Neuren Pharmaceuticals has received a Neuren trofinetide EU regulatory update following a negative trend vote from the Committee for Medicinal Products for Human Use (CHMP) regarding its marketing authorisation application (MAA) for trofinetide in the treatment of Rett syndrome. The vote followed Acadia Pharmaceuticals’ oral explanation to the European Medicines Agency committee. Subject to the outcome of the CHMP vote in February, Acadia intends to request a re-examination of the opinion by the CHMP upon its formal adoption.
The setback affects potential EU market access only. Existing approvals in the United States, Canada, and Israel remain unaffected, with more than 1,000 patients currently on active treatment globally across these markets.
Re-examination timeline and next steps
Under EU legislation, Acadia has a defined pathway to challenge the CHMP’s assessment through a formal re-examination process. The company has confirmed its intention to pursue this route if the negative opinion is formally adopted in February.
The re-examination procedure follows three distinct stages:
- Request submission: Acadia has 15 calendar days from receipt of the formal opinion to request re-examination
- Grounds submission: The company then has 60 calendar days from receipt of the opinion to submit detailed grounds supporting its re-examination request
- CHMP review: The committee has up to 60 days after receiving the grounds to re-examine its opinion and issue a revised assessment
This timeline means a final outcome on EU market access could potentially be determined within four to five months of the February formal opinion, assuming Acadia proceeds with re-examination immediately upon receiving the negative assessment.
What is the CHMP and how does EU drug approval work?
The Committee for Medicinal Products for Human Use serves as the European Medicines Agency’s scientific committee responsible for evaluating marketing authorisation applications for medicines intended for human use. The committee provides opinions to the European Commission, which holds the authority to grant marketing authorisations valid across all EU member states.
A trend vote indicates the direction of the committee’s assessment but does not represent the final decision. The formal opinion follows separately and carries legal weight for the subsequent re-examination process.
Re-examination is a standard procedural mechanism within the EU regulatory framework. The pathway exists precisely because initial assessments can be reconsidered when additional clarification, context, or evidence is provided. Negative opinions have been overturned through this process in previous cases, making it a genuine remedial pathway rather than a formality.
Trofinetide’s global commercial momentum continues
The European setback contrasts with strong real-world performance across trofinetide’s approved markets. The therapy, marketed as DAYBUE in the United States, has achieved significant patient uptake since its FDA approval.
Patient numbers span a remarkably broad demographic, from newly diagnosed 2-year-olds to adults who have lived with Rett syndrome for decades. An ongoing real-world experience study in the United States continues to show outcomes that closely mirror the impact observed in the rigorous randomised clinical trials that supported initial approvals.
| Market | Regulatory Status |
|---|---|
| United States | FDA Approved |
| Canada | Approved |
| Israel | Approved |
| European Union | MAA Under Review |
For Neuren investors, the critical point is straightforward. The company receives royalties from DAYBUE sales under its exclusive worldwide licence with Acadia Pharmaceuticals. The United States represents the primary commercial market for these royalties, and that revenue stream remains entirely unaffected by the EU regulatory assessment. European approval represents expansion opportunity and future upside rather than core existing revenue.
Management commentary signals commitment to EU pathway
Both Neuren and Acadia management have issued statements affirming their commitment to pursuing EU market access through the re-examination process.
“While the negative trend vote is disappointing and not what we hoped for, we believe the strong data that supported the approval of trofinetide for the treatment of Rett syndrome in the United States, Canada, and Israel speak to the meaningful benefits that trofinetide can deliver,” said Catherine Owen Adams, Acadia’s Chief Executive Officer. “We now have more than 1,000 patients on active treatment globally, from newly diagnosed 2-year-olds to adults who have lived with their disease for decades. Our ongoing real-world experience study in the U.S. continues to show outcomes that closely mirror the impact observed in rigorous randomized clinical trials conducted across a broad age range. We look forward to working with the EMA and other stakeholders to advance trofinetide as an important potential treatment option in the EU. Our commitment to the Rett syndrome community in the EU remains steadfast, and we are fully dedicated to making trofinetide available to individuals and families who urgently need a new therapeutic option.”
Neuren CEO Jon Pilcher commented: “Given the totality of experience with trofinetide in clinical trials and real world use over many years, this negative trend vote is frustrating for us and the Rett syndrome community in the EU. We fully support Acadia’s intention to seek re-examination of the CHMP opinion in February, if necessary.”
The alignment between licensor and licensee is significant. Both parties view the setback as a temporary regulatory hurdle rather than a terminal outcome for EU market entry, and both have publicly committed resources and effort to the re-examination pathway.
Neuren’s broader pipeline provides additional catalysts
Neuren is not dependent on trofinetide alone. The company’s wholly-owned second drug candidate, NNZ-2591, is advancing through development for multiple neurodevelopmental disorders with positive Phase 2 results across three distinct conditions: Phelan-McDermid syndrome, Pitt Hopkins syndrome, and Angelman syndrome.
Each NNZ-2591 programme has been granted orphan drug designation in both the United States and the European Union. These designations provide development incentives and recognise the urgent unmet medical need in these rare neurological disorders that emerge in early childhood.
Unlike trofinetide, which is licensed to Acadia, NNZ-2591 represents wholly-owned upside for Neuren shareholders. Positive clinical trial results in these indications could provide value independent of trofinetide’s commercial performance or geographical expansion.
What this means for Neuren investors
The Neuren trofinetide EU regulatory update presents a setback to European expansion plans but does not materially alter the company’s near-term commercial fundamentals or revenue trajectory. Several key considerations frame the investment impact:
- US royalty stream unaffected: Neuren’s core revenue from DAYBUE sales in the United States continues without disruption
- Defined regulatory pathway available: The re-examination process provides a clear procedural route with specific timelines
- Timeline for resolution: If re-examination proceeds immediately following the February formal opinion, a revised outcome could be determined within four to five months
- Broader pipeline intact: NNZ-2591 development across three neurodevelopmental disorders represents wholly-owned upside independent of trofinetide licensing arrangements
- Management commitment confirmed: Both Neuren and Acadia have publicly committed to pursuing re-examination, signalling confidence in the underlying clinical data
The EU market represents future expansion opportunity rather than current revenue. While a successful re-examination would add incremental commercial upside, the negative trend vote does not threaten existing value drivers. Investors should monitor the formal CHMP opinion in February and any subsequent re-examination outcomes as potential catalysts for the EU market opportunity.
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