Update on the role of gemtuzumab-ozogamicin in the treatment of acute myeloid leukemia

Gemtuzumab-ozogamicin (GO) is an antibody-drug conjugate (ADC) in which a monoclonal antibody targeting CD33 is covalently linked to the toxin calicheamicin. GO was initially approved by the United States Food and Drug Administration (FDA) for the treatment of adult patients with CD33(+) acute myeloid leukemia (AML) in 2000. However, GO was recalled from the US market due to the lack of efficacy, and higher incidence of hepatotoxicities, including hepatic veno-occlusive disease (VOD), observed in phase 3 SWOG-0106 study. Since then, several other phase 3 studies have evaluated the efficacy of GO in the frontline treatment of adult patients with AML using different GO doses and schedules. The pivotal study that led to the reconsideration of GO was the French ALFA-0701 study, which used a lower and fractionated dose of GO in combination with standard chemotherapy (SC). Patients treated with the GO combination had a significantly longer survival outcome. The modified schedule also improved the toxicity profile. A systematic review and meta-analysis of over 3000 patients treated in five phase 3 studies showed that adding GO to SC improved relapse-free and overall survival. Most importantly, 6 mg/m(2) dose of GO was associated with higher grade > 3 hepatoxicities and VOD than 3 mg/m(2). The survival benefit was significant in the favorable and intermediate cytogenetic risk groups. This led to the reapproval of GO in 2017 for the treatment of patients with CD33(+) AML. Currently, several clinical trials are exploring the role of GO with various combinations and in eliminating the measurable residual disease in patients with CD33(+) AML.