Positive trofinetide results in Rett syndrome surprise

Shares of Acadia Pharmaceuticals (Nasdaq: ACAD) closed up more than 21% at $23.07 yesterday, after the US drugmaker released better than expected clinical results for its trofinetide.

The company announced positive top-line results from the pivotal, Phase III Lavender study evaluating the efficacy and safety of trofinetide in 187 girls and young women aged five-20 years with Rett syndrome. The 12-week placebo-controlled study demonstrated a statistically-significant improvement over placebo for both co-primary endpoints. On the Rett Syndrome Behavior Questionnaire (RSBQ), change from baseline to week 12 was -5.1 versus -1.7 (p=0.0175; effect size=0.37). The Clinical Global Impression–Improvement (CGI-I) score at week 12 was 3.5 vs 3.8 (p=0.0030; effect size=0.47). The RSBQ is a caregiver assessment of the core symptoms of Rett syndrome and the CGI-I is a global physician assessment of worsening or improving of Rett syndrome.

Additionally, trofinetide demonstrated a statistically-significant separation over placebo on the key secondary endpoint, the Communication and Symbolic Behavior Scales Developmental Profile Infant-Toddler Checklist–Social composite score (CSBS-DP-IT–Social) change from baseline to week 12 was -0.1 vs -1.1 (p=0.0064; effect size=0.43).