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VE303

Phase 3

Clostridium Difficile | Monoclonal antibody | Infectious Disease |PureTech Health plc|Last Updated: Jul 27, 2026

Success Probability

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Market & Valuation

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Trial Design

RandomizedDouble-BlindPLACEBO_CONTROLLEDDMCBiomarker
Total Trials1
Total Enrollment852

FDA Designations

No designations recorded

Clinical trial landscape

VE303 · 3 trials · 13 indications

Phase 3 1Phase 2 1Phase 1 1
NCT06237452VE303 for Prevention of Recurrent Clostridioides Difficile InfectionClostridium Difficile
RECRUITING852 Analytics
PHASE3RECRUITING
VE303 for Prevention of Recurrent Clostridioides Difficile Infection
Clostridium DifficileUnlock trial analytics

Study Endpoints

Primary Endpoints

CDI Recurrence Rate at Week 8
8 weeks

Proportion of participants with laboratory-confirmed CDI recurrence before or at Week 8.

CDI Recurrence Week 8
8 weeks

Percentage of participants with toxin-positive, laboratory-confirmed, or clinically diagnosed and treated CDI recurrence before or at Week 8 (i.e., 8 weeks after the first dose of study treatment).

Safety of VE303 measured by incidence adverse events (AEs)
12 months post-dose

Measured in terms of incidence of AEs according to CTCAE V4.0

Tolerability of VE303 using modified PROMIS questionnaire (v1.0)
12 months post-dose

Characterized the highest well tolerated dose regimen of VE303 using modified PROMIS questionnaire (v1.0)

Secondary Endpoints

VE303 Strains Detected
24 weeks
VE303 Relative Abundance
24 weeks
Evaluate the colonization of the intestinal microbiota with VE303 component bacteria
12 months post-dose
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Study Design & Arms

AllocationRANDOMIZED
MaskingQUADRUPLE
ModelPARALLEL
PurposePREVENTION

Treatment Arms

ArmTypeDescription
VE303EXPERIMENTALSubjects assigned to the VE303 arm will take 3 capsules containing VE303 per day for 14 days after completing 10 to 21 days of standard of care antibiotic treatment for the qualifying CDI episode.
PlaceboPLACEBO_COMPARATORSubjects assigned to the placebo arm will take 3 placebo capsules per day for 14 days after completing 10 to 21 days of standard of care antibiotic treatment for the qualifying CDI episode.
VE303 High DoseEXPERIMENTALStudy subjects assigned the high dose VE303 arm took 10 capsules (dosage: 8.0 × 10\^9 CFU daily) containing VE303 per day for 14 days.
VE303 Low DoseEXPERIMENTALStudy subjects assigned to the low dose VE303 arm took 2 capsules (dosage: 1.6 × 10\^9 CFU daily) containing VE303 per day for 14 days.
Cohort 1EXPERIMENTALCohort 1 received oral vancomycin followed by a single dose of VE303.
Cohort 2EXPERIMENTALCohort 2 received oral vancomycin followed by a single day of 5 doses of VE303.
Cohort 3EXPERIMENTALCohort 3 received oral vancomycin followed by a single day of 10 doses of VE303.
Cohort 4EXPERIMENTALCohort 4 received oral vancomycin followed by 5 days of 10 doses daily of VE303.
Cohort 5EXPERIMENTALCohort 5 received oral vancomycin followed by 14 days of 10 capsules daily of VE303
Cohort 6EXPERIMENTALCohort 6 received 21 days of 10 doses daily of VE303
Cohort 7EXPERIMENTALCohort 7 received oral vancomycin followed by 10 doses of VE303 daily for 2 days, followed by 2 doses of VE303 daily for 3 days
Cohort 8EXPERIMENTALCohort 8 received oral vancomycin followed by 10 doses of VE303 daily for 2 days, followed by 2 doses of VE303 daily for 3 days
Cohort 9EXPERIMENTALCohort 8 received oral vancomycin followed by 10 doses of VE303 daily for 2 days, followed by 2 doses of VE303 daily for 3 days
Vancomycin onlyPLACEBO_COMPARATORThis cohort only received oral vancomycin.

Interventions

NameTypeDescription
VE303BIOLOGICALVE303 is a live biotherapeutic product (LBP) consisting of 8 clonally derived, nonpathogenic, nontoxigenic, commensal bacteria strains manufactured under Good Manufacturing Practices (GMP) conditions.
PlaceboBIOLOGICALPlacebo capsules contain microcrystalline cellulose. Placebo capsules are visually identical to and not discernible from VE303 capsules. Placebo capsules will not contain any VE303 drug product.
Oral VancomycinDRUGVancomycin, when taken by mouth, is used to treat Clostridium difficile-associated diarrhea.
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Eligibility Criteria

Age Range12 Years to N/A
SexALL
Healthy VolunteersNo
Study Sites215

Key Inclusion Criteria (For enrollment in Stage 1: recurrent CDI population): * Age ≥ 12 years where permitted, and ≥ 18 years in other locations, with a laboratory-confirmed qualifying episode of CDI and at least 1 prior occurrence within the last 6 months Key Inclusion Criteria (For enrollment i...

Countries:United StatesAustraliaBelgiumBrazilBulgariaCanadaCzechiaDenmarkFranceGeorgiaGermanyHungaryIrelandIsraelItalyMexicoNetherlandsPolandPortugalRomaniaSouth KoreaSpainTaiwanUnited Kingdom
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Frequently asked questions about VE303

What is VE303 used for?

VE303 is an investigational therapy being studied for the prevention of recurrent Clostridioides difficile infection (CDI), also referred to as Clostridium difficile infection. It is being evaluated in patients with a history of recurrent CDI, as well as in healthy volunteers for early-phase safety studies.

Who is developing VE303?

VE303 is being developed by PureTech Health plc, a biopharmaceutical company listed on the London Stock Exchange under the ticker PRTC. The company is advancing VE303 through clinical trials for the prevention of recurrent Clostridioides difficile infection.

What phase is VE303 in?

VE303 is currently in Phase 3 clinical development. A Phase 3 trial (NCT06237452) is recruiting participants to evaluate VE303 for the prevention of recurrent Clostridioides difficile infection. Earlier Phase 1 and Phase 2 studies have been completed.

What clinical trials is VE303 in?

VE303 is being studied in a Phase 3 trial (NCT06237452) for prevention of recurrent Clostridioides difficile infection, with an enrollment target of 852 participants. Completed trials include a Phase 2 study (NCT03788434) in patients with recurrent CDI and a Phase 1 first-in-human study (NCT04236778) in healthy volunteers.

Is VE303 FDA approved?

VE303 is not FDA approved. It is an investigational drug currently in Phase 3 clinical development for the prevention of recurrent Clostridioides difficile infection. The therapy has not yet received regulatory approval and remains under evaluation in clinical trials.

What does VE303 target?

VE303 is a monoclonal antibody therapy being developed for infectious disease, specifically targeting Clostridioides difficile infection. The drug is designed to address recurrent CDI, though its specific molecular target has not been disclosed in the available clinical trial information.