Fortress Biotech and Sentynl Therapeutics Fail to Secure FDA Approval for CUTX-101 in Rare Pediatric Menkes Disease

Fortress Biotech and Sentynl Therapeutics did not secure FDA approval for CUTX-101, a drug intended to treat Menkes disease, a rare and fatal pediatric disorder1 2 7.

The FDA issued a Complete Response Letter (CRL) for the New Drug Application (NDA), citing cGMP (current Good Manufacturing Practice) deficiencies at the drug's manufacturing facility1 3 5.

The CRL did not identify any concerns regarding the efficacy or safety data of CUTX-101, nor any other approvability issues apart from manufacturing1 2.

Sentynl Therapeutics took over development and commercialization responsibility from Cyprium Therapeutics (a Fortress subsidiary) in December 2023 and is expected to work on resolving the FDA’s concerns for resubmission1 2 8.

Following a recent FDA re-inspection in September 2025, the manufacturing facility has provided responses, and Sentynl expects to request a meeting with the FDA to discuss next steps1 3.

CUTX-101 has previously received FDA Breakthrough Therapy, Fast Track, Rare Pediatric Disease, and Orphan Drug designations8.

Manufacturing and control-related issues are currently the leading reason for FDA rejections in rare disease drug applications5 7.