Acadia Pharmaceuticals shares jumped in pre-market trading after the company said the European Medicines Agency’s Committee for Medicinal Products for Human Use (CHMP) issued a positive opinion recommending approval of DAYBU for the neurobehavioral symptoms of Rett syndrome in patients aged five and older. The decision moves the therapy one step closer to availability across Europe, with the European Commission expected to make a final determination in the coming months.
Rett syndrome is a rare, severe neurological disorder that affects daily functioning and quality of life. Acadia said that, if authorized by the European Commission, DAYBU would be the first EU treatment specifically targeting the condition’s neurobehavioral symptoms—an area where there are currently no approved therapies.
Key takeaways
- Stock move: Acadia Pharmaceuticals shares rose 1.54% in the regular session and were up further in pre-market trading after the CHMP recommendation.
- Catalyst: The CHMP issued a positive opinion for DAYBU covering neurobehavioral symptoms of Rett syndrome in patients aged five and older.
- Clinical backing: The recommendation was supported by Phase 3 LAVENDER study results, including statistically significant and clinically meaningful improvements on key endpoints.
- Next step: The European Commission is expected to issue a final decision in the coming months, which will determine whether approval expands to the full European market.
- Implication: A successful outcome could establish a first-in-EU targeted option for a patient population with significant unmet need.
What drove the move
Acadia said the CHMP positive opinion recommends approval of DAYBU for neurobehavioral symptoms of Rett syndrome for patients aged five and older. The company framed the decision as a milestone given the absence of any approved therapies in Europe for these specific symptoms.
The regulatory recommendation was based on data from the Phase 3 LAVENDER study. Acadia reported statistically significant and clinically meaningful improvements on measures including the Rett Syndrome Behaviour Questionnaire (RSBQ) and the Clinical Global Impression-Improvement (CGI-I) scale. The company said these changes relate to symptoms that are particularly burdensome for patients and caregivers.
Market reaction and what investors will watch
Acadia’s stock closed Thursday’s trading at $23.72, up 1.54%. In pre-market trading, the shares were at $27.17, up 14.54%, reflecting investors’ focus on regulatory progress and the potential commercial implications of EU approval.
While a CHMP positive opinion is an important regulatory step, the approval is not final. The European Commission’s decision—anticipated in the coming months—will determine whether DAYBU receives authorization and the timing of any market launch across participating countries.
How approval could expand across Europe
Acadia said that if the European Commission approves DAYBU, authorization would cover all 27 EU member states, along with Iceland, Liechtenstein, and Norway. That broader geographic scope could increase the addressable market relative to a limited initial rollout and may influence how investors model future demand and reimbursement pathways.
The company’s statement also drew attention to patient advocacy perspectives. Rett Syndrome Europe said the CHMP decision is a source of “hope” for families who have waited decades for a targeted treatment option.
Bigger picture: regulatory milestones in rare disease
For investors in biotech and rare-disease development, CHMP positive opinions typically represent a high-signal milestone because they indicate that regulators have reached a preliminary view that benefits outweigh risks based on available evidence. Still, outcomes can diverge between CHMP recommendations and European Commission rulings, so the market will likely remain sensitive to any further regulatory communication as the final decision approaches.
Acadia Chief Executive Catherine Owen Adams called the CHMP opinion an “important milestone,” pointing to the continued unmet need for therapies aimed specifically at Rett syndrome neurobehavioral symptoms in Europe.
What to watch next: Investors will be focused on the European Commission’s final decision timeline, any details on label scope following the CHMP recommendation, and updates on commercialization planning and country-level implementation across the EU and associated European markets. With the decision expected in the coming months, the next regulatory headline will likely be the principal driver of sentiment for the stock.
