Impact of omitting fluorouracil from FOLFIRI plus bevacizumab as second-line chemotherapy for patients with metastatic colorectal cancer

Purpose: Fluorouracil, leucovorin, and irinotecan (FOLFIRI) plus bevacizumab is the standard second-line chemotherapy for patients with metastatic colorectal cancer (mCRC) who are refractory or intolerant to fluoropyrimidines and oxaliplatin. However, the benefits of incorporating fluoropyrimidines into second-line chemotherapy for patients with mCRC who are refractory to fluoropyrimidines are unknown.

Methods: We retrospectively evaluated patients with mCRC who were administered irinotecan plus bevacizumab or FOLFIRI plus bevacizumab as second-line chemotherapy at a single institution from January 2010 to April 2020. We compared the efficacy and safety of irinotecan plus bevacizumab (IRI group) with those of FOLFIRI plus bevacizumab (FOLFIRI group).

Results: Of the 255 enrolled patients, 107 (IRI/FOLFIRI group, 31/76 patients) were eligible for analysis. After a median follow-up of 13.1 months (range 1.2-48.4) and 14.3 months (range 0.9-46.5) for the IRI and FOLFIRI groups, respectively, the median progression-free survival was 6.4 months and 5.8 months [adjusted hazard ratio (aHR), 0.82; 95% confidence interval (CI) 0.50-1.34, p = 0.44] and the median overall survival was 16.6 months and 16.5 months (aHR, 1.01; 95% CI 0.59-1.69; p = 0.97) in the IRI and FOLFIRI groups, respectively. All-grade nausea, stomatitis, neutropenia, thrombocytopenia, Grade 3/4 neutropenia, and febrile neutropenia occurred more frequently in the FOLFIRI group than in the IRI group.

Conclusion: Our study suggests omitting fluorouracil from FOLFIRI plus bevacizumab as the second-line chemotherapy decreases adverse events without affecting the treatment efficacy in patients with mCRC who are refractory to fluoropyrimidines. Further randomized prospective studies are warranted to validate our result.