Active — Not RecruitingPhase 1/2

To Understand the Safety and Effects of a C. Difficile Vaccine With New Adds-Ons That Will Be Given to Healthy Adults

United States936 participantsStarted 2023-03-23

Plain-language summary

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 prevent severe diarrhea caused by a germ called Clostridoides difficile (C. diff). Three new formulations of the C. diff vaccine will be used in this study, in addition to a C. diff vaccine formulation that has been studied in previous clinical trials. The purpose of this study is to understand if giving the new C. diff vaccine formulations helps people make as many antibodies as giving the previously studied C. diff vaccine formulation. The study is divided into 2 phases. Phase 1 will evaluate 3 new formulations of the C. diff vaccine and 2 dosing schedules spread out over 2 months or 6 months. The Phase 1 portion of the study is seeking participants: * who are healthy adults of 65 to 84 years of age * who have not had a C. diff infection before * who have not received a C. diff vaccine or C. diff monoclonal antibody therapy before. All participants in Phase 1 will receive study injections with active vaccine or placebo at each vaccination visit, depending on the vaccine group to which they are assigned. A placebo does not contain any active ingredients. Participants in Phase 1 will attend at least 9 study visits and will take part in the study for approximately 18 months. Based on the results of Phase 1, 1 or 2 of the new C. diff vaccine formulations will be chosen for further study in Phase 2. 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 participants: * who are healthy adults ≥65 years of age; and 50 through 64 years of age (Cohort 4 only) * who have not had a C. diff infection before * who have not received a C. diff vaccine or C. diff monoclonal antibody therapy before. Phase 2 participants will receive active C. diff vaccine or placebo at each vaccination visit. Participants in Phase 2 will attend at least 6 and up to 12 study visits and will take part in the study for up to 4 years. A booster stage for selected participants in Phase 2 will have participants receive active C. diff vaccine or placebo to examine immune persistence. The booster stage participants will attend at least 10 additional study visits and will take part in the study for 6 years. A newly added cohort will evaluate the safety and effects of active C. diff vaccine formulation in participants 50 through 64 years of age. Participants will receive C. diff vaccine or placebo and will attend at least 6 study visits over a period of 18 months.

Who can participate

Age range50 Years

SexALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

Inclusion criteria

✓. Each phase of the study will enroll participants in different age categories:
✓. Healthy participants as determined by medical history, clinical assessment, and the judgment of the investigator.
✓. Participants who are willing and able to comply with all scheduled visits, investigational plan, laboratory tests, lifestyle considerations, and other study procedures.
✓. Capable of giving personally signed informed consent, which includes compliance with the requirements and restrictions listed in the ICD and in this protocol.

Exclusion criteria

✕. Fertile male participants and WOCBP who are unwilling or unable to use an effective method of contraception from the signing of informed consent until at least 28 days after the last dose of study intervention.
✕. Serious chronic disorder, including history of metastatic malignancy, severe COPD requiring supplemental oxygen, end-stage renal disease with or without dialysis, cirrhosis of the liver, clinically unstable cardiac disease, or any other disorder that, in the investigator's opinion, would make the participant inappropriate for entry into the study.
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What they're measuring

Phase 1: Percentage of participants reporting local reactions

Timeframe: For 7 days after each vaccination

Phase 1: Percentage of participants reporting systemic events

Timeframe: For 7 days after each vaccination

Phase 1: Percentage of participants reporting adverse events

Timeframe: From each vaccination through 1 month after vaccination

Phase 1: Percentage of participants reporting serious adverse events

Timeframe: From Dose 1 (Day 1) through 6 months after the last dose

Phase 1: Percentage of participants reporting medically attended adverse events

Timeframe: From Dose 1 (Day 1) through 6 months after the last dose of study intervention

Phase 1: Percentage of participants with abnormal hematology and chemistry laboratory values

Timeframe: 1 week after Dose 1 (Day 7) and 1 month after each dose (through Month 7)

Phase 2: Percentage of participants reporting local reactions

Timeframe: For 7 days after each vaccination

Trial details

NCT IDNCT05805826

SponsorPfizer

Sponsor typeINDUSTRY

Study typeINTERVENTIONAL

Primary completion2031-06-19

View on ClinicalTrials.gov More Clostridoides Difficile Associated Disease trials

Plain-language summary

Who can participate

Age range50 Years

SexALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

Inclusion criteria

✓. Each phase of the study will enroll participants in different age categories:
✓. Healthy participants as determined by medical history, clinical assessment, and the judgment of the investigator.
✓. Participants who are willing and able to comply with all scheduled visits, investigational plan, laboratory tests, lifestyle considerations, and other study procedures.
✓. Capable of giving personally signed informed consent, which includes compliance with the requirements and restrictions listed in the ICD and in this protocol.

Exclusion criteria

✕. Fertile male participants and WOCBP who are unwilling or unable to use an effective method of contraception from the signing of informed consent until at least 28 days after the last dose of study intervention.
✕. Serious chronic disorder, including history of metastatic malignancy, severe COPD requiring supplemental oxygen, end-stage renal disease with or without dialysis, cirrhosis of the liver, clinically unstable cardiac disease, or any other disorder that, in the investigator's opinion, would make the participant inappropriate for entry into the study.
✕