Efficacy and safety of gemtuzumab ozogamicin in patients with CD33-positive acute myeloid leukemia in first relapse

Purpose: Three open-label, multicenter trials were conducted to evaluate th e efficacy and safety of single-agent Mylotarg (gemtuzumab ozagamicin; CMA- 676; Wyeth Laboratories, Philadelphia, PA), an antibody-targeted chemothera py agent, in patients with CD33-positive acute myeloid leukemia (AML) in un treated first relapse. Patients and Methods: The study population comprised 142 patients with AML in first relapse with no history of an antecedent hematologic disorder and a median age of 61 years. All patients received Mylotarg as a a-hour intrav enous infusion, at a dose of 9 mg/m(2), at 2-week intervals for two doses. Patients were evaluated for remission, survival, and treatment-emergent adv erse events. Results: Thirty percent of patients treated with Mylotarg obtained remissio n as characterized by 5% or less blasts in the marrow, recovery of neutroph ils to at least 1,500/muL, and RBC and platelet transfusion independence. A lthough patients treated with Mylotarg had relatively high incidences of my elosuppression, grade 3 or 4 hyperbilirubinemia (23%), and elevated hepatic transaminase levels (17%), the incidences of grade 3 or 4 mucositis (4%) a nd infections (28%) were relatively low. There was a low incidence of sever e nausea and vomiting (11%) and no treatment-related cardiotoxicity, cerebe llar toxicity, or alopecia. Many patients received Mylotarg on an outpatien t basis (38% and 41% of patients for the first and second doses, respective ly). Among the 142 patients, the median total duration of hospitalization w as 24 days; 16% of patients required 7 days of hospitalization or less. Conclusion: Administration of the antibody-targeted chemotherapy agent Mylo targ to patients with CD33-positive AML, in first relapse induces complete remissions with what appears to be a favorable safety profile. (C) 2001 by American Society of Clinical Oncology.