The Food and Drug Administration (FDA) has accepted for Priority Review the New Drug Application (NDA) for trofinetide for the treatment of Rett syndrome.

Trofinetide is a novel synthetic analogue of the amino-terminal tripeptide of IGF-1 designed to treat the core symptoms of Rett syndrome by reducing neuroinflammation and supporting synaptic function.

The NDA is supported by data from the randomized, double-blind, placebo-controlled phase 3 Lavender study ( Identifier: NCT04181723), which evaluated the efficacy and safety of trofinetide in 187 females 5 to 20 years of age with Rett syndrome. Patients were randomly assigned to receive trofinetide or placebo orally or via gastrostomy tube twice daily for 12 weeks. 

The coprimary endpoints were the change from baseline to week 12 in the Rett Syndrome Behaviour Questionnaire (RSBQ) total score (a caregiver assessment) and the Clinical Global Impression-Improvement (CGI-I) score (a physician assessment). 

Findings from the study showed that treatment with trofinetide demonstrated a statistically significant improvement over placebo on the coprimary endpoints. Trofinetide also met a key secondary endpoint demonstrating a statistically significant improvement from baseline to week 12 in the Communication and Symbolic Behavior Scales Developmental Profile Infant-Toddler Checklist–Social composite score compared with placebo.

“In clinical trials, trofinetide demonstrated a significant improvement in a range of Rett syndrome symptoms,” said Jeffrey L. Neul, MD, PhD, Annette Schaffer Eskind Chair and Director, Vanderbilt Kennedy Center, Professor of Pediatrics, Division of Neurology, Pharmacology, and Special Education, Vanderbilt University Medical Center and phase 3 Lavender study investigator. “We look forward to the FDA’s review of this submission and the prospect of having access to the first approved treatment for Rett syndrome.”

A Prescription Drug User Fee Act target date of March 12, 2023 has been set for the application.


Acadia Pharmaceuticals announces trofinetide New Drug Application for the treatment of Rett syndrome has been accepted for filing and review by US FDA. News release. Acadia Pharmaceuticals Inc. Accessed September 12, 2022.