Bevacizumab every 4 weeks is as effective as every 2 weeks in combination with biweekly FOLFIRI in metastatic colorectal cancer

Purpose The efficacy and tolerability of bevacizumab every 2 or 4 weeks using the same dosage in combination with biweekly FOLFIRI were retrospectively evaluated in metastatic colorectal cancer (mCRC) patients in the first-line and second-line therapy. Patients and methods A total of 332 patients from six centers were evaluated. The patients had received biweekly FOLFIRI in combination with bevacizumab 5 mg/kg every 2 weeks or every 4 weeks schedule for various reasons in individual patients. Results Approximately 70 % of all patients had 2-week treatment schedule. In the first-line therapy ( n = 240), the overall response rate (ORR) was 34.1 % in 2-week and 36.3 % in 4-week groups. Median progression-free survival (PFS) was 8 months (95 %CI, 6.8–9.2) and 9 months (95 %CI, 6.6–11.4) ( p = 0.074), and median overall survival (OS) was 22 months (95 %CI, 15.8–28.2) and 20 months (95 %CI, 8.1–31.9) ( p = 0.612) in 2- and 4-week groups, respectively. One-year survival rate was 76.2 % for 2-week group and 73.2 % for 4-week group. In the second-line therapy ( n = 92), the ORR was similar between the groups (24.5 vs 25.9 % in 2- and 4-week groups, respectively). Median PFS was 6 months (95 %CI, 4.7–7.3) and 11 months (95 %CI, 6.3–15.7) ( p = 0.074), and median OS was 15 months (95 %CI, 9.6–20.4) and 17 months (95 %CI, 13.7–20.3) ( p = 0.456) for 2-week and for 4-week groups, respectively. One-year survival rate was 61.3 % for 2-week and 71.3 % for 4-week groups. Toxicity profile was similar in 2- and 4-week groups and included neutropenia, febrile neutropenia, nausea and vomiting, diarrhea, mucositis, bleeding, hypertension, thromboembolism and fistulization. Conclusion Bevacizumab 5 mg/kg every 2 weeks or every 4 weeks in combination with biweekly FOLFIRI had similar efficacy and tolerability in mCRC. Because of the retrospective nature of our study, the data should be examined cautiously. However, our study clearly points out the need for determination of optimum biological dosing interval of bevacizumab in well-designed, prospective, randomized trials.