) study is a prospective, community-based observational cohort study that evaluated the effectiveness and safety of first-line treatment patterns, assessing the impact of chemotherapy choice and treatment duration.

Methods: The ARIES study enrolled patients with metastatic colorectal cancer (mCRC) receiving first-line chemotherapy with bevacizumab and followed them longitudinally. The protocol did not specify treatment regimens or assessments. Analyses included all patients who initiated bevacizumab in combination with either first-line oxaliplatin with infusional 5-fluorouracil and leucovorin (FOLFOX) or irinotecan with infusional 5-fluorouracil and leucovorin (FOLFIRI). Progression-free survival (PFS) and overall survival (OS) times were estimated using Kaplan-Meier methods. Hazard ratios (HRs) were estimated with multivariate Cox regression analysis, adjusting for potential confounding factors.

Results: In total, 1,550 patients with first-line mCRC were enrolled (median follow-up, 21 months) and most received FOLFOX-bevacizumab (n = 968) or FOLFIRI-bevacizumab (n = 243) as first-line therapy. The baseline characteristics and median treatment duration were generally similar between subgroups. There were no significant differences in the median PFS (10.3 months vs. 10.2 months) or OS (23.7 months vs. 25.5 months) time between the FOLFOX-bevacizumab and FOLFIRI-bevacizumab subgroups, respectively, by unadjusted analyses. Multivariate analyses showed FOLFIRI-bevacizumab resulted in a similar PFS (HR, 1.03; 95% confidence interval [CI], 0.88-1.21) and OS (HR, 0.95; 95% CI, 0.78-1.16) outcome as with FOLFOX-bevacizumab. The incidence proportions of bevacizumab-associated adverse events were similar for FOLFOX- and FOLFIRI-based therapies.

Conclusions: In first-line mCRC patients, the FOLFOX-bevacizumab and FOLFIRI-bevacizumab regimens were associated with similar treatment patterns and clinical outcomes.