Inotuzumab ozogamicin in the management of acute lymphoblastic leukaemia

Whilst most adult patients with acute lymphoblastic leukaemia will go into remission with standard induction chemotherapy, many will relapse. Response rates to standard salvage chemotherapy regimens are low and the outlook on relapse is very poor and associated with significant morbidity and mortality hence the need for newer targeted approaches. Inotuzumab ozogamicin (previously known as CMC-544) is an antibody-drug conjugate and consists of a monoclonal anti-CD22 antibody bound to calicheamicin. The target, CD22, is widely expressed on acute lymphoblastic leukaemia cells making it a potential therapeutic target. The calicheamicin is delivered intracellularly and causes leukaemia cell apoptosis. Overall response rates of 57% were observed in a Phase II study and the final results of a Phase III randomised controlled trial comparing this drug to the investigator choice 'standard of care' chemotherapy are eagerly awaited. Whilst initial results are promising, there have been concerns regarding liver toxicity and the incidence of veno-occlusive disease of the liver especially in patients who have previously received or go on to allogeneic stem cell transplant.