Fortress Biotech And Cyprium Therapeutics Secure FDA Acceptance Of CUTX-101 NDA Resubmission For Menkes Disease

Fortress Biotech, Inc. and its majority-owned subsidiary, Cyprium Therapeutics, announced that the U.S. Food and Drug Administration has accepted the resubmission of the New Drug Application for CUTX-101, a copper histidinate therapy intended for the treatment of pediatric patients with Menkes disease. The FDA has classified the resubmission as a Class 1 filing, setting a new Prescription Drug User Fee Act target action date of January 14, 2026.

In December 2023, Sentynl Therapeutics, a U.S.-based biopharmaceutical company wholly owned by Zydus Lifesciences, assumed full responsibility for the development and commercialization of CUTX-101 from Cyprium. Following this transition, Sentynl resubmitted the revised NDA on November 14, 2025, after receiving a complete response letter from the FDA on September 30, 2025. The response letter cited observations related solely to current good manufacturing practice compliance at the manufacturing site. 

It did not raise any concerns regarding the efficacy or safety of CUTX-101, nor did it identify any other issues affecting the drug’s approvability. Clinical data supporting the NDA demonstrate that CUTX-101 provides a significant improvement in overall survival for patients with Menkes disease when treatment is initiated early. These positive efficacy results formed the basis of the original NDA submission, which had previously been granted Priority Review by the FDA.

Under the terms of the agreement with Sentynl, Cyprium is entitled to receive a Rare Pediatric Disease Priority Review Voucher if CUTX-101 is approved. In addition, Cyprium is eligible to receive royalties on net sales of the therapy, as well as up to $129 million in combined development and commercial milestone payments from Sentynl. The FDA’s acceptance of the resubmitted NDA marks an important step forward in the regulatory review process for CUTX-101 and represents continued progress toward providing a treatment option for children affected by Menkes disease.