Abstract Background Patients with renal comorbidity are at risk of severe Clostridioides difficile infection (CDI) and recurrence. Fecal microbiota, live-jslm (REBYOTA™, abbreviated here as RBL, previously known as RBX2660) is the first FDA-approved, microbiota-based live biotherapeutic for the prevention of recurrent CDI (rCDI) in adults following antibiotic treatment for rCDI. An ad hoc subgroup analysis of PUNCH CD3-OLS (NCT03931941), an ongoing, open-label, phase 3 trial evaluating the efficacy and safety of RBL, assessed outcomes in participants with renal comorbidity. Methods PUNCH CD3-OLS participants were ≥ 18 years old with medically documented rCDI, including first recurrence determined by the treating physician, and assessed with standard-of-care (SOC) diagnostic methods. After SOC antibiotics, participants received a single dose of rectally administered RBL. Treatment success was defined as remaining recurrence free for 8 weeks after treatment. Treatment-emergent adverse events (TEAEs) through 6 months of treatment were reported. Participants with renal comorbidity were identified from the medical history dictionary-derived terms in the modified intent-to-treat (mITT) population. Results Within the mITT population, 98 of 402 participants with adjudicated outcomes had renal comorbidity, including chronic kidney disease (n=29) and end-stage renal failure (n=5). Of participants with renal comorbidity, 50% had Charlson Comorbidity Index scores of ≥ 5, versus 18% of participants without renal comorbidity. Treatment success was achieved by 66% (65/98) and 77% (235/304) of participants with and without renal comorbidity, respectively. TEAEs occurred in 71% (n=70) of participants with renal comorbidity and 64% (n=194) of participants without renal comorbidity. In both groups, most TEAEs were moderate in severity and related to preexisting conditions. Serious TEAEs were reported by 16% (n=16) and 8% (n=24) of participants with and without renal comorbidity, respectively. The most commonly reported serious TEAE was CDI recurrence, occurring in 3.1% (n=3) and 1.6% (n=5) of participants with and without renal comorbidity, respectively. Conclusion RBL treatment success and TEAE incidence were numerically comparable for those with and without renal comorbidity. Disclosures Monika Fischer, MD, Ferring Pharmaceuticals Inc.: Advisor/Consultant|Rebiotix Inc., a Ferring Company: Board Member|Seres Pharmaceuticals: Advisor/Consultant Joan Thul, BA, Ferring Pharmaceuticals Inc.: Employee Beth Guthmueller, AS, Rebiotix Inc., a Ferring Company: Employee Christian Sandrock, MD, Allergan: Advisor/Consultant|National Institutes of Health: Grant/Research Support|Shionogi: Advisor/Consultant|The Health Resources & Services Administration: Grant/Research Support Nicholas Van Hise, PharmD, Ferring Pharmaceuticals Inc.: Advisor/Consultant|Ferring Pharmaceuticals Inc.: investigator Glenn S. Tillotson, PhD, Dynavax: Advisor/Consultant|Ferring Pharmaceuticals: Advisor/Consultant|Peggy Lillis Foundation: Honoraria|Spero Therapeutics: Advisor/Consultant