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Preventing recurrent C. difficile infection with the AZD5148 antibody

A Phase IIb, Randomized, Double-blind, Placebo-controlled Study to Evaluate the Efficacy and Safety of AZD5148 for Prevention of Recurrence of Clostridioides Difficile Infection in Individuals 18 Years of Age and Above

Phase 2 Interventional AstraZeneca · NCT07285213

This will try a single dose of the antibody AZD5148 versus placebo to see if it prevents repeat C. difficile infections in adults being treated for a current infection.

Quick facts

PhasePhase 2
Study typeInterventional
Enrollment230 (estimated)
Ages18 Years and up
SexAll
SponsorAstraZeneca Industry-sponsored
Drugs / interventionsbezlotoxumab
Locations114 sites (Phoenix, Arizona and 113 other locations)
Trial IDNCT07285213 on ClinicalTrials.gov

What this trial studies

Up to 230 adults with a laboratory-confirmed C. difficile episode who are receiving standard-of-care antibiotics will be randomized 1:1 to receive a single dose of AZD5148 or placebo. The investigational product will be given by investigator choice as an intramuscular injection or an intravenous push, and randomization will be stratified by geographic region. Participants will have up to two visits for eligibility confirmation and dosing, up to seven planned visits overall with stool sample collection, weekly then monthly follow-up contacts from site staff, and electronic diary symptom reporting. Safety, tolerability, and recurrence of infection will be monitored during the follow-up period.

Who should consider this trial

Good fit: Adults aged 18 or older with a positive local C. difficile toxin test on an unformed stool, receiving standard antibiotic therapy for the current episode (planned duration 10–25 days) and weighing at least 40 kg are eligible.

Not a fit: People with a history of inflammatory bowel disease, those with chronic non‑CDI causes of loose stools, individuals not on standard CDI antibiotic therapy, and those under 18 are unlikely to benefit from this trial.

Why it matters

Potential benefit: If successful, AZD5148 could reduce the chance of C. difficile coming back after treatment, lowering the need for repeat antibiotics, hospital visits, and complications.

How similar studies have performed: Similar monoclonal antibody approaches (for example bezlotoxumab) have previously reduced C. difficile recurrence, so this builds on an existing, successful concept.

Eligibility criteria

Show full inclusion / exclusion criteria 
Inclusion Criteria:

Participant must be ≥ 18 years of age at the time of signing the informed consent, capable of giving signed informed consent.

Participants with a qualifying C. difficile infection episode at the time of providing informed consent defined by:

* Positive local C. difficile toxin test (eg, immune assay or CCNA) on an unformed stool sample collected during this episode, and
* Receipt of standard of care antibacterial drug therapy for C. difficile infection (fidaxomicin, vancomycin or metronidazole) for this episode, with planned duration of at least 10 and at most 25 days at time of IMP administration.

Note: Diarrhea is not required to be present on the day of investigational medicinal product (IMP) administration.

Body weight ≥ 40 kg

Exclusion Criteria:

History of inflammatory bowel disease (eg, ulcerative colitis, Crohn's disease, microscopic colitis).

Participant with a non - CDI (C. difficile infection) condition such that the participant routinely passes loose stool (eg, patients with an ostomy)

Planned surgery for C. difficile infection within 24 hours of enrollment

Current toxic megacolon and/or small bowel ileus

Any history of total colectomy or bariatric surgery (bariatric surgery which does not disrupt the gastrointestinal lumen, ie, restrictive procedures such as banding, are permitted).

Major gastrointestinal surgery as assessed by the Investigator (eg, significant bowel resection or diversion) within 90 days before enrollment (this does not include appendectomy or cholecystectomy)

Due to receive more than 25 days of antibacterial drug therapy for C. difficile infection for the qualifying C. difficile infection episode

Treatment with a fecal donor transplant or fecal microbiota product in the 180 days before IMP administration, are receiving or planned administration for the qualifying episode of C. difficile infection, or planned administration during the 180 days after IMP administration

Treatment with bezlotoxumab in the 180 days before IMP administration, are receiving or planned administration for the qualifying episode of CDI, or planned administration during the 180 days after IMP administration.

Where this trial is running

Phoenix, Arizona and 113 other locations

+64 more sites — see ClinicalTrials.gov for the full list.

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
View on ClinicalTrials.gov → Find more trials like this →
Conditions Clostridioides Difficile InfectionClostridioides Difficile infectionC. DiffCDiffClostridiodes Difficile Infection prevention of recurrence
Last reviewed 2026-06-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.