Phase II study of preoperative bevacizumab, capecitabine and radiotherapy for resectable locally-advanced rectal cancer

Abstract

Background: to evaluate whether the addition of bevacizumab (BVZ) to capecitabine-based chemoradiotherapy in the preoperative treatment of locally advanced rectal cancer (LARC) improves efficacy measured by the pathological complete response (pCR) rate. Methods: a phase II two-step design was performed. Patients received four cycles of therapy consisting of: BVZ 10 mg/kg in first infusion on day 1 and 5 mg/kg on days 15, 29, 43, capecitabine 1800 mg/m2/day 5 days per week during radiotherapy, which consisted of external-beam irradiation (45 Gy in 1.8 Gy dose per session over 5 sessions/week for 5 weeks). Six to eight weeks after completion of all therapies surgery was undergone. To profile the biological behaviour during BVZ treatment we measured molecular biomarkers before treatment, during BVZ monotherapy, and during and after combination therapy. Microvessel density (MVD) was measured after surgery. Results: forty-three patients were assessed and 41 were included in the study. Three patients achieved a pathological complete response (3/40: 7.5%) and 27 (67.5%) had a pathological partial response, (overall pathological response rate of 75%). A further 8 patients (20%) had stable disease, giving a disease control rate of 95%. Downstaging occurred in 31 (31/40: 77.5%) of the patients evaluated. This treatment resulted in an actuarial 4-year disease-free and overall survival of 85.4 and 92.7% respectively. BVZ with chemoradiotherapy showed acceptable toxicity. No correlations were observed between biomarker results and efficacy variables. Conclusion: BVZ with capecitabine and radiotherapy seem safe and active and produce promising survival results in LARC.