Acadia Pharmaceuticals Inc. (Nasdaq: ACAD) today announced that the United States Patent and Trademark Office (USPTO) has issued a Notice of Allowance for U.S. Patent Application No. 17/590,496, titled “Methods and Compositions for Treatment of Rett Syndrome.” The Notice of Allowance indicates that the USPTO has determined that the application meets the requirements for patentability, and the patent is expected to issue following completion of standard administrative steps.

The patent application covers weight-banded dosing of trofinetide for the treatment of Rett syndrome. Following issuance and including six months of pediatric exclusivity, the patent is expected to provide protection for trofinetide in the United States through March 28, 2041, extending patent protections by almost five years. Trofinetide is also protected by a method of use patent for the treatment of Rett syndrome, which expires in July 2036.

“This Notice of Allowance is an important addition to the intellectual property protections for trofinetide and reflects our commitment to supporting both current formulations of DAYBUE and the Rett syndrome community for the long term,” said Catherine Owen Adams, Chief Executive Officer of Acadia. “We are pleased that this patent is expected to extend protections for trofinetide in the United States from 2036 into 2041.”

The Notice of Allowance relates to the weight-banded dosing regimen used for trofinetide, which is marketed in the United States as DAYBUE® and DAYBUE® STIX for the treatment of Rett syndrome in adults and pediatric patients 2 years of age and older.

About Rett Syndrome

Rett syndrome is a rare, complex, neurodevelopmental disorder and occurs in approximately one of every 10,000 to 15,000 female births worldwide.1-3 A child with Rett syndrome generally exhibits an early period of apparently normal development until six to 18 months, when many of their skills seem to slow down or stagnate. This is typically followed by a regression phase when the child loses acquired communication skills and purposeful hand use. The child may then experience a plateau period in which they could show mild recovery in cognitive interests, but body movements remain severely diminished. As they age, those individuals living with Rett may continue to experience a stage of motor deterioration, which can last the rest of the patient’s life.2 Rett syndrome is typically caused by a genetic mutation on the MECP2 gene.4 In preclinical studies, deficiency in MeCP2 function is thought to lead to impairment in synaptic communication and brain plasticity, and the deficits in synaptic function may be associated with Rett manifestations.4-6

Symptoms of Rett syndrome may also include development of hand stereotypies, such as hand wringing and clapping, and gait abnormalities.7 Most individuals living with Rett syndrome typically live into adulthood and require intense round-the-clock care.1,8 Rett syndrome is associated with a substantial physical, psychological, social, and economic burden, significantly affecting the quality of life of both patients and their caregivers.9-11

About DAYBUE® (trofinetide) and DAYBUE® STIX (trofinetide)

Trofinetide is a synthetic analog of the N-terminal tripeptide of insulin-like growth factor 1. The mechanism by which trofinetide exerts therapeutic effects in patients with Rett syndrome is unknown. In animal studies, trofinetide has been shown to increase branching of dendrites and synaptic plasticity signals.10

About Acadia Pharmaceuticals

Acadia is committed to turning scientific promise into meaningful innovation that makes the difference for underserved neurological and rare disease communities around the world. Our commercial portfolio includes the first and only FDA-approved treatments for Parkinson’s disease psychosis and Rett syndrome. We are developing the next wave of therapeutic advancements with a robust and diverse pipeline that includes mid- to late-stage programs in Alzheimer’s disease psychosis and Lewy body dementia psychosis, along with earlier-stage programs that address other underserved patient needs. At Acadia, we’re here to be their difference. For more information, visit us at acadia.com and follow us on LinkedIn and X.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements include all statements other than statements of historical fact and can be identified by terms such as “may,” “will,” “should,” “expects,” “expected”, “anticipates,” and similar expressions (including the negative thereof) intended to identify forward-looking statements. Forward-looking statements contained in this press release, include, but are not limited to, statements about: (i) the future issuance of U.S. Patent Application No. 17/590,496, which, if issued, will expire in March 2041, and the benefits Acadia expects to realize from its issuance; (ii) the expected expiry of the trofinetide method of use patent for the treatment of Rett syndrome in July 2036; and (iii) the efficacy and safety profile of DAYBUE and DAYBUE STIX. Forward-looking statements are subject to known and unknown risks, uncertainties, assumptions and other factors that may cause our actual results, performance or achievements to differ materially and adversely from those anticipated or implied by our forward-looking statements. Such risks, uncertainties, assumptions and other factors include, but are not limited to: the inherent uncertainty of the patent issuance process and the intellectual property protections provided by Acadia’s patents, our ability to continue to successfully commercialize DAYBUE and DAYBUE STIX and our ability to continue to stay in compliance with applicable laws and regulations. Given the risks and uncertainties, you should not place undue reliance on these forward-looking statements. For a discussion of these and other risks, uncertainties, assumptions and other factors that may cause our actual results, performance or achievements to differ, please refer to our quarterly report on Form 10-Q for the period ended June 30, 2026 filed with the Securities and Exchange Commission on August 5, 2026, as well as our subsequent filings with the Securities and Exchange Commission from time to time. The forward-looking statements contained herein are made as of the date hereof, and we undertake no obligation to update them after this date, except as required by law.

References

1 Fu C, Armstrong D, Marsh E, et al. Consensus guidelines on managing Rett syndrome across the lifespan. BMJ Paediatrics Open. 2020;4:e000717.

2 Kyle SM, Vashi N, Justice MJ. Rett syndrome: a neurological disorder with metabolic components. Open Biol. 2018; 8:170216.

3 May DM, Neul JL, Satija A, et al. Real-world clinical management of individuals with Rett syndrome: a physician survey. J Med Econ. 2023;26(1):1570-1580.

4 Amir RE, Van den Veyver IB, Wan M, et al. Rett syndrome is caused by mutations in X-linked MECP2, encoding methyl-CpG-binding protein 2. Nat Genet. 1999; 23(2):185-188.

5 Fukuda T, Itoh M, Ichikawa T, et al. Delayed maturation of neuronal architecture and synaptogenesis in cerebral cortex of Mecp2-deficient mice. J Neuropathol Exp Neurol. 2005; 64(6):537-544.

6 Asaka Y, Jugloff DG, Zhang L, et al. Hippocampal synaptic plasticity is impaired in the Mecp2-null mouse model of Rett syndrome. Neurobiol Dis. 2006; 21(1):217-227.

7 Neul JL, Kaufmann WE, Glaze DG, et al. Rett syndrome: revised diagnostic criteria and nomenclature. Ann Neurol. 2010; 68(6):944-950.

8 Tarquinio DO, Hou W, Neul JL, et al. The changing face of survival in Rett syndrome and MECP2-related disorders. Pediatr Neurol. 2015; 53(5):402-411.

9 Prange EO, Beisang A, Pehlivan D, et al. Expert Consensus on Real-World Use of Trofinetide for Rett Syndrome Using a Modified Delphi Method. Annals of the Child Neurology Society. 2026; 38–51.

10 Kaufmann WE, Percy AK, Neul JL, et al. Burden of illness in Rett syndrome: initial evaluation of a disorder-specific caregiver survey. Orphanet J Rare Dis. 2024;19(1):296.

11 Gold WA, Percy AK, Neul JL, et al. Rett syndrome. Nat Rev Dis Primers. 2024;10(1):84.

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