C. difficile Vaccine for C. difficile Infection

Recruiting at 27 trial locations

Overseen By Pfizer CT.gov Call Center

Age: 65+

Sex: Any

Trial Phase: Phase 1 & 2

Sponsor: Pfizer

Must not be taking: Anticoagulants, Immunosuppressants

Disqualifiers: Chronic disorders, Immunodeficiency, C. diff history, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 15

689 Participants Needed

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial tests a vaccine designed to prevent severe diarrhea caused by the C. diff germ. Researchers aim to determine if new versions of the vaccine produce as many antibodies (infection-fighting proteins) as a previously tested version. The study consists of two phases, examining different vaccine formulations and schedules to ensure safety and effectiveness. Ideal participants are healthy adults aged 65 and older who have never had a C. diff infection or received any related vaccine or therapy. As a Phase 1 trial, the research focuses on understanding how the treatment works in people, offering participants the opportunity to be among the first to receive this new vaccine.

Do I need to stop my current medications to join the trial?

The trial protocol does not specify if you need to stop taking your current medications. However, if you are on immunosuppressive therapy or corticosteroids, you may not be eligible to participate.

Is there any evidence suggesting that this trial's treatments are likely to be safe?

Earlier studies on C. difficile vaccine options have shown promising safety results. For the first version, most side effects were mild to moderate, such as pain at the injection site and tiredness, and they usually resolved quickly. For the second version, about 50% to 75% of participants experienced some side effects, but these were generally not serious. The third version also showed good results, being well-tolerated and boosting immune responses in many participants.

The earlier C. diff vaccine, to which these new versions are compared, was tested in past trials and found to be safe with similar mild side effects. These findings suggest that the new vaccine versions are likely to be well-tolerated. However, since this study is in the early stages (Phase 1 and 2), researchers continue to collect data to confirm these safety results with different dosing schedules. ^{1 2 3 4 5}

Why are researchers excited about this trial's treatments?

Researchers are excited about these C. difficile vaccine formulations because they offer a fresh approach to preventing C. difficile infections, which are typically managed with antibiotics and, in some cases, fecal microbiota transplants. Unlike these existing treatments, which focus on managing active infections, the vaccine formulations aim to prevent infections from occurring in the first place. The novel formulations potentially offer broader protection by targeting key toxins produced by C. difficile, which could lead to better immune responses compared to previous vaccines. This proactive strategy could be a game-changer in reducing the incidence of C. difficile infections, especially in vulnerable populations.

What evidence suggests that this trial's C. diff vaccine formulations could be effective for preventing C. diff infection?

This trial evaluates multiple C. difficile vaccine formulations. Research has shown that a previously tested C. difficile vaccine reduced symptom duration but did not fully meet its primary objectives. In studies with a new version of the vaccine, 75% of hamsters were protected from death and became immune to future C. diff infections. This suggests potential effectiveness in humans, but more data is needed. These vaccines aim to help the body produce antibodies, proteins that fight infections like C. diff, which causes severe diarrhea. Although none of these vaccines have received approval yet, ongoing research in this trial focuses on identifying the most effective one to prevent C. diff infections. ^{1 6 7 8 9}

Who Is on the Research Team?

Pfizer CT.gov Call Center

Principal Investigator

Pfizer

Are You a Good Fit for This Trial?

Healthy adults aged 65-84 for Phase 1, and 50-84 for Phase 2, who've never had a C. diff infection or received any C. diff vaccine or therapy. Participants must be able to follow the study plan and give informed consent. Exclusions include those on immunosuppressive therapy, involved in other investigational studies, with certain medical conditions or history of severe allergies to vaccines.

Inclusion Criteria

I can sign the consent form and follow the study's rules.

I am willing and able to follow all study requirements.

You are considered medically healthy based on your history, examination, and the investigator's discretion.

Exclusion Criteria

I have never received an experimental vaccine or antibody therapy for C. difficile.

I do not have a serious chronic disorder that would prevent me from joining the study.

I am not on immunosuppressive therapy or have taken corticosteroids in the last 28 days.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Phase 1 Treatment

Evaluation of 3 new formulations of the C. diff vaccine and 2 dosing schedules over 2 or 6 months

18 months

At least 9 visits

Phase 2 Treatment

Evaluation of the safety and effects of the new C. diff vaccine formulation(s) chosen in Phase 1

Up to 4 years

6 to 12 visits

Follow-up

Participants are monitored for safety and effectiveness after treatment

12 months

What Are the Treatments Tested in This Trial?

Interventions

• C. difficile vaccine formulation 1
• C. difficile vaccine formulation 2
• C. difficile vaccine formulation 3
• C. difficile vaccine (previously studied formulation)
• Saline Placebo

Trial Overview The trial is testing three new formulations of a C. difficile vaccine against one previously studied formulation and a saline placebo to see if they're safe and can help the body produce antibodies against C. diff infection. The study has two phases: Phase 1 tests different dosing schedules; based on these results, one or two formulations will advance to Phase 2.

How Is the Trial Designed?

Group I: C. difficile vaccine formulation 3, Schedule 4 (Phase 1) Experimental Treatment 2 Interventions

Novel vaccine formulation 3

Group II: C. difficile vaccine formulation 3, Schedule 2 (Phase 1) Experimental Treatment 2 Interventions

Novel vaccine formulation 3

Group III: C. difficile vaccine formulation 2, Schedule 7 (Phase 2) Experimental Treatment 2 Interventions

Novel vaccine formulation 2

Group IV: C. difficile vaccine formulation 2, Schedule 6 (Phase 2) Experimental Treatment 1 Intervention

Novel vaccine formulation 2

Group V: C. difficile vaccine formulation 2, Schedule 5 (Phase 2) Experimental Treatment 2 Interventions

Novel vaccine formulation 2

Group VI: C. difficile vaccine formulation 2, Schedule 4, (Phase 2) Experimental Treatment 2 Interventions

Novel vaccine formulation 2

Group VII: C. difficile vaccine formulation 2, Schedule 4 (Phase 2) Experimental Treatment 2 Interventions

Novel vaccine formulation 2

Group VIII: C. difficile vaccine formulation 2, Schedule 4 (Phase 1) Experimental Treatment 2 Interventions

Novel vaccine formulation 2

Group IX: C. difficile vaccine formulation 2, Schedule 3 (Phase 1) Experimental Treatment 2 Interventions

Novel vaccine formulation 2

Group X: C. difficile vaccine formulation 2, Schedule 1, (Phase 2) Experimental Treatment 1 Intervention

Novel vaccine formulation 2

Group XI: C. difficile vaccine formulation 1, Schedule 4 (Phase 1) Experimental Treatment 1 Intervention

Novel vaccine formulation 1

Group XII: C. difficile vaccine formulation 1, Schedule 2 (Phase 1) Experimental Treatment 2 Interventions

Novel vaccine formulation 1

Group XIII: C difficile vaccine formulation 2, Schedule 1 (Phase 2) Experimental Treatment 2 Interventions

Novel vaccine formulation 2

Group XIV: C. difficile vaccine (previously studied formulation) Schedule 1 (Phase 1) Active Control 2 Interventions

Previously studied C. difficile vaccine formulation

Group XV: C. difficile vaccine (previously studied formulation) , Schedule 1 (Phase 2) Active Control 2 Interventions

Previously studied C. difficile vaccine formulation

Who Is Running the Clinical Trial?

Pfizer

Lead Sponsor

Trials

4,712

Recruited

50,980,000+

Known For

Vaccine Innovations

Top Products

Viagra, Zoloft, Lipitor, Prevnar 13

Albert Bourla

Pfizer

Chief Executive Officer since 2019

PhD in Biotechnology of Reproduction, Aristotle University of Thessaloniki

Patrizia Cavazzoni

Pfizer

Chief Medical Officer

MD from McGill University

Citations

1. academic.oup.com academic.oup.com/cid/article/79/6/1503/7740506

CLOVER (CLOstridium difficile Vaccine Efficacy tRial) Study: A ... Results are from the safety population. Median (range) follow-up time after dose 3 was 35.6 months (0.0–51.8) and 35.7 months (0.3–51.9) in the PF ...

2. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC12115615/

Against Clostridioides difficile Infection: An Update on Vaccine ... Although several C. difficile vaccines have entered clinical trials, there is currently no approved vaccine on the market.

3. sciencedirect.com sciencedirect.com/science/article/pii/S0264410X24009435

Preferences for a Clostridioides difficile vaccine among ... This study assessed US adults' willingness to receive a C.diff vaccine and examined how vaccine attributes influence their choices.

4. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC10223210/

Mucosal Vaccination Strategies against Clostridioides ... This mini-review summarizes the progress toward mucosal vaccines against C. difficile toxins, cell–surface components, and spore proteins.

5. clinicaltrials.gov clinicaltrials.gov/study/NCT05805826?term=NCT05805826&rank=1

To Understand the Safety and Effects of a C. Difficile ... Phase 2 will evaluate the safety and effects of the new C. diff vaccine formulation(s) chosen in Phase 1. The Phase 2 portion of the study is seeking ...

6. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC11911797/

Safety and Immunogenicity of an Adjuvanted Clostridioides ... The vaccine candidate was immunogenic, especially when given with AS01 adjuvant, and was well tolerated with an acceptable safety profile.

7. sciencedirect.com sciencedirect.com/science/article/pii/S0264410X23012963

A phase 3 study evaluating the lot consistency ... The most common treatment-related AEs were injection site pain (n = 8; 0.8 %) and fatigue (n = 3; 0.3 %) in the vaccine groups and injection ...

8. clinicaltrial.be clinicaltrial.be/en/details/264363?per_page=100&only_recruiting=0&only_eligible=0

To Understand the Safety and Effects of a C. Difficile Va... An antibody is a substance your body makes to fight off infection. This study will explore the safety and antibody response of a vaccine to ...

9. desertking.com desertking.com/c-difficile-vaccine-candidate-safety-immunogenicity-phase-1/

C. difficile Vaccine Candidate: Safety & Immunogenicity Most reported adverse events were mild to moderate in severity and were transient, with the most common AEs being injection site pain, fatigue, ...