Neuren Pharmaceuticals (ASX:NEU) reported that primary endpoints for its planned single phase-three clinical trial of its drug candidate NNZ-2591 as a treatment for Phelan-McDermid syndrome were confirmed at a meeting with the US Food and Drug Administration, according to a Monday Australian bourse filing.

The co-primary endpoints in the double-blind placebo-controlled study of treatment for 13 weeks will be the change from baseline in the receptive communication sub-domain of the Vineland adaptive

behavior scales, third edition, and the overall score in the Phelan-McDermid syndrome assessment of change.

The firm said it remains on track to commence the phase three trial by the middle of the year, subject to regulatory review of the final version of the trial protocol.

Both measures included in the primary endpoints showed clinically meaningful improvement in the firm's phase two open-label clinical trial, the filing noted.