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A study to evaluate the effectiveness of AZD5148 in preventing the recurrence of Clostridioides difficile infection in adults.

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This study investigates a way to prevent the return of Clostridioides difficile infection, a type of infection in the gut that often causes severe diarrhea. The research aims to determine if a new medication can reduce how often the infection comes back after the initial treatment. The medication being tested is called AZD5148, which is a monoclonal antibody. A monoclonal antibody is a type of protein made in a laboratory that is designed to find and attach to specific targets in the body, such as the toxin B produced by the bacteria.

Participants in the study will receive either AZD5148 or a placebo. The medication will be given as an intravenous infusion, which means it is delivered directly into a vein through a needle or tube. This treatment is administered alongside standard care, which includes regular antibacterial drugs used to treat the current infection. During the study, individuals will be monitored to see if the infection returns within a specific period of time.

The research process

The trial runs in 3 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Administration of study treatment

    A single dose of AZD5148, which is a monoclonal antibody (a type of protein designed to target a specific part of the body) designed to fight toxin B produced by Clostridioides difficile, is administered.

    The treatment is given through an intravenous infusion (a liquid delivered directly into a vein) or as an intramuscular push (an injection into a muscle).

    This administration occurs while standard of care antibacterial drug therapy, which refers to the regular medical treatment used for this infection, is being provided.

  2. Step 2

    Placebo administration

    In some cases, a placebo is administered instead of the active medication. A placebo is a substance that has no active medicinal effect and is used for comparison purposes.

  3. Step 3

    Monitoring period

    The progress is monitored through day 91 to evaluate if the treatment prevents the recurrence (the return) of the Clostridioides difficile infection.

Who can join the trial?

8 criteria

  • You must be at least 18 years old at the time you sign the consent form, which is the document where you agree to participate in the study.
  • You must be able to provide a signed informed consent, meaning you understand the study and agree to take part.
  • You must have had a recent episode of Clostridioides difficile infection (a type of bacterial infection in the gut).
  • You must have had 3 or more unformed stools (loose or watery bowel movements) within a 24-hour period for 2 days in a row.
  • Your stool sample must have tested positive for C. difficile toxin (a harmful substance produced by the bacteria) using a laboratory test.
  • You must be currently receiving standard of care antibacterial drug therapy, which refers to the usual medicines used to treat this infection, such as fidaxomicin, vancomycin, or metronidazole.
  • The treatment with these standard antibiotics must be planned to last between 10 and 25 days at the time you receive the study medicine.
  • Your body weight must be at least 40 kg.

Who cannot join the trial?

14 criteria

  • A history of inflammatory bowel disease, which refers to long-term swelling and irritation in the digestive tract, such as ulcerative colitis, Crohn’s disease, or microscopic colitis.
  • Having a condition other than C. difficile infection that causes regular loose stools, such as having an ostomy (a surgical opening that allows waste to leave the body).
  • Having a planned surgery for C. difficile infection within 24 hours of joining the study.
  • Having toxic megacolon, which is a severe complication where the colon becomes very swollen, or small bowel ileus, which is a condition where the muscles in the small intestine stop moving food through.
  • A history of a total colectomy (surgical removal of the entire large intestine) or bariatric surgery (weight loss surgery), unless the surgery was a restrictive type like banding that does not change the path of the digestive tract.
  • Having had major gastrointestinal surgery, such as removing a large part of the bowel, within 90 days before joining the study, though removing the appendix or gallbladder is allowed.
  • Being scheduled to receive more than 25 days of antibacterial drug therapy (medicine used to kill bacteria) for the current infection.
  • Having received a fecal donor transplant (transferring healthy stool from a donor) or fecal microbiota product within 180 days before, during, or within 180 days after receiving the study medicine.
  • Having received or planning to receive bezlotoxumab (a specific medicine for this infection) within 180 days before, during, or within 180 days after receiving the study medicine.
  • Taking specific medications like cholestyramine, nitazoxanide, rifaximin, tigecycline, or fusidic acid within 2 days before the study medicine, or being unable to avoid these medicines for 180 days after.
  • Receiving any licensed vaccine within 14 days before or 14 days after receiving the study medicine.
  • Receiving a high dose of human immunoglobulin (proteins used to help the immune system) within 4 weeks before or within 180 days after receiving the study medicine.
  • Planning to take medications that slow down gastrointestinal peristalsis (the natural wave-like muscle movements that move food through the gut), such as loperamide or diphenoxylate hydrochloride/atropine sulfate, within 14 days after receiving the study medicine.
  • Taking opioid medications (strong pain relievers) when the diarrhea first started, unless the person is on a stable dose or is expected to stop or reduce the dose.
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Investigated drugs

AZD5148 is an experimental medicine given through a vein to help prevent the infection caused by a bacteria called Clostridioides difficile from coming back after a person has been treated with antibiotics.

What is already known about the treatment

AZD5148 - This medication is an experimental immunotherapy given through a liquid injection into a vein to help prevent the return of a specific bacterial infection. It is currently being studied in clinical trials and belongs to a class of drugs known as monoclonal antibodies. The drug works by specifically targeting and neutralizing a harmful toxin produced by the bacteria, preventing it from damaging the body.

Investigated diseases

Recurrence of Clostridioides difficile infection - This condition occurs when an individual experiences a return of symptoms after an initial bout of infection caused by the bacterium Clostridioides difficile. The bacteria often produce toxins that damage the lining of the digestive tract. After a person starts to feel better, the bacteria or their toxins may persist in the gut. This can lead to the symptoms returning shortly after the initial infection has seemingly cleared. The cycle of infection and recovery can repeat if the bacteria are not fully managed.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IITrial ID2025-521416-19-00Protocol codeD8820C00003 PRISMEstimated enrolment259 patientsSponsorAstraZeneca AB

sourced from the EU Clinical Trials Register and site verification

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