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Comparison of Ridinilazole Versus Vancomycin Treatment for Clostridium Difficile Infection (Ri-CoDIFy 1)

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
ClinicalTrials.gov Identifier: NCT03595553
Recruitment Status : Completed
First Posted : July 23, 2018
Results First Posted : March 3, 2023
Last Update Posted : March 3, 2023
Information provided by (Responsible Party):
Summit Therapeutics

Brief Summary:

Summit is developing ridinilazole as a novel antimicrobial for Clostridioides difficile Infection (CDI), formerly known as Clostridium difficile Infection, with the goal of demonstrating an improved Sustained Clinical Response rate in subjects treated with ridinilazole as compared to subjects treated with vancomycin.

A phase 2 proof of concept study, with vancomycin as comparator, demonstrated these attributes with a comparable safety profile. A high fecal concentration of ridinilazole and little systemic exposure were noted.

The rationale for this phase 3 study is to confirm the improvement in sustained clinical response of CDI over vancomycin and to compare the safety and tolerability of ridinilazole to that of vancomycin.

Ridinilazole plasma concentration will be assessed in a subset of patients.

Condition or disease Intervention/treatment Phase
Clostridioides Difficile Infection Drug: Ridinilazole Drug: Vancomycin Phase 3

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 759 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Masking Description: In both arms patients receive the same number of doses per day. Placebo tablets are included to maintain same number and appearance of IP in both arms.
Primary Purpose: Treatment
Official Title: A Phase 3, Randomized, Double-blind, Active Controlled Study to Compare the Efficacy and Safety of Ridinilazole (200 mg, Bid) for 10 Days With Vancomycin (125 mg, Qid) for 10 Days in the Treatment of Clostridium Difficile Infection (CDI)
Actual Study Start Date : January 28, 2019
Actual Primary Completion Date : November 17, 2021
Actual Study Completion Date : November 17, 2021

Resource links provided by the National Library of Medicine

Arm Intervention/treatment
Experimental: ridinilazole
ridinilazole 200mg bid
Drug: Ridinilazole
ridinilazole (200 mg bid)
Other Name: 2,2'-di(pyridin-4-yl)-1H,1'H-5,5'-bi(benzimidazole), 2,2'-bis(4-pyridyl)-3H,3'H-5,5'-bibenzimidazole, 2-pyridin-4-yl-6-(2-pyridin-4-yl-3H-benzimidaz

Active Comparator: vancomycin
vancomycin 125 mg qid
Drug: Vancomycin
vancomycin (125 mg qid)

Primary Outcome Measures :
  1. Number of Participants With Sustained Clinical Response (SCR) Defined as Clinical Response and no Recurrence of CDI Through 30 Days Post End of Treatment (EOT). [ Time Frame: Day 40 ]
    This primary outcome measures the number of participants with Sustained Clinical Response (SCR). SCR is defined as Clinical Response and no recurrence of CDI through 30 days post End of Treatment (EOT). At D40, D70 and D100 the Investigator or medically qualified designee will determine if the patient has a sustained clinical response or experienced RECURRENCE since the previous assessment. The Investigator will assess cure/failure and recurrence based on available information which includes, but is not limited to, improvement from baseline in the number of UBMs, signs & symptoms of CDI, and the requirement for CDI medication. The Investigator should assess cure/failure in a way that best reflects the Investigator's standard clinical practice.

Secondary Outcome Measures :
  1. Clinical Response [ Time Frame: Day 12 ]

    defined as

    • less than 3 unformed bowel movements (UBMs) for consecutive days and maintained through EOT without further CDI treatment at EOT + 2 days, or
    • the investigator's assessment that the subject no longer needs specific CDI antimicrobial treatment after completion of the course of study medication.

  2. Clinical Cure [ Time Frame: Day 12 ]
    defined as the resolution of diarrhea (<3 UBMs in the 1-day period immediately prior to EOT, that is maintained for 2 days after EOT).

  3. Sustained Clinical Response Over 60 Days [ Time Frame: Day 70 ]
    defined as Clinical Response and no recurrence of CDI through 60 days post EOT

  4. Sustained Clinical Response Over 90 Days [ Time Frame: Day 100 ]
    defined as Clinical Response and no recurrence of CDI through 90 days post EOT

  5. Relative Abundance of the 3 Main Bile Acid Groups (Conjugated Primary, Primary and Secondary Bile Acids) From Baseline to EOT. [ Time Frame: Day 10 ]
    This secondary outcome measures the relative abundance of the 3 main Bile Acid Groups (Conjugated Primary, Primary and Secondary Bile Acids) from Baseline to EOT.

  6. Percentage of Change of α-diversity (Shannon Index) of the Microbiota in Stool Samples From Baseline to EOT. [ Time Frame: Day 10 ]
    This secondary outcome measures the percentage of change of α-diversity (Shannon Index) of the microbiota in stool samples from baseline to EOT. Shannon index is a weighted statistic measuring both species richness and evenness. The Shannon Index is calculated by taking the relative abundance of each species and sums the relative abundance times the natural log of the relative abundance for each species. The value is converted into a positive value by times minus one. A higher Shannon Index means higher diversity

  7. Measure of β-diversity of the Gut Microbiota Between Baseline and EOT Stool Samples (Bray-Curtis Index/Dissimilarity). [ Time Frame: Day 10 ]
    This secondary outcome measures the β-diversity of the gut microbiota in stool samples from baseline to EOT. Bray-Curtis index/dissimilarity measures how different two samples are in the microbiome composition. The Bray-Curtis dissimilarity is graded between 0 and 1, where 0 means the two samples have the same composition (that is they share all the species and every species has the same abundance), and 1 means the two samples do not share any species.

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria

Patients are eligible to be included in the study only if all the following criteria apply:

  1. Patient must be at least 18 years of age, at the time of signing the informed consent.
  2. Have signs and symptoms of CDI including diarrhea such that in the Investigator's opinion, CDI antimicrobial therapy is required. Diarrhea is defined as a change in bowel habits, with ≥3 unformed bowel movements (UBMs) (5, 6 or 7 on the Bristol Stool Chart) in the 24 h prior to randomization.
  3. Have the presence of either toxin A and/or B of C. difficile in the stool determined by a positive free toxin test (using a Sponsor agreed test). The stool sample must be current (produced within 72 hours prior to randomization).
  4. Male or Female

    Male patients:

    • A male patient must agree to use contraception as detailed in Section 10.4 of this protocol during the treatment period and for at least 30 days after the last dose of study treatment and refrain from donating sperm during this period.

    Female patients:

    • A female patient is eligible to participate if she is not pregnant, not breastfeeding, and at least one of the following conditions applies: i. Not a woman of childbearing potential (WOCBP) OR ii. A WOCBP who agrees to follow the contraceptive guidance during the treatment period and for at least 30 days after the last dose of study treatment.

  5. Has provided documented signed informed consent and any authorizations required by local law (e.g. Protected Health Information [PHI]). If unable to read, understand and sign the informed consent form a legally authorized representative (LAR) may provide consent on the patient's behalf if permitted by the Institutional Review Board (IRB)/Ethics Committee (EC).

Exclusion Criteria

Patients are excluded from the study if any of the following criteria apply:

  1. Have had more than one prior episode of CDI in the previous 3 months or more than 3 episodes in the past 12 months prior to randomization.
  2. Have a history of chronic diarrheal disease including inflammatory bowel disease (Crohn's disease or ulcerative colitis).
  3. Have had a positive diagnostic test for other GI pathogens, considered to be clinically relevant, within 2 weeks of randomization.
  4. Have had major gastrointestinal (GI) surgery (e.g. significant bowel resection) within 3 months of randomization (this does not include appendectomy). The presence of a colostomy or ileostomy or likely requirement of an ostomy during the study.
  5. Have life threatening or fulminant CDI with evidence of hypotension, septic shock, peritoneal signs or absence of bowel sounds, or toxic megacolon.
  6. History of bone marrow or hematopoietic stem cell transplant at any time or a known current history of a severely compromised/suppressed immune system that, in the opinion of the Investigator, would make the patient unsuitable for the study.
  7. Have had more than the equivalent of 24 hours of dosing of antimicrobial treatment active against the current episode of CDI prior to randomization. (i.e. more than four doses of oral vancomycin, two doses of fidaxomicin or three doses of metronidazole).
  8. Prior or current use of anti-toxin antibodies including bezlotoxumab within the past 6 months prior to randomization.
  9. Are unable to discontinue products used affecting disease progression at randomization.
  10. Has been involved in a clinical trial and received an investigational medicinal product for indications other than CDI within 1 month or five half-lives (whichever is longer) or within 3 months if the investigational medical product was for CDI.
  11. Have received an investigational vaccine against C. difficile.
  12. Patients that the Investigator feels are inappropriate for the study this would include those;

    1. with any other condition that, in the Investigator's judgment, would make the patient unsuitable for inclusion in the study.
    2. who, in the opinion of the Investigator, are not likely to complete the study for whatever reason, e.g. short life expectancy.
    3. with known hypersensitivity or intolerance to ridinilazole, vancomycin, and/or their excipients
    4. who are unwilling or unable to comply with protocol requirements, e.g. complete the full course of study treatment per schedule, attend study visits, report diarrhea/suspected recurrence, provide stool samples, ingest capsules/tablets or blood draws.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT03595553

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Sponsors and Collaborators
Summit Therapeutics
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Study Director: Lori Styles, MD Summit Therapeutics
  Study Documents (Full-Text)

Documents provided by Summit Therapeutics:
Study Protocol  [PDF] August 9, 2021
Statistical Analysis Plan  [PDF] November 19, 2021

Additional Information:
Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
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Responsible Party: Summit Therapeutics
ClinicalTrials.gov Identifier: NCT03595553    
Obsolete Identifiers: NCT03595566
Other Study ID Numbers: SMT19969/C004
First Posted: July 23, 2018    Key Record Dates
Results First Posted: March 3, 2023
Last Update Posted: March 3, 2023
Last Verified: March 2023
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No

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Studies a U.S. FDA-regulated Drug Product: Yes
Studies a U.S. FDA-regulated Device Product: No
Keywords provided by Summit Therapeutics:
Clostridioides difficile
Clostridium difficile
C. difficile
C. diff
Additional relevant MeSH terms:
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Communicable Diseases
Clostridium Infections
Disease Attributes
Pathologic Processes
Gram-Positive Bacterial Infections
Bacterial Infections
Bacterial Infections and Mycoses
Anti-Bacterial Agents
Anti-Infective Agents
Antiparasitic Agents