Alkermes’ ALKS 5461 has been hit with a potential setback in the US after regulatory advisors failed to back its approval for major depressive disorder (MDD).

The once-daily drug has a novel mechanism of action for the adjunctive treatment of MDD in patients with an inadequate response to standard antidepressant therapies.

In 2016, ALKS 5461 missed targets in two late-stage studies, failing to induce a significant change in baseline on the Montgomery-Åsberg Depression Rating Scale (MADRS) compared to placebo, and failing to show a treatment effect versus placebo.

A third Phase III trial reported later in the year did however show that treatment with ALKS 5461 significantly reduced symptoms of depression in patients with MDD compared to placebo, and formed the basis of Alkermes marketing application for the drug.

But the US Food and Drug Administration’s Psychopharmacologic Drugs Advisory Committee has now voted 21 to 2 that the drug’s benefit-risk profile is not adequate to support its approval.

"We were disappointed and surprised by the FDA's characterisation of the safety and efficacy data for ALKS 5461 and the resulting outcome of the Advisory Committee vote, particularly for the patients, their families and treatment providers who need and deserve access to novel therapies that work differently than currently available antidepressants," said Richard Pops, the firm’s chief executive.

"We remain steadfast in our commitment to make a meaningful difference in the lives of people suffering with serious mental health conditions, and will continue to work with the FDA as it completes its review of the ALKS 5461 regulatory submission."

The FDA does not have to follow the recommendation of its Committee but generally tends to do so. In any case, a decision on whether to approve ALKS 5461 is expected by January 31.