07:59 AM EDT, 06/09/2025 (MT Newswires) -- Axsome Therapeutics ( AXSM ) said Monday that it received a refuse to file letter from the US Food and Drug Administration for its new drug application for AXS-14 in fibromyalgia.

According to Axsome, the regulator found that its NDA was not sufficient for a substantive review, as the second of two placebo-controlled trials was inadequate because it used flexible dosing and had a primary endpoint at 8 weeks, while the first study used a fixed dose and a 12-week primary endpoint, the company said.

No concerns were raised over the results of both studies, with both meeting their primary endpoints, Axsome said.

The company said it plans to conduct an additional controlled trial in Q4 to address the FDA's feedback.

Shares of Axsome Therapeutics ( AXSM ) were down 4.8% in recent premarket activity Monday.