Gemtuzumab ozogamicin can reduce minimal residual disease in patients with childhood acute myeloid leukemia

BACKGROUND Gemtuzumab ozogamicin (GO) is an active agent for the treatment of CD33-postive acute myeloid leukemia (AML) and may improve the outcome of specific patient subgroups when combined with conventional chemotherapy. However, to the best of the authors' knowledge, the effects of GO on levels of minimal residual disease (MRD) are unknown. METHODS Pediatric patients with AML who received GO, either alone or in combination with chemotherapy on the AML02 multicenter trial, were analyzed to determine the effects of GO on MRD and outcome. RESULTS Among 17 patients who received GO alone because of persistent leukemia, 14 had a reduction in their MRD level and 13 became MRD negative. Of the 29 who received chemotherapy in combination with GO after responding poorly to chemotherapy, 28 demonstrated reduced MRD and 13 became MRD negative. Treatment with GO effectively reduced MRD before hematopoietic stem cell transplantation and was not found to be associated with increased treatment-related mortality after transplantation. CONCLUSIONS GO is effective in reducing MRD levels in pediatric patients with AML and may improve the outcome of those patients at high risk of disease recurrence. Cancer 2013;119:4036–4043. © 2013 American Cancer Society.