Zydus Lifesciences arm’s pediatric Menkes disease drug CUTX-101 flagged by USFDA in CRL

Drug firm Zydus Lifesciences Limited on Wednesday (October 1) said its US subsidiary, Sentynl Therapeutics, Inc., has received a Complete Response Letter (CRL) from the US Food and Drug Administration (USFDA) regarding its New Drug Application (NDA) for copper histidinate (CUTX-101), a treatment for Menkes disease in pediatric patients.

In its letter, the USFDA outlined certain findings that need to be addressed before clarifying the path forward. The concerns relate specifically to a current Good Manufacturing Practices (CGMP) inspection of the facility where CUTX-101 is manufactured.

Zydus noted that it had recently submitted responses to the USFDA following a re-inspection in September 2025, proving the facility’s CGMP compliance, and is currently awaiting the Establishment Inspection Report (EIR).



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Sentynl said it will request a meeting with the USFDA to discuss the CRL and the resubmission of its CUTX-101 NDA. The company said that the Complete Response Letter did not cite any issues with the drug’s efficacy or safety data and raised no other approvability concerns.

Matt Heck, CEO, Sentynl, said, "We recognise the USFDA's decision and remain dedicated to working with the Agency to clarify next steps. Our commitment to patients is unchanged. We believe in the promise of our therapy and are prepared to address the feedback and pursue resubmission promptly."

Menkes disease is a rare X-linked recessive pediatric genetic disease that impacts an estimated 1 in 34,810 to as high as 1 in 8,664 live male births. Patients with Menkes disease are born with the inability to absorb dietary copper and subsequently have impaired copper transport across the blood-brain barrier.

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CUTX101 is a subcutaneous injectable formulation of copper histidinate that restores copper homeostasis and maintains copper levels in patients with Menkes disease.

The CUTX-101 NDA was initially granted Priority Review by the FDA and is supported by positive topline clinical efficacy results for CUTX-101, demonstrating significant improvement in overall survival for Menkes disease subjects who received early treatment with CUTX-101.



Shares of Zydus Lifesciences Ltd ended at ₹993.90, up by ₹12.20, or 1.24%, on the BSE.



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