A Phase 2 interventional study of REC-3964 in Recurrent Clostridioides Difficile Infection, sponsored by Recursion Pharmaceuticals Inc.. Terminated at 2 sites in United States. Open to participants aged 18 Years to 115 Years. Per ClinicalTrials.gov, last updated 2025-11-17.
Sponsored by Recursion Pharmaceuticals Inc. · Phase 2, Interventional, and Treatment
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).
Study was terminated due to sponsor decision. This decision was not related to safety concerns.
251 studies on the registry are indexed under Clostridium Infections; 51 are open to participants now.
This study's enrollment of 3 is below the median of 64 across 185 interventional studies indexed under Clostridium Infections.
Browse Clostridium Infections studies →Recursion Pharmaceuticals Inc. is the lead sponsor of 7 studies on the registry; 3 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Key Inclusion Criteria:
Key Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will receive 500 mg REC-3964 q12h REC-3964 250 mg capsules
Drug: REC-3964
Participants will receive 250 mg REC-3964 q12h REC-3964 250 mg capsules
Drug: REC-3964
Participants will undergo watchful waiting
REC-3964 given at a dose of either 500 mg q12h or 250 mg q12h
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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: Up to 8 weeks
Rate of Recurrent Clostridioides Difficile Infection (rCDI)
Recurrent CDI was defined as a new episode of CDI associated with a new positive Clostridioides difficile stool toxin within 8 weeks of the cessation of initial curative treatment. The number of unformed \[types 5-7 on the Bristol stool scale\] bowel movements per day were recorded by the participant in the stool diary in order to identify a new episode of diarrhea. All new episodes of diarrhea were tested for toxigenic Clostridioides difficile to confirm CDI recurrence. The rate of rCDI was defined as the proportion of participants who had the Clostridioides difficile recurrence among randomized participants.
Time frame: 8 weeks
Time to Recurrence of rCDI
Recurrent CDI was defined as a new episode of CDI associated with a new positive Clostridioides difficile stool toxin within 8 weeks of the cessation of initial curative treatment. The number of unformed \[types 5-7 on the Bristol stool scale\] bowel movements per day were recorded by the participant in the stool diary in order to identify a new episode of diarrhea. All new episodes of diarrhea were tested for toxigenic Clostridioides difficile to confirm CDI recurrence. Time to recurrence of rCDI was to be assessed using Kaplan-Meier estimation.
Time frame: Up to 8 weeks
Number of Participants With Severe rCDI
Recurrent CDI was defined as a new episode of CDI associated with a new positive Clostridioides difficile stool toxin within 8 weeks of the cessation of initial curative treatment. The number of unformed \[types 5-7 on the Bristol stool scale\] bowel movements per day were recorded by the participant in the stool diary in order to identify a new episode of diarrhea. All new episodes of diarrhea were tested for toxigenic Clostridioides difficile to confirm CDI recurrence. Severe CDI was defined as CDI with white blood cell count \>15,000 cells/milliliter and/or serum creatinine ≥1.5 milligram/deciliter.
Time frame: Up to 8 weeks
Number of Participants With rCDI Who Had Associated Hospital Admissions
Recurrent CDI was defined as a new episode of CDI associated with a new positive Clostridioides difficile stool toxin within 8 weeks of the cessation of initial curative treatment. The number of unformed \[types 5-7 on the Bristol stool scale\] bowel movements per day were recorded by the participant in the stool diary in order to identify a new episode of diarrhea. All new episodes of diarrhea were tested for toxigenic Clostridioides difficile to confirm CDI recurrence.
Time frame: Up to 8 weeks
Maximum Observed Plasma Concentration (Cmax) of REC-3964
Time frame: Pre-dose, 1 hour, 3 hours, and 6 hours post morning dose on Day 1 and Day 15
Time to Maximum Plasma Concentration (Tmax) of REC-3964
Time frame: Pre-dose, 1 hour, 3 hours, and 6 hours post morning dose on the Day 1 and Day 15
Trough Plasma Concentration (Ctrough) of REC-3964
Time frame: Pre-dose on Day 15
Due to early study termination, only 3 participants were enrolled.
| Milestone | REC-3964 250 mg | REC-3964 500 mg | Observation |
|---|---|---|---|
| Started | 1 | 1 | 1 |
| Completed | 1 | 1 | 1 |
| Not completed | 0 | 0 | 0 |
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.
| Participants | REC-3964 250 mg | REC-3964 500 mg | Observation |
|---|---|---|---|
| Number of Participants With Survival Without Recurrence or Requirement for Additional Clostridioides Difficile Infection (CDI) Treatment | 1 | 1 | 1 |
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.
| Participants | REC-3964 250 mg | REC-3964 500 mg | Observation |
|---|---|---|---|
| Number of Participants With Treatment-emergent Adverse Events (TEAEs) | 0 | 0 | 1 |
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.
| Participants | REC-3964 250 mg | REC-3964 500 mg | Observation |
|---|---|---|---|
| Number of Participants With Related TEAEs | 0 | 0 | 0 |
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.
| Participants | REC-3964 250 mg | REC-3964 500 mg | Observation |
|---|---|---|---|
| Number of Participants With Serious TEAEs | 0 | 0 | 0 |
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.
| Participants | REC-3964 250 mg | REC-3964 500 mg | Observation |
|---|---|---|---|
| Number of Participants With TEAEs Leading to Study Drug Discontinuation | 0 | 0 | 0 |
Recurrent CDI was defined as a new episode of CDI associated with a new positive Clostridioides difficile stool toxin within 8 weeks of the cessation of initial curative treatment. The number of unformed \[types 5-7 on the Bristol stool scale\] bowel movements per day were recorded by the participant in the stool diary in order to identify a new episode of diarrhea. All new episodes of diarrhea were tested for toxigenic Clostridioides difficile to confirm CDI recurrence. The rate of rCDI was defined as the proportion of participants who had the Clostridioides difficile recurrence among randomized participants.
No measurements were reported for this outcome.
Recurrent CDI was defined as a new episode of CDI associated with a new positive Clostridioides difficile stool toxin within 8 weeks of the cessation of initial curative treatment. The number of unformed \[types 5-7 on the Bristol stool scale\] bowel movements per day were recorded by the participant in the stool diary in order to identify a new episode of diarrhea. All new episodes of diarrhea were tested for toxigenic Clostridioides difficile to confirm CDI recurrence. Time to recurrence of rCDI was to be assessed using Kaplan-Meier estimation.
No measurements were reported for this outcome.
Recurrent CDI was defined as a new episode of CDI associated with a new positive Clostridioides difficile stool toxin within 8 weeks of the cessation of initial curative treatment. The number of unformed \[types 5-7 on the Bristol stool scale\] bowel movements per day were recorded by the participant in the stool diary in order to identify a new episode of diarrhea. All new episodes of diarrhea were tested for toxigenic Clostridioides difficile to confirm CDI recurrence. Severe CDI was defined as CDI with white blood cell count \>15,000 cells/milliliter and/or serum creatinine ≥1.5 milligram/deciliter.
No measurements were reported for this outcome.
Recurrent CDI was defined as a new episode of CDI associated with a new positive Clostridioides difficile stool toxin within 8 weeks of the cessation of initial curative treatment. The number of unformed \[types 5-7 on the Bristol stool scale\] bowel movements per day were recorded by the participant in the stool diary in order to identify a new episode of diarrhea. All new episodes of diarrhea were tested for toxigenic Clostridioides difficile to confirm CDI recurrence.
No measurements were reported for this outcome.
No measurements were reported for this outcome.
No measurements were reported for this outcome.
No measurements were reported for this outcome.
Collected over Up to 8 weeks. Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| REC-3964 250 mg | 0/1 (0%) | 0/1 (0%) | 0/1 (0%) |
| REC-3964 500 mg | 0/1 (0%) | 0/1 (0%) | 0/1 (0%) |
| Observation | 0/1 (0%) | 0/1 (0%) | 1/1 (100%) |
| Event | REC-3964 250 mg | REC-3964 500 mg | Observation |
|---|---|---|---|
| ConstipationGastrointestinal disorders | 0/1 | 0/1 | 1/1 |
| PharyngitisInfections and infestations | 0/1 | 0/1 | 1/1 |
All enrolled participants. Due to the small sample size, data were not reported for participant confidentiality reasons.
| Age, Continuous(years) | REC-3964 250 mg | REC-3964 500 mg | Observation | Total |
|---|
| Sex: Female, Male(Participants) | REC-3964 250 mg | REC-3964 500 mg | Observation | Total |
|---|---|---|---|---|
| Female | — | — | — | 0 |
| Male | — | — | — | 0 |
| Ethnicity (NIH/OMB)(Participants) | REC-3964 250 mg | REC-3964 500 mg | Observation | Total |
|---|---|---|---|---|
| Hispanic or Latino | — | — | — | 0 |
| Not Hispanic or Latino | — | — | — | 0 |
| Unknown or Not Reported | — | — | — | 0 |
| Race (NIH/OMB)(Participants) | REC-3964 250 mg | REC-3964 500 mg | Observation | Total |
|---|---|---|---|---|
| American Indian or Alaska Native | — | — | — | 0 |
| Asian | — | — | — | 0 |
| Native Hawaiian or Other Pacific Islander | — | — | — | 0 |
| Black or African American | — | — | — | 0 |
| White | — | — | — | 0 |
| More than one race | — | — | — | 0 |
| Unknown or Not Reported | — | — | — | 0 |
PDFs hosted by the registry, ClinicalTrials.gov.
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Recursion Pharmaceuticals Inc.