Atossa Therapeutics secures U.S. Food and Drug Administration Rare Pediatric Disease designation for (Z)-endoxifen in McCune-Albright Syndrome, unlocking potential Priority Review Voucher eligibility.
Written By: Farha Farheen, PharmD
Reviewed By: Pharmacally Editorial Team
Atossa Therapeutics, Inc. has received Rare Pediatric Disease (RPD) designation from the U.S. Food and Drug Administration (FDA) for its investigational therapy (Z)-endoxifen to treat McCune-Albright Syndrome (MAS) in females.
The RPD designation applies to therapies addressing serious or life-threatening conditions primarily affecting individuals from birth to 18 years, with fewer than 200,000 cases in the U.S. If approved, (Z)-endoxifen could qualify for a Priority Review Voucher (PRV), which accelerates FDA review of another drug application or can be sold recent PRV transactions have fetched $100 million to $205 million.
Steven Quay, President and Chief Executive Officer of Atossa Therapeutics, called the designation an important regulatory milestone supporting (Z)-endoxifen’s broader development. He noted MAS as a rare pediatric disorder (affecting ~1:100,000–1:1,000,000) with significant unmet needs, especially hormone dysregulation and precocious puberty in young girls. “(Z)-Endoxifen targets key disease drivers while unlocking non-dilutive value via the RPD program,” Quay said.
Quay highlighted Atossa’s participation in an FD/MAS Alliance research priorities workshop at Children’s Hospital of Philadelphia, uniting clinicians, researchers, patients, and advocates to outline needs and advance treatments. The company prioritizes collaboration as (Z)-endoxifen development advances, with pediatric studies planned.
Janet Rea, Senior Vice President of Research and Development, said the RPD pathway fosters FDA engagement to refine strategy. She emphasized (Z)-endoxifen’s rationale as a selective estrogen receptor modulator and degrader (SERM/D), poised to tackle estrogen-driven MAS features.
McCune-Albright Syndrome is a rare genetic disorder from GNAS gene mutations causing mosaic endocrine dysfunction. It features fibrous dysplasia of bone, café-au-lait skin pigmentation, and hyperfunctioning endocrinopathies. In girls, it often manifests as gonadotropin-independent precocious puberty, leading to rapid growth, early bone maturation, short stature, plus risks like thyroid issues or acromegaly. Treatments are limited, underscoring the need for targeted options like (Z)-endoxifen.
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About the Writer
Farha Farheen, Pharm.D, is a pharmacy professional with a strong interest in pharmacovigilance and clinical research. She has completed her Doctor of Pharmacy (Pharm.D) along with her internship as a Clinical Pharmacist. She has hands-on experience in adverse drug reaction (ADR) reporting, safety data documentation, and pharmacovigilance workflows, and is proficient in using VigiFlow. She is also a patent holder for an antibacterial formulation enriched with bioactive substances, granted by the German Patent and Trademark Office.