Neuren Pharmaceuticals (ASX:NEU) has secured another significant regulatory milestone in its Rett syndrome program, announcing that partner Acadia Pharmaceuticals has received U.S. FDA approval for DAYBUE STIX, a new dye- and preservative-free powder formulation of trofinetide for oral solution.
The approval expands treatment options for children and adults living with Rett syndrome, offering families greater flexibility in managing dose volume and taste.
DAYBUE STIX becomes the second FDA-approved formulation of trofinetide, alongside the original DAYBUE oral solution, making them the only approved treatments for Rett syndrome in the United States. The powder can be mixed with a range of water-based liquids, a feature Neuren says will improve ease of administration for both caregivers and patients with high support needs.
Neuren CEO Jon Pilcher said the approval reflects Acadia’s continued investment in broadening access to the therapy. “The Neuren team is excited about the approval of this new treatment option for Rett syndrome families and the continued investment and innovation for trofinetide by our global partner, Acadia. Caregivers can mix DAYBUE STIX with a variety of water-based liquids, providing flexibility to modify the taste and volume of their loved one’s dose,” he said. “We look forward to seeing the impact as DAYBUE STIX becomes more broadly available during 2026.”
The FDA decision was supported by a bioequivalence study demonstrating that the powder formulation provides exposure comparable to that of the original liquid version of DAYBUE. This means patients switching between formulations can expect the same efficacy and safety profile established in clinical trials. Acadia expects DAYBUE STIX to be available on a limited basis in the first quarter of 2026, with broader availability planned for early in the second quarter. The existing oral solution will remain on the market.
Under its global licensing agreement, Acadia holds exclusive worldwide rights to develop and commercialise trofinetide, while Neuren receives royalties on all net sales and remains eligible for future development and commercial milestone payments.
Trofinetide is a synthetic analogue of a naturally occurring neurotrophic peptide and the first therapy to address the core symptoms of Rett syndrome, a rare neurodevelopmental disorder that emerges in early childhood and has historically lacked approved treatment options.