O2–072 - Treatment of Refractory or Relapsed AML with Gemutuzumab Ozogamicin Combined with Arac-Based Chemotherapy

Abstract

Gemtuzumab ozogamicin (GO) was originally approved in U.S.A. for the treatment of elderly patients with acute myelogenous leukemia (AML) after relapse. Although GO was recently withdrawn from the U.S. market due to lack of definitive survival benefit and excessive toxicity, several recent clinical trials have revealed the benefit of adding GO to the conventional induction chemotherapy. However, its efficacy for refractory or relapsed AML has not been demonstrated. We thus performed a retrospective analysis of 9 patients with AML treated with GO (6mg/m2) combined with cytarabine (AraC)-based chemotherapy as a salvage regimen for patients not achieving complete remission (CR) after the first cycle of induction chemotherapy (4 cases) or patients at the first relapse (5 cases). Cases of AML secondary to myelodysplastic syndrome or myeloproliferative disorder were not excluded. Median age of the patients was 67 (19-81) years old. CR was achieved in 6 out of 9 patients, and 2 of the 6 who achieved CR survived more than 6 months. Toxicity was mild, and the median durations of neutropenia (neutrophil count < 1.0x109/L) and thrombocytopenia (platelet count < 100x109/L) were 25 and 26 days, respectively. Grade 3/4 non-hematologic adverse events were febrile neutropenia (8 patients), stomatitis (2 patients), and nausea (2 patients), and one patient died of sepsis. Some of the previous trials showed significant increases in overall survival and relapse-free survival for newly diagnosed AML mostly with lower dose of GO (3 mg/m2). However, adequate dose and schedule of GO in combination with induction chemotherapy have not been established. Moreover, role of GO for refractory or relapsed cases have never been thoroughly investigated. Our retrospective analysis, although with small numbers of patients, shows the possibility that GO may be effective for refractory or relapsed AML with acceptable toxicity.