Successful interim therapy with imatinib prior to allogeneic stem cell transplantation in Philadelphia chromosome-positive acute myeloid leukemia

Objectives: Imatinib (Glivec, STI571) has been successfully used in patients with chronic myelogenous leukemia and acute lymphoblastic leukemia with the Philadelphia chromosome (Ph). We used imatinib interim therapy for four consecutive patients with newly diagnosed Ph⁺ acute myeloid leukemia (AML). We monitored the patient status for minimal residual disease by real-time quantitative polymerase chain reaction. Methods and results: Imatinib was administered on an interim schedule after each chemotherapy course. After the first imatinib cycle, all patients remained in sustained complete hematologic remission (CHR) with a decrease in the breakpoint cluster region of the Abelson oncogene locus transcript. All patients received a second imatinib cycle following consolidation and showed sustained CHR, including two cases with complete molecular remission. All cases underwent hematopoietic stem cell transplantation (HSCT) in favorable condition, and are still alive with a leukemia-free status at 6, 6, 9, and 25 months after HSCT. Conclusions: As a first-line interim therapy, imatinib appears to be a useful treatment strategy to provide a bridge to HSCT in patients with Ph⁺ AML. Further studies with a larger patient population and longer follow-up are needed for accurate assessment of the impact of imatinib on the long-term outcome of transplantation for patients with Ph⁺ AML.