Recent Significance of Allogeneic Hematopoietic Stem Cell Transplantation for Adult T Cell Leukemia/Lymphoma (ATL)

Introduction: Adult T cell leukemia/lymphoma (ATL) is a poor prognostic T-cell malignancy and the median survival time of aggressive type ATL is about a year regardless of intensive chemotherapy. Since 2001, several studies mainly from Japan show that allogeneic hematopoietic stem cell transplantation (allo-HSCT) has improved overall survival (OS) of ATL. To confirm the survival of the ATL patients received treatment such as chemotherapy and allo-HSCT and the usefulness of allo-HSCT on ATL, we analyzed retrospectively the patients with ATL treated recently in our institute.

Patients and methods: There were total 198 patients who were consecutively hospitalized and received treatments as ATL between July, 2006 and December, 2013 in Imamura Bun-in Hospital that located at Kagoshima, an endemic area of HTLV-1 infection in Japan. This time we studied about backgrounds (age, gender, subtypes of ATL, performance status (PS) at diagnosis and clinical stage) of the patients, content of allo-HSCT, prognostic index for acute and lymphoma type ATL (ATL-PI) and survival duration from diagnosis retrospectively. The comparisons between the mean values were performed by Student’s t test or the Mann–Whitney test. The overall survival from diagnosis (OS) was analyzed with Kaplan-Meir method and Cox regression analysis about OS was performed. Statistical significance defined P<0.05. Statistical analysis ware performed with STATA Version 12 software (Stata Corp).

Results: Median age of the patients was 62.5 (range: 32.5-90.5) years old and they were 104 male and 94 female. One hundred forty four patients were initially diagnosed as acute type ATL, 26 as lymphoma type, 18 as chronic type and 10 as smoldering type respectively. ECOG PS at diagnosis was score 0 to 1 in 155 patients (78.3 %) and score 2 to 4 in 43 patients (21.7 %). Clinical stage at diagnosis was stage I to II in 12 patients (6 %) and stage III, IV in others (94 %). Eventually 68 patients received allo-HSCT (allo-bone marrow transplantation in 48, allo-peripheral blood stem cell transplantation in 5 and cord blood transplantation in 15 patients) and all of them were acute and lymphoma type. Fifty-three patients received stem cell from unrelated donors. The median study observation period was 293.5 (range: 7-2539) days. In all 198 patients OS rate at 1 and 3 year were 41.9 % and 17.9 % respectively and 50% OS was 9.8 months and the results were comparable to the past reports. Overall survival rate at 1- and 3-year of the patients who were able to be received allo-HSCT was 54.8 % and 36.5 %, and 50% OS of them was 16.2 months. Overall survival rate at 1- and 3-year of the patients who were not received allo-HSCT and mainly received chemotherapies such as CHOP or VCAP-AMP-VECP regimens was 35.0 % and 7.3 %, and 50% OS was 8.2 months. ATL-PI was reported as a new prognostic prediction tool for patients with acute and lymphoma type ATL, and had prognostic power in acute and lymphoma type ATL who were not received allo-BMT in the present study (1 year OS : 57.2 %, 34.6 % and 18.8 % at low, intermediate and high risk respectively, p<0.000). In the patients received allo-HSCT, there were no patients with high risk of ATL-PI and the patients with low risk were liable to have worse OS than the patients with intermediate risk (1 year OS : 50.4 %, 62.2 % and 3 year OS : 25.7 %, 56.6 % at low and intermediate risk respectively, p=0.114).

Conclusions: This retrospective analysis estimates that outcome of chemotherapies for ATL patients were not so improved and allo-HSCT has promising strategy for the patients with ATL who has indication for that. But we reveal that some of patients with low risk of ATL-PI received allo-BMT have poor outcome, these findings should be confirmed in a prospective study.