Clinical-stage biopharmaceutical company Atossa Therapeutics Inc (Nasdaq:ATOS) announced on Monday that the US Food and Drug Administration (FDA) has granted Rare Pediatric Disease (RPD) designation to (Z)-endoxifen for the treatment of McCune-Albright Syndrome (MAS) in females.

RPD designation is granted to drug candidates intended to treat serious or life-threatening diseases that primarily affect individuals from birth to 18 years of age. Upon approval of a qualifying marketing application, drugs with RPD designation may be eligible for a Priority Review Voucher (PRV), which can be used to obtain priority review for a future application, or may be sold or transferred to another sponsor. In the last 18–24 months, disclosed PRV sales have ranged from approximately USD100m to USD205m.

MAS is an extremely rare genetic disorder caused by activating mutations in the GNAS gene, leading to mosaic endocrine dysregulation. MAS qualifies as a rare paediatric disease due to its serious manifestations, including gonadotropin-independent precocious puberty, accelerated bone maturation, and endocrine abnormalities affecting children and adolescents.