Seres shares slide after SER-109's failure in C Difficile trial

Shares in US-based microbiome therapeutics platform company Seres Therapeutics (Nasdaq: MCRB) dropped by a massive 76% on Friday after the failure of its Phase II trial of the Clostridium difficile infection (CDI) treatment SER-109.

The study’s primary endpoint of reducing the relative risk of CDI recurrence at up to eight weeks was not achieved in results which shocked Seres and its boss Roger Pomerantz.

Based on eight-week data, CDI recurrence occurred in 44% of the 59 patients who received SER-109, compared to 53% of the 30 subjects who took placebo.