The US Food and Drug Administration (FDA) has recently approved the expansion of the applicable population of Pfizer's targeted anticancer drug Mylotarg (gemtuzumab ozogamicin) for patients with newly diagnosed CD33-positive acute myeloid leukemia (AML) aged ≥1 month. The approval was approved through the priority review process.
Now, Mylotarg can be used to treat newly diagnosed CD33-positive AML (children and adults aged ≥1 month), relapsed or refractory CD33-positive AML (children and adults aged ≥2 years).
The efficacy and safety of Mylotarg in the pediatric population are supported by the research data of AAML0531 (NCT00372593). This is a multicenter, randomized study enrolling 1063 newly diagnosed AML patients aged 0-29 years. In the study, these patients were randomly assigned to receive 5 cycles of chemotherapy alone or in combination with Mylotarg (dose 3 mg/m2, induction 1 on day 6 and intensive 2 on day 7). The main efficacy outcome index was the event-free survival (EFS) from the start of the trial to induction failure, relapse, or all-cause death.
The data show that the EFS hazard ratio (HR) of Mylotarg+chemotherapy combined with chemotherapy monotherapy is 0.84% (95%CI: 0.71-0.99). In the Mylotarg+chemotherapy group, the estimated percentage of patients without induction failure, recurrence, or death within 5 years was 48% (95%CI: 43-52%), compared with 40% (95%CI: 36%-45%) in the chemotherapy alone group ). There was no difference in overall survival (OS) between the 2 treatment groups.
Among the patients treated with Mylotarg, the most common grade 3 adverse reactions that occurred during induction 1 and enhancement 2 were infection, febrile neutropenia, decreased appetite, hyperglycemia, mucositis, hypoxia, bleeding, transaminase Elevation, diarrhea, nausea and hypotension.
Mylotarg is the first AML therapeutic drug targeting CD33, which is an antibody drug conjugate (ADC), which is conjugated by a cytotoxic agent calicheamicin and a monoclonal antibody targeting CD33 Made. CD33 is an antigenic protein expressed on up to 90% of AML cells in patients. When Mylotarg binds to the CD33 antigen on the cell surface, it is absorbed into the cell, releasing calicheamicin and causing cell death.
In the United States, Mylotarg received accelerated approval in 2000 as a monotherapy (high-dose) for adult patients with CD33-positive AML who experienced first relapse, were aged ≥60 years, and were not suitable for other cytotoxic chemotherapy. However, in 2010, Pfizer voluntarily withdrew Mylotarg from the US market after Mylotarg failed to show clinical efficacy in a confirmatory trial and had a higher incidence of fatal toxicity compared to chemotherapy. However, in the Japanese market, Mylotarg is still being sold and provided to patients through sympathetic medication programs.
Because the demand for drugs in patients with acute myeloid leukemia (AML) has not been met, clinicians are still very interested in evaluating Mylotarg with different doses and different courses of treatment. With the support of Pfizer, these independent researchers conducted clinical trials to obtain more information about the effectiveness and safety of Mylotarg.
In September 2017, Mylotarg was approved by the US FDA: (1) for newly diagnosed adult patients with CD33-positive AML; (2) for children and adult patients aged ≥2 years, CD33-positive, relapsed or refractory AML.