FDA Approves Copper Histidinate Injection to Treat Menkes Disease

The FDA approved copper histidinate (Zycubo) injection, marking it the first-ever treatment option for pediatric patients looking to manage Menkes disease, according to a Fortress Biotech news release.¹ This approval may be a saving grace for childhood patients and their parents, as they now have access to a safer and more effective option for treating Menkes during a child’s first few weeks of life.²

“With today’s action, children with this devastating, degenerative disease will have an FDA-approved treatment option and the potential to live longer,” Christine Nguyen, MD, deputy director of the Office of Rare Diseases, Pediatrics, Urologic and Reproductive Medicine in the FDA’s Center for Drug Evaluation and Research (CDER), said in a news release.³ “The FDA will continue to work with the rare disease community to advance drug development for patients with Menkes disease and other rare conditions.”

According to the Cleveland Clinic, approximately 1 out of every 8664 male births experience the disease, and up to 255 newborns report it every year, highlighting its prominence as a notable rare disease among children. Furthermore, seeking treatment is a crucial step for children with the condition, as experts have reported that early management of symptoms is paramount in a child’s first 25-28 days of life.²

Prior to the approval of Cyprium Therapeutics’ copper histidinate injection, infants with Menkes disease—sometimes referred to as “kinky hair disease”—typically did not live past 3 years old. The disease’s main effects include a disruption in patients’ ability to use copper, causing complications in their nervous system, bones, hair, and more.

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Opening New Doors in the Treatment of Rare Diseases

“Zycubo is a copper replacement therapy given by subcutaneous injection,” wrote authors of an FDA news release.³ “It delivers copper in a form that bypasses the genetic defect in intestinal absorption, allowing the body to better use the mineral.”

As it is a genetic disorder, Menkes disease has the potential for affecting patients of all ages, races, and populations. However, even Menkes disease among children 5 to 10 years old is not as serious an issue as uncovering the disease shortly after a child’s birth. In those 5 to 10 years, patients typically report occipital horn syndrome—a less severe and milder form of Menkes.²

Instead, parents should be aware of the potential for Menkes disease when they are expecting a child. Pregnancy should lead expecting parents to explore medical records and understand their baby’s potential for disease as well as get the right treatment options at the right time.

“The approval of ZYCUBO is a pivotal milestone for our company and patients suffering from Menkes disease, as it is the first and only FDA-approved treatment for this rare, often fatal, pediatric disease,” Lindsay A. Rosenwald, MD, chairman, president, and CEO of Fortress Biotech, and chairman at Cyprium, said in the news release.¹ “In connection with FDA approval, ZYCUBO was granted a Rare Pediatric Disease Voucher which will be transferred from Sentynl to our majority-owned subsidiary Cyprium.”

How and Why Copper Histidinate Works for Menkes Disease

According to the US Department of Health and Human Services’ Genetic and Rare Diseases Information Center, pathogenetic variants—or genetic mutations—are the main pathways for the disease to go from a parent to child. During that process, the child’s X chromosome is mutated.⁴

Furthermore, the mutation’s attachment to patients’ X chromosome leads to an understanding of why Menkes disease disproportionately impacts male patients. Since men and boys only have 1 X chromosome, compared with women’s 2, genes are more easily mutated.

Aside from symptoms like low body temperature, seizures, and the aforementioned “kinky” or crinkly hair, Menkes disease mainly affects children’s ability to produce the protein responsible for controlling copper.² With the approval of copper histidinate injections, the newly approved formula is able to bypass the genetic mutation that causes the disease.³

The FDA explored the drug’s safety and efficacy in 2 open-label, single-arm clinical trials featuring pediatric participants 3 years old and younger. With trial populations consisting of 66 treated patients and 17 untreated patients, researchers observed a 78% reduction in mortality risk among treated patients. Common side effects from the injections included infections, respiratory problems, seizures, vomiting, fever, anemia, and injection site reactions.

“This approval marks an unprecedented advance for children with Menkes disease,” concluded Tracy Beth Hoeg, MD, PhD, acting director of CDER.³ “The company demonstrated a large improvement in overall survival compared with untreated patients, using an innovative trial design that addressed the challenges of studying an ultra-rare disease.”

READ MORE: Pediatrics Resource Center

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REFERENCES

1. Fortress Biotech and Cyprium Therapeutics announce U.S. FDA approval of Zycubo® (copper histidinate), the first and only approved treatment for Menkes disease in the United States. News Release. Fortress Biotech. January 13, 2026. Accessed January 15, 2026. https://www.fortressbiotech.com/news-media/press-releases/detail/730/fortress-biotech-and-cyprium-therapeutics-announce-u-s-fda

2. Menkes disease. Cleveland Clinic. April 18, 2022. Accessed January 15, 2026. https://my.clevelandclinic.org/health/diseases/6068-menkes-disease

3. FDA approves first treatment for children with Menkes disease. News Release. FDA. January 12, 2026. Accessed January 15, 2026. https://www.fda.gov/news-events/press-announcements/fda-approves-first-treatment-children-menkes-disease

4. Menkes disease. US Department of Health and Human Services. December 2025. Accessed January 15, 2026. https://rarediseases.info.nih.gov/diseases/1521/menkes-disease