T-CELL ACUTE LYMPHOBLASTIC LEUKEMIA IN DAILY HEMATOLOGICAL PRACTICE

ABSSUB-4258 

Background: Adult patients with T-cell acute lymphoblastic leukemia (T-ALL) or T-cell lymphoblastic lymphoma (T-LBL) form a subgroup of patients with inferior outcome compared to patients with B-cell precursor lymphoid malignancies.

Aims: Aim of this analysis was to describe features and outcome of patients with T-ALL or T-LBL treated using two similar protocols including consolidation by an allogeneic or autologous stem cell transplantation.

Methods: All adult patients diagnosed with T-ALL or T-LBL at our centre between 1997 and 2013 were included into this analysis. We describe baseline features of these patients, treatment options and treatment outcomes. The data were analysed for response and relapse rate and factors affecting survival.

Results: A total number of 44 patients aged 17 to 77 years (median age 31 years) at the time of diagnosis were included into this analysis; thirty (68%) patients with T-ALL and fourteen (32%) with T-LBL, thirty-three (75%) men and 11 (25%) women. Older, less intensive treatment protocol was used in 29 (66%) cases, whereas a newer, slightly more intensive one was used in 15 (34%) patients. Allogeneic hematopoietic stem cell transplantation (SCT) was performed in 6 (14%) patients, autologous SCT followed by maintenance therapy in 9 (20%) patients. Thirty-seven (88%) out of 42 evaluable patients achieved a complete hematologic remission (CR) in the median time of 28 days (range 9 to 121 days).

Twenty-two (55%) patients in CR or partial remission (PR) eventually relapsed. The prognosis of these relapsed patients was extremely dismal; nineteen (86%) of them died irrespectively of the salvage treatment used.

During the follow-up period with a median of 16.4 months (range 1 to 173 months) twenty-five (57%) patients died. Most common causes of death were disease progression (48%), infection (32%) and non-infectious treatment toxicity (8%). Nineteen (43%) patients remain alive in follow-up.

Five-year progression-free (PFS) and overall survival (OS) in the whole cohort were 30% and 37%, respectively. The survival was not influenced by age, diagnosis (T-ALL vs. T-LBL) nor the treatment protocol used. As expected, the most significant risk factor for shorter OS was occurrence of relapse; 5-year OS in patients with relapse vs. without relapse was 14% vs. 87%, respectively, and median OS was 14.5 months vs. not reached, respectively, p<0.002.

Allogeneic SCT was superior to chemotherapy alone; 5-year PFS 63% vs. 18% (p=0.02), 5-year OS 63% vs. 21% (p=0.01). Autologous SCT followed by maintenance therapy offers similar non-inferior survival improvement with 5-year PFS 45% and 5-year OS 67%. This difference remains statistically significant even in the transplant-eligible subgroup of patients under the age of 35.

Summary/Conclusion: Adult patients with T-cell acute lymphoblastic leukemia or T-cell lymphoblastic lymphoma form a less common subgroup of patients with inferior outcome. Autologous stem cell transplant followed by maintenance therapy offers a promising option for transplant-eligible patients without a donor. The prognosis of relapsed patients is extremely poor and these patients are therefore candidates for further analyses.

Supported by Czech Leukemia Study Group – for Life (CELL), research grants MSMT (2013-2015, no. 7E13008); MSMT projects SuPReMMe (CZ.1.07/2.3.00/20.0045) and VaVPI CEITEC (CZ.1.05/1.1.00/02.0068).

Keywords: Allogeneic hematopoietic stem cell transplant, Autologous hematopoietic stem cell transplantation, Chemotherapy, T cell acute lymphoblastic leukemia

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