Histidine copper (Zycubo), as a copper replacement therapy, has a specific range of applicable diseases, and there are also clear contraindications. Accurately mastering this information helps to avoid misuse and potential risks.

I. Indications

1. Core indication: Menkes disease

(1) Zycubo is indicated for the treatment of Menkes disease in pediatric patients.

(2) Menkes disease is an X‑linked recessive disorder of copper metabolism caused by pathogenic variants in the ATP7A gene, leading to impaired intestinal copper absorption, defective copper transport across the blood‑brain barrier, and dysfunction of multiple copper‑dependent enzymes.

(3) This product is administered via subcutaneous injection, bypassing the impaired gastrointestinal absorption pathway and directly providing bioavailable copper to replenish the body's copper stores.

2. Target population for treatment

(1) The eligible population is pediatric patients, including all ages from the neonatal period to under 17 years. In clinical studies, enrolled infants began treatment as early as within the first few days of life.

(2) For infants with a confirmed or highly suspected diagnosis of Menkes disease, early initiation of treatment (within 4 weeks of birth) is associated with greater survival benefit.

II. Contraindications and restricted use

1. Absolute contraindications

Histidine copper has no absolute contraindications.

2. Restricted use: Occipital horn syndrome

(1) Zycubo is explicitly not indicated for the treatment of Occipital Horn Syndrome.

(2) Although this condition also involves copper metabolism abnormalities due to ATP7A gene mutations, it is a milder phenotypic variant of Menkes disease, and its clinical course and pathophysiological mechanisms differ from classic Menkes disease.

(3) Use of this product for this indication lacks evidence of efficacy and safety and should be avoided as a confusion in prescribing.

3. Population restrictions

(1) This product is intended only for pediatric patients. Adults (especially those over 65 years) have no indication for use because Menkes disease does not occur in this age group.

(2) For other states of copper deficiency in non‑pediatric populations, this product has not been studied and should not be used arbitrarily.

III. Pre‑treatment assessment and decision‑making

1. Mandatory tests before initiating therapy

(1) Before the first dose, the following baseline tests must be completed: serum copper and ceruloplasmin levels, serum electrolytes, liver and kidney function, and complete blood count.

(2) These parameters not only serve as the basis for diagnosis and baseline status assessment, but also as references for subsequent safety monitoring.

2. Risk factors for careful evaluation

(1) Patients with Menkes disease already have impaired copper transport and may have pre‑existing copper‑accumulation‑related damage to the kidneys, liver, and hematopoietic system.

(2) After initiating treatment, copper load may further increase, especially during the first two years of life when organ functions are immature, leading to higher toxicity risk.

(3) Before treatment, the patient's baseline liver and kidney function and hematological status should be thoroughly assessed. For those with significant organ damage, the therapeutic benefit must be weighed against potential risks.

3. Shared decision‑making in treatment

(1) Initiation of Zycubo therapy should be determined by a specialist based on genetic diagnostic results, clinical presentation, and laboratory findings.

(2) Caregivers should fully understand the indications and restrictions of this product, actively participate in treatment decisions, and cooperate in completing the pre‑treatment evaluation and subsequent monitoring plan.