Due to the nature of Clostridium difficile infections, particularly the high rate of recurrence following standard treatments, participating in a clinical trial may be an option for sufferers who don’t respond to antibiotics. Some clinical trials focus on developing vaccines and other preventatives. Those trials often need healthy volunteers who haven’t had a CDI to participate. The following are large, active trials focused on C. diff treatment and prevention. For smaller scale and local trials, please visit our In Your State page and search for ones near you.

What is a Clinical Trial?

A clinical trial is a research study that using human volunteers that is intended to add to medical knowledge. Clinical trials can vary in size from a single location in one country to multiple locations in multiple countries. Some research studies may determine if an investigational product can be administered to children or special populations. Some studies assess a drug’s long-term effectiveness and its impact on the quality of a person’s life.

All studies of a drug, biological product, or medical device regulated by FDA must be reviewed, approved, and monitored by an institutional review board (IRB) or Ethics Committee (EC). All clinical trials are conducted using Principles of Good Clinical Practice (GCP) and are under the supervision of an IRB or EC whose mission is to ensure the safety and welfare of study participants. To learn more about clinical trials, please visit Clinical Trials.gov.


Rebiotix Inc.

The PUNCH CD 3 study is a Phase 3 clinical study to evaluate the safety and efficacy of Rebiotix RBX2660 for the prevention of recurrent Clostridium difficile infection (CDI).

This prospective, randomized, double-blinded, placebo-controlled clinical research study is expected to enroll up to 270 patients at 60 research sites in the U.S. and Canada. Patients that meet the study requirements and choose to enroll will be randomized to received either RBX2660, an investigational new drug, or a placebo. Two out of every three study patients will receive RBX2660, and one out of every three study patients will receive the placebo study treatment (2:1 randomization). Study patients whose CDI returns within 8 weeks after blinded study treatment may be scheduled to receive an RBX2660 treatment (no placebo). The study’s primary endpoint will compare the proportion of patients with treatment success following treatment with RBX2660 to prevent recurrent CDI within 8 weeks of blinded treatment as compared to placebo.

To learn more or join the study, visit the Clinical Trials.gov.

Seres Therapeutics

Seres Therapeutics is developing Ecobiotic ® drugs designed to prevent C. diff infections from coming back again.

Most C. diff infections occur after antibiotic treatment. Why? Our gut contains trillions of microbes, called the microbiome, which protects us from bacterial invaders that can cause disease. Antibiotics kill both good and bad bacteria, leaving holes in this ecology (community) of microbes. When the microbiome is damaged, bad bacteria, like C. diff, can take advantage and cause disease. Although specific antibiotics can kill the active C. diff bacteria, the sleeping forms (ie, spores) are untouched. These spores turn into active C. diff bacteria and cause disease again and again – usually after antibiotic treatment has finished.

Seres Therapeutics has developed an oral medicine called SER-109, which aims to prevent C. diff from coming back by repairing the microbiome. This Ecobiotic® drug is being studied in a large Phase 3 clinical trial that is enrolling patients who have had multiple C. diff infections. This important clinical study is being done in the United States and Canada and may provide the final clinical data needed to support FDA drug approval. For more information, please follow this link to the patient website: https://serescdiffstudy.com/

Seres Therapeutics is also enrolling patients into a Phase 1 trial for SER-262, which is an Ecobiotic ® drug for those experiencing their first C. diff infection. For more information, please follow this link: http://www.serestherapeutics.com/ser-262-ser-262-001-study


Crestovo’s PRISM3 CP101 Clinical Trial

PRISM 3 is a multicenter, randomized, placebo-controlled trial to evaluate the efficacy and safety of CP101 in approximately 240 patients with recurrent CDI at clinical sites throughout the U.S. The primary endpoint of PRISM 3 is prevention of recurrence of CDI through eight weeks following administration of CP101, compared to placebo. CP101 is Crestovo’s potential first-in-class, lead microbiome therapy generated from the company’s Full-Spectrum MicrobiotaTM (FSMTM) platform. Click here to see if there’s a study site near you and if you’re eligible. 

Vaccine & Preventatives

Sanofi-Pasteur Cdiffense Trial

The objective of the Cdiffense trial is to evaluate the safety, immunogenicity and efficacy of a toxoid vaccine for the prevention of primary symptomatic Clostridium difficile Infection. The trial is being conducted in 17 countries. Click here to see if there’s a study site near you and if you’re eligible.

Synthetic Biologics’ SYN-004 Phase 2b Proof-of-Concept Clinical Trial

A global, multi-center, randomized, double-blind, placebo-controlled clinical trial to evaluate the ability of SYN-004 to degrade certain IV beta-lactam antibiotics within the GI tract to maintain the natural balance of the gut microbiome for the prevention of C. difficile infection, C. difficile associated diarrhea and antibiotic-associated diarrhea in patients hospitalized for a lower respiratory tract infection and receiving IV ceftriaxone. Click here to see if there’s a study site in the U.S. near you and if you’re eligible. Click here to learn more about SYN-004.