Gemtuzumab ozogamicin in combination with intensive chemotherapy in relapsed or refractory acute myeloid leukemia.

The prognosis of refractory/relapsed acute myeloid leukemia (AML) remains poor. The complete response (CR) rate after relapse is around 25%, with 11% of patients still alive after 5 years. The efficacy and toxicity of fractionated gemtuzumab ozogamicin (fGO; 3 mg/m2, days 1, 4, 7) in combination with intensive chemotherapy were retrospectively evaluated in patients with refractory/relapsed AML. Thirty-six patients (median age 54 years) were included. European LeukemiaNet classification was as follows: favorable (n=6), intermediate-I (n=13), intermediate-II (n=8), adverse (n=9). Median CR duration was 7.16 months (1.63-96.8). The overall response rate was 38.8%, with CR in eight patients (22.2%) and CR with incomplete platelet recovery (CRp) in six patients (16.7%). Two-year overall survival was 26% (95% confidence interval [CI]: 12-42) and 2-year relapse free-survival was 18.5% (95% CI: 6.6-35.0). Salvage therapy with fractionated GO in patients with very high-risk disease produced a 38.8% response rate and may be considered as a bridge therapy to transplant.