FDA Refuses to Review Axsome's Fibromyalgia Drug, Company Plans New Trial

Axsome Therapeutics has encountered a significant setback in its efforts to bring esreboxetine, a potential treatment for fibromyalgia, to market. The U.S. Food and Drug Administration (FDA) has refused to review the company's new drug application (NDA) for the asset, citing concerns over one of the two trials included in the filing.

FDA Feedback and Trial Design Issues

The FDA's refuse to file (RTF) letter focused on the design of one of the placebo-controlled trials submitted by Axsome. While one study, which used a 12-week endpoint and fixed dosing, was deemed adequate and well-controlled, the agency took issue with a phase 2 study that employed an 8-week endpoint and flexible dosing.

Herriot Tabuteau, M.D., CEO of Axsome, stated, "The clear feedback provided by the FDA's Division of Anesthesiology, Addiction Medicine and Pain Medicine allows us to move expeditiously with the continued development of this important investigational medicine for the approximately 17 million patients in the U.S. living with fibromyalgia."

Axsome's Response and Future Plans

In response to the FDA's decision, Axsome has announced plans to initiate a new phase 3 trial by the end of 2025. This study will mirror the trial design that the FDA found sufficient, incorporating a 12-week endpoint and fixed dosing. The company aims to address the agency's concerns and strengthen its application for esreboxetine.

An Axsome spokesperson confirmed to Fierce Biotech that the new trial will be a phase 3 study, designed to meet the FDA's requirements. The company remains optimistic about the potential of esreboxetine, emphasizing that both previous trials met their primary endpoints.

Financial and Market Impact

The news of the FDA's refusal to review the NDA had a temporary impact on Axsome's stock, which initially slipped but rebounded to $112 per share by 11 a.m. ET on the day of the announcement. Analysts from William Blair commented on the situation, stating, "We expect shares to be down modestly in response to the fibromyalgia RTF letter, but ultimately this news has limited impact on our growth thesis for Axsome."

As of March 31, Axsome reported approximately $301 million in cash and cash equivalents, according to its first-quarter earnings report. This financial position may help the company navigate the costs associated with conducting an additional clinical trial.