Allogeneic stem cell transplant for chronic myeloid leukemia as a still promising option in the era of the new target therapy

Background/Aim. Introducing tyrosine kinase inhibitors (TKIs) has essentially changed curative approach, to be precise, clearly improved treatment efficacy for chronic myeloid leukemia (CML). Thus, the place and usage of allogeneic stem cell transplant (SCT) in CML treatment - as a former "nearly monopolistic" therapeutic manner - is nowadays controversial. The objective of this retrospective study was to evaluate the results obtained in the treatment of CML patients, with a particular attempt to define parameters critical for clinical benefit and superior overall outcome following allogeneic SCT. Methods. A total of 32 CML patients (27 in chronic phase and 5 with advanced disease), with female/male ratio 11/21, aged from 9 to 54 (32 in average) years, underwent allogeneic SCTs (1993 to 2009). The initial treatment for 25 patients was interferon alpha (IFN-α) with or without ARA-C, and additional 7 patients with no response to imatinib mesylat (IM). The time from diagnosis to SCT was approximately 12 (range 3- 37) months. The patient were categorized according to the risk for the disease, transplant-related mortality (TRM) scoring system, and stem cell (SC) source. The basic conditioning regimen was a combination of busulphan and cyclophosphamide (BuCy-2). Graft-versus-host disease (GvHD) was typically prevented with cyclosporine-A (CsA) and methotrexate (MTX). Results. Engraftment was observed in 26 (84.4%) patients, with polymorphonuclear (PMNs) and platelet (Plt) recovery on the 15th (range 10-22) and 19th (range 11-29) posttranspalnt days, respectively. Acute GvHD (aGvHD) had 13/26 (50%), and chronic GvHD (cGvHD) 10/21 (47.1%) patients. The incidence of overall TRM was 46.8% (15/32), while early death was noticed in 4 (12.5%) patients. A cause of death in 9 (28.1%) patients was cGvHD, in 2 (6.25%) patients infection, and in 3 (9.35%) cases disease-relapse was occurred. Fourteen (43.7%) of the patients are still alive, 9 from the low-risk group for TRM, with long-term survival from 1 to 16 years. Patients who received SCs from peripheral blood (PB) vs bone marrow (BM) had significantly faster engraftment (p < 0.05), lower oropharingeal mucositis rate (25% vs 70%; p < 0.05), but more frequent cGvHD (83.3% vs 30.3%; p < 0.05). A significantly improved (log-rank = 2.39; p < 0.01) overall survival (OS) was obtained in BM-setting. Conclusion. The results obtained in this study are in accordance with data from analogous clinical trials. Exactly, in the era of the new target therapy (TKI application), allogeneic SCT can be still a convenient therapeutic approach for well-selected CMLpatients, especially for those with initial high-risk disease and lower probability of TRM.