The Neuren Pharmaceuticals Ltd (ASX: NEU) share price has declined more than 8% after giving US updates.
Neuren Pharmaceuticals aims to develop new drug therapies to treat multiple serious neurological disorders that emerge in early childhood and have no or limited approved treatment options.
DAYBYE (trofinetide) and DAYBUE STIX (trofinetide) are approved by the US Food and Drug Administration (FDA) for the treatment of Rett syndrome. Neuren has granted an exclusive worldwide licence to Acadia Pharmaceuticals to develop and commercialise trofinetide.
US FDA meeting feedback for NNZ-2591 HIE
After the ASX closed yesterday, it announced an update after meetings with the US FDA about the development of NNZ-2591 for each of hypoxic ischemic encephalopathy (HIE) and Pitt Hopkins syndrome (PTHS).
Neuren received feedback on its plan to submit a pre-investigational new drug (IND) application for the treatment of HIE and the proposed initial clinical study of the pharmacokinetics, tolerability and safety for one month in neonates and infants.
The FDA “generally accepted” this clinical study and the doses to be evaluated, providing some guidance on the inclusion & exclusion criteria and safety monitoring. The FDA requested more juvenile animal study data to support dosing in neonatal participants before initiating the clinical study.
The company plans to generate this data before submitting the IND application and starting the clinical study later in 2026. It’s also advancing the logistical requirements to execute the study.
Neuren also revealed the FDA encouraged the ASX share to submit a future meeting request to discuss appropriate endpoints, study population and safety monitoring for a subsequent study.
PTHS
The FDA feedback about PTHS indicated that in a controlled trial to demonstrate the efficacy, a PTHS-specific clinical global impression (CGI) scale may be used as a co-primary endpoint if it is accompanied by an observer-reported functional outcome measure.
This is a similar approach that was agreed and being implemented in Neuren’s ongoing phase 3 trial in Phelan McDermid syndrome (PMS).
It’s assessing alternative trial designs and endpoint analysis methodologies to accommodate that PTHS is significantly more rare and generally more profoundly disabling than PMS.
The ASX share said that a further interaction with the FDA will likely be required to finalise the assessment. Neuren still intends to initiate the next trial in 2026.
Voucher program reauthorised
The company announced to the ASX this morning that on 3 February 2026, the US Congress reauthorised the rare pediatric disease priority review voucher program to 30 September 2029.
This provides for the award of a voucher to drug developers that receive US FDA approval for a drug for a designated rare pediatric disease.
The voucher entitles the holder to priority review of a different drug or may be transferred or sold to another drug developer. It noted in January 2026, a drug developer announced the sale of a voucher for US$200 million.
FDA approval of NNZ-2591 for PMS, PTHS or Angelman syndrome would qualify Neuren for a voucher, of which Neuren would retain 100% ownership and proceeds of any sale.
Final thoughts on the Neuren share price
Biotechnology can be a complex sector with various elements influencing its success, delay or failure. I don’t know if this decline is a good time to invest or not, so I’d happy to leave the investing in this company to others.
Hopefully the company is successful at helping patients and completing the process with the FDA. For now, there are other ASX growth shares I’d prefer.
