Menkes Disease

Overview

Menkes disease is a rare, X-linked genetic disorder in which harmful variants in the ATP7A gene prevent the body from transporting copper normally. Copper is needed by many enzymes that support brain development, energy production, connective tissue, blood vessels, and the nervous system. The classic form affects boys far more often than girls, usually begins in infancy, and can cause seizures, poor growth, developmental delay, weak muscle tone, distinctive sparse or kinky hair, and progressive neurodegeneration. Without effective early treatment, classic Menkes disease commonly causes death in early childhood, often before age three. FDA overview

The disease-targeted standard of care in the United States is now subcutaneous copper histidinate, approved by the FDA as Zycubo on January 12, 2026 for pediatric Menkes disease. It replaces copper in a form that can partly bypass the transport defect, but it does not correct the underlying ATP7A mutation; patients require ongoing monitoring of copper, kidney and liver function, blood counts, seizures, nutrition, and other complications. Zycubo prescribing information

Scope of Recent Research (2020–present)

Research since 2020 has become more therapeutically diverse, centered on three questions: how to deliver copper into the brain and mitochondria, how to restore ATP7A function through gene addition, and how to identify affected newborns before irreversible neurological injury begins. The field remains small and no therapy has yet demonstrated a definitive cure in humans, but recent mouse gene-therapy results and early clinical evidence for copper-shuttling treatment have moved the field from supportive copper replacement toward plausible disease-modifying combination strategies. AAV9-ATP7A mouse study Elesclomol-copper clinical report

Major Breakthroughs and Emerging Therapies

Copper replacement has become an approved treatment, although not a genetic cure. In January 2026, the FDA approved copper histidinate for pediatric Menkes disease based on two open-label studies compared with contemporaneous external controls. The FDA reported a 78% lower risk of death among children who began treatment within four weeks of birth; nearly half of early-treated children survived beyond six years, while no untreated comparator survived beyond six years. This is a major improvement in care, but its benefit depends strongly on treatment timing and residual biological function, and it cannot fully restore copper handling in all organs. FDA approval announcement

Small-molecule copper shuttling with elesclomol is the most prominent non-gene experimental strategy. Elesclomol is a small molecule that can carry copper into mitochondria, the cellular structures that make energy. In a 2020 study, elesclomol-copper improved brain cytochrome-c oxidase activity, reduced neurodegeneration, and improved survival in the mottled-brindled mouse model of severe Menkes disease. Elesclomol mouse study Subsequent animal work found that orally administered elesclomol could use dietary copper to correct copper-deficiency phenotypes in worms and mice, suggesting that less burdensome delivery methods may ultimately be possible. Oral elesclomol animal study A further preclinical safety study found a substantial separation between doses that restored mitochondrial copper-enzyme activity and doses associated with laboratory markers of copper-induced cellular toxicity. Elesclomol safety-window study

The first reported clinical use of elesclomol-copper is encouraging but preliminary. A 2025 report described two children treated under an exceptional-use protocol in Spain with weekly subcutaneous elesclomol-copper alongside daily copper histidinate. One child who began treatment at 20 months showed improvements in several developmental domains, while the child treated from two months of corrected age retained scores in the normal range in most measured domains through 29 months. Both children had injection-site inflammation and fat necrosis, and connective-tissue complications—including vascular, lung, and bladder problems—persisted. The authors concluded that a larger formal trial is required. Elesclomol-copper clinical report

Gene addition is the leading potentially curative approach. Instead of editing each patient’s mutation, researchers are using adeno-associated virus 9, or AAV9, as a delivery vehicle for a functional, codon-optimized, reduced-size copy of ATP7A. In a 2025 study, one intravenous AAV9-ATP7A dose given shortly after birth, combined with subcutaneous copper histidinate during the first month of life, produced 95% long-term survival in the lethal mottled-brindled mouse model and improved brain copper, neurochemical measures, growth, and motor function. AAV9-ATP7A mouse study This combination is particularly compelling because gene addition could restore functions of ATP7A that copper alone cannot replace, while copper histidinate supplies the substrate that the restored transporter must handle. AAV9-ATP7A mouse study

Clinical Trials and Experimental Approaches

The most consequential recent clinical development is not a new randomized trial but the FDA approval of Zycubo, copper histidinate, for pediatric Menkes disease. The approval rested on two open-label, single-arm studies with treatment for up to three years and external untreated comparator groups; the product label requires laboratory monitoring because copper accumulation can contribute to kidney injury, liver dysfunction, and blood abnormalities. FDA approval announcement Zycubo prescribing information

A registered gene-therapy study, NCT05507996, was an investigator-initiated, single-center, open-label Early Phase 1 study of recombinant AAV administration sponsored by Kunming Hope of Health Hospital in China. The study enrolled one participant, was completed and terminated in November 2022 because the principal investigator decided to stop it, and has posted no results. It therefore does not establish clinical efficacy or safety for AAV gene therapy in Menkes disease. NCT05507996 trial record

The elesclomol-copper experience in two children was conducted under an exceptional-use clinical protocol rather than a conventional registered efficacy trial. Its reported developmental findings are important proof-of-concept evidence, but the sample size, absence of an untreated concurrent control group, and combination with copper histidinate mean that the independent contribution of elesclomol remains uncertain. Elesclomol-copper clinical report

Methodologies and Scientific Approaches

The principal preclinical platform is the mottled-brindled mouse, which carries an Atp7a defect and develops severe copper-transport failure resembling classic Menkes disease. Researchers use this model to test survival, growth, motor behavior, brain and organ copper concentrations, mitochondrial function, brain neurochemistry, vector distribution, and tissue pathology after treatment. The 2025 AAV9 study also used droplet-digital PCR to measure viral-vector genomes and in situ RNA detection to map expression of the introduced ATP7A gene. AAV9-ATP7A mouse study

Small-molecule studies combine cell culture and animal models to measure copper-dependent enzymes—especially mitochondrial cytochrome-c oxidase—and biomarkers of excessive copper exposure, such as changes in lipoylated proteins and iron-sulfur-cluster proteins. Human experimental treatment has used standardized developmental testing, including the Bayley Scales of Infant and Toddler Development, alongside copper, ceruloplasmin, catecholamine, cerebrospinal-fluid, hair-structure, and imaging measurements. Elesclomol safety-window study Elesclomol-copper clinical report

Leading Institutions and Funding

The U.S. National Institutes of Health, Nationwide Children’s Hospital, and the associated Center for Gene Therapy led the recent AAV9-ATP7A work. Their 2025 mouse study reported support from NIH grant U01NS129343, NIH intramural support, Nationwide Children’s Hospital, the Menkes Disease Research Fund, and a gene-therapy fellowship. AAV9-ATP7A mouse study In March 2024, the National Institute of Neurological Disorders and Stroke awarded an approximately $4.1 million, three-year grant to the Research Institute at Nationwide Children’s Hospital and principal investigator Stephen Kaler to complete preclinical work, manufacturing, and investigational-new-drug preparation for AAV-ATP7A gene therapy. NINDS AAV-ATP7A grant announcement

Texas A&M University investigators have driven the elesclomol program, including the original 2020 mouse study and subsequent work on oral delivery and toxicity biomarkers. Elesclomol mouse study Elesclomol safety-window study The 2025 exceptional-use clinical report was led by investigators affiliated with Institut de Recerca Sant Joan de Déu and collaborating Spanish and international institutions, with support reported from the Menkes International Association, Amigos de Nono Foundation, Ramón Areces Foundation, Spanish Research Agency, and NIH grants. Elesclomol-copper clinical report

Strengths, Limitations, and Challenges

The strongest recent evidence is that treating extremely early matters and that combining approaches may be better than relying on copper alone. Copper histidinate now has FDA-recognized survival benefit, elesclomol-copper may improve delivery of copper into mitochondria and possibly the brain, and AAV9-ATP7A plus copper histidinate produced an unusually strong rescue in a severe mouse model. FDA approval announcement Elesclomol-copper clinical report AAV9-ATP7A mouse study

The central limitation is translation to newborn children. AAV9-ATP7A has not yet shown efficacy in a reported human trial, and the highest AAV dose tested in mice caused evidence consistent with acute kidney toxicity from excess copper exposure. AAV9-ATP7A mouse study Copper histidinate itself requires monitoring for accumulation-related kidney, liver, and hematologic toxicity. Zycubo prescribing information For elesclomol-copper, human evidence currently consists of two children, injection-site toxicity occurred, and persistent connective-tissue disease raises the possibility that improving mitochondrial copper delivery alone may not restore all ATP7A-dependent functions. Elesclomol-copper clinical report

Outlook and Future Directions

As of October 23, 2026, Menkes disease is closer to effective disease modification than to a proven cure. The most important milestones to watch are: broader real-world outcomes after early Zycubo treatment; a formal, adequately monitored elesclomol-copper trial; completion of toxicology, manufacturing, and regulatory work for AAV9-ATP7A; and a first well-designed trial of AAV gene addition plus copper histidinate in newborns identified before neurological decline. A durable cure will likely require safely restoring ATP7A function in the brain and peripheral tissues early enough to prevent—not merely slow—irreversible injury. AAV9-ATP7A mouse study NINDS AAV-ATP7A grant announcement

References

• FDA approval of Zycubo for pediatric Menkes disease — U.S. Food and Drug Administration, 2026.
• Zycubo prescribing information — U.S. Food and Drug Administration, 2026.
• Elesclomol alleviates Menkes pathology and mortality in mice — Guthrie et al., 2020.
• Oral elesclomol treatment in copper-deficiency animal models — Yuan, Korolnek, and Kim, 2022.
• Elesclomol safety window in copper-deficiency models — Zulkifli et al., 2025.
• Elesclomol-copper therapy in two children with Menkes disease — Godoy-Molina et al., 2025.
• Intravenous AAV9-ATP7A plus copper histidinate in a Menkes mouse model — Venkataraman et al., 2025.
• NCT05507996: Recombinant AAV administration for Menkes syndrome — ClinicalTrials.gov, 2022.
• NINDS grant for AAV-ATP7A gene-therapy development — Cyprium Therapeutics and Fortress Biotech, 2024.