To Compare Ridinilazole Versus Vancomycin Treatment for Clostridium Difficile Infection (Ri-CoDIFy 2)
![]() |
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. Know the risks and potential benefits of clinical studies and talk to your health care provider before participating. Read our disclaimer for details. |
ClinicalTrials.gov Identifier: NCT03595566 |
Recruitment Status :
Recruiting
First Posted : July 23, 2018
Last Update Posted : April 9, 2021
|
- Study Details
- Tabular View
- No Results Posted
- Disclaimer
- How to Read a Study Record
Summit is developing ridinilazole as a novel antimicrobial for Clostridium difficile Infection (CDI), formerly known as Clostridium difficile Infection, with the goal of achieving comparable cure rates to standard of care, but reducing rates of recurrent disease.
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.
Condition or disease | Intervention/treatment | Phase |
---|---|---|
Clostridioides Difficile Infection | Drug: ridinilazole Drug: vancomycin | Phase 3 |
Study Type : | Interventional (Clinical Trial) |
Estimated Enrollment : | 680 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 the 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 |
Estimated Primary Completion Date : | June 2021 |
Estimated Study Completion Date : | September 2021 |

Arm | Intervention/treatment |
---|---|
Experimental: ridinilazole |
Drug: ridinilazole
ridinilazole 200mg bid |
Active Comparator: vancomycin |
Drug: vancomycin
vancomycin 125mg qid |
- Sustained clinical response defined as clinical cure at the Assessment of Cure (AOC) visit and no recurrence of CDI within 30 days post end of treatment (EOT) [ Time Frame: Day 40 ]
- Clinical cure at Assessment of Cure (AOC) visit [ Time Frame: Day 12 ]
- Sustained clinical response over 60 days [ Time Frame: Day 70 ]defined as clinical cure at the AOC visit and no recurrence of CDI within 60 days post EOT
- Sustained clinical response over 90 days [ Time Frame: Day 100 ]defined as clinical cure at the AOC visit and no recurrence of CDI within 90 days post EOT
- Investigator assessment of clinical cure at the AOC visit [ Time Frame: Day 12 ]
- Investigator assessment of sustained clinical response at 30, 60- and 90-days post EOT [ Time Frame: Days 40, 70 and 100 ]
- Relative abundance and diversity of the microbiome and bile salt composition in fecal samples at the end of treatment [ Time Frame: Day 1 to Day 40 ]

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.
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:
- Patient must be at least 18 years of age, at the time of signing the informed consent.
- 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.
- 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).
-
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.
- 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:
- 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.
- Have a history of chronic diarrheal disease including inflammatory bowel disease (Crohn's disease or ulcerative colitis).
- Have had a positive diagnostic test for other GI pathogens, considered to be clinically relevant, within 2 weeks of randomization.
- 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.
- Have life threatening or fulminant CDI with evidence of hypotension, septic shock, peritoneal signs or absence of bowel sounds, or toxic megacolon.
- 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.
- 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).
- Prior or current use of anti-toxin antibodies including bezlotoxumab within the past 6 months prior to randomization.
- Are unable to discontinue products used affecting disease progression at randomization.
- 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.
- Have received an investigational vaccine against C. difficile.
-
Patients that the Investigator feels are inappropriate for the study this would include those;
- with any other condition that, in the Investigator's judgment, would make the patient unsuitable for inclusion in the study.
- who, in the opinion of the Investigator, are not likely to complete the study for whatever reason, e.g. short life expectancy.
- with known hypersensitivity or intolerance to ridinilazole, vancomycin, and/or their excipients
- 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.

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): NCT03595566
Contact: Mary Alvarado | +1 617 401 3341 | mary.alvarado@summitplc.com |

Study Director: | Jos Houbiers, MD, PhD | Summit Therapeutics |
Responsible Party: | Summit Therapeutics |
ClinicalTrials.gov Identifier: | NCT03595566 |
Other Study ID Numbers: |
SMT19969/C005 |
First Posted: | July 23, 2018 Key Record Dates |
Last Update Posted: | April 9, 2021 |
Last Verified: | April 2021 |
Individual Participant Data (IPD) Sharing Statement: | |
Plan to Share IPD: | No |
Studies a U.S. FDA-regulated Drug Product: | Yes |
Studies a U.S. FDA-regulated Device Product: | No |
Clostridium difficile Clostridioides difficile C. difficile C. diff |
Infection Communicable Diseases Clostridium Infections Gram-Positive Bacterial Infections |
Bacterial Infections Vancomycin Anti-Bacterial Agents Anti-Infective Agents |