Patent win extends DAYBUE’s US exclusivity window by nearly five years
The United States Patent and Trademark Office (USPTO) has issued a Notice of Allowance for a new patent covering the weight-banded dosing of trofinetide, extending US patent protection to March 28, 2041 — nearly five years beyond the existing method-of-use patent expiry of July 2036. Neuren Pharmaceuticals (ASX: NEU) reported the development on 29 September 2026, noting that the allowance was announced by its commercialisation partner, Acadia Pharmaceuticals (Nasdaq: ACAD). The product in question is DAYBUE® and DAYBUE® STIX, approved for the treatment of Rett syndrome in adults and paediatric patients 2 years of age and older.
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What the new patent covers
The Notice of Allowance relates to US Patent Application No. 17/590,496, titled “Methods and Compositions for Treatment of Rett Syndrome.” It covers the weight-banded dosing regimen used for trofinetide in its commercially marketed forms — the actual dosing method applied in practice, not a speculative future use.
A Notice of Allowance indicates the USPTO has determined the application meets the requirements for patentability. The patent is expected to issue following completion of standard administrative steps.
The March 28, 2041 expiry includes six months of paediatric exclusivity. Together with the existing method-of-use patent, DAYBUE now carries two layers of US patent protection:
| Patent Type | Coverage | Expiry |
|---|---|---|
| Method of use patent | Treatment of Rett syndrome | July 2036 |
| Weight-banded dosing patent (new) | Weight-banded dosing regimen for trofinetide | March 28, 2041 (incl. 6 months paediatric exclusivity) |
Why patent life matters for biotech investors
Patent exclusivity prevents generic competitors from entering the market during the protected period, preserving the commercial window in which a branded therapy can generate revenue. For royalty-dependent companies like Neuren — which has granted an exclusive worldwide licence to Acadia for the development and commercialisation of trofinetide — a longer exclusivity runway translates directly into more years of potential royalty income. The extension to March 2041 adds approximately five years to that window compared to the existing patent position.
DAYBUE royalty income grew 23% in Q1 2026 to US$10.4 million as net sales reached US$101 million, with US market penetration still sitting at only 28% in the broader community setting and the STIX formulation attracting treatment-naive patients rather than cannibalising existing users.
Investment case: a stronger royalty asset and a pipeline in motion
The patent extension is a value-protective development for Neuren’s royalty stream, reinforcing the commercial durability of DAYBUE without altering the underlying product or approval status. It is a meaningful addition to existing protections rather than a wholly new milestone.
Neuren is not a single-asset company. Its investigative drug candidate, NNZ-2591 (ercanetide), is in clinical development across several neurodevelopmental disorders:
- Phelan-McDermid syndrome: Currently in a Phase 3, randomised, double-blind, placebo-controlled trial (“Koala”) evaluating children aged 3 to 12 years, with a 52-week open-label extension study underway.
- Pitt Hopkins syndrome: In development under orphan drug designation in the US and EU, with FDA Fast Track and Rare Pediatric Disease designations.
- Angelman syndrome: Same designation profile as above.
- Hypoxic ischemic encephalopathy (HIE): Also in development for this serious condition caused by brain injury before or shortly after birth.
Progress in the Koala trial represents the next material clinical catalyst for investors to monitor, alongside the now-extended DAYBUE royalty window through to March 2041.
For investors wanting to understand the clinical and commercial stakes in more depth, our deep-dive into the Phelan-McDermid syndrome Phase 3 trial covers the trial design, first-mover positioning in a zero-competition orphan market, and the FDA designations supporting NNZ-2591’s regulatory pathway.
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