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Clostridium Difficile Vaccine Efficacy Trial (Clover)

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
 
ClinicalTrials.gov Identifier: NCT03090191
Recruitment Status : Completed
First Posted : March 24, 2017
Results First Posted : February 13, 2023
Last Update Posted : February 13, 2023
Sponsor:
Information provided by (Responsible Party):
Pfizer

Study Description
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Brief Summary:

The Clover trial is evaluating an investigational vaccine that may help to prevent Clostridium difficile infection. Participants in the study are adults 50 years of age and older, who are at risk of developing Clostridium difficile infection. The study will assess whether the vaccine prevents the disease, and whether it is safe and well tolerated.

Each subject will receive 3 doses of Clostridium difficile vaccine or placebo and be followed for up to 3 years after vaccination for potential Clostridium difficile infection.


Condition or disease Intervention/treatment Phase
Clostridium Difficile Infection Biological: Clostridium difficile vaccine Biological: Placebo Phase 3

Study Design
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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 17535 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary Purpose: Prevention
Official Title: A PHASE 3, PLACEBO-CONTROLLED, RANDOMIZED, OBSERVER-BLINDED STUDY TO EVALUATE THE EFFICACY, SAFETY, AND TOLERABILITY OF A CLOSTRIDIUM DIFFICILE VACCINE IN ADULTS 50 YEARS OF AGE AND OLDER
Actual Study Start Date : March 29, 2017
Actual Primary Completion Date : December 21, 2021
Actual Study Completion Date : December 21, 2021

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Vaccines

Arms and Interventions
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Arm Intervention/treatment
Experimental: Clostridium difficile vaccine Biological: Clostridium difficile vaccine
Toxoid-based Clostridium difficile vaccine
Placebo Comparator: Placebo Biological: Placebo
Normal saline solution (0.9% sodium chloride)


Outcome Measures
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Primary Outcome Measures :
  1. Number of First Primary Episodes of Clostridium Difficile Infection (CDI) (Definition 1) Follow-up After Dose 3 [ Time Frame: From 14 days after Dose 3 to the end of the surveillance period (mean follow-up after dose 3 was 34.2 months) ]
    CDI definition 1 for a primary episode of CDI (no previous CDI onset in the prior 8 weeks) was defined as either a) presence of diarrhea, defined as passage of 3 or more unformed stools (Bristol stool chart types 5-7) in 24 or fewer consecutive hours, and stool sample that was positive for the toxin B gene (by polymerase chain reaction [PCR)] and positive for toxin A and/or toxin B, as measured in the central laboratory; or b) Pseudomembranous colitis diagnosed at colonoscopy, at surgery, or histopathologically; and corresponding stool sample that was positive for the toxin B gene (via PCR) as measured in the central laboratory. End of surveillance period was defined as accumulation of at least 40 CDI cases.

  2. Number of First Primary Episodes of Clostridium Difficile Infection (CDI) (Definition 1) Follow-up After Dose 2 [ Time Frame: From 14 days after Dose 2 to the end of the surveillance period (mean follow-up after dose 2 was 36 months) ]
    CDI definition 1 for a primary episode of CDI (no previous CDI onset in the prior 8 weeks) was defined as either a) presence of diarrhea, defined as passage of 3 or more unformed stools (Bristol stool chart types 5-7) in 24 or fewer consecutive hours, and stool sample that was positive for the toxin B gene (by PCR) and positive for toxin A and/or toxin B, as measured in the central laboratory; or b) Pseudomembranous colitis diagnosed at colonoscopy, at surgery, or histopathologically; and corresponding stool sample that was positive for the toxin B gene (via PCR) as measured in the central laboratory. End of surveillance period was defined as accumulation of at least 40 CDI cases.

  3. Percentage of Participants Reporting Local Reactions Within 7 Days After Dose 1 [ Time Frame: Within 7 days after Dose 1 at Month 0 ]
    Local reactions included redness, swelling and pain at injection site. These were recorded by participants in an electronic diary (e-diary). Redness and swelling were measured and recorded in measuring device units. One measuring device unit= 0.5 centimeter (cm) and graded as mild: 2.5 to 5.0 cm, moderate: greater than (>) 5.0 to 10.0 cm, severe: >10.0 cm. Grade 4 indicated necrosis or exfoliative dermatitis for redness and necrosis for swelling Pain at injection site was graded as mild: did not interfere with daily activity, moderate: interfered with daily activity, severe: prevented daily activity. Grade 4 indicated emergency room visit or hospitalization.

  4. Percentage of Participants Reporting Local Reactions Within 7 Days After Dose 2 [ Time Frame: Within 7 days after Dose 2 at Month 1 ]
    Local reactions included redness, swelling and pain at injection site. These were recorded by participants in an e-diary. Redness and swelling were measured and recorded in measuring device units. One measuring device unit= 0.5 cm and graded as mild: 2.5 to 5.0 cm, moderate: > 5.0 to 10.0 cm, severe: >10.0 cm. Grade 4 indicated necrosis or exfoliative dermatitis for redness and necrosis for swelling. Pain at injection site was graded as mild: did not interfere with daily activity, moderate: interfered with daily activity, severe: prevented daily activity. Grade 4 indicated emergency room visit or hospitalization.

  5. Percentage of Participants Reporting Local Reactions Within 7 Days After Dose 3 [ Time Frame: Within 7 days after Dose 3 at Month 6 ]
    Local reactions included redness, swelling and pain at injection site. These were recorded by participants in an e-diary. Redness and swelling were measured and recorded in measuring device units. One measuring device unit= 0.5 cm and graded as mild: 2.5 to 5.0 cm, moderate: > 5.0 to 10.0 cm, severe: >10.0 cm. Grade 4 indicated necrosis or exfoliative dermatitis for redness and necrosis for swelling. Pain at injection site was graded as mild: did not interfere with daily activity, moderate: interfered with daily activity, severe: prevented daily activity. Grade 4 indicated emergency room visit or hospitalization.

  6. Percentage of Participants Reporting Systemic Events Within 7 Days After Dose 1 [ Time Frame: Within 7 days after Dose 1 at Month 0 ]
    Systemic events included fever, fatigue, headache, joint pain, muscle pain and vomiting. These were recorded by participants in an e-diary. Fever was categorized as: mild: (38.0 to 38.4 degree Celsius [deg C]), moderate: (38.5 to 38.9 deg C), severe (39.0 to 40.0 deg C), potentially life threatening (> 40.0 deg C). Fatigue, headache, joint pain and muscle pain were graded as mild: did not interfere with activity, moderate: some interference with activity, severe: prevented daily activity, grade 4: emergency room visit or hospitalization. Vomiting was graded as mild: 1 to 2 times in 24 hours, moderate: >2 times in 24 hours, severe: required intravenous hydration, grade 4: emergency room visit or hospitalization for hypotensive shock.

  7. Percentage of Participants Reporting Systemic Events Within 7 Days After Dose 2 [ Time Frame: Within 7 days after Dose 2 at Month 1 ]
    Systemic events included fever, fatigue, headache, joint pain, muscle pain and vomiting. These were recorded by participants in an e-diary. Fever was categorized as: mild: (38.0 to 38.4 deg C), moderate: (38.5 to 38.9 deg C), severe (39.0 to 40.0 deg C), potentially life threatening (> 40.0 deg C). Fatigue, headache, joint pain and muscle pain were graded as mild: did not interfere with activity, moderate: some interference with activity, severe: prevented daily activity, grade 4: emergency room visit or hospitalization. Vomiting was graded as mild: 1 to 2 times in 24 hours, moderate: >2 times in 24 hours, severe: required intravenous hydration, grade 4: emergency room visit or hospitalization for hypotensive shock.

  8. Percentage of Participants Reporting Systemic Events Within 7 Days After Dose 3 [ Time Frame: Within 7 days after Dose 3 at Month 6 ]
    Systemic events included fever, fatigue, headache, joint pain, muscle pain and vomiting. These were recorded by participants in an e-diary. Fever was categorized as: mild: (38.0 to 38.4 deg C), moderate: (38.5 to 38.9 deg C), severe (39.0 to 40.0 deg C), potentially life threatening (> 40.0 deg C). Fatigue, headache, joint pain and muscle pain were graded as mild: did not interfere with activity, moderate: some interference with activity, severe: prevented daily activity, grade 4: emergency room visit or hospitalization. Vomiting was graded as mild: 1 to 2 times in 24 hours, moderate: >2 times in 24 hours, severe: required intravenous hydration, grade 4: emergency room visit or hospitalization for hypotensive shock.

  9. Number of Participants Reporting Adverse Events (AEs) [ Time Frame: From Day 1 of Dose 1 to 1 Month after Dose 3 (7 Months) ]
    An AE was defined as any untoward medical occurrence in a participant who received investigational product without regard to possibility of causal relationship. AEs included both serious and all non-serious adverse events. An SAE was defined as any untoward medical occurrence at any dose that resulted in any of the following outcomes: death; life-threatening (immediate risk of death); required inpatient hospitalization or prolongation of existing hospitalization; persistent or significant disability/incapacity (substantial disruption of the ability to conduct normal life functions); congenital anomaly/birth defect; or that was considered as an important medical event. AEs included both SAEs and all Non-SAEs (except local and systemic events).

  10. Number of Participants Reporting Serious Adverse Events (SAEs) [ Time Frame: From Day 1 of Dose 1 up to 6 months after Dose 3 (up to Month 12) ]
    An SAE was defined as any untoward medical occurrence at any dose that resulted in any of the following outcomes: death; life-threatening (immediate risk of death); required inpatient hospitalization or prolongation of existing hospitalization; persistent or significant disability/incapacity (substantial disruption of the ability to conduct normal life functions); congenital anomaly/birth defect; or that was considered as an important medical event.


Secondary Outcome Measures :
  1. Number of All Episodes of CDI (Definition 1 and 2) After Dose 3 [ Time Frame: From 14 days after Dose 3 to the end of the surveillance period (mean follow-up after dose 3 was 34.2 months) ]
    CDI definition 1 for primary episode of CDI (no previous CDI onset in prior 8 weeks) and CDI definition 2 for recurrent episode (episode occurred 8 weeks or less after onset of previous episode [provided symptoms of previous episode resolved]) were both defined as either a) presence of diarrhea, (passage of 3 or more unformed stools [Bristol stool chart types 5-7]) in 24 or fewer consecutive hours, stool sample positive for toxin B gene (by PCR),positive for toxin A and/or toxin B, as measured in central laboratory; or b) Pseudomembranous colitis diagnosed at colonoscopy, surgery, histopathologically; and corresponding stool sample positive for toxin B gene (via PCR) as measured in central laboratory. End of surveillance period was defined as accumulation of at least 40 CDI cases.

  2. Time to Resolution for Participants With First Primary Episodes of CDI (Definition 1) After Dose 3 [ Time Frame: From 14 days after Dose 3 to the end of the surveillance period (mean follow-up after dose 3 was 34.2 months) ]
    Resolution of the event was the last day on which the event was recorded in the e-diary or the date the event ends if it was unresolved during the participant diary-recording period (end date collected on the case report form [CRF]). CDI definition 1 for a primary episode of CDI (no previous CDI onset in the prior 8 weeks) was defined as either a) presence of diarrhea, defined as passage of 3 or more unformed stools (Bristol stool chart types 5-7) in 24 or fewer consecutive hours, and stool sample that was positive for the toxin B gene (by PCR) and positive for toxin A and/or toxin B, as measured in the central laboratory; or b) Pseudomembranous colitis diagnosed at colonoscopy, at surgery, or histopathologically; and corresponding stool sample that was positive for the toxin B gene (via PCR) as measured in the central laboratory. End of surveillance period was defined as accumulation of at least 40 CDI cases.

  3. Proportion of Participants Who Required Medical Attention During First Primary Episode of CDI (Definition 1) After Dose 3 [ Time Frame: From 14 days after Dose 3 to the end of the surveillance period (mean follow-up after dose 3 was 34.2 months) ]
    CDI definition 1 for a primary episode of CDI (no previous CDI onset in the prior 8 weeks) was defined as either a) presence of diarrhea, defined as passage of 3 or more unformed stools (Bristol stool chart types 5-7) in 24 or fewer consecutive hours, and stool sample that was positive for the toxin B gene (by PCR) and positive for toxin A and/or toxin B, as measured in the central laboratory; or b) Pseudomembranous colitis diagnosed at colonoscopy, at surgery, or histopathologically; and corresponding stool sample that was positive for the toxin B gene (via PCR) as measured in the central laboratory. End of surveillance period was defined as accumulation of at least 40 CDI cases.

  4. Number of Participants With Recurrent Episodes of CDI (Definition 2) After Dose 3 [ Time Frame: From 14 days after Dose 3 to the end of the surveillance period (mean follow-up after dose 3 was 34.2 months) ]
    CDI definition 2 for a recurrent episode (an episode of CDI that occurred 8 weeks or less after the onset of a previous CDI episode [provided the symptoms of the previous episode had resolved]), was defined as either a) presence of diarrhea, defined as passage of 3 or more unformed stools (Bristol stool chart types 5-7) in 24 or fewer consecutive hours; and stool sample that was positive for the toxin B gene (by PCR) and positive for toxin A and/or toxin B, as measured in the central laboratory; or b) Pseudomembranous colitis diagnosed at colonoscopy, at surgery, or histopathologically; and corresponding stool sample that was positive for the toxin B gene (by PCR) as measured in the central laboratory. End of surveillance period was defined as accumulation of at least 40 CDI cases.

  5. Number of All Episodes of CDI (Definition 1 and 2) After Dose 2 [ Time Frame: From 14 days after Dose 2 to the end of the surveillance period (mean follow-up after dose 2 was 36 months) ]
    CDI definition 1 for primary episode of CDI (no previous CDI onset in prior 8 weeks) and CDI definition 2 for recurrent episode (episode occurred 8 weeks or less after onset of previous episode [provided symptoms of previous episode resolved]) were both defined as either a) presence of diarrhea, (passage of 3 or more unformed stools [Bristol stool chart types 5-7]) in 24 or fewer consecutive hours, stool sample positive for toxin B gene (by PCR),positive for toxin A and/or toxin B, as measured in central laboratory; or b) Pseudomembranous colitis diagnosed at colonoscopy, surgery, histopathologically; and corresponding stool sample positive for toxin B gene (via PCR) as measured in central laboratory. End of surveillance period was defined as accumulation of at least 40 CDI cases.

  6. Number of Participants With Recurrent Episodes of CDI (Definition 2) After Dose 2 [ Time Frame: From 14 days after Dose 2 to the end of the surveillance period (mean follow-up after dose 2 was 36 months) ]
    CDI definition 2 for a recurrent episode (an episode of CDI that occurred 8 weeks or less after the onset of a previous CDI episode [provided the symptoms of the previous episode had resolved]), was defined as either a) presence of diarrhea, defined as passage of 3 or more unformed stools (Bristol stool chart types 5-7) in 24 or fewer consecutive hours; and stool sample that was positive for the toxin B gene (by PCR) and positive for toxin A and/or toxin B, as measured in the central laboratory; or b) Pseudomembranous colitis diagnosed at colonoscopy, at surgery, or histopathologically; and corresponding stool sample that was positive for the toxin B gene (by PCR) as measured in the central laboratory. End of surveillance period was defined as accumulation of at least 40 CDI cases.

  7. Number of First Primary Episode of CDI (Definition 1) After Dose 2 and Before Dose 3 [ Time Frame: From 14 days after Dose 2 to Dose 3 or the day the third vaccination was expected (168 days after Dose 2) for participants who received only 2 doses ]
    CDI definition 1 for a primary episode of CDI (no previous CDI onset in the prior 8 weeks) was defined as either a) presence of diarrhea, defined as passage of 3 or more unformed stools (Bristol stool chart types 5-7) in 24 or fewer consecutive hours, and stool sample that was positive for the toxin B gene (by PCR) and positive for toxin A and/or toxin B, as measured in the central laboratory; or b) Pseudomembranous colitis diagnosed at colonoscopy, at surgery, or histopathologically; and corresponding stool sample that was positive for the toxin B gene (via PCR) as measured in the central laboratory. End of surveillance period was defined as accumulation of at least 40 CDI cases.

  8. Number of Participants With Recurrent Episode of CDI (Definition 2) After Dose 2 and Before Dose 3 [ Time Frame: From 14 days after Dose 2 to Dose 3 or the day the third vaccination was expected (168 days after Dose 2) for participants who received only 2 doses ]
    CDI definition 2 for a recurrent episode (an episode of CDI that occurred 8 weeks or less after the onset of a previous CDI episode [provided the symptoms of the previous episode had resolved]), was defined as either a) presence of diarrhea, defined as passage of 3 or more unformed stools (Bristol stool chart types 5-7) in 24 or fewer consecutive hours; and stool sample that was positive for the toxin B gene (by PCR) and positive for toxin A and/or toxin B, as measured in the central laboratory; or b) Pseudomembranous colitis diagnosed at colonoscopy, at surgery, or histopathologically; and corresponding stool sample that was positive for the toxin B gene (by PCR) as measured in the central laboratory. End of surveillance period was defined as accumulation of at least 40 CDI cases.


Eligibility Criteria
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Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.


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Ages Eligible for Study:   50 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • Evidence of a personally signed and dated informed consent document.
  • Willing and able to comply with study procedures.
  • Subjects with an increased risk of future contact with healthcare systems or subjects who have received systemic antibiotics in the previous 12 weeks.
  • Ability to be contacted by telephone during study participation.
  • Negative urine pregnancy test for female subjects of childbearing potential.

Exclusion Criteria:

  • Investigator site staff members directly involved in the conduct of the study and their family members, site staff members otherwise supervised by the investigator, or subjects who are Pfizer employees, including their family members, directly involved in the conduct of the study.
  • Participation in other studies involving investigational drug(s)/vaccine(s) within 28 days prior to study entry until 1 month after the third vaccination.
  • Previous administration of an investigational C difficile vaccine or C difficile mAb therapy.
  • Prior episode of CDI..
  • Receipt of blood products or immunoglobulins within 6 months before enrollment.

  • Subjects who may be unable to respond to vaccination due to:

    • Metastatic malignancy; or
    • End-stage renal disease; or
    • Any serious medical disorder likely to be fatal within the next 12 months; or
    • Congenital or acquired immunodeficiency; or
    • Receipt of high dose systemic corticosteroids for 14 days within 28 days of enrollment; or
    • Receipt of chronic systemic treatment with other known immunosuppressant medications, or radiotherapy, within 6 months of enrollment.
  • Known infection with human immunodeficiency virus (HIV).
  • Any bleeding disorder or anticoagulant therapy that would contraindicate intramuscular injection.
  • Any contraindication to vaccination or vaccine components, including previous anaphylactic reaction to any vaccine or vaccine-related components.
  • Prior small- or large-bowel resection.
  • Any condition or treatment resulting in frequent diarrhea.
  • Other acute or chronic condition or abnormality that may increase the risk associated with study participation or IP administration or may interfere with interpretation of study results
  • Pregnant or breastfeeding female subjects; male subjects and female subjects who are sexually active and at risk for pregnancy and will not/cannot use 2 methods of contraception
Contacts and Locations
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Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT03090191


Locations
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Sponsors and Collaborators
Pfizer
Investigators
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Study Director: Pfizer CT.gov Call Center Pfizer
  Study Documents (Full-Text)

Documents provided by Pfizer:
Study Protocol  [PDF] September 28, 2020
Statistical Analysis Plan  [PDF] December 2, 2021

More Information
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Additional Information:

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Responsible Party: Pfizer
ClinicalTrials.gov Identifier: NCT03090191    
Other Study ID Numbers: B5091007
2016-003866-14 ( EudraCT Number )
CLOVER ( Other Identifier: Alias Study Number )
First Posted: March 24, 2017    Key Record Dates
Results First Posted: February 13, 2023
Last Update Posted: February 13, 2023
Last Verified: January 2023
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: Yes
Plan Description: Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical_trials/trial_data_and_results/data_requests.
URL: https://www.pfizer.com/science/clinical_trials/trial_data_and_results/data_requests

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Studies a U.S. FDA-regulated Drug Product: Yes
Studies a U.S. FDA-regulated Device Product: No
Additional relevant MeSH terms:
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Clostridium Infections
Gram-Positive Bacterial Infections
Bacterial Infections
Bacterial Infections and Mycoses
Infections