Top-line data from Sage Therapeutics’ Phase III Mountain clinical trial have shown that SAGE-217 failed to meet the primary endpoint in adults with major depressive disorder (MDD).

SAGE-217 is an investigational neuroactive steroid (NAS) positive allosteric modulator (PAM) of GABAA receptor. The oral drug candidate is being developed for the treatment of depression.

The double-blind, placebo-controlled MOUNTAIN study assessed the safety and efficacy of a 20mg or 30mg once-nightly dose of SAGE-217 over two weeks in 581 MDD patients compared to placebo.

The primary endpoint was the change in the 17-item Hamilton Rating Scale for Depression (HAM-D) total score from baseline to day 15.

Secondary endpoints included the change in the Montgomery-Åsberg Depression Rating Scale (MADRS) and the Hamilton Anxiety Rating Scale (HAM-A) total score.

The trial did not meet its primary endpoint by failing to demonstrate a statistically significant decrease in the 17-item HAM-D total score at day 15, compared to placebo.

Patients treated with the 30mg dose experienced a mean decrease of 12.6 in HAM-D total score versus 11.2 with placebo.

However, the 30mg dose led to statistically significant reductions in the HAM-D total score at days three, eight and 12.

SAGE-217 was generally well-tolerated with a safety profile similar to that observed in prior trials. Overall adverse events (AEs) were similar between the study groups during the treatment period and 28-day follow-up.

The most common AEs associated with SAGE-217 were headache, somnolence, dizziness, diarrhoea, sedation, nausea and fatigue.

Sage Therapeutics chief medical officer Steve Kanes said: “As a designated breakthrough therapy, we are evaluating the path forward to more fully inform a potentially expedited pathway to approval, and any amendments we might consider to the ongoing SAGE-217 pivotal programme.”

SAGE-217 is part of five additional pivotal trials. Two trials yielded positive results in MDD and postpartum depression (PPD), and three are ongoing.