EU panel backs Daybu to treat Rett syndrome behavioral issues

Daybu (trofinetide), marketed as Daybue and Daybue Stix in the U.S., could become the first treatment for Rett syndrome neurobehavioral issues in the European Union, if the European Commission approves a committee’s recommendation.

The European Medicines Agency’s Committee for Medicinal Products for Human Use (CHMP) issued a positive opinion after re-examining an application from Acadia Pharmaceuticals seeking approval of Daybu to treat Rett patients ages 5 and older. Acadia previously applied for EU approval of Daybu, but the CHMP concluded that the available clinical data did not sufficiently demonstrate the treatment’s benefits in patients aged 2 and older. The company requested that the panel re-examine the data, resulting in the new opinion.

“The CHMP’s positive opinion for Daybu is an important milestone,” Catherine Owen Adams, Acadia’s CEO, said in a company press release. Because there are no treatments approved for the neurobehavioral symptoms of Rett syndrome in the EU, “our commitment is to make a meaningful difference in the lives of patients, caregivers, and the wider Rett community by addressing this significant unmet need.”

Daybue, a liquid, and Daybue Stix, a powder formulation, are approved in the U.S. for Rett patients aged 2 and older.

Rett syndrome is caused by mutations in the MECP2 gene, which is needed for nerve cells to communicate. Children with Rett often develop normally at first, but then normal development stalls and previously learned skills, such as speech, are lost. In the later stages of Rett, children may recover some cognitive and social skills, but motor symptoms often worsen or new ones appear during adolescence and adulthood.

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Daybu contains trofinetide, a lab-made version of a part of insulin-like growth factor 1, a signaling protein that helps nerve cells develop. Trofinetide is thought to help nerve cells form healthier connections, supporting the brain’s ability to adapt and learn. The goal of treatment is to ease neurobehavioral symptoms, reducing the burden on caregivers and improving patients’ lives.

“For decades, families in Europe affected by Rett syndrome have had no medicine specifically approved for the neurobehavioral symptoms of this condition, despite the profound impact they have on almost every aspect of daily life,” said Pedro Rocha, president of Rett Syndrome Europe. The CHMP opinion “represents hope,” Rocha said.

The CHMP’s recommendation was mainly based on LAVENDER (NCT04181723), a Phase 3 clinical study that tested the treatment, taken orally twice daily, against a placebo in 187 patients, ages 5 to 20. After about three months, patients who received the treatment showed significantly greater improvements in behavior, communication, and overall health.

If the European Commission agrees with the recommendation, the approval will cover all 27 EU member states, as well as Iceland, Liechtenstein, and Norway. Acadia said it expects a decision “in the coming months.”