TheraRadar
Landscape / Infectious Disease
Data updated: Jun 28, 2026

C. difficile Clinical Trial Landscape

C. difficile is being studied across 176 clinical trials registered since 2008, with 22 programs currently active.

The competitive pipeline includes 6 active Phase 3 trials, 8 active Phase 2 trials, and 7 active Phase 1 trials. Top industry sponsors include AstraZeneca, Vedanta Biosciences, Inc., Acurx Pharmaceuticals Inc..

Trial activity

22 active / 176 total since 2008
Active by phase 6 Ph3 / 45 8 Ph2 / 73 7 Ph1 / 31 1 Ph4 / 27

Sponsor activity

Who is running trials now — green active, blue completed, red failed/terminated.

Sorted by active Active Done Failed
AstraZeneca 1 1 0
Vedanta Biosciences, Inc. 1 1 0
Acurx Pharmaceuticals Inc. 1 1 0
Theriva Biologics, Inc. 1 1 0
Lumen Bioscience, Inc. 1 0 0
Pfizer 0 8 0
Sanofi 0 3 2
Actelion 0 4 1
Astellas 0 4 1
Rebiotix Inc. 0 5 0
Merck 0 5 0
Summit Therapeutics 0 3 1
Seres Therapeutics, Inc. 0 4 0
Finch Research and Development LLC. 0 2 1
Cubist Pharmaceuticals LLC, a subsidiary of Merck & Co., Inc. (Rahway, New Jersey USA) 0 3 0

All 15 active C. difficile sponsors

Unlock the remaining 7 sponsors with active / completed / failed counts — sortable and exportable.

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How the field has grown

New-trial starts peaked in 2019 (16 registered); 2025 saw 5. The right-hand chart shows median Phase 3 enrollment by start year — the number in parentheses is that year's Phase 3 trial count (25 in total), so single-trial years (and years with no Phase 3 starts) are obvious. Both are by trial start date; the current year is partial.

New trials started by year

2016
8
2017
14
2018
13
2019
16
2020
9
2021
6
2022
5
2023
4
2024
7
2025
5
2026
6

TheraRadar.com

Median Phase 3 enrollment by start year

2016 (1)
64
2017 (5)
263
2018 (3)
153
2019 (4)
776
2020 (1)
263
2021 (3)
19
2022 (1)
24
2023 (2)
71
2024 (3)
375
2025 (1)
300
2026 (1)
76

TheraRadar.com

Full trial pipeline

Every active and completed trial across Phase 1–4, with enrollment analytics. Sortable, filterable, exportable with Pro.

NCT07458984 RECRUITING
FMT Capsules for rCDI
Helsinki University Central Hospital n=76
NCT06237452 RECRUITING
VE303 for Prevention of Recurrent Clostridioides Difficile Infection
Vedanta Biosciences, Inc. n=852
NCT05330182 RECRUITING
LMN-201 for Prevention of C. Difficile Infection Recurrence
Lumen Bioscience, Inc. n=375
NCT07221370 RECRUITING
Enteral Vancomycin as Primary Prophylaxis Against Clostridioides Difficile Infection in Critically Ill Patients
Riverside University Health System Medical Center n=176
NCT06979609 RECRUITING
Secondary Prevention of Clostridioides Difficile Using Vancomycin
McGill University Health Centre/Research Institute of the McGill University Health Centre n=300
NCT05266807 RECRUITING
Fecal Microbiota Transplantation in Clostridioides Difficile Infection First Episode and First Recurrence
Benoit Guery n=100
NCT05831189 COMPLETED
A Multi-center, Single-arm Trial Exploring the Safety and Clinical Effectiveness of RBX2660 Administered by Colonoscopy to Adults With Recurrent Clostridioides Difficile Infection
Ferring Pharmaceuticals n=41
NCT04138706 COMPLETED
Initial Vancomycin Taper for the Prevention of Recurrent Clostridium Difficile Infection
McGill University Health Centre/Research Institute of the McGill University Health Centre n=263
NCT03105479 TERMINATED
Comparison of Cadazolid Versus Vancomycin in Children With Clostridium Difficile-associated Diarrhea (CDAD)
Actelion n=1
NCT05201079 COMPLETED
Primary or Recurrent Clostridioides Difficile Infection Treatment With Capsules of Lyophilised Faecal Microbiota vs Fidaxomicin
Mikrobiomik Healthcare Company S.L. n=93
NCT01983683 COMPLETED
Efficacy and Safety of Cadazolid Versus Vancomycin in Subjects With Clostridium Difficile-associated Diarrhea
Actelion n=631
NCT01987895 COMPLETED
Efficacy and Safety of Cadazolid Versus Vancomycin in Subjects With Clostridium Difficile - Associated Diarrhea
Actelion n=632
NCT05320068 COMPLETED
Oral Vancomycin Vs Placebo in the Prevention of Recurrence of Clostridioides Difficile's Infection
Julia Orígüen n=24
NCT02218372 COMPLETED
A Study to Investigate the Safety and Efficacy of Fidaxomicin (Oral Suspension or Tablets) and Vancomycin (Oral Liquid or Capsules) in Pediatric Subjects With Clostridium Difficile-associated Diarrhea (CDAD)
Astellas Pharma Europe B.V. n=148
NCT02179658 COMPLETED
A Study to Compare Safety and Efficacy of OPT-80(Fidaxomicin) With Vancomycin in Subjects With Clostridium Difficile-associated Diarrhea (CDAD)
Astellas Pharma Inc n=210
NCT03796650 TERMINATED
Fecal Transplantation for Primary Clostridium Difficile Infection
Oslo University Hospital n=104
NCT03931941 COMPLETED
Microbiota Restoration Therapy for Recurrent Clostridium Difficile Infection (PUNCH CD3-OLS)
Rebiotix Inc. n=793
NCT03244644 COMPLETED
Microbiota Restoration Therapy for Recurrent Clostridium Difficile Infection (PUNCHCD3)
Rebiotix Inc. n=320
NCT03005379 TERMINATED
Microbiota or Placebo After Antimicrobial Therapy for Recurrent C. Difficile at Home (MATCH)
VA Office of Research and Development n=153
NCT03918629 COMPLETED
Clostridium Difficile Vaccine 2-Dose Versus 3-Dose Study
Pfizer n=1,994
NCT05153499 TERMINATED
A Trial of CP101 for the Prevention of Recurrent CDI (PRISM4)
Finch Research and Development LLC. n=19
NCT04802837 TERMINATED
Safety, Tolerability and the Pharmacokinetics of Ridinilazole in Adolescent Subjects
Summit Therapeutics n=2
NCT03182907 COMPLETED
Bezlotoxumab (MK-6072) Versus Placebo in Children With Clostridium Difficile Infection (CDI) (MK-6072-001)
Merck Sharp & Dohme LLC n=148
NCT03183128 COMPLETED
ECOSPOR III - SER-109 Versus Placebo in the Treatment of Adults With Recurrent Clostridium Difficile Infection
Seres Therapeutics, Inc. n=182
NCT03183141 COMPLETED
ECOSPOR IV: An Open-Label Study Evaluating SER-109 in Recurrent Clostridioides Difficile Infection
Seres Therapeutics, Inc. n=263
NCT02395848 TERMINATED
Efficacy of 30-day Duration of Fidaxomicin for Recurrent C. Difficile Infection
McMaster University n=31
NCT03595553 COMPLETED
Comparison of Ridinilazole Versus Vancomycin Treatment for Clostridium Difficile Infection
Summit Therapeutics n=759
NCT03090191 COMPLETED
Clostridium Difficile Vaccine Efficacy Trial
Pfizer n=17,535
NCT03579459 COMPLETED
Evaluation Of Clostridium Difficile Vaccine Lot Consistency In Healthy Adults 65 To 85 Years Of Age
Pfizer n=1,317
NCT01598311 COMPLETED
A Study of CB-183,315 in Participants With Clostridium Difficile Associated Diarrhea (MK-4261-006)
Cubist Pharmaceuticals LLC, a subsidiary of Merck & Co., Inc. (Rahway, New Jersey USA) n=608
NCT02801656 WITHDRAWN
Fecal Microbiota Transplantation for Primary Clostridium Difficile Diarrhea
Memorial University of Newfoundland
NCT01887912 TERMINATED
Study of a Candidate Clostridium Difficile Toxoid Vaccine in Subjects at Risk for C. Difficile Infection
Sanofi Pasteur, a Sanofi Company n=9,302
NCT02301000 TERMINATED
IMT for Primary Clostridium Difficile Infection
Oslo University Hospital n=21
NCT02254811 COMPLETED
FMT Delivered by Capsule Versus Colonoscopy for Recurrent C. Diff
University of Alberta n=116
NCT02743234 COMPLETED
Fecal Microbiota Transplantation for Relapsing Clostridium Difficile Infection
University of Aarhus n=64
NCT01597505 COMPLETED
Study of CB-183,315 in Participants With Clostridium Difficile Associated Diarrhea (MK-4261-005)
Cubist Pharmaceuticals LLC, a subsidiary of Merck & Co., Inc. (Rahway, New Jersey USA) n=606
NCT01691248 COMPLETED
Safety and Efficacy of Fidaxomicin Versus Placebo for Prophylaxis Against Clostridium Difficile-Associated Diarrhea in Adults Undergoing Hematopoietic Stem Cell Transplantation (MK-5119-001)
Optimer Pharmaceuticals LLC, a subsidiary of Merck & Co., Inc. (Rahway, New Jersey USA) n=611
NCT01241552 COMPLETED
A Study of MK-3415, MK-6072, and MK-3415A in Participants Receiving Antibiotic Therapy for Clostridium Difficile Infection (MK-3415A-001)
Merck Sharp & Dohme LLC n=1,452
NCT01513239 COMPLETED
A Study of MK-6072 and MK-3415A in Participants Receiving Antibiotic Therapy for Clostridium Difficile Infection (MK-3415A-002)
Merck Sharp & Dohme LLC n=1,203
NCT01143272 TERMINATED
Probiotic Saccharomyces Boulardii for the Prevention of Antibiotic-associated Diarrhoea
Bernhard Nocht Institute for Tropical Medicine n=477
NCT01202630 SUSPENDED
BIO-K+ CL1285 for Prevention of Recurrent Clostridium Difficile Infection
Bio-K Plus International Inc. n=140
NCT01226992 TERMINATED
Oral Vancomycin Followed by Fecal Transplant Versus Tapering Oral Vancomycin
University Health Network, Toronto n=81
NCT01295918 COMPLETED
Probiotic Lactobacillus Reuteri to Prevent Antibiotic-associated Diarrhea and Clostridium Difficile-related Infections in Hospitalized Children
St Marina University Hospital, Varna, Bulgaria n=100
NCT00747071 WITHDRAWN
Safety and Validation of Efficacy of Oral Administration of the Food Additive Colostrum Derived Anti Clostridium Difficile Antibodies
Hadassah Medical Organization
NCT00958308 COMPLETED
Efficacy and Safety Study in the Prevention of Antibiotic-Associated Diarrhea (AAD) and Clostridium Difficile-Associated Diarrhea (CDAD) in Hospitalized Adult Patients Exposed to Nosocomial Infection
Bio-K Plus International Inc. n=255

Full C. difficile Pipeline

Every trial across Phase 1–4, plus enrollment analytics. Sortable, filterable, exportable.

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Data: ClinicalTrials.gov · Trials registered 2008 onwards · Industry sponsors only