Acadia’s DAFFODIL™ Study Confirms DAYBUE’s Safety For Treatment Of Young Rett Syndrome Patients

Acadia Pharmaceuticals has announced the publication of results from the DAFFODIL™ study in the journal Med. This open-label Phase 2/3 study evaluated the safety, tolerability, and exploratory efficacy of DAYBUE® (trofinetide) in girls aged two to four with Rett syndrome. Findings indicated that the safety profile in this younger age group was consistent with that observed in patients aged five and older in previous trials, including the LAVENDER™, LILAC-1™, and LILAC-2™ studies. These combined results played a crucial role in securing FDA approval for DAYBUE in patients two years and older.

Alan Percy, M.D., Professor of Pediatrics, Neurology, Neurobiology, Genetics, and Psychology at the University of Alabama, Birmingham and lead DAFFODIL author, commented, “Rett syndrome is a debilitating condition that often causes patients to lose acquired communication and motor skills starting as early as six to 18 months old which presents significant challenges for these children and their families. Outcomes from DAFFODIL further underscore trofinetide’s safety and tolerability across patient age groups and provide additional data to inform treatment plans and dosing for patients closer to the onset of symptoms.”

The study reported diarrhoea (80%) and vomiting (53.3%) as the most common treatment-emergent adverse events (TEAEs), though all cases were mild to moderate in severity. Two participants discontinued treatment due to adverse events. A structured diarrhoea management plan, including stopping laxatives and introducing fibre, effectively reduced discontinuations, with only one case leading to study withdrawal over the 78-week period.

“The final DAFFODIL results provide critical insights into the safety and tolerability of DAYBUE in younger pediatric Rett syndrome patients, including effective strategies to mitigate common side effects of treatment. These findings, along with the caregiver exit interview feedback from the study, further our understanding of trofinetide’s role in managing this complex condition and the potential benefits of longer-term treatment,” said Ponni Subbiah, M.D., M.P.H., Acadia’s Senior Vice President, Global Head of Medical Affairs and Chief Medical Officer. 

Additionally, four serious TEAEs were reported, though none were linked to DAYBUE treatment. The study reinforces the safety and tolerability of DAYBUE in younger Rett syndrome patients, supporting its continued use as an FDA-approved therapy. These findings contribute to the growing body of evidence backing DAYBUE’s role in managing Rett syndrome symptoms across a broad age range.