Maintenance treatment with fluoropyrimidine plus bevacizumab versus fluoropyrimidine alone after induction chemotherapy for metastatic colorectal cancer: The BEVAMAINT - PRODIGE 71 - (FFCD 1710) phase III study.

Background: Maintenance treatments with fluoropyrimidine alone or combined with bevacizumab after induction chemotherapy are two standard options in first-line metastatic colorectal cancer (mCRC). However, no trial has compared these two maintenance regimens.

Methods: BEVAMAINT is a multicenter, open-label, randomized phase III trial comparing fluoropyrimidine alone or plus bevacizumab as maintenance treatment after induction polychemotherapy in mCRC. The primary endpoint is the time-to-treatment failure (TTF), calculated from date of randomization to first radiological progression, death, start of a new chemotherapy regimen (different from induction or maintenance chemotherapy) or end of maintenance treatment without introduction of further chemotherapy. We expect a 2-month TTF improvement from 6 months in the monotherapy arm to 8 months in the combination arm (hazard ratio [HR], 0.75). Based on a two-sided α risk of 5% and a power of 80%, using Schoenfeld method, 379 events are required (planned enrolment, 400 patients). Patients with mCRC, whose disease is measurable according to RECIST 1.1 criteria and controlled (objective response or stable disease) - but remains unresectable - after 4 to 6 months of induction polychemotherapy (doublet or triplet chemotherapy with or without anti-EGFR or bevacizumab), and who have recovered from limiting adverse events of induction polychemotherapy are eligible for randomization. Randomization is stratified according to center, response to induction chemotherapy (objective response vs stable disease), ECOG performance status (0-1 vs 2), maintenance fluoropyrimidine (5-fluorouracil vs capecitabine) and primary tumor status (resected vs not). Capecitabine or bolus and infusional 5-fluorouracil plus folinic acid (simplified LV5FU2 regimen) are both accepted for maintenance chemotherapy, at investigator's discretion. Clinical evaluation, tumor imaging, carcinoembryonic antigen and circulating tumor DNA dosages are planned at enrolment and every 9 weeks. The maintenance treatment will be discontinued in the event of unbearable toxicity, progression or patient refusal. After maintenance discontinuation, reintroduction of induction polychemotherapy is recommended; otherwise a second-line treatment is started. The enrolment has begun in January 2020.