Efficacy, Safety, and Biomarkers of Neoadjuvant Bevacizumab, Radiation Therapy, and Fluorouracil in Rectal Cancer: A Multidisciplinary Phase II Study

TLDR: Bvacizumab with chemoradiotherapy appears safe and active and yields promising survival results in locally advanced rectal cancer.

Abstract: Purpose To assess the safety and efficacy of neoadjuvant bevacizumab with standard chemoradiotherapy in locally advanced rectal cancer and explore biomarkers for response. Patients and Methods In a phase I/II study, 32 patients received four cycles of therapy consisting of: bevacizumab infusion (5 or 10 mg/kg) on day 1 of each cycle; fluorouracil infusion (225 mg/m2/24 hours) during cycles 2 to 4; external-beam irradiation (50.4 Gy in 28 fractions over 5.5 weeks); and surgery 7 to 10 weeks after completion of all therapies. We measured molecular, cellular, and physiologic biomarkers before treatment, during bevacizumab monotherapy, and during and after combination therapy. Results Tumors regressed from a mass with mean size of 5 cm (range, 3 to 12 cm) to an ulcer/scar with mean size of 2.4 cm (range, 0.7 to 6.0 cm) in all 32 patients. Histologic examination revealed either no cancer or varying numbers of scattered cancer cells in a bed of fibrosis at the primary site. This treatment resulted in an actuari...