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О ACADIA Exhibit 99.1 Acadia Pharmaceuticals Announces Positive Top - line Results from the Pivotal Phase 3 Lavender Trial of Trofinetide in Rett Syndrome - Trofinetide met co - primary efficacy endpoints demonstrating statistically significant improvement over placebo in the Rett Syndrome Behaviour Questionnaire ( RSBQ ) ( p = 0.0175 ) and the Clinical Global Impression of Improvement ( CGI - I ) ( p = 0.0030 ) - Trofinetide met key secondary endpoint demonstrating statistically significant improvement over placebo in CSBS - DP - IT - Social ( p = 0.0064 ) , caregiver scale of ability to communicate - Pre - New Drug Application meeting with the U.S. FDA planned for the first quarter 2022 - Conference call and webcast to be held today at 4:30 p.m. Eastern Time SAN DIEGO — December 6 , 2021 - Acadia Pharmaceuticals Inc. ( Nasdaq : ACAD ) today announced positive top - line results from the pivotal , Phase 3 Lavender ™ study evaluating the efficacy and safety of trofinetide in 187 girls and young women aged 5-20 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 Behaviour Questionnaire ( RSBQ ) , change from baseline to week 12 was -5.1 vs. -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 ) . " These are encouraging results for patients and families affected by Rett syndrome . Patients reported improvements in core symptoms , like being able to respond to a choice when asked by their parents , or experiencing more freedom from the repetitive hand movements that create obstacles in other areas of their lives , " said Jeffrey L. Neul , M.D. , Ph.D. , Annette Schaffer Eskind Chair and Director , Vanderbilt Kennedy Center ; Professor of Pediatrics , Division of Neurology , Pharmacology , and Special Education , Vanderbilt University Medical Center and Lavender study investigator . " The positive Lavender study results support a potential treatment for Rett syndrome and represent an important step forward in addressing this rare and serious neurological disease . " Study treatment discontinuation rates related to treatment emergent adverse events ( TEAEs ) were 17.2 % in the trofinetide group as compared to 2.1 % in the placebo group . The most common adverse events were diarrhea ( 80.6 % with trofinetide vs. 19.1 % with placebo ) , of which 97.3 % in the trofinetide arm were characterized as mild - to - moderate , and vomiting ( 26.9 % with trofinetide vs. 9.6 % with placebo ) , of which 96 % in the trofinetide arm were characterized as mild - to - moderate .