Fortress Biotech, Inc. (FBIO) and its majority-owned subsidiary Cyprium Therapeutics have received U.S. FDA approval for ZYCUBO, the first and only approved treatment for Menkes disease in the United States.
The approval represents a major milestone for patients with this rare and often fatal pediatric disorder, which previously had no FDA-approved therapy.
Menkes disease is a severe X-linked recessive condition caused by mutations in the ATP7A copper transporter gene. Infants with the disorder are unable to absorb or transport copper, leading to profound neurological impairment, connective tissue abnormalities, and high mortality- often before age three if untreated.
ZYCUBO is a subcutaneous injectable formulation of copper histidinate designed to restore copper homeostasis and maintain systemic copper levels.
The FDA approval was supported by clinical data showing a nearly 80% reduction in the risk of death for patients who received early treatment compared with an untreated external control cohort. Median overall survival reached 177.1 months in the treated group versus 17.6 months in controls.
As part of the approval, the FDA granted a Rare Pediatric Disease Priority Review Voucher (PRV), which will be transferred from Sentynl Therapeutics to Cyprium under a prior agreement. Cyprium is also eligible to receive tiered royalties and up to $129 million in development and sales milestones from Sentynl, which assumed full responsibility for ZYCUBO's development and commercialization in 2023.
ZYCUBO has received Breakthrough Therapy, Fast Track, Rare Pediatric Disease, and Orphan Drug Designation in the U.S., and copper histidinate has also been granted Orphan Designation by the European Medicines Agency.
The approval adds to Fortress Biotech's recent momentum, marking its third FDA approval in 15 months, following Emrosi for the treatment of inflammatory lesions of rosacea in adults and UNLOXCYT for adults with advanced cutaneous squamous cell carcinoma who cannot undergo curative surgery or radiation. Management highlighted the milestone as further validation of its portfolio-building strategy.
FBIO has traded between $1.33 and $4.53 over the past year. The stock is currently trading in the pre-market at $4.04, down 3.08%.
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