1950. Prevention of Recurrent Clostridium difficile at Six Months following Treatment with Microbiota-based Therapy RBX2660: Durability Results from a Phase 2 Open-Label Study
Session: Poster Abstract Session: Clinical Trials
Saturday, October 6, 2018
Room: S Poster Hall
Background: Numerous microbiota-based therapies are being evaluated for prevention of C. difficile infection (rCDI), a public health threat with high recurrence rates associated with the current standard of care. RBX2660, a standardized microbiota-based drug, was efficacious for preventing rCDI in a double-blinded Phase 2b clinical study (PUNCH CD 2). Herein we report the durability of RBX2660 beyond the initial primary clinical end-point of a subsequent Phase 2 open-label study, demonstrating rCDI prevention at 6 months post-treatment.

Methods: This prospective, multi-center, open-label Phase 2 study enrolled subjects who had experienced either ≥2 recurrences of CDI following standard-of-care antibiotic therapy or ≥2 episodes of severe CDI requiring hospitalization. Participants received up to 2 doses of RBX2660 delivered via enema with doses 7 days apart. The primary endpoint of the open-label clinical study defined efficacy as absence of CDI at 8 weeks from the last dose. Safety follow-ups and durability assessments occurred via telephone at 3, 6, 12, and 24 months. The study is ongoing, and not all subjects have completed their assessments.

Results: This study included 149 RBX2660-treated subjects and 110 historical control subjects from 31 and 4 centers, respectively, in the USA and Canada. At 8-weeks post-treatment, RBX2660’s efficacy in preventing rCDI (79.9%; 119/149) was higher than CDI-free rates in the historical control group (51.8%, 57/110; p<0.001). Of the 119 subjects who were determined to be treatment success at 8-weeks, 117 have data through 6-months, of which 8 were exited for non-CDI reasons. Of those 109 subjects through the 6-month follow-up, 3 (2.8%) had a new CDI beyond 8-weeks after enema. The 6-month long-term CDI-free rate was 97.2% (106/109) (median follow-up: 182 days; mean: 177 days).

Conclusion: RBX2660, a microbiota-based drug, was efficacious for the prevention of recurrent CDI with long-term durability at 6-months post-treatment; a result consistent with 6-month rCDI prevention reported for the Phase 2b PUNCH CD 2 trial. Long-term follow-up of RBX2660 safety and efficacy 24 months is ongoing.

This analysis was funded by Rebiotix Inc., Roseville, MN.

Sarah Mische, PhD, Rebiotix, Inc., Roseville, MN, Robert Orenstein, DO, FIDSA, Infectious Diseases, Mayo Clinic Arizona, Phoenix, AZ, Erik R. Dubberke, MD, MSPH, FIDSA, FSHEA, Washington University School of Medicine, St. Louis, MO, Sahil Khanna, MBBS, MS, Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, Gail Hecht, MD, Division of Gastroenterology and Nutrition, Loyola University Medical Center, Maywood, IL, Herbert Dupont, MD, FIDSA, St. Luke's Hospital and Kelsey Research Foundation and Kelsey-Seybold Clinic, Houston, TX, Christine Lee, MD, FRCPC, McMaster University, Hamilton, ON, Canada and Ken Blount, PhD, Rebiotix Inc., Roseville, MN


S. Mische, Rebiotix, Inc.: Employee , Salary .

R. Orenstein, Rebiotix, Inc.: Scientific Advisor , Consulting fee .

E. R. Dubberke, Rebiotix, Inc.: Scientific Advisor , Consulting fee .

S. Khanna, Rebiotix, Inc.: Scientific Advisor , Consulting fee and Research support .

G. Hecht, Rebiotix, Inc.: Scientific Advisor , Consulting fee .

H. Dupont, Rebiotix, Inc.: Investigator , Research support .

C. Lee, Rebiotix, Inc.: Scientific Advisor , Consulting fee .

K. Blount, Rebiotix, Inc.: Employee , Salary .

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