Pathological response and safety of two neoadjuvant strategies with bevacizumab in MRI-defined locally advanced T3 resectable rectal cancer: A randomized, noncomparative phase II study

Abstract

Background: In T3 rectal cancer (RC), preoperative chemoradiotherapy [5-fluorouracil (5-FU-RT)] reduces local recurrences, but does not affect overall survival. New therapeutic options are still necessary to improve clinical outcomes. Patients and methods: This randomized, noncomparative, open-label, multicenter, two arms, phase II study was conducted in MRI-defined locally advanced T3 resectable RC. In arm A, patients received 12-week bevacizumab plus 5-FU, leucovorin and oxaliplatin (Folfox-4) followed with bevacizumab-5-FU-RT before total mesorectal excision (TME). In arm B, patients received only bevacizumab-5-FU-RT before TME. Primary end point was pathological complete response (pCR) rate. Results: Forty-six patients were randomized in arm A and 45 patients in arm B. In arm A, the rate of pCR was 23.8% [95% confidence interval (CI) 12.1% to 39.5%] statistically superior to the defined standard rate of 10%, P = 0.015. In arm B, the rate of pCR of 11.4% (95% CI 3.8% to 24.6%) was not different from 10%, P = 0.906. No death occurred during the study period, from the start until 8 weeks following surgery. Postoperative fistulas were reported for 16 patients (7 in arm A and 9 in arm B). Conclusion: Even if the addition of bevacizumab induced manageable toxicities including an increased risk of postoperative fistula and no treatment-related death, arm B did not achieve the expected pCR rate in the population of patients included. Induction bevacizumab-Folfox-4 followed by bevacizumab-5-FU-RT is promising. It is however necessary to continue investigations in the management of locally advanced RC.