Fortress Biotech Inc and its majority-owned subsidiary Cyprium Therapeutics Inc have entered into a definitive asset purchase agreement to sell Cyprium’s Rare Pediatric Disease Priority Review Voucher (PRV) for $205 million in gross proceeds, subject to closing conditions.
The PRV was granted following the January 12, 2026 approval of Zycubo (copper histidinate), formerly known as CUTX-101, by the U.S. Food and Drug Administration for the treatment of Menkes disease.
In December 2023, Sentynl Therapeutics Inc assumed full responsibility for the development and commercialization of Zycubo from Cyprium.
Upon FDA approval in January 2026, the Rare Pediatric Disease PRV was issued and immediately transferred back to Cyprium pursuant to its transaction agreement with Sentynl.
Under the Sentynl deal, Cyprium:
Cyprium is obligated to pay 20% of the PRV sale proceeds to the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), part of the National Institutes of Health.
Fortress highlighted the PRV sale as part of a broader series of recent milestones, including three FDA approvals over the past 15 months:
The company also recently completed the sale of its former subsidiary Checkpoint Therapeutics to Sun Pharmaceutical Industries Ltd..
Leadership noted that the transaction further strengthens Fortress’ capital position and supports continued pipeline execution across oncology, dermatology, and rare disease programs.
Cyprium remains focused on Menkes disease and related copper metabolism disorders.
Beyond Zycubo, Cyprium and NICHD maintain an exclusive global license to develop and commercialize AAV-ATP7A gene therapy, an adeno-associated virus (AAV)-based therapy designed to deliver functional copies of the defective copper transporter gene in Menkes patients.
The gene therapy program:
The PRV sale is subject to customary closing conditions, including expiration of the waiting period under the Hart-Scott Rodino (HSR) Antitrust Improvements Act.
For Fortress and Cyprium, the $205 million transaction represents a significant non-dilutive capital event following the approval of a rare disease therapy — while maintaining long-term economic participation in Zycubo through royalties and milestone payments.