Efficacy and safety of gemtuzumab ozogamicin in patients with poor-prognosis acute myeloid leukemia

The objective of this work was to determine the safety and efficacy of gemtuzumab ozogamicin in patients with poor prognosis acute myeloid leukemia (AML). Patients with the following diagnoses/characteristics were treated with 1-3 infusions of gemtuzumab ozogamicin at a dose of 9 mg/m²: (1) relapse of AML ≤ 6 months of first complete remission (CR); (2) AML refractory to chemotherapy at initial induction or at first relapse; (3) AML in second or greater relapse; (4) myeloid blast crisis of chronic myeloid leukemia (CML); (5) untreated patients ≥ 70 years or ≥ 55 years with abnormal cytogenetics (excluding inv 16, t(15;17) and t(8;21) and/or an antecedent hematologic disorder; (6) refractory anemia with excess blasts in transformation (RAEBT). Forty-three patients, ages 19-84 (mean 62), were treated, including 7 patients with untreated AML age > 70 years, 2 with untreated RAEBT, 14 with AML first salvage (first remission 0-6 months), 15 with AML ≥ second salvage and 14 with myeloid blast phase of CML. The overall response rate was 14%, with 4/43 (9%) patients achieving CR and 2/43 (5%) achieving CR without platelet recovery. The most significant toxicity was neutropenic fever, which occurred in 84% of patients. In conclusion, in patients with relapsed/refractory AML, gemtuzumab ozogamicin has a comparable response rate to single-agent chemotherapy and may offer a more favorable toxicity profile.