• First Phase 3 trial ever conducted in Phelan-McDermid syndrome (PMS)
• Koala Phase 3 clinical trial evaluating safety and efficacy of NNZ-2591 in children aged 3 to 12 with PMS
• Trial has Fast Track, Rare Pediatric Disease and Orphan Drug designations from FDA

Neuren Pharmaceuticals (ASX: NEU) has reported that the first participant has completed the 4-week screening period and commenced the 13-week period of twice-daily dosing in its Koala Phase 3 clinical trial of NNZ-2591 for Phelan-McDermid syndrome (PMS). This is the first Phase 3 trial ever to be conducted in PMS, for which there are no approved treatment options. Koala is a randomized, double-blind, placebo-controlled trial evaluating the safety and efficacy of NNZ-2591 in approximately 160 children aged 3 to 12 years with PMS. The program has Fast Track, Rare Pediatric Disease and Orphan Drug designations from the US Food and Drug Administration. More participants are scheduled to start dosing or start screening during February and March, with 25 families already referred to the two activated trial sites and an additional 37 families on waitlists for a trial site in a convenient geographical location. Neuren is also the Presenting Sponsor of the 2026 Phelan-McDermid Syndrome Foundation Family Conference, 'The Climb We Make Together', which will take place in Colorado in July 2026.

Neuren is excited to have started the treatment phase of the Koala Phase 3 study and is very encouraged by the level of interest in the PMS community. The company anticipates strong momentum for the Koala trial as additional sites around the US progressively activate during the first half of 2026.