Neuren Pharmaceuticals (ASX:NEU) has received formal written feedback from the US Food and Drug Administration outlining the regulatory requirements for its lead candidate, NNZ-2591, in treating Pitt Hopkins syndrome and hypoxic-ischemic encephalopathy.
The company confirmed that the FDA has validated its planned Investigational New Drug opening study for HIE, pending the submission of additional juvenile animal data.
Neuren anticipates submitting this data in time to commence the HIE study in late 2026.
For the Pitt Hopkins syndrome program, the FDA has approved the use of a syndrome-specific clinical global impression scale as a co-primary endpoint.
The alignment mirrors the strategy used in Neuren's ongoing Phase 3 trial for Phelan-McDermid syndrome.
While CEO Jon Pilcher expressed disappointment over the FDA's delayed "written responses only" format, he emphasised that the company remains well-funded with a "clear path forward" and expects minimal financial impact from the revised guidance.
Neuren shares fell 10% earlier this week following a "negative trend vote" from European regulators regarding its Rett syndrome treatment, trofinetide.
However, with fast track designations already secured for NNZ-2591 across three rare syndromes, the company aims to maintain its momentum in the pediatric neurology space.