[Long-term complete remission after single therapy with gemtuzumab ozogamicin for refractory AML in an elderly...

Gemtuzumab ozogamicin (GO) is a humanized anti-CD33 monoclonal antibody conjugated to calicheamicin, that is rapidly internalized after binding to CD33. This is followed by intracellular release of calicheamicin, which induces double-stranded DNA breaks, cell cycle arrest, and apoptosis. So GO is a more selective agent for acute myeloid leukemia (AML), because the CD33 antigen is expressed on AML, while it is not expressed on normal hematopoietic stem cells and nonhematopoietic tissues. However, some studies indicated that this agent showed resistance to refractory AML cells via various mechanisms, and that there were no potent effects. In this study, we report a 76-year-old female with recurrent AML who responded to single therapy with GO, achieving complete remission for more than 1 year after the start of administration, although additional remission induction was impossible. The response to GO can be stratified with reference to the response to conventional chemotherapy.