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ECOSPORTM is our current Phase 2 clinical study focused on the safety and efficacy of SER-109, a drug for the potential prevention of recurrent Clostridium difficile infection (CDI) in adults who have had three or more episodes of CDI within the previous nine months. The FDA has designated SER-109 as a Breakthrough Therapy. A Breakthrough Therapy is a drug intended to treat a serious or life-threatening disease and preliminary clinical evidence indicates that the drug may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints.

Our SER-109 ECOSPORTM Study, The FDA has designated SER-109 as a Breakthrough Therapy. A RandomizEd, Double Blind, Placebo COntrolled, Parallel Group Study of SER 109 to Prevent Recurrent ClOstRidium difficile Infection (SERES-004) no longer recruiting patients. Our SER-109, ECOSPORTM II Study, an Open-Label Extension of Study SERES-004 Evaluating SER-109 in Patients with Recurrent Clostridium difficile Infection (SERES-005), is currently active.

Interim 8-week results announced July 29, 2016 from the SER-109 Phase 2 ECOSPOR study indicate that the study’s primary efficacy endpoint was not achieved. The company continues to gather and analyze study data.

Our SER-109, ECOSPORTM II Study: An Open-Label Extension of Study SERES-004 Evaluating SER-109 in Patients with Recurrent Clostridium difficile Infection (SERES-005) is still open for enrollment.

This page contains information for those interested in learning more about ECOSPORTM and participating in the research study. Please contact us at 617.945.9626 x304 or visit for more information if you are interested in participating in this study.

About Clostridium difficile

Clostridium difficile (C. difficile) is a bacterium that causes an infection of the gut. Most doctors and patients call this infection “C. diff” for short. C. difficile infection (CDI) can cause many loose watery bowel movements (diarrhea) and painful stomach cramps. The main cause of CDI is antibiotics, which wipe out the good bacteria of the gut, which may permit some bad bacteria, like C. difficile, to take over and cause infection.

Many patients can be successfully treated for CDI with antibiotics that target these bad bacteria. However, some patients keep getting the infection again and again. Recurrent C. diff is a major problem because there are no good methods to prevent the infection from recurring. Part of the problem is that the good bacteria are still missing from the gut. Without those good bacteria, the patient has no defense against getting CDI again—even if antibiotics stop the diarrhea for a little while.

For someone with recurrent CDI, diarrhea is a daily problem that can be frequent and start without warning. Patients with frequent diarrhea and stomach discomfort have trouble doing many of their usual daily activities. Some even have trouble leaving the house. However, the good news is that research is going on right now to find a medicine to prevent CDI from recurring. ECOSPORTM is a current study to evaluate an investigational medicine called SER-109.

ECOSPOR™ Clinical Trial

Learn more about our Phase 2 ECOSPORTM trial


Our Lead Candidate SER-109

Learn more about SER-109, our lead development candidate


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