Positive Topline Data From Phase 3 C diff Trial

August 11, 2020

Administration of the investigational oral microbiome therapeutic SER-109 resulted in a statistically significant decrease in the proportion of patients who had C diff recurrence within 8 weeks of administration versus placebo.

Topline results from the phase 3 ECOSPOR III study of an oral microbiome treatment for recurrent C difficile infection meet the study’s primary endpoint, according to Seres Therapeutics.

Administration of the investigational oral microbiome therapeutic SER-109 resulted in a statistically significant decrease of 30.2% in the proportion of patients who had C diff recurrence within 8 weeks of administration versus placebo.

Only 11.1% of patients administered SER-109 experienced a CDI recurrence, versus 41.3% of placebo patients.

When study results were characterized by the alternative metric of sustained clinical response, 88.9% of patients in the SER-109 arm achieved this objective.

According to Seres, the study’s efficacy results surpass the statistical threshold provided in consultation with the US Food and Drug Administration (FDA) that could allow it to fulfill requirements for a Biologics License Application.

SER-109 safety results were favorable, with an adverse event profile comparable to placebo.

Eric D. Shaff, President and Chief Executive Officer of Seres, commented on results in a company press release.

“Our results represent the first-ever positive pivotal clinical study results for a targeted microbiome drug candidate. We believe these Phase 3 data provide strong validation for our underlying microbiome therapeutics platform, which has been the scientific basis for the Company, as well as persuasive clinical evidence supporting our other active pipeline programs.”

Current approaches to C diff provide only modest improvements in sustained clinical response rates, leaving behind patients with recurrent disease.

Unapproved FMT (fecal microbiota transplantation) is poorly characterized clinically and has been associated with safety concerns. However, there have been positive results in some studies, presenting a need for balance and research.

“The recent quarantine and shipping hold of FMT from a major stool bank highlights the urgent need for an approved effective and safe treatment for recurrent CDI,” authors of the Seres Therapeutics press release wrote.