Acadia Pharmaceuticals' DAYBUE™ Receives Health Canada Nod for Pioneering Rett Syndrome Treatment

Acadia Pharmaceuticals Inc. (Nasdaq: ACAD) has announced that Health Canada has approved DAYBUE™ (trofinetide) for use in treating Rett syndrome in both adults and children aged two and older, under the Priority Review process. This Notice of Compliance marks DAYBUE as the first approved treatment in Canada specifically for Rett syndrome.

Rett syndrome is a rare and complex neurodevelopmental disorder, primarily affecting females, which typically manifests after an initial period of normal development within the first two years of life. In Canada, it’s estimated that between 600 and 900 individuals are living with this condition. Patients with Rett syndrome experience a significant decline in abilities, leading to symptoms such as loss of speech, limited hand function, abnormal gait, and repetitive hand movements like wringing, clapping, or rubbing. Most individuals with Rett syndrome live into adulthood, requiring constant care and support.

Health Canada’s approval of DAYBUE™ was based on promising outcomes from the Phase 3 LAVENDER™ study, which evaluated the effectiveness and safety of trofinetide against a placebo in 187 girls and young women aged 5 to 20 with Rett syndrome. The study focused on two primary measures: the change in the Rett Syndrome Behaviour Questionnaire (RSBQ) total score, reflecting caregiver observations, and the Clinical Global Impression-Improvement (CGI-I) scale score, offering a clinician’s perspective. At 12 weeks, both measures showed statistically significant improvements over baseline. 

The RSBQ, a 45-item questionnaire filled out by caregivers, covers a range of Rett syndrome symptoms, including breathing irregularities, stereotypic hand movements, repetitive behaviors, night-time difficulties, vocalization, facial expressions, eye contact, and mood. Additionally, a key secondary measure—the Communication and Symbolic Behavior Scales Development Profile™ Infant-Toddler Checklist Social Composite Score (CSBS-DP-IT Social)—also showed statistically significant improvements compared to the placebo.

Catherine Owen Adams, Acadia’s Chief Executive Officer, said in a statement, “Health Canada’s authorization of DAYBUE is a significant milestone for the Rett syndrome community in Canada and another step forward in Acadia’s commitment to increase access to this therapy for patients and their families. We look forward to bringing DAYBUE to Canadian patients with Rett syndrome as soon as possible.”

Anita Datta, MD, FRCPC, Pediatric Neurologist and Epileptologist, Co-Director of the Rett Program at BC Children’s Hospital, and Clinical Associate Professor at the Faculty of Medicine at UBC, stated, “Rett syndrome is a debilitating and complex neurodevelopmental disorder that presents differently across patients and can lead to a range of symptoms throughout a patient’s life. Until now, treatment options have primarily focused on symptomatic management, as specific therapies for Rett syndrome have not existed.”

Sabrina Millson, President of the Ontario Rett Syndrome Association (O.R.S.A.), commented, “Rett syndrome not only has a significant impact on the individuals living with this disorder, but on their families, friends and loved ones as well. Today’s news is a historic milestone for the Canadian Rett syndrome community, who have eagerly awaited an approved treatment. Now that this therapy has been approved, we hope it will be made accessible through private and publicly funded drug plans as quickly as possible for all those who could benefit from it.”