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

NCT05805826 | Active Not Recruiting Phase 1 DMC FDA Drug

• 2 other identifiers: C4771001NCT05805826
• Study Type: interventional
• Target: 936
• Locations: 1 country
• Sites: 23

Brief 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.

Conditions

Clostridoides Difficile Associated Disease

Keywords

Clostridioides difficile; Clostridium difficile; C. diff; Persistence; Vaccine; Cohort

Outcome Measures

Primary Outcomes (16)

• Phase 1: Percentage of participants reporting local reactions

  Injection site pain, redness, and swelling as self-reported in electronic diaries

  For 7 days after each vaccination

• Phase 1: Percentage of participants reporting systemic events

  Vomiting, diarrhea, headache, fatigue, new or worsening muscle pain, new or worsening joint pain, and fever, as self-reported in electronic diaries

  For 7 days after each vaccination

• Phase 1: Percentage of participants reporting adverse events

  As elicited by investigational site staff

  From each vaccination through 1 month after vaccination

• Phase 1: Percentage of participants reporting serious adverse events

  As elicited by investigational site staff

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

• Phase 1: Percentage of participants reporting medically attended adverse events

  As elicited by investigational site staff

  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

  As measured at the central laboratory

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

• Phase 2: Percentage of participants reporting local reactions

  Injection site pain, redness, and swelling as self-reported in electronic diaries

  For 7 days after each vaccination

• Phase 2: Percentage of participants reporting systemic events

  Vomiting, diarrhea, headache, fatigue, new or worsening muscle pain, new or worsening joint pain, and fever, as self-reported in electronic diaries

  For 7 days after each vaccination

• Phase 2: Percentage of participants reporting adverse events

  As elicited by investigational site staff

  From each dose of study intervention through 1 month after each dose of study intervention

• Phase 2: Percentage of participants reporting adverse events

  As elicited by investigational site staff

  From the first dose of study intervention through 1 month after the last dose of study intervention

• Phase 2: Percentage of participants reporting medically attended adverse events

  As elicited by investigational site staff

  From the first dose of study intervention through 6 months after the last dose of study intervention

• Phase 2: Percentage of participants reporting serious adverse events

  As elicited by investigational site staff

  From the first dose of study intervention through 6 months after the last dose of study intervention

• Phase 2: Geometric mean concentration (GMT) of C. difficile toxin A- and toxin B-specific neutralizing antibodies

  As measured at the central laboratory

  1 month after the last dose of study intervention

• Phase 2: Geometric mean ratio (GMR) of C. difficile toxin A- and toxin B- specific neutralizing antibodies

  As measured at the central laboratory

  1 month after the last dose of study intervention

• Phase 2: Geometric mean fold-rise (GMFR) of C. difficile toxin A- and toxin B-specific neutralizing antibody concentrations

  As measured at the central laboratory

  From before vaccination to 1 month after the last dose

• Phase 2: Geometric mean ratio (GMR) of C. difficile toxin A- and toxin B-specific neutralizing antibodies

  As measured at the central laboratory

  At Month 7 comparing data from ≥65 years of age to data from 50 through 64 years of age

Secondary Outcomes (12)

• Phase 1: Percentage of participants reporting serious adverse events

  From 6 months through 12 months after the last dose of study intervention

• Phase 1: Percentage of participants reporting medically attended adverse events

  From 6 months through 12 months after the last dose of study intervention

• Phase 1: Geometric mean concentration (GMC) of C. difficile toxin A- and toxin B-specific neutralizing antibodies

  1 month after each dose, before the last dose, 6 months after the last dose, and 12 months after the last dose

• Phase 1: Geometric mean fold-rise (GMFR) of C. difficile toxin A- and toxin B-specific neutralizing antibody concentrations

  From before Dose 1 (Day 1) to 1 month after each dose, and to 6 months and 12 months after the last dose

• Phase 2: Percentage of participants reporting medically attended adverse events

  From 6 month through 12 months after the last dose of study intervention

Study Arms (18)

C. difficile vaccine formulation 1, Schedule 2 (Phase 1)

EXPERIMENTAL

Novel vaccine formulation 1

Biological: C. difficile vaccine formulation 1.; Other: Saline Placebo.

C. difficile vaccine formulation 2, Schedule 3 (Phase 1)

EXPERIMENTAL

Novel vaccine formulation 2

Biological: C. difficile vaccine formulation 2.; Other: Saline Placebo.

C. difficile vaccine formulation 3, Schedule 2 (Phase 1)

EXPERIMENTAL

Novel vaccine formulation 3

Biological: C. difficile vaccine formulation 3.; Other: Saline Placebo.

C. difficile vaccine formulation 1, Schedule 4 (Phase 1)

EXPERIMENTAL

Novel vaccine formulation 1

Other: Saline Placebo.

C. difficile vaccine formulation 2, Schedule 4 (Phase 1)

EXPERIMENTAL

Novel vaccine formulation 2

Biological: C. difficile vaccine formulation 2.; Other: Saline Placebo.

C. difficile vaccine formulation 3, Schedule 4 (Phase 1)

EXPERIMENTAL

Novel vaccine formulation 3

Biological: C. difficile vaccine formulation 3.; Other: Saline Placebo.

C. difficile vaccine (previously studied formulation) Schedule 1 (Phase 1)

ACTIVE COMPARATOR

Previously studied C. difficile vaccine formulation

Biological: C. difficile vaccine (previously studied formulation).; Other: Saline Placebo.

C difficile vaccine formulation 2, Schedule 1 (Phase 2)

EXPERIMENTAL

Novel vaccine formulation 2

Biological: C. difficile vaccine formulation 2.; Other: Saline Placebo.

C. difficile vaccine formulation 2, Schedule 4 (Phase 2)

EXPERIMENTAL

Novel vaccine formulation 2

Biological: C. difficile vaccine formulation 2.; Other: Saline Placebo.

C. difficile vaccine formulation 2, Schedule 5 (Phase 2)

EXPERIMENTAL

Novel vaccine formulation 2

Biological: C. difficile vaccine formulation 2.; Other: Saline Placebo.

C. difficile vaccine formulation 2, Schedule 6 (Phase 2)

EXPERIMENTAL

Novel vaccine formulation 2

Biological: C. difficile vaccine formulation 2.

C. difficile vaccine (previously studied formulation) , Schedule 1 (Phase 2)

ACTIVE COMPARATOR

Previously studied C. difficile vaccine formulation

Biological: C. difficile vaccine (previously studied formulation).; Other: Saline Placebo.

C. difficile vaccine formulation 2, Schedule 7 (Phase 2)

EXPERIMENTAL

Novel vaccine formulation 2

Biological: C. difficile vaccine formulation 2.; Other: Saline Placebo.

C. difficile vaccine formulation 2, Schedule 1, (Phase 2)

EXPERIMENTAL

Novel vaccine formulation 2

Biological: C. difficile vaccine formulation 2.

C. difficile vaccine formulation 2, Schedule 4, (Phase 2)

EXPERIMENTAL

Novel vaccine formulation 2

Biological: C. difficile vaccine formulation 2.; Other: Saline Placebo.

C. difficile vaccine formulation 2, Schedule 8, (Phase 2)

EXPERIMENTAL

Novel vaccine formulation 2

Biological: C. difficile vaccine formulation 2.; Other: Saline Placebo.

C. difficile vaccine formulation 2, Schedule 9, (Phase 2)

EXPERIMENTAL

Novel vaccine formulation 2

Biological: C. difficile vaccine formulation 2.; Other: Saline Placebo.

Saline placebo, Schedule 4 (Phase 2)

PLACEBO COMPARATOR

Saline placebo

Other: Saline Placebo.

Interventions

C. difficile vaccine (previously studied formulation). BIOLOGICAL

Toxoid based Clostridioides difficile vaccine (previously studied formulation) given as an intramuscular injection

C. difficile vaccine (previously studied formulation) , Schedule 1 (Phase 2); C. difficile vaccine (previously studied formulation) Schedule 1 (Phase 1)

C. difficile vaccine formulation 1. BIOLOGICAL

C. difficile vaccine formulation 1 given as an intramuscular injection

C. difficile vaccine formulation 1, Schedule 2 (Phase 1)

C. difficile vaccine formulation 2. BIOLOGICAL

C. difficile vaccine formulation 2 given as an intramuscular injection

C difficile vaccine formulation 2, Schedule 1 (Phase 2); C. difficile vaccine formulation 2, Schedule 1, (Phase 2); C. difficile vaccine formulation 2, Schedule 3 (Phase 1); C. difficile vaccine formulation 2, Schedule 4 (Phase 1); C. difficile vaccine formulation 2, Schedule 4 (Phase 2); C. difficile vaccine formulation 2, Schedule 4, (Phase 2); C. difficile vaccine formulation 2, Schedule 5 (Phase 2); C. difficile vaccine formulation 2, Schedule 6 (Phase 2); C. difficile vaccine formulation 2, Schedule 7 (Phase 2); C. difficile vaccine formulation 2, Schedule 8, (Phase 2); C. difficile vaccine formulation 2, Schedule 9, (Phase 2)

C. difficile vaccine formulation 3. BIOLOGICAL

C. difficile vaccine formulation 3 given as an intramuscular injection

C. difficile vaccine formulation 3, Schedule 2 (Phase 1); C. difficile vaccine formulation 3, Schedule 4 (Phase 1)

Saline Placebo. OTHER

0.9% sodium chloride solution given as an intramuscular injection

C difficile vaccine formulation 2, Schedule 1 (Phase 2); C. difficile vaccine (previously studied formulation) , Schedule 1 (Phase 2); C. difficile vaccine (previously studied formulation) Schedule 1 (Phase 1); C. difficile vaccine formulation 1, Schedule 2 (Phase 1); C. difficile vaccine formulation 1, Schedule 4 (Phase 1); C. difficile vaccine formulation 2, Schedule 3 (Phase 1); C. difficile vaccine formulation 2, Schedule 4 (Phase 1); C. difficile vaccine formulation 2, Schedule 4 (Phase 2); C. difficile vaccine formulation 2, Schedule 4, (Phase 2); C. difficile vaccine formulation 2, Schedule 5 (Phase 2); C. difficile vaccine formulation 2, Schedule 7 (Phase 2); C. difficile vaccine formulation 2, Schedule 8, (Phase 2); C. difficile vaccine formulation 2, Schedule 9, (Phase 2); C. difficile vaccine formulation 3, Schedule 2 (Phase 1); C. difficile vaccine formulation 3, Schedule 4 (Phase 1); Saline placebo, Schedule 4 (Phase 2)

Eligibility Criteria

• Age: 50 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Each phase of the study will enroll participants in different age categories:
• Phase 1: Participants ≥65 to \<85 years of age; Phase 2: Participants ≥65 years of age; Cohort 4 Participants 50 through 64 years of age.
• 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.

You may not qualify if:

• 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.
• Any contraindication to vaccination or vaccine components, including previous hypersensitivity or anaphylactic reaction to any vaccine or vaccine-related components.
• Prior episode of CDI, confirmed by either laboratory test or diagnosis of pseudomembranous colitis at colonoscopy, at surgery, or histopathologically.
• Any bleeding disorder or anticoagulant therapy that would contraindicate intramuscular injection.
• Known or suspected immunodeficiency or other conditions associated with immunosuppression, including, but not limited to, leukocyte, lymphocyte, or immunoglobulin class/subclass deficiencies or abnormalities, generalized malignancy, HIV infection, leukemia, lymphoma, or organ or bone marrow transplant.
• Other medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk of study participation or, in the investigator's judgment, make the participant inappropriate for the study.
• Previous receipt of an investigational C difficile vaccine or C difficile mAb therapy.
• Receipt of blood product or immunoglobulin within 6 months before enrollment.
• Currently receives treatment with immunosuppressive therapy, including cytotoxic agents or systemic corticosteroids, or planned receipt throughout the study. Participants may not be enrolled if corticosteroids were administered within 28 days before study intervention administration.
• Participation in other studies involving investigational drugs, investigational vaccines, or investigational devices within 28 days prior to study entry through 12 months after the last dose of study intervention.
• Phase 1 only: Any screening hematology and/or blood chemistry laboratory value that meets the definition of a ≥ Grade 1 abnormality.
• Investigator site staff directly involved in the conduct of the study and their family members, site staff otherwise supervised by the investigator, and sponsor and sponsor delegate employees directly involved in the conduct of the study and their family members.

Sponsors & Collaborators

• Pfizer: lead

Study Sites (23)

HOPE Research Institute

Phoenix, Arizona, 85032, United States

Location

Anaheim Clinical Trials, LLC

Anaheim, California, 92801, United States

Location

Alliance for Multispecialty Research, LLC

Doral, Florida, 33172, United States

Location

Indago Research & Health Center, Inc

Hialeah, Florida, 33012, United States

Location

Research Centers of America

Hollywood, Florida, 33024, United States

Location

Miami Clinical Research

Miami, Florida, 33155, United States

Location

New Horizon Research Center

Miami, Florida, 33165, United States

Location

Charisma Medical and Research Center

Miami Lakes, Florida, 33014, United States

Location

Private Practice - Dr. Hector Fabregas

Pembroke Pines, Florida, 33026, United States

Location

DBC Research USA

Pembroke Pines, Florida, 33029, United States

Location

BRCR Medical Center Inc.

Plantation, Florida, 33322, United States

Location

Clinical Research Trials of Florida

Tampa, Florida, 33607, United States

Location

Great Lakes Clinical Trials - Ravenswood

Chicago, Illinois, 60640, United States

Location

Alliance for Multispecialty Research, LLC

Wichita, Kansas, 67226, United States

Location

Prism Research LLC dba Nucleus Network

Saint Paul, Minnesota, 55114, United States

Location

Washington University School of Medicine

St Louis, Missouri, 63110, United States

Location

Washington University

St Louis, Missouri, 63130, United States

Location

NYU Langone Health

New York, New York, 10016, United States

Location

Rochester Clinical Research, Inc.

Rochester, New York, 14609, United States

Location

Qcare Site Services Inc. d/b/a Avacare

Durham, North Carolina, 27703, United States

Location

CTI Clinical Research Center

Cincinnati, Ohio, 45212, United States

Location

Benchmark Research

Austin, Texas, 78705, United States

Location

Dynamed Clinical Research, LP d/b/a DM Clinical Research

Tomball, Texas, 77375, United States

Location

Related Links

• To obtain contact information for a study center near you, click here.

Study Officials

• Pfizer CT.gov Call Center

  Pfizer

  STUDY DIRECTOR

Study Design

• Study Type: interventional
• Phase: phase 1
• Allocation: RANDOMIZED
• Masking: TRIPLE
• Who Masked: PARTICIPANT, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: PREVENTION
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Model Details: Parallel assignment

Study Record Dates

• First Submitted: March 21, 2023
• First Posted: April 10, 2023
• Study Start: March 23, 2023
• Primary Completion (Estimated): June 19, 2031
• Study Completion (Estimated): June 19, 2031
• Last Updated: April 29, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will share

Locations

US (23)