A New Copper Treatment for Children with Menkes Disease

Zycubo (copper histidinate; Instructions for Use pronunciation zye kyoo boe) is a copper replacement product given subcutaneously after reconstitution. On the USPI it is indicated for Menkes disease in pediatric patients and is not indicated for Occipital Horn Syndrome.

Distinct path — not this label: Compounded or historical copper-histidine preparations used under research protocols are not the labelled commercial Zycubo vial. Occipital Horn Syndrome is explicitly excluded on the Limitations of Use. Today’s approved US route is Sentynl Zycubo NDA 211241 as described here.

The FDA approved NDA 211241 on 12 January 2026 (Novel Drug Approvals for 2026 table row 1). Approval letter signed Christine P. Nguyen, MD, Deputy Director, Office of Rare Diseases, Pediatrics, Urologic and Reproductive Medicine (electronic signature CHRISTINE P NGUYEN 01/12/2026 03:00:58 PM). NDA dated/received 31 October 2024; complete response to a 30 September 2025 action letter acknowledged via amendment 14 November 2025. Applicant: Sentynl Therapeutics, Inc., Solana Beach, CA. Letter addressee: Eileen P. Banaga, VP, Regulatory Affairs and Quality. RPM named on letter: Jennifer Ford. Dating period: 12 months from manufacture when stored at 2–8 °C. Rare Pediatric Disease Priority Review Voucher awarded (PRV NDA 211241). Not referred to an advisory committee. Reference ID 5726294. Priority Review, Fast Track, Breakthrough Therapy, and Orphan Drug designations noted on the FDA press announcement.

Where this is taking place

Approved prescription route today: United States — FDA-labelled Zycubo for pediatric Menkes disease, with caregiver subcutaneous injection after clinician training when appropriate. This is a metabolic genetics / rare-disease / pediatric neurology conversation with baseline and ongoing copper, ceruloplasmin, electrolyte, kidney, liver, and CBC monitoring — not a casual retail pickup and not a DIY import or unlabelled compound.

Outside the United States: At the time of writing, no confirmed Health Canada Notice of Compliance, European Commission marketing authorisation, MHRA licence, TGA ARTG listing, Swissmedic authorisation, or PMDA/MHLW licence for Zycubo / copper histidinate. EMA orphan designation ≠ EC marketing authorisation. Do not import on your own.

Trial 1 — NCT00001262 — Copper Histidine Therapy for Menkes Diseases. Lead sponsor: Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). Status: completed. Enrolment 60. Principal Investigator on the record: Stephen G. Kaler, M.D. (NICHD). Country: United States.

Trial 2 — NCT00811785 — Molecular Bases of Response to Copper Treatment in Menkes Disease, Related Phenotypes, and Unexplained Copper Deficiency. Lead sponsor: Cyprium Therapeutics, Inc. Collaborators: NICHD; National Center for Complementary and Integrative Health (NCCIH). Status: completed. Enrolment 93. Country: United States.

USPI efficacy uses both trials plus an untreated contemporaneous external control cohort collected under a Trial 2 protocol amendment. These completed trials are not a new-enrolment path for newly labelled commercial use.

The practical route in the US is a metabolic genetics / Menkes-experienced clinician who can confirm the diagnosis (including ATP7A context when available), start labelled Zycubo as early as appropriate, teach reconstitution and subcutaneous injection, and schedule lab monitoring — not treating NCT00001262 / NCT00811785 as open recruitment.

Approval matrix

Access by country

• United States: Ask a metabolic genetics / rare-disease clinic about FDA-labelled Zycubo. Labelled 12 January 2026 for Menkes disease in pediatric patients. Recommended dosage: 1.45 mg SC twice daily (8–12 hours apart) if <1 year; 1.45 mg SC once daily if 1 year to <17 years. Reconstitute one vial with 1 mL sterile 0.9% Sodium Chloride Injection; withdraw 0.5 mL; inject subcutaneously (abdomen ≥2 inches from navel, buttocks, outer upper arm or thigh); rotate sites. Carton: one 2.9 mg single-dose vial — NDC 42358-329-01. Store vials refrigerated 2–8 °C. Baseline labs before start; then monitor copper, ceruloplasmin, electrolytes, kidney, liver, CBC every 6 weeks for 6 months, every 3 months for 18 months, then every 6 months. Prior authorisation and specialty-pharmacy logistics still apply. No list price or copay dollars in this article. Suspected adverse reactions: Sentynl Therapeutics 1-888-507-5206 or FDA MedWatch 1-800-FDA-1088. Patient support / injection questions on IFU: SentynlCares | ZYCUBO Patient Support Services 1-888-251-2800. This is US commercial labelled supply, not a DIY import or unlabelled compound.

• Canada: Zycubo authorisation not confirmed. Ask the Canadian metabolic genetics clinic what legal paths exist in Canada when a Canadian Zycubo label does not yet exist.

• European Union / United Kingdom / Australia / Japan / other countries: Regulator authorisation not confirmed on the sources checked. An EMA orphan designation is not a licence. Completed US trials are not a commercial foreign label.

• If your regulator has not authorised it: do not import on your own. Ask the local clinician about documented special-access / named-patient rules, referral to a centre in a labelled country, or waiting — without treating a US vial as a foreign pack.

Who is eligible (from the US label)

This is a pediatric Menkes disease conversation on the USPI — subcutaneous copper replacement — not Occipital Horn Syndrome and not an adult Menkes marketing indication on this label.

United States (USPI / Instructions for Use, revised / issued January 2026):

• Indication: Treatment of Menkes disease in pediatric patients.
• Limitation of use: Not indicated for Occipital Horn Syndrome.
• Recommended dosage: <1 year: 1.45 mg SC twice daily (8–12 hours between injections). 1 year to <17 years: 1.45 mg SC once daily.
• Before start: Baseline serum copper and ceruloplasmin, electrolytes, kidney and liver function, CBC.
• Missed dose: Give as soon as possible; next scheduled dose at least 6 hours later.
• Contraindications: None (USPI §4).
• Warning: Copper accumulation with risk of kidney injury, liver dysfunction, and hematologic abnormalities — intensify lab follow-up and consider reducing frequency, withholding, or discontinuing if labs worsen.
• Caregiver administration: Allowed after proper training if the healthcare provider determines it is appropriate (see IFU).
• Pregnancy / lactation: No adequate human data; discuss with clinician if relevant.
• Geriatrics: Menkes is a pediatric disease; trials did not include patients ≥65.
• Trial efficacy population (USPI): severe pathogenic ATP7A variants (duplication/deletion, nonsense, or canonical splice); born after 1999; early cohort started within 4 weeks of birth.

Not labelled on the sources checked for this article:

• Occipital Horn Syndrome.
• Adult-onset marketing indication as a separate labelled population (label is pediatric Menkes).
• EU, UK, Canadian, Japanese, Australian, or Swiss Zycubo marketing authorisations (not confirmed here).
• Treating completed NCT00001262 / NCT00811785 records as open commercial enrolment.

What the pivotal studies showed (USPI)

Use the USPI for a prescription conversation. Journals are supportive reading.

Trials — NCT00001262 and NCT00811785:

• Open-label, single-arm copper histidinate for up to 3 years; compared with untreated contemporaneous external controls.
• Pooled efficacy population (severe ATP7A; born after 1999): 66 treated + 17 external control (83 total) for the analyses described.
• Cohorts: ZYCUBO-ET (start within 4 weeks of birth, n=31) vs EC-ET (n=17); ZYCUBO-LT (start after 4 weeks, n=35) vs EC-LT (n=16).

USPI Table 3 — Primary OS (early treatment):

In ZYCUBO-ET, 15 (48%) survived >6 years, including 7 (23%) >12 years; no EC-ET patients survived >6 years.

USPI Table 4 — Secondary OS (late treatment):

Both pivotal CT.gov records are completed. They support the US label. They are not routes for new commercial starters outside labelled US distribution. No expanded access is listed on the CT.gov records retrieved for this article.

How it is taken (US label)

Safety watchpoints (plain language)

• Copper buildup: Can affect kidneys, liver, and blood counts — especially in the first two years of life. Clinics check labs on a set schedule and may hold or change dosing if labs worsen.
• Kidney signs to report: New acidosis, electrolyte problems, protein in urine, or falling kidney function.
• Liver: Rising transaminases reported.
• Blood: Anemia reported.
• Common (≥7% pooled safety, n=129): Pneumonia, viral infection, respiratory failure, seizure, bacterial infection, hemorrhage, hypotension, vomiting, tachycardia, fever, volume depletion, fracture, dyspnea, transaminase elevation, diarrhea, fungal infection, anemia, local injection-site reaction.
• Serious (≥5%): Pneumonia, dehydration, seizure, respiratory distress, RSV, cardiopulmonary failure, upper respiratory infection, respiratory failure, vomiting.

How to talk with a clinician

Bring: genetic / clinical Menkes diagnosis details (ATP7A if known), age and weight, current copper/ceruloplasmin labs, seizure and infection history, and any prior copper therapy.

Useful questions:

1. Does my child meet the labelled pediatric Menkes indication (and not Occipital Horn Syndrome)?
2. Can we start as early as appropriate, and what is the BID vs once-daily plan for our age?
3. Who will teach reconstitution and subcutaneous injection, and what is the lab schedule?
4. How will specialty pharmacy / prior authorisation work for NDC 42358-329-01?
5. If we are outside the US, what legal options exist without importing a US vial on our own?

Bottom line

Zycubo (copper histidinate) is the first FDA-labelled therapy for Menkes disease in pediatric patients — a subcutaneous copper replacement approved 12 January 2026 (NDA 211241; Novel 2026 row 1). Dose: 1.45 mg SC twice daily under age 1, then once daily from age 1 to under 17. Early treatment OS HR 0.22 vs external controls (NCT00001262 / NCT00811785). Watch copper-related kidney, liver, and blood toxicity. United States is the approved prescription route on the sources checked; other major regulators not confirmed. Completed trials are not a new enrolment path. Authorized is not funded.