A randomized, double-blind, placebo-controlled, single and multiple ascending dose Phase 1 study to determine the safety, pharmacokinetics and food and faecal microbiome effects of ibezapolstat administered orally to healthy subjects

Background

Clostridioides difficile infection is the most common cause of healthcare-associated infections in the USA, with limited treatment options. Ibezapolstat is a novel DNA polymerase IIIC inhibitor with in vitro activity against C. difficile.

Objectives and methods

Randomized, double-blind, placebo-controlled study to assess the safety, tolerability and pharmacokinetics of ibezapolstat in healthy volunteers. Microbiome changes associated with ibezapolstat were compared with vancomycin over a 10 day course using shotgun metagenomics.

Results

A total of 62 subjects aged 31 ± 7 years (45% female; average BMI: 25 ± 3 kg/m²) were randomized. Ibezapolstat was well tolerated with a safety signal similar to placebo. Ibezapolstat had minimal systemic absorption with the majority of plasma concentrations less than 1 µg/mL. In the multiday, ascending dose study, ibezapolstat concentrations of 2000 µg/g of stool were observed by Day 2 and for the remainder of the dosing time period. In the multiday, multiple-dose arm, baseline microbiota was comparable between subjects that received ibezapolstat compared with vancomycin. At Day 10 of dosing, differential abundance analysis and β-diversity demonstrated a distinct difference between the microbiome in subjects given vancomycin compared with either dose of ibezapolstat (P = 0.006). α-Diversity changes were characterized as an increase in the Actinobacteria phylum in subjects that received ibezapolstat and an increase in Proteobacteria in subjects given vancomycin.

Conclusions

Ibezapolstat was shown to be safe and well tolerated, with minimal systemic exposure, high stool concentrations and a distinct microbiome profile compared with oral vancomycin. These results support further clinical development of ibezapolstat for patients with C. difficile infection.

Clostridioides (Formerly Clostridium) difficile Infection During Hospitalization Increases the Likelihood of Nonhome Patient Discharge

BACKGROUND

Clostridioides (formerly Clostridium) difficile infection (CDI) is associated with significant morbidity and mortality, including frequent hospitalizations. However, the impact of CDI after hospital discharge is poorly understood. The purpose of this study was to assess patient discharge disposition and understand CDI-related risk factors for nonhome discharge.

METHODS

Using a nationally representative database of Veterans Health Administration (VHA) patients (2003-2014) and a validation database from hospitalized non-VHA patients in Houston, Texas, admission and discharge disposition was obtained for patients with CDI and matched controls. Incidence of and clinical/microbiologic risk factors for nonhome discharge were assessed using these databases.

RESULTS

A total of 15173 VHA patients with CDI and 48599 non-CDI control patients originally admitted from the community were included. Significantly more patients with CDI were discharged to a nonhome location compared with controls (18% vs 8%; P < .0001), most commonly hospice/death (12%) or nursing home/long-term care facility (6%). Results were confirmed using a propensity-matched analysis and a validation cohort of 1941 hospitalized patients with CDI in Houston, Texas. Age, comorbidities, severe CDI, and ribotypes F027, F001, and F053-163 were associated with a nonhome discharge (P < .05 for all).

CONCLUSIONS

Hospitalized patients with CDI frequently required a higher level of medical care residence at discharge compared with non-CDI patients. Risk factors for discharge to a higher level of care included CDI disease severity and variables associated with recurrent CDI.

710. Increased Clinical Failure Rates Associated with Reduced Metronidazole Susceptibility in Clostridioides difficile

Background

Current national guidelines suggest limiting metronidazole (MTZ) use due to increased treatment failures in patients with Clostridioides difficile infections (CDI). However, the reason for these increased failure rates is unclear. We hypothesized an increase in the minimum inhibitory concentration (MIC) of MTZ to C. difficile may contribute to these poor response rates. The objective of this study was to examine clinical response rates in patients with CDI who received MTZ monotherapy vs. other therapies stratified by MTZ susceptibility.

Methods

Stool samples that tested positive for C. difficile (2017–2018) were collected from two large academic hospital systems in Texas. C. difficile was isolated from stool and visually screened for growth on heme-containing agar plates with MTZ at 2 mg/L (defined as reduced susceptibility). Blinded investigators reviewed electronic medical records to identify the treatment received and determine clinical success or failure for each patient. Treatment failure rates were assessed in patients that received MTZ monotherapy vs. other therapies stratified by MTZ susceptibility. Results were analyzed using multivariate logistic regression analysis.

Results

A total of 172 C. difficile isolates were included of which 55.8% displayed reduced susceptibility to MTZ. Clinical success rates with MTZ varied based on disease severity (mild-moderate: 80.4%; severe/severe-complicated: 64%). Treatment success rates were higher in patients infected with MTZ susceptible isolates (88.4%) compared with those infected with isolates showing reduced MTZ susceptibility (60.5%; P = 0.004.) In multivariate logistic regression after controlling for disease severity, patients infected with strains displaying reduced MTZ susceptibility and treated with MTZ were more likely to experience treatment failure compared with patients with susceptible isolates (OR = 6.8; 95% CI:1.96–23.8; P = 0.003). In patients given non-MTZ-based therapies, reduced susceptibility to MTZ was not predictive of failure to other treatments.

Conclusion

This is the first report to demonstrate that increased clinical failure rates for MTZ monotherapy are associated with reduced susceptibility to MTZ.

Disclosures

K. Garey, Summit Therapeutics: Collaborator, Research support.