February 3, 2026
Finance

EU Regulatory Panel Issues Negative Opinion on Acadia Pharmaceuticals' Rett Syndrome Treatment

Acadia prepares to seek re-examination following EMA committee rejection of trofinetide authorization in Europe

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Summary

The European Medicines Agency's Committee for Medicinal Products for Human Use (CHMP) has issued an unfavorable opinion on Acadia Pharmaceuticals' marketing authorization application for trofinetide, a treatment for Rett syndrome. While the decision marks a setback in Europe, Acadia notes prior approvals in the US, Canada, and Israel and plans to request a re-examination of the ruling.

Key Points

The EMA’s CHMP issued a negative opinion on Acadia's trofinetide marketing authorization for Rett syndrome in Europe.
Acadia plans to request a re-examination of the CHMP's opinion following formal adoption of the negative vote.
Trofinetide is approved in the US, Canada, and Israel as the first treatment for Rett syndrome, a rare genetic neurological disorder primarily affecting females.
Acadia’s recent Phase 3 trial of intranasal carbetocin for Prader-Willi syndrome did not demonstrate significant benefits over placebo.

The Committee for Medicinal Products for Human Use (CHMP), part of the European Medicines Agency (EMA), recently delivered an adverse opinion concerning Acadia Pharmaceuticals Inc.'s application to market trofinetide for the treatment of Rett syndrome within the European Union. This notification followed an oral explanation by the committee, culminating in a negative vote regarding the Marketing Authorization Application (MAA) submitted by Acadia.

Acadia Pharmaceuticals (NASDAQ: ACAD) is considering the next procedural steps and, depending on the finalized CHMP decision expected in February, intends to formally request a re-examination of the CHMP’s opinion. Such a request aligns with the regulatory framework established under EU legislation, which grants applicants the right to appeal within specific timeframes after receiving a committee's assessment.

The re-examination process allows the applicant to submit formal grounds for reconsideration within 60 calendar days of receiving the opinion, with the CHMP allotted up to 60 days thereafter to evaluate the submission. This mechanism provides an opportunity to address concerns or provide additional data that might influence the committee’s view.

Chief Executive Officer Catherine Owen Adams expressed disappointment regarding the vote’s outcome but emphasized confidence in trofinetide’s clinical data. She stated, "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." This highlights Acadia’s position that despite European regulatory hurdles, the treatment has demonstrated therapeutic value recognized by other international health authorities.

To contextualize, trofinetide is marketed as Daybue in the United States following its FDA approval in March 2023 for patients aged two years and older with Rett syndrome. Rett syndrome is a rare genetic disorder predominantly affecting females and is characterized by progressive neurological decline including loss of motor skills and language capabilities. Daybue represents the first and only approved pharmacological treatment targeting this debilitating condition.

In addition to pursuing the European regulatory pathway for trofinetide, Acadia Pharmaceuticals advances other neurological disorder treatments, including ongoing clinical evaluations. Recently, the company released topline data from its Phase 3 COMPASS PWS trial assessing intranasal carbetocin (ACP-101) in patients with Prader-Willi syndrome (PWS), specifically targeting hyperphagia symptoms. Unfortunately, this study did not meet its primary efficacy endpoint nor show significant improvement over placebo across secondary endpoints.

Financial markets have responded to the regulatory developments. At the time of reporting, ACAD shares traded down 6.12% at $24.53 per share, reflecting investor concerns over the setback in Europe. It is important to note that stock fluctuations in biotech firms often mirror regulatory outcomes and clinical trial results due to their profound effects on product commercialization potential.

Looking forward, the company’s strategic approach centers on exercising its right to appeal through the EU’s formal re-examination process, potentially providing a vehicle for reassessment of the available data. Should this process result in a favorable revision, it might pave the way for European approval aligning with prior regulatory acceptances in other regions.

Overall, this development underscores the complexities and challenges pharmaceutical companies face when seeking approval for treatments targeting rare diseases. The European regulatory environment maintains rigorous standards, and while setbacks occur, pathways exist for further dialogue and review should applicants pursue them within established parameters.

Risks
  • The negative CHMP opinion could delay or prevent European regulatory approval for trofinetide, impacting market access and revenue potential in the EU.
  • Failure to achieve primary and secondary endpoints in recent clinical trials, such as for carbetocin in PWS, may affect pipeline progression and investor confidence.
  • Stock price volatility reflecting regulatory and clinical risks can influence Acadia's financing capacity and strategic flexibility.
  • The outcome of the CHMP re-examination process remains uncertain, adding regulatory unpredictability to Acadia’s European plans.
Disclosure
Education only / not financial advice
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