Role of Allogeneic Stem Cell Transplantation for Adult Chronic Myeloid Leukemia in the Imatinib Era

Due to superior survival in the short to medium term, the first-generation ABL kinase inhibitor imatinib mesylate has generally supplanted all other therapies as the initial treatment of choice in chronic phase chronic myeloid leukemia. The role of allogeneic stem cell transplantation (alloSCT) has shifted from a preferred first-line therapy to a possible second- or third-line therapy. However, despite generally excellent responses to imatinib, some patients respond poorly or lose response, and the risk-benefit equation in these cases may rapidly shift in favor of the alloSCT option. These patients need to be identified as soon as possible so that the alloSCT option can be applied while they are still in controlled chronic phase. Monitoring of imatinib response in patients who have suitable donors and are potentially eligible for alloSCT needs to be frequent, sensitive, and accurate. Clear criteria for switching from imatinib therapy to the alloSCT option should be established for each patient according to the specific risk profile of the transplant. The potential efficacy and safety of clinical trials combining reduced intensity alloSCT with ABL kinase inhibitor therapy warrants further consideration.