The Clostridioides Difficile Trial of REC-3964

NCT06536465 | Terminated Phase 2 Results FDA Drug

• 1 other identifier: REC-3964-201
• Study Type: interventional
• Target: 3
• Locations: 1 country
• Sites: 2

Brief Summary

This is a multi-center, open-label study to investigate the safety, tolerability, pharmacokinetics (PK) and efficacy of REC-3964 (doses of either 250 mg or 500 mg PO every 12 hours) for the reduction of Clostridioides difficile infection (CDI).

Conditions

Recurrent Clostridioides Difficile Infection

Keywords

Cdiff Infection; Clostridiodes difficile infection; Cdiff

Outcome Measures

Primary Outcomes (5)

• Number of Participants With Survival Without Recurrence or Requirement for Additional Clostridioides Difficile Infection (CDI) Treatment

  Recurrent CDI was defined as a new episode of CDI associated with a new positive Clostridioides difficile stool toxin or requirement for additional CDI treatment during the 8-week Follow-up Period after cure of preceding CDI with initial curative treatment.

  8 weeks

• Number of Participants With Treatment-emergent Adverse Events (TEAEs)

  A TEAE was the development of an undesirable medical condition or the deterioration of a pre-existing medical condition following or during exposure to a pharmaceutical product, whether or not considered causally related to the product.

  Up to 8 weeks

• Number of Participants With Related TEAEs

  A TEAE was the development of an undesirable medical condition or the deterioration of a pre-existing medical condition following or during exposure to a pharmaceutical product, whether or not considered causally related to the product. An Investigator who was qualified in medicine determined relationship to the study drug for each AE (unrelated or related). The Investigator decided whether, in his or her medical judgment, if there was a reasonable biological possibility that the event may have been caused by the study drug.

  Up to 8 weeks

• Number of Participants With Serious TEAEs

  A TEAE was the development of an undesirable medical condition or the deterioration of a pre-existing medical condition following or during exposure to a pharmaceutical product, whether or not considered causally related to the product. A Serious TEAE was defined as results in death, immediately life-threatening, requires in-participant hospitalization or prolongation of existing hospitalization, results in persistent or significant disability or incapacity in conducting activities of daily living for at least 28 days, results in a congenital abnormality or birth defect, or an important medical event that may jeopardize the participant or may require medical intervention.

  Up to 8 weeks

• Number of Participants With TEAEs Leading to Study Drug Discontinuation

  A TEAE was the development of an undesirable medical condition or the deterioration of a pre-existing medical condition following or during exposure to a pharmaceutical product, whether or not considered causally related to the product.

  Up to 8 weeks

Secondary Outcomes (7)

• Rate of Recurrent Clostridioides Difficile Infection (rCDI)

  8 weeks

• Time to Recurrence of rCDI

  Up to 8 weeks

• Number of Participants With Severe rCDI

  Up to 8 weeks

• Number of Participants With rCDI Who Had Associated Hospital Admissions

  Up to 8 weeks

• Maximum Observed Plasma Concentration (Cmax) of REC-3964

  Pre-dose, 1 hour, 3 hours, and 6 hours post morning dose on Day 1 and Day 15

Study Arms (3)

REC-3964 High-dose

EXPERIMENTAL

Participants will receive 500 mg REC-3964 q12h REC-3964 250 mg capsules

Drug: REC-3964

REC-3964 Low-dose

EXPERIMENTAL

Participants will receive 250 mg REC-3964 q12h REC-3964 250 mg capsules

Drug: REC-3964

Observation

NO INTERVENTION

Participants will undergo watchful waiting

Interventions

REC-3964 DRUG

REC-3964 given at a dose of either 500 mg q12h or 250 mg q12h

REC-3964 High-dose; REC-3964 Low-dose

Eligibility Criteria

• Age: 18 Years - 115 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Be 18 years of age or older with Clostridioides difficile infection (CDI) diarrhea associated with a positive stool test for C. difficile toxin\[s\] prior to the preceding curative treatment.
• The CDI episode, severe or otherwise, must have resolved after receiving vancomycin with a standard duration of treatment. The participant must be randomized within 2 days of completing the preceding curative treatment.
• Have high risk for rCDI (a recurrent CDI episode within the last 6 months, age ≥65 years, immunocompromised state, or severe CDI with resolution prior to enrollment into the study).

You may not qualify if:

• Have an active, symptomatic, chronic diarrheal illness from other causes, such as ulcerative colitis or Crohn's disease.
• Diarrhea that requires on-study treatment with agents that would confound the interpretation of the study results.

Sponsors & Collaborators

• Recursion Pharmaceuticals Inc.: lead

Study Sites (2)

GANJ - Toms River - Ocean Family Gastroenterology

Toms River, New Jersey, 08755, United States

Location

Southern Star Research Institute, LLC

San Antonio, Texas, 78229, United States

Location

MeSH Terms

Conditions

Clostridium Infections

Condition Hierarchy (Ancestors)

Gram-Positive Bacterial Infections; Bacterial Infections; Bacterial Infections and Mycoses; Infections

Limitations and Caveats

Due to the early termination of the study, only 3 participants were enrolled. Data are limited due to the small sample size.

Results Point of Contact

• Title: Recursion Pharmaceuticals
• Organization: Recursion Pharmaceuticals, Inc.

clinicaltrials@recursionpharma.com

385-374-1724

Publication Agreements

• PI is Sponsor Employee: No
• Restrictive Agreement: Yes

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: July 15, 2024
• First Posted: August 5, 2024
• Study Start: October 14, 2024
• Primary Completion: May 6, 2025
• Study Completion: May 6, 2025
• Last Updated: November 17, 2025
• Results First Posted: November 17, 2025

Record last verified: 2025-11

Data Sharing

• IPD Sharing: Will not share

Locations

US (2)