N08C9 (Alliance): A Phase 3 Randomized Study of Sulfasalazine Versus Placebo in the Prevention of Acute Diarrhea in Patients Receiving Pelvic Radiation Therapy.

Author(s): Miller RC,  Petereit DG,  Sloan JA,  Liu H,  Martenson JA,  Bearden JD 3rd,  Sapiente R,  Seeger GR,  Mowat RB,  Liem B,  Iott MJ,  Loprinzi CL,  Alliance for Clinical Trials in Oncology

Journal: Int J Radiat Oncol Biol Phys

Date: 2016 Jul 15

Major Program(s) or Research Group(s): NCORP

PubMed ID: 27354129

PMC ID: PMC4955745

Abstract: PURPOSE: To provide confirmatory evidence on the use of sulfasalazine to reduce enteritis during pelvic radiation therapy (RT), following 2 prior single-institution trials suggestive that benefit existed. METHODS AND MATERIALS: A multi-institution, randomized, double-blind, placebo-controlled phase 3 trial was designed to assess the efficacy of sulfasalazine versus placebo in the treatment of RT-related enteritis during RT including the posterior pelvis (45.0-53.5 Gy) and conducted through a multicenter national cooperative research alliance. Patients received 1000 mg of sulfasalazine or placebo orally twice daily during and for 4 weeks after RT. The primary endpoint was maximum severity of diarrhea (Common Terminology Criteria for Adverse Events version 4.0). Toxicity and bowel function were assessed by providers through a self-administered bowel function questionnaire taken weekly during RT and for 6 weeks afterward. RESULTS: Eighty-seven patients were enrolled in the trial between April 29, 2011, and May 13, 2013, with evenly distributed baseline factors. At the time of a planned interim toxicity analysis, more patients with grade ≥3 diarrhea received sulfasalazine than received placebo (29% vs 11%, P=.04). A futility analysis showed that trial continuation would be unlikely to yield a positive result, and a research board recommended halting study treatment. Final analysis of the primary endpoint showed no significant difference in maximum diarrhea severity between the sulfasalazine and placebo arms (P=.41). CONCLUSIONS: Sulfasalazine does not reduce enteritis during pelvic RT and may be associated with a higher risk of adverse events than placebo. This trial illustrates the importance of confirmatory phase 3 trials in the evaluation of symptom-control agents.