Acadia Daybu CHMP OK for Rett syndrome

Key Takeaways

• CHMP adopted a positive opinion for Daybu (trofinetide) on 25 June 2026 after a re-examination procedure.
• Proposed indication: neurobehavioural symptoms of Rett syndrome in adults and children aged 5+.
• EMA cites pivotal 12-week study 003; LAVENDER (NCT04181723) enrolled 187 participants.
• EC decision is pending; authorisation would cover the EU-27 plus EEA EFTA states if granted.

Daybu CHMP opinion at a glance

Field	Detail
Product	Daybu (trofinetide) 200 mg/ml oral solution
Applicant	Acadia Pharmaceuticals (Netherlands) B.V. / Acadia Pharmaceuticals B.V.
Regulator step	CHMP positive opinion after re-examination (25 June 2026)
Indication	Neurobehavioural symptoms of Rett syndrome, ages 5 years and older
ATC	N07XX24 (other nervous system drugs)
Pivotal evidence	Study 003 / Phase 3 LAVENDER (NCT04181723), n=187
Next step	European Commission marketing-authorisation decision
Orphan	Orphan designation during development; maintenance under EMA review

What did CHMP recommend for Daybu?

On its Daybu EPAR overview page, EMA states that on 25 June 2026 CHMP, following a re-examination, adopted a positive opinion recommending a marketing authorisation for Daybu for neurobehavioural symptoms of Rett syndrome. The product would be a 200 mg/ml oral solution of trofinetide, a synthetic analogue of the N-terminal tripeptide of insulin-like growth factor 1. EMA notes that the mechanism in Rett syndrome is not fully understood.

EMA’s CHMP 22–25 June 2026 meeting highlights add that the committee had initially refused the application and, after re-examination, recommended authorisation for a restricted indication. Neurobehavioural symptoms listed by EMA include repetitive hand movements, restlessness, mood problems, anxiety, sleep issues, and communication problems.

Why does the re-examination matter for EU patients?

Acadia previously faced a negative CHMP opinion on a broader Rett file. The June 2026 positive opinion narrows the population to ages 5 years and older and focuses on neurobehavioural symptoms rather than a wider disease claim. EMA says Daybu should be prescribed by physicians experienced in Rett syndrome treatment.

In its 26 June 2026 Business Wire release on the CHMP recommendation, Acadia said that if the European Commission grants authorisation, Daybu would be the first therapy approved for this indication in the EU, with the decision expected in the coming months and coverage across all 27 member states plus Iceland, Liechtenstein, and Norway.

What clinical data underpin the opinion?

EMA’s Daybu page says benefits are primarily based on pivotal study 003, a 12-week placebo-controlled study with statistically significant improvements on co-primary and key secondary endpoints for behavioural aspects and CGI-I. Effect sizes were described as small, but clinical relevance was considered acceptable on the totality of data. Common side effects listed include diarrhoea, vomiting, and weight loss.

ClinicalTrials.gov record NCT04181723 for LAVENDER lists a completed Phase 3, randomised, double-blind, placebo-controlled study of oral trofinetide in girls and women with Rett syndrome. Actual enrollment was 187. Co-primary outcomes were change in Rett Syndrome Behaviour Questionnaire (RSBQ) total score from baseline to week 12 and CGI-I score at week 12. Treatment was weight-based oral or G-tube dosing twice daily for 12 weeks.

What happens between CHMP opinion and EU access?

A CHMP positive opinion is not the same as EU approval. The European Commission must still adopt a marketing authorisation decision. Until that decision, Daybu remains pending. Orphan designation status will also be reassessed by EMA at the authorisation stage.

For national access after any EC approval, HTA bodies and payers in member states will still negotiate price and reimbursement. Sponsors and clinicians should watch the Daybu EPAR and SmPC publication once a Commission decision is posted.

How does this fit Acadia’s EU regulatory path?

The June 2026 outcome reverses an earlier refusal path via re-examination under EU medicines procedures. Acadia’s Netherlands affiliate is the marketing-authorisation applicant named by EMA. Separately, Acadia has flagged routine US financial reporting calendars; those calendars are not a substitute for the CHMP/EC regulatory milestones that determine EU availability of Daybu.

For related EU regulatory context on NovaPharmaNews, see PRAC June 2026 highlights, the 2026 EU drugs agency report, and Vanda’s EMA orphan positive opinion.

What remains unproven or pending?

EC approval timing is not guaranteed. Long-term outcomes beyond the 12-week pivotal window, real-world effectiveness in EU practice, and orphan maintenance are not settled by the CHMP opinion alone. Efficacy magnitude was characterised by EMA as small; clinicians should read the forthcoming SmPC rather than extrapolate from US Daybue labelling without EU-specific documents.

Frequently Asked Questions

Primary Sources

1. EMA: Daybu (trofinetide) medicine overview
2. EMA: CHMP meeting highlights 22–25 June 2026
3. Business Wire: Acadia Daybu CHMP positive opinion (26 June 2026)
4. ClinicalTrials.gov: LAVENDER Phase 3 trofinetide study (NCT04181723)