Fortress Biotech & Cyprium Therapeutics Secure U.S. FDA Approval For ZYCUBO®, The First Approved Menkes Disease Therapy

Fortress Biotech, Inc. and its majority-owned subsidiary, Cyprium Therapeutics, Inc., announced that the U.S. Food and Drug Administration (FDA) has approved ZYCUBO® (copper histidinate, formerly known as CUTX-101) for the treatment of Menkes disease in pediatric patients. Menkes disease is a rare, X-linked recessive disorder caused by mutations in the ATP7A gene, which prevent proper absorption and transport of copper, leading to severe developmental and neurological issues. Until now, no FDA-approved treatment has been available in the United States. ZYCUBO is a subcutaneous injectable therapy that restores copper levels and helps maintain copper homeostasis in affected patients.

In December 2023, Sentynl Therapeutics, a wholly-owned subsidiary of Zydus Lifesciences Limited, assumed responsibility for the development and commercialization of CUTX-101 from Cyprium. As part of the FDA approval, a Rare Pediatric Disease Priority Review Voucher (PRV) was issued and, under the terms of the transaction with Sentynl, will be transferred to Cyprium. Cyprium is also eligible to receive tiered royalties on net sales of ZYCUBO and up to $129 million in aggregate development and sales milestones from Sentynl.

Lindsay A. Rosenwald, M.D., Chairman, President, and CEO of Fortress, and Chairman of Cyprium, described the approval of ZYCUBO as a pivotal milestone, representing the first and only FDA-approved therapy for Menkes disease. Rosenwald highlighted that this approval, alongside other recent approvals including Emrosi™ and UNLOXCYT™ (cosibelimab-ipdl), as well as the sale of Checkpoint Therapeutics to Sun Pharma, demonstrates the success of Fortress’ business model in advancing therapies and generating value across its portfolio.

Lung S. Yam, M.D., Ph.D., President and CEO of Cyprium, noted that the approval reflects more than three decades of research and dedication by teams at Cyprium, Fortress, and Sentynl. He also acknowledged the contribution of Menkes disease patients and their families who participated in clinical studies, which helped advance understanding of this devastating condition.

The FDA approval of ZYCUBO is supported by positive clinical data showing significant efficacy. In patients receiving early treatment with ZYCUBO, there was a nearly 80% reduction in the risk of death compared with an untreated external control cohort. Median overall survival for early-treated patients was 177.1 months, compared with 17.6 months for the control group. Common adverse reactions observed in clinical trials (occurring in 7% or more of patients) included pneumonia, viral infections, respiratory failure, seizures, bacterial infections, hemorrhage, hypotension, vomiting, tachycardia, fever, volume depletion, fractures, dyspnea, elevated transaminases, diarrhea, fungal infections, anemia, and local injection site reactions.

ZYCUBO has been granted Breakthrough Therapy, Fast Track, Rare Pediatric Disease, and Orphan Drug Designation by the FDA. Copper histidinate has also received Orphan Drug Designation from the European Medicines Agency. This approval marks a significant step forward for patients with Menkes disease and reinforces Fortress and Cyprium’s commitment to developing treatments for rare and underserved conditions.