In a Phase 1b clinical study, a preparation of a non-living single strain of the bacterium Prevotella histicola, isolated from the small intestine of a human donor (EDP1815), is being evaluated for its use in psoriasis. The study includes two cohorts of 12 and 18 patients with mild to moderate psoriasis for 28 days, with follow-up treatment through 42 days.

The early results have shown that the formulation was well tolerated at daily doses of up to 8.0×101 cells administered for up to 28 days, with a tolerability profile comparable to placebo. No serious adverse events were reported.

After 28 days of treatment, the mean percentage reduction in Psoriasis Severity Index (PASI) score for EDP1815 -treated group was 16%, compared to 1% for placebo, which further improved to 21% in the high dose cohort at 42 days of treatment. The study is a breakthrough with optimistic results from the pre-clinical and phase I trials.