Gemtuzumab(Mylotarg) is a monoclonal antibody-chemotherapeutic drug conjugate targeting CD33 antigen specifically for the treatment of CD33-positive acute myeloid leukemia (AML). It provides precision treatment for a large number of adult patients by precisely killing leukemia cells, and also provides more treatment options for relapsed or refractory cases.

Gemtuzumab/Gemtuzumab(Mylotarg) has shown significant efficacy in the treatment of adult patients with AML

Clinical trial data support

The Phase III ALFA-0701 study used a regimen of gemtuzumab combined with daunorubicin + cytarabine. The 3-year event-free survival rate of adult AML patients was significantly better than that of the control group (17.1%) and increased to 40.8%. For newly diagnosed CD33-positive patients, combined treatment can achieve a complete remission rate (CR) of 80% and extend the median overall survival to 34.6 months.

Advantages of combined therapy

The standardized regimen of Gemtuzumab ozogamicin includes an induction phase (3 mg/m² on days 1, 4, and 7) and a consolidation phase (3 mg/m² on day 1). Compared with chemotherapy alone, the combined regimen significantly reduces the positive rate of minimal residual disease (MRD) and is still effective for patients with high-risk cytogenetics. The specification of Pfizer's original drug in the United States is 5 mg/bottle, the price is about US$8,586, and it needs to be administered through central venous infusion.

After clarifying the efficacy data, patients need to understand the accessibility of the drug in China. The following content will explain the current status of Gemtuzumab ozogamicin.

Is Gemtuzumab ozogamicin available in any country?

As of 2024, Gemtuzumab has not been approved by the China National Medical Products Administration (NMPA) and has not been included in the medical insurance catalog. Domestic regular medical institutions cannot provide this drug.

Cross-border drug purchase and clinical trial channels

If patients purchase Pfizer's original drug in the United States through authorized pharmacies in Hong Kong and other places, they need to provide overseas prescriptions and bear the transportation costs (2-8℃ throughout the journey). Eligible patients in some hospitals conducting international multicenter clinical trials can apply for free treatment. Be alert to the risk of counterfeit drugs from unofficial channels, and it is recommended to obtain them through formal medical intermediaries first.

Progress in Generic Drug R&D

Currently, no generic gemtuzumab is available worldwide, and the patent protection period of the original drug has not expired. Chinese pharmaceutical companies have started the development of biosimilars, and it is expected that alternative products may be launched in the next 3-5 years, but equivalence needs to be verified through rigorous clinical trials.

After understanding the drug acquisition channels, family members of child patients need to pay attention to special medication requirements. The following content will explain the core precautions for children's use.

Precautions for the use of gemtuzumab in children

Gemtuzumab can be used for children with CD33-positive AML aged 1 month and above, but the dose needs to be accurately adjusted according to the body surface area (BSA), and adverse reaction monitoring should be strengthened.

Dose adjustment and age limit

Children with BSA ≥ 0.6㎡ are given 3mg/m², and those with BSA < 0.6㎡ are calculated at 0.1mg/kg. The safety of single-drug use in children with relapsed/refractory AML under 2 years old has not been established, and the risk-benefit ratio needs to be strictly evaluated. Before treatment, acetaminophen (15 mg/kg) and diphenhydramine (1 mg/kg) should be taken in advance to prevent allergic reactions.

Safety monitoring points

Children need to test liver function (ALT, AST) and blood routine every week during treatment, and be alert to the risk of veno-occlusive liver disease (VOD). If ascites, liver pain or sudden weight gain occurs, the drug should be stopped immediately and defibrotide should be given. Platelet transfusion support is required when platelets are <50×10⁹/L.

Avoid live vaccines (such as measles and varicella vaccines) during treatment. It is recommended to complete all immunization plans before taking the drug. After opening, the gemtuzumab solution needs to be used as soon as possible and infused within 6 hours as much as possible. If persistent fever, dyspnea or subcutaneous bleeding occurs, the attending physician should be contacted in time. Through standardized treatment and home care, gemtuzumab is expected to bring longer survival and improved quality of life to AML patients.