Gemtuzumab ozogamicin (GO) in relapsed/refractory patients with acute myeloid leukemia.

Objective: Gemtuzumab ozogamicin (GO) is a humanized anti-CD33 antibody, linked to calicheamicin, which has been approved in Japan recently. We conducted to evaluate the efficacy and toxicity of GO in our patients with relapsed or refractory AML retrospectively.

Patients And Methods: Data were collected between March 1, 2000, and March 1, 2006, on 10 patients with relapsed or refractory AML(excluding FAB: M3). Scheduled treatment was two doses of GO monotherapy, 14-28 days apart.

Results: Of the 10 assessable patients, two patients achieved CR. CR duration of one patient lasted for 52 months with post-remission treatment. Grade 4 neutropenia occurred in 9 patients, and the incidence of grade 3 or 4 thrombocytopenia was 100%, with no severe bleeding events. Two patients developed infusion-related adverse events that included grade 3 allergic reaction with shock status. Liver damage (grade 3 or 4) were observed in 40% of patients after GO treatment. No patient developed hepatic veno-occlusive disease including 2 patients who underwent HSCT.

Conclusion: GO is a valuable new treatment option for relapsed or refractory AML patients, however, the benefit from single agent appears insufficient. On going clinical trials including combination with other antileukemic agents might better define the role of GO.