A Phase 1/2 interventional study of EXL01 and EXL01 in Clostridioides Difficile Infection and Recurrent Infection, sponsored by Hospices Civils de Lyon. Recruiting at 10 sites in France. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-10-20.
Sponsored by Hospices Civils de Lyon · Phase 1/2, Interventional, and Treatment
Clostridioides difficile infection (CDI) is the leading cause of nosocomial diarrhea in Europe, with over 120,000 cases and almost 3,700 deaths per year. This infection is characterized by a high risk of recurrence after cure, ranging from almost 20% after a first episode to over 60% after 2 recurrences, or in the case of specific risk factors.
Currently, first-line treatment of CDI is based on oral antibiotics such as fidaxomicin or vancomycin. These antibiotic treatments, which are effective in 89% and 86% of first-episode cases respectively, do not correct the microbiological imbalance underlying the onset of CDI and may, on the contrary, encourage recurrence by contributing to the maintenance of a deleterious change in the microbiota (dysbiosis) through the elimination of bacteria other than C. difficile, due to their spectrum of activity. In a number of patients, this ecological imbalance can no longer be restored after antibiotic treatment, leading to multiple recurrences of CDI.
In this context, fecal microbiota transplantation (FMT) has been validated for over 10 years for the prevention of recurrence in multi-recurrent CDI. The principle of FMT is based on the use of a pharmaceutical preparation made from the stool of a healthy donor, administered within the digestive tract of a patient for therapeutic purposes.
Currently, in the case of multiple recurrences, it is the recommended first-line treatment (from 2 recurrences) and the most effective, with a clinical efficacy preventing recurrence of CDI in 69% to 89% of cases at 8 weeks post-treatment, with a good safety profile.
Among the microbial factors promoting CDI, the loss of the bacterial species Faecalibacterium prausnitzii constitutes a specific therapeutic target. F. prausnitzii is a commensal bacterium of the human gut, making up nearly 5% of the fecal microbiota, and has been shown to be associated with an individual's state of health. A drop in its relative abundance is associated with an increased risk of numerous diseases, such as Crohn's disease and colorectal cancer. In CDI, F prausnitzii is greatly diminished. Moreover, low abundance of F. prausnitzii is predictive of C. difficile recurrence. Its abundance in stools is increased after FMT and is also predictive of response to treatment. From a pathophysiological point of view, one of the preventive effects of F. prausnitzii on recurrence would be mediated by its ability to hydrolyze the bile acids involved in the germination of C. difficile spores.
The aim of this Phase I/II trial is to assess the efficacy and safety of oral administration of EXL01, a single isolated unmodified strain of F. prausnitzii, in preventing CDI recurrence in high-risk patients at W8. The study will be conducted in 2 parts. The phase I (Part A) is planned to include 6 patients. The phase II (Part B) will include 50 patients in two arms (25 patients respectively in the placebo and EXL01 arm).
251 studies on the registry are indexed under Clostridium Infections; 51 are open to participants now.
This study's planned enrollment of 56 is below the median of 64 across 185 interventional studies indexed under Clostridium Infections.
Browse Clostridium Infections studies →Hospices Civils de Lyon is the lead sponsor of 1,866 studies on the registry; 448 are open to participants now.
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≥3rd episode of proven C. difficile infection (≥3 liquid stools per day and detection of toxigenic C. difficile in stool by PCR or enzyme-linked immunosorbent assay or immunochromatography or toxigenic culture) within 6 months with an interval ≤ 12 weeks since the end of treatment of the previous episode of resolved CDI or 2nd episode of proven C. difficile infection (≥3 liquid stools per day and detection of toxigenic C. difficile in the stools by PCR or enzyme-linked immunosorbent assay or immunochromatography or toxigenic culture) within 6 months with an interval ≤ 12 weeks since the end of treatment of the previous episode of resolved CDI with at least one of the following risk factors:
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.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Relapsed and refractory
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Excipients
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Life expectancy
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
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Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
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Drug: EXL01
Drug: EXL01
Drug: Placebo
Following a at least 10-days vancomycin treatment : Oral EXL01 including: * 10 capsules per day in week 1 and 2 * 4 capsules per day, in weeks 3 and 4 * 1 capsule per day in weeks 5 to 8 Phase I : EXL01 during a 8 weeks open-label period
Following a at least 10-days vancomycin treatment : Oral EXL01 including: * 10 capsules per day in week 1 and 2 * 4 capsules per day, in weeks 3 and 4 * 1 capsule per day in weeks 5 to 8 Phase II: EXL01 during a 8 weeks double blind placebo-controlled period
Following a at least 10-days vancomycin treatment: Oral placebo including: * 10 capsules per day in week 1 and 2 * 4 capsules per day, in weeks 3 and 4 * 1 capsule per day in weeks 5 to 8 Phase II : Placebo during a 8 weeks double blind placebo-controlled period
Incidence of Treatment-Emergent Adverse Events
Phase I The primary endpoint is the occurrence of serious adverse events (CTCAE grade≥3) during treatment and follow-up and discontinuation of treatment due to adverse events attributed to treatment
Time frame: at Week 1, Week 2, Week 4, Week 8, Week 16
Evaluation of the efficacy of EXL01 in preventing recurrence of C. difficile infection in patients at high risk of recurrence
Phase II The primary endpoint is the proportion of patients at W8 after the start of treatment who had a recurrence of toxigenic C. difficile defined by ≥3 liquid stools per day for more than 48 hours + detection of C. difficile toxin in stool (enzyme-linked immunosorbent assay or toxigenic culture +/- PCR) resulting in the initiation of CDI-specific treatment.
Time frame: at Week 8
Evaluation of the efficacy of EXL01 in preventing recurrence of C. difficile infection in patients at high risk of recurrence
Phase I Proportion of patients at W8 after the start of treatment who had a recurrence of toxigenic C. difficile defined by ≥3 liquid stools per day for more than 48 hours + detection of C. difficile toxin in stool (enzyme-linked immunosorbent assay or toxigenic culture +/- PCR) resulting in the initiation of specific treatment for CDI.
Time frame: at Week 8
Evaluation of the safety and tolerability profile of oral EXL01
Phase II Occurrence of adverse events (CTCAE grade≥3) during treatment and follow-up, and discontinuation of treatment due to adverse events
Time frame: at Week 2, Week 4, Week 8, Week 16
Number of stools per day over the past 24 hours
Phase I Assessment of digestive symptoms during treatment and follow-up Digestive symptoms are measured at each visit using a stool calendar
Time frame: at Week 0, Week 1, Week 2, Week 4, Week 8, Week 16
Stool consistency, as assessed by the Bristol scale, over the past 24 hours
Phase I Digestive symptoms are measured at each visit using the stool calendar
Time frame: at Week 0, Week 1, Week 2, Week 4, Week 8, Week 16
Abdominal discomfort assessed by a validated irritable bowel syndrome scale
Phase I Assessment of digestive symptoms during treatment and follow-up Digestive symptoms are measured at each visit (IBS-SSS modified, GCSI, GERDQ)
Time frame: at Week 8, Week 16
Number of stools per day over the past 24 hours
Phase II Assessment of digestive symptoms during treatment and follow-up Digestive symptoms are measured at each visit using a stool calendar
Time frame: at Week 0, Week 2, Week 4, Week 8, Week 16
Stool consistency, as assessed by the Bristol scale, over the past 24 hours
Phase II Digestive symptoms are measured at each visit using the stool calendar
Time frame: at Week 0, Week 2, Week 4, Week 8, Week 16
Abdominal discomfort assessed by a validated irritable bowel syndrome scale
Phase II Assessment of digestive symptoms during treatment and follow-up Digestive symptoms are measured at each visit (IBS-SSS modified, GCSI, GERDQ)
Time frame: at Week 8, Week 16
Assessment of patient quality of life during treatment and follow-up
Phases I and II Patient quality of life at W8 and M4 measured by a validated digestive disease quality of life questionnaire (GIQLI)
Time frame: At Week 8 and Week 16
Assessment of recurrence of C. difficile infection
Phases I and II percentage of patients with recurrence of C. difficile infection at M4
Time frame: At Week 16
Evaluation of the presence of EXL01 in the fecal microbiota
Phases I and II Level of F. prausnitzii (qPCR) in stool at W8 versus W0
Time frame: At Week 8
Assessment of EXL01 persistence in the intestinal microbiota
Phases I and II Level of F. prausnitzii (qPCR) in stool at M4 versus W0
Time frame: At Week 0 and Week 16
16S rRNA sequencing or shotgun
Phase I Gut microbiota composition at each visit
Time frame: at Week 0, Week 1, Week 2, Week 4, Week 8, Week 16
16S rRNA sequencing or shotgun
Phase II Gut microbiota composition at each visit
Time frame: at Week 0, Week 2, Week 4, Week 8, Week 16
Assessment of the persistence of toxigenic C. difficile in the stool of patients in clinical remission during the study.
Phase I Percentage of patients at each visit with a positive stool PCR test for toxigenic C. difficile considered to be in clinical remission
Time frame: at Week 0, Week 1, Week 2, Week 4, Week 8, Week 16
Assessment of the persistence of toxigenic C. difficile in the stool of patients in clinical remission during the study.
Phase II Percentage of patients at each visit with a positive stool PCR test for toxigenic C. difficile considered to be in clinical remission
Time frame: at Week 0, Week 2, Week 4, Week 8, Week 16
Assessment of recurrences of C. difficile infection requiring hospitalization
phases I and II percentage of patients with recurrence of C. difficile infection requiring hospitalization at W8
Time frame: At Week 8
Assessment of recurrences of C. difficile infection requiring hospitalization
phases I and II percentage of patients with recurrence of C. difficile infection requiring hospitalization at M4
Time frame: at Week 16
Assessment of recurrences of C. difficile infection requiring surgery
phases I and II phases I and II percentage of patients with a recurrence of C. difficile infection requiring surgery at W8
Time frame: at Week 8
Assessment of recurrences of C. difficile infection requiring surgery
phases I and II percentage of patients with recurrent C. difficile infection requiring surgery at M4
Time frame: at Week 16
Started May 2024 (actual). Primary completion is estimated for Jan 2028, 44 months after the start.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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Studies of the drug tested here: Faecalibacterium prausnitzii-containing Bacterial Strain Formulation EXL01