US-based, microbiome therapeutics platform company Seres has failed to achieve the primary endpoint of its Phase II ECOSPOR clinical trial of SER-109 to address multiply recurrent Clostridium Difficile infection (CDI).
SER-109 is an investigational oral, single-dose capsule, which is being tested to prevent the recurrence of CDI in adults who experienced three or more occurrences within nine months.
The randomised, double-blind, placebo-controlled Phase II trial was conducted over a period of 24 weeks involving 89 patients with multiply recurrent CDI, and designed to evaluate the safety and efficacy of SER-109.
The interim eight-week results were based on the trial involving 59 patients who were randomised to be administered with SER-109, as well as the remaining 30 patients with placebo.
SER-109 was administered orally on a single dose regimen after an antibiotic treatment for CDI.
The primary endpoint of the trial was to establish the efficacy of SER-109 in limiting the relative risk of CDI recurrence up to eight weeks post treatment.
CDI recurrence was characterised by diarrhea for two or more days and the requirement for antibiotic treatment.
Analysis of an eight-week data revealed no significant difference in the frequency of CDI recurrence within the group administered with SER-109, to that of the group receiving placebo.
Seres chairman and CEO Roger Pomerantz said: “These are unexpected clinical results in view of the positive data in our prior investigator-sponsored Phase Ib trial, as well as in a wide range of supporting clinical and preclinical data.
“Specifically, the recurrence rates observed in the overall SER-109 treatment group, the age stratified subgroups, and in the placebo groups are inconsistent with our expectations.
“Our priority is to complete a full review of the clinical results and microbiome data of the Phase II study and to compare it to data from the prior investigator sponsored Phase Ib.”
Seres is planning to make the necessary changes to the development of SER-109 based on the study's further data analysis.