Gemtuzumab ozogamicin: an anti-CD33 immunoconjugate for the treatment of acute myeloid leukaemia

Background: Gemtuzumab ozogamicin consists of a semisynthetic derivative of calicheamicin, a potent cytotoxic antibiotic, linked to a humanized anti-CD33 monoclonal antibody. Objectives: To describe the pharmacology of gemtuzumab ozogamicin and to provide an overview of clinical trials in acute myeloid leukaemia. Methods: Review and summary of publications on gemtuzumab ozogamicin indexed in the PubMed electronic database. Results/conclusions: Gemtuzumab ozogamicin has shown moderate activity as a single agent in patients with CD33-positive refractory or relapsed acute myeloid leukaemia, with more promising results in acute promyelocytic leukaemia. The side effect profile may be an improvement on conventional chemotherapy, except for a higher frequency of veno-occlusive disease or sinusoidal obstructive syndrome, especially after a subsequent haematopoietic stem cell transplantation. Because of the different mechanisms of action and non-overlapping toxicities, the integration of this immunoconjugate with standard chemotherapy is a rational approach, and Phase III trials are ongoing both in the induction and in the post-remission settings.