Mylotarg is a monoclonal antibody drug targeting CD33 antigen, developed and produced by Pfizer in the United States. Its main ingredient is gemtuzumab, and the dosage form is lyophilized powder injection, each bottle containing 4.5mg white to gray lyophilized powder.

Gemtuzumab instructions, medical insurance, price, efficacy, adverse reactions

The drug needs to be reconstituted and diluted for intravenous infusion. The concentration after reconstitution is 1mg/mL, and the concentration range after dilution is 0.075-0.234mg/mL. The storage conditions are strict and need to be refrigerated in a dark environment at 2-8°C. The validity period is 24 months.

Indications and recommended doses

Gemtuzumab is suitable for adult and pediatric patients with CD33-positive acute myeloid leukemia (AML). The treatment plan is divided into two modes: combined chemotherapy and monotherapy. The recommended dose for adult combination regimen is 3mg/㎡, and the induction dose for monotherapy is 6mg/㎡ on the first day and 3mg/㎡ on the eighth day. Pediatric patients need to adjust the dose according to body surface area (3 mg/m2 for BSA ≥ 0.6 m2, 0.1 mg/kg for BSA < 0.6 m2). Oral acetaminophen, diphenhydramine and corticosteroids are required before medication to prevent infusion reactions.

Drug price and economic burden

The Hong Kong version of Gemtuzumab is 5 mg/bottle. Since the treatment cycle usually requires multiple courses, the total cost may be as high as tens of thousands of dollars. Pfizer may provide patient assistance programs or installment payment options. It is recommended to contact the pharmaceutical company directly to consult support policies.

Clinical efficacy and pharmacokinetics

Gemtuzumab was first approved by the FDA in 2000, but was withdrawn from the market in 2010 due to controversy over its efficacy. After being reapproved in 2017, studies have confirmed that it has significant efficacy in specific CD33-positive AML patients.

Pharmacokinetic data showed that when the drug was administered at a dose of 9 mg/㎡, the peak blood concentration was 3.0 mg/L after the first dose and rose to 3.6 mg/L after the second dose. The drug targets CD33 and binds to DNA to induce apoptosis of leukemia cells, and is particularly suitable for relapsed or refractory cases.

Common adverse reactions and treatment

The most common adverse reactions of gemtuzumab ozogamicin include bleeding, infection, fever, nausea, vomiting, and abnormal liver function (such as elevated AST and ALT). Serious risks include hepatotoxicity (such as veno-occlusive disease), infusion-related reactions (such as hypotension, respiratory failure), and bleeding caused by bone marrow suppression.

Liver function, blood cell counts, and electrocardiograms should be monitored regularly during medication. If abnormalities occur, the drug should be discontinued immediately and supportive treatment should be taken. Pregnant and lactating women are prohibited from using it, and people of childbearing age should strictly use contraception.

Medication guidance for special populations

Elderly patients have a higher risk of infection when using gemtuzumab ozogamicin and need to be monitored more closely; children over 1 month old can be combined with chemotherapy, but the safety of monotherapy for children under 2 years old is not clear. Pregnant women may cause fetal damage and should be strictly avoided; breastfeeding women should suspend breastfeeding for at least 1 month. All patients need to take medication under the supervision of a professional medical team to ensure accurate dosage and timely treatment of adverse reactions.

Drug interactions and storage specifications

No clear interactions between gemtuzumab and other drugs have been found, but the risk of QT interval prolongation should be vigilant, especially for patients with electrolyte disorders or taking other cardiotoxic drugs. Storage must be maintained at 2-8°C in a light-proof environment, and professional cold chain equipment must be used for transportation. The reconstituted solution must be used within 6 hours to avoid freezing or light that may cause the drug to become ineffective.