Gemtuzumab ozogamicin treatment in acute myeloid leukemia

This study aimed to investigate if gemtuzumab ozogamicin with induction and consolidation treatment was suitable for patients with acute myeloid leukemia and abnormal genes. 

This study concluded that patients who achieve complete remission after induction therapy and treated with gemtuzumab ozogamicin had significantly fewer relapses than patients who receive standard treatment.  

There are several steps in treating leukemia. Induction treatment is the first treatment received and is normally followed up by another treatment. Consolidation treatment is used to kill any cancer cells left in the body after initial treatment. Standard induction and consolidation chemotherapy are not always effective in patients with acute myeloid leukemia (AML) and mutations (abnormalities) in the NPM1 gene. Patients with these mutations may respond better to more intensive induction and consolidation treatment. 

Gemtuzumab ozogamicin (GO; Mylotarg) is a targeted therapy that can be used to treat AML. It was unknown if GO with induction and consolidation treatment would be suitable for AML patients with high CD33 expression and mutated NPM1. 

This study involved 588 patients with high CD33 expression and mutated NPM1. One group of 296 patients were treated with standard induction therapy including idarubicin (Idamycin), cytarabine (Cytosar-U), etoposide (Etopophos) and all-trans-retinoic acid (ATRA). Another group of 292 patients received the standard treatment plus GO. The main outcome measured was event-free survival (EFS; survival without complication from leukemia or its treatment). 

There was a similar response rate in both groups. However, the occurrence of relapse in patients achieving a complete remission (CR – no signs of cancer) or CR with incomplete hematologic recovery (CR without recovery of normal blood cell counts) was lower in the GO group compared to the standard group. At 2 years, 36.9% of patients had relapsed compared to 25.5% in the GO group.  

More patients over 70 years of age died during early induction therapy in the GO group. The most common cause of death in both groups was infection.

The 2-year EFS rate was 52.6% in the standard treatment group and 58.1% in the GO group. In women under 70 years the addition of GO resulted in a 33% higher EFS. 

This study concluded that patients who achieve a CR after induction therapy including GO had significantly fewer relapses.

This study received funding support from Pfizer, the manufacturer of GO.