Seres Therapeutics Stock Plunges As Ulcerative Colitis Candidate Disappoints In Mid-Stage Study

Seres Therapeutics Inc MCRB has announced topline results from the Phase 2b ECO-RESET study evaluating SER-287 in patients with mild-to-moderate ulcerative colitis (UC).
The study did not meet its primary endpoint of improving clinical remission rates compared to placebo.
Given the lack of a clinical efficacy signal identified in ECO-RESET, the Company has decided to close the study's open-label and maintenance portions.
Microbiome endpoints and analyses are expected in the second half of 2021.
No meaningful clinical differences and no statistical significance were observed in absolute clinical remission rates among the three treatment arms (10.3% for the full induction dose, n=68 and 10.6% for the step-down induction dose, n=66 versus 11.6% for placebo, n=69).
There were also no meaningful differences observed across the three treatment groups for endoscopic improvement, endoscopic remission, or symptomatic remission.
Treatment-emergent adverse events (AEs) were observed in 67.6%, 46.2%, and 50.7% of subjects in the induction dose, step-down, and placebo treatment arms, respectively.
The majority of observed AEs were mild or moderate in intensity.
Both dosing regimens of SER-287 were generally well tolerated.
Price Action: MCRB shares are down 37.60% at $13.00 during the premarket session on the last check Thursday.