Kraft, Colleen S.

Abstract Background Patients experiencing ≥1 recurrence of CDI are at elevated risk for subsequent recurrences and complications versus those with an initial CDI episode. Treatment selection for recurrent CDI (rCDI) is influenced by the number of recurrences a patient has experienced. Fecal microbiota spores, live-brpk (VOWST™; formerly SER-109, hereafter referred to as VOS for Vowst Oral Spores) is an oral microbiota-based therapeutic to prevent rCDI in adults with rCDI after antibacterial treatment for rCDI, thought to work by enabling rapid restoration of the microbiome. We report results from an integrated analysis of two Phase 3 trials to further describe safety/efficacy of VOS in patients, stratified by number of prior CDI recurrences. Methods The randomized, controlled ECOSPOR III trial enrolled 182 patients with ≥2 CDI recurrences, and the open-label, single-arm ECOSPOR IV trial enrolled 263 patients with ≥1 CDI recurrence. VOS was given as 4 capsules over 3 consecutive days after completing antibiotic treatment. Treatment-emergent adverse events (TEAEs) were collected through Week 8 after VOS; serious TEAEs/AEs of special interest were collected through Week 24. Efficacy endpoint included rCDI (toxin-positive diarrhea requiring treatment) through Week 8. Results A total of 77 patients had 1, 150 patients had 2, and 121 patients had ≥3 prior CDI recurrences; incidence of TEAEs was 44%, 70%, and 67%, respectively (Table 1). No serious TEAEs, TEAEs of special interest, or TEAEs leading to study withdrawal were considered related to VOS by investigators. TEAEs in ≥15% of patients with 1, 2, or ≥3 prior CDI recurrences were flatulence (6%; 29%; 29%), abdominal pain (6%; 27%; 16%), fatigue (1%; 26%; 20%), abdominal distension (3%; 22%; 20%), and diarrhea (27%; 21%; 23%). On-study recurrence rate through Week 8 in the overall population was 9.5% (95% CI: 6.6%–13.0%); in those with 1 or multiple (≥2) CDI recurrences, rates (95% CI) were 6.5% (2.1%–14.5%) and 10.3% (7.0%–14.6%), respectively. Conclusion This integrated analysis confirms VOS was well tolerated and rCDI rates were low/consistent in patients, regardless of the number of CDI recurrences. Results suggest VOS may be considered in patients with rCDI, regardless of the number of prior CDI recurrences. Disclosures Matthew Sims, MD, PhD, Adaptive Phage Therapeutics: Grant/Research Support|Applied Biocode: Advisor/Consultant|Applied Biocode: Grant/Research Support|Astra Zeneca: Grant/Research Support|Biotest AG: Grant/Research Support|ContraFect: Grant/Research Support|Janssen: Grant/Research Support|Leonard-Meron Biosciences: Grant/Research Support|Novozyme: Grant/Research Support|OpGen: Advisor/Consultant|OpGen: Grant/Research Support|Pfizer: Grant/Research Support|Prenosis: Advisor/Consultant|Prenosis: Grant/Research Support|QIAGEN: Grant/Research Support|Seres: Advisor/Consultant|Seres: Grant/Research Support|Summit Therapeutics: Grant/Research Support|Venatorx: Advisor/Consultant Colleen S. Kraft, MD, MSc, Ferring: Advisor/Consultant|Seres: Advisor/Consultant Lisa von Moltke, MD, Cara Therapeutics: Board Member|Cara Therapeutics: Stocks/Bonds (Public Company)|Seres Therapeutics: Employee|Seres Therapeutics: Stocks/Bonds (Public Company) Brooke Hasson, PhD, Seres Therapeutics: employee|Seres Therapeutics: Stocks/Bonds (Public Company) Maximilian von Eynatten, MD, Nestlé Health Science: Employment Darrell Pardi, MD, AMT, Inc: Grant/Research Support|Boehringer Ingelheim: Grant/Research Support|Exe GI: Grant/Research Support|Immunic: Advisor/Consultant|Lilly: Advisor/Consultant|Rise Therapeutics: Advisor/Consultant|Rise Therapeutics: Grant/Research Support|Seres Therapeutics: Advisor/Consultant|Seres Therapeutics: Expert Testimony|Vedanta: Advisor/Consultant|Vedanta: Grant/Research Support

Abstract Background Although comorbidities are risk factors for recurrent Clostridioides difficile infection (rCDI), many clinical trials exclude patients with medical conditions such as malignancy or immunosuppression. In a phase 3, double-blind, placebo-controlled, randomized trial (ECOSPOR III), fecal microbiota spores, live (VOWST, Seres Therapeutics; hereafter “VOS,” formerly SER-109), an oral microbiota therapeutic, significantly reduced the risk of rCDI at week 8. We evaluated the efficacy of VOS compared with placebo in patients with comorbidities and other risk factors for rCDI. Methods Adults with rCDI were randomized to receive VOS or placebo (4 capsules daily for 3 days) following standard-of-care antibiotics. In this post hoc analysis, the rate of rCDI through week 8 was assessed in VOS-treated participants compared with placebo for subgroups including (i) Charlson comorbidity index (CCI) score category (0, 1–2, 3–4, ≥5); (ii) baseline creatinine clearance (<30, 30–50, >50 to 80, or >80 mL/minute); (iii) number of CDI episodes, inclusive of the qualifying episode (3 and ≥4); (iv) exposure to non-CDI-targeted antibiotics after dosing; and (v) acid-suppressing medication use at baseline. Results Of 281 participants screened, 182 were randomized (59.9% female; mean age, 65.5 years). Comorbidities were common with a mean overall baseline age-adjusted CCI score of 4.1 (4.1 in the VOS arm and 4.2 in the placebo arm). Across all subgroups analyzed, VOS-treated participants had a lower relative risk of recurrence compared with placebo. Conclusions In this post hoc analysis, VOS reduced the risk of rCDI compared with placebo, regardless of baseline characteristics, concomitant medications, or comorbidities.

ImportanceA safe and effective treatment for recurrent Clostridioides difficile infection (CDI) is urgently needed. Antibiotics kill toxin-producing bacteria but do not repair the disrupted microbiome, which promotes spore germination and infection recurrence.ObjectivesTo evaluate the safety and rate of CDI recurrence after administration of investigational microbiome therapeutic SER-109 through 24 weeks.Design, Setting, and ParticipantsThis phase 3, single-arm, open-label trial (ECOSPOR IV) was conducted at 72 US and Canadian outpatient sites from October 2017 to April 2022. Adults aged 18 years or older with recurrent CDI were enrolled in 2 cohorts: (1) rollover patients from the ECOSPOR III trial who had CDI recurrence diagnosed by toxin enzyme immunoassay (EIA) and (2) patients with at least 1 CDI recurrence (diagnosed by polymerase chain reaction [PCR] or toxin EIA), inclusive of their acute infection at study entry.InterventionsSER-109 given orally as 4 capsules daily for 3 days following symptom resolution after antibiotic treatment for CDI.Main Outcomes and MeasuresThe main outcomes were safety, measured as the rate of treatment-emergent adverse events (TEAEs) in all patients receiving any amount of SER-109, and cumulative rates of recurrent CDI (toxin-positive diarrhea requiring treatment) through week 24 in the intent-to-treat population.ResultsOf 351 patients screened, 263 were enrolled (180 [68.4%] female; mean [SD] age, 64.0 [15.7] years); 29 were in cohort 1 and 234 in cohort 2. Seventy-seven patients (29.3%) were enrolled with their first CDI recurrence. Overall, 141 patients (53.6%) had TEAEs, which were mostly mild to moderate and gastrointestinal. There were 8 deaths (3.0%) and 33 patients (12.5%) with serious TEAEs; none were considered treatment related by the investigators. Overall, 23 patients (8.7%; 95% CI, 5.6%-12.8%) had recurrent CDI at week 8 (4 of 29 [13.8%; 95% CI, 3.9%-31.7%] in cohort 1 and 19 of 234 [8.1%; 95% CI, 5.0%-12.4%] in cohort 2), and recurrent CDI rates remained low through 24 weeks (36 patients [13.7%; 95% CI, 9.8%-18.4%]). At week 8, recurrent CDI rates in patients with a first recurrence were similarly low (5 of 77 [6.5%; 95% CI, 2.1%-14.5%]) as in patients with 2 or more recurrences (18 of 186 [9.7%; 95% CI, 5.8%-14.9%]). Analyses by select baseline characteristics showed consistently low recurrent CDI rates in patients younger than 65 years vs 65 years or older (5 of 126 [4.0%; 95% CI, 1.3%-9.0%] vs 18 of 137 [13.1%; 95% CI, 8.0%-20.0%]) and patients enrolled based on positive PCR results (3 of 69 [4.3%; 95% CI, 0.9%-12.2%]) vs those with positive toxin EIA results (20 of 192 [10.4%; 95% CI, 6.5%-15.6%]).Conclusions and RelevanceIn this trial, oral SER-109 was well tolerated in a patient population with recurrent CDI and prevalent comorbidities. The rate of recurrent CDI was low regardless of the number of prior recurrences, demographics, or diagnostic approach, supporting the beneficial impact of SER-109 for patients with CDI.Trial RegistrationClinicalTrials.gov identifier: NCT03183141