236. Treatment of Recurrent Clostridioides difficile Infection With RBX2660 in Patients ≥ 65 Years Old With Underlying Comorbidities

Background Disruptions to gut microbiota composition can result in dysbiosis and subsequent intestinal colonization by opportunistic pathogens such as Clostridioides difficile.1,2 The incidence of Clostridioides difficile infection (CDI) in persons ≥ 65 years old is greater than in those < 65 years old,3 with 1 in 11 CDI patients ≥ 65 years old dying within 1 month of diagnosis.4 We report the efficacy and safety of RBX2660, a microbiota-based live biotherapeutic, in patients with recurrent CDI (rCDI) who were ≥ 65 years old with comorbidities. This is a subgroup analysis of the PUNCH CD3 trial (NCT03244644), a prospective, multicenter, randomized, double-blind, placebo-controlled phase 3 trial. Methods Participants enrolled in PUNCH CD3 were ≥ 18 years old with documented rCDI who completed standard-of-care antibiotic therapy prior to treatment with RBX2660 or placebo. Treatment success was defined as remaining recurrence-free 8 weeks after intervention. In this subgroup analysis, we assessed outcomes of participants ≥ 65 years old with underlying cardiac disorders, chronic kidney disease (CKD), and gastrointestinal (GI) disorders. The treatment-emergent adverse events (TEAEs) were summarized for the double-blind treatment period within 8 weeks and censored if a patient received open-label RBX2660 after CDI recurrence. Results In the modified intent-to-treat population, 119 of 262 participants (45%) were ≥ 65 years old. Of these 119 participants, 42% had a cardiac disorder, 19% had CKD, and 61% had a GI disorder; the respective RBX2660 treatment success rates were 69%, 68%, and 67% (Figure 1). In the total safety population, the overall incidence of TEAEs was 52% with RBX2660 treatment compared to 44% with placebo treatment; mild events accounted for most of the difference (40% vs 30%) (Table 1). The overall incidence of TEAEs was 51% in RBX2660-treated participants ≥ 65 years old and 61%, 68%, and 51% in those participants with a cardiac disorder, CKD, or GI disorder, respectively. Most TEAEs were mild or moderate in severity and related to a pre-existing condition. Conclusion RBX2660 is safe and efficacious across a range of medically complex patients and consistently reduced rCDI in adults ≥ 65 years old, regardless of baseline comorbidities. Disclosures Glenn S. Tillotson, PhD, Ferring Pharmaceuticals: Advisor/Consultant|Paratek Pharmaceuticals: Grant/Research Support|Spero Pharmaceuticals: Advisor/Consultant|Taro Pharmaceuticals: Advisor/Consultant Paul Feuerstadt, MD, FACG, AGAF, Ferring/Rebiotix Pharmaceuticals: Advisor/Consultant|Ferring/Rebiotix Pharmaceuticals: Grant/Research Support|Merck and Co: Advisor/Consultant|SERES Therapeutics: Advisor/Consultant|SERES Therapeutics: Grant/Research Support|Takeda Pharmaceuticals: Advisor/Consultant Stuart Johnson, M.D., Ferring Pharmaceuticals: Membership on Ferring Publication Steering Committee|Ferring Pharmaceuticals: Employee|Summit Plc: Advisor/Consultant Adam Harvey, PhD, Ferring Pharmaceuticals: Employment.