Risk Factors for GI Adverse Events in a Phase III Randomized Trial of Bevacizumab in First-Line Therapy of Advanced Ovarian Cancer: A Gynecologic Oncology Group Study

Abstract

Purpose To evaluate risk factors for GI adverse events (AEs) within a phase III trial of bevacizumab in first-line ovarian cancer therapy. Patients and Methods Women with previously untreated advanced disease after surgery were randomly allocated to six cycles of platinum-taxane chemotherapy plus placebo cycles (C)2 to C22 (R1); chemotherapy plus bevacizumab C2 to C6 plus placebo C7 to C22 (R2); or chemotherapy plus bevacizumab C2 to C22 (R3). Patients were evaluated for history or on-study development of potential risk factors for GI AEs defined as grade ≥ 2 perforation, fistula, necrosis, or hemorrhage. Results Of 1,873 patients enrolled, 1,759 (94%) were evaluable, and 2.8% (50 of 1,759) experienced a GI AE: 10 of 587 (1.7%, R1), 20 of 587 (3.4%, R2), and 20 of 585 (3.4%, R3). Univariable analyses indicated that previous treatment of inflammatory bowel disease (IBD; P = .005) and small bowel resection (SBR; P = .032) or large bowel resection (LBR; P = .012) at primary surgery were significantly associated with a GI AE. The multivariable estimated relative odds of a GI AE were 13.4 (95% CI, 3.44 to 52.3; P < .001) for IBD; 2.05 (95% CI, 1.09 to 3.88; P = .026) for LBR; 1.95 (95% CI, 0.894 to 4.25; P = .093) for SBR; and 2.15 for bevacizumab exposure (aggregated 95% CI, 1.05 to 4.40; P = .036). Conclusion History of treatment for IBD, and bowel resection at primary surgery, increase the odds of GI AEs in patients receiving first-line platinum-taxane chemotherapy for advanced ovarian cancer. After accounting for these risk factors, concurrent bevacizumab doubles the odds of a GI AE, but is not appreciably increased by continuation beyond chemotherapy.