European Commission approves Daybue as first treatment for Rett syndrome in the EU

The authorisation gives patients aged five years and older the first treatment specifically approved for Rett syndrome across the European Union, with Acadia preparing for an initial German launch in the fourth quarter of 2026.

The European Commission has granted marketing authorisation to Daybue (trofinetide) for the treatment of neurobehavioural symptoms associated with Rett syndrome in patients aged five years and older, making it the first and only authorised treatment for the condition in the EU.

The decision extends trofinetide’s regulatory reach beyond existing approvals in the US, Canada and Israel and follows a regulatory process in which Acadia Pharmaceuticals pursued re-examination after an earlier negative CHMP assessment.

Field	Content
Alert Type	Drug Approval
Drug Name	Daybue (trofinetide)
Indication	Treatment of neurobehavioural symptoms associated with Rett syndrome in patients aged five years and older. (BiotechDispatch)
Therapy Area(s)	Neurology; Rare disease; Neurodevelopmental disorders
Geography	European Union; Iceland; Liechtenstein; Norway
What Happened	On 25 August 2026, the European Commission granted marketing authorisation for Daybue (trofinetide) to treat neurobehavioural symptoms associated with Rett syndrome in patients aged five years and older. The authorisation applies across all 27 EU member states and extends to Iceland, Liechtenstein and Norway. Acadia Pharmaceuticals holds the exclusive worldwide licence to develop and commercialise trofinetide from Neuren Pharmaceuticals. Daybue becomes the first and only authorised treatment specifically for Rett syndrome in the EU. (BiotechDispatch)
Why It Matters	Until this authorisation, there was no treatment specifically approved for Rett syndrome in the EU. Daybue therefore introduces a disease-specific pharmacological treatment option for eligible European patients and extends access to a therapy already commercialised in other markets, including the US and Canada. (BiotechDispatch)
Supporting Context	The European approval follows an extended regulatory process. Acadia originally submitted the MAA in January 2025, but in February 2026 the CHMP communicated a negative trend vote, prompting plans for re-examination. The subsequent European Commission authorisation therefore represents a reversal of the programme's earlier regulatory trajectory. (Neuren Pharmaceuticals)
Key Takeaway	European approval makes Daybue the first authorised treatment specifically for Rett syndrome in the EU and expands trofinetide into another major commercial market.
What to Watch	Acadia expects to launch Daybue in Germany early in the fourth quarter of 2026. Under its licensing agreement, Neuren is due $35 million following the first commercial sale in Europe and is eligible for up to $170 million in European sales milestones plus tiered royalties ranging from the mid-teens to low twenties per cent. (BiotechDispatch)
Primary Source	Acadia Pharmaceuticals / Neuren Pharmaceuticals
Relevant Date	25 August 2026

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