Examining long-term treatment outcomes in patients with T-cell ALL

This study examined treatment outcomes in patients with T-cell acute lymphoblastic leukemia (T-ALL). Researchers reported that certain subgroups of T-ALL patients, such as those with specific genetic changes, affected long-term survival. More studies are needed to confirm these preliminary results.

T-cell acute lymphoblastic leukemia (T-ALL) is a specific type of acute lymphoblastic leukemia (ALL).  T-ALL affects the lymphoid-cell-producing stem cells (immature blood cells), in particular, a type of white blood cell called T lymphocytes. In contrast, ALL commonly affects B lymphocyte cells. B lymphocytes make antibodies to help fight infection. T lymphocytes help B lymphocytes make the antibodies that help fight infection. T-ALL is aggressive and gets worse quickly if it is not treated. Identifying predictors of treatment success is important to help improve clinical outcomes of T-ALL.

The aim of this study was to examine factors important in treatment success for T-ALL patients.

1,643 patients with newly diagnosed ALL were included in this study. Of these, 356 were classified as having the T-ALL variant. All patients were treated with induction therapy (with the aim to induce a remission, no sign of disease) using a combination of 4 chemotherapy drugs. Patients were followed for up to 7 years.

Complete remission after induction therapy was achieved in 94% of T-ALL patients. This was similar to patients with B-cell ALL (93%). Gender, white blood cell counts at diagnosis, specific genetic abnormalities, or cancer spread to the central nervous system did not affect remission rates.

The overall survival rate (proportion who have not died from any cause since treatment) at 5 years was 48%. This was similar to patients with B-cell ALL (42%). Patients with specific genetic abnormalities were associated with significantly better survival. These included being positive for the CD1a and lack of expression of the CD13 protein. Complex genetic changes on a chromosomal level (cell structures that carry genetic information) were associated with poorer survival. Patients with central nervous system involvement had similar survival rates (47%) compared to those without (48%).

The next therapy after induction therapy was either stem cell transplantation (from a donor) or additional chemotherapy (carried out in 178 patients). 33 patients were randomly assigned to receive a stem cell transplant using their own previously harvested stem cells.

5-year overall survival was 51% for patients treated with chemotherapy and those receiving their own stem cell transplant. Patients receiving a stem cell transplant from a sibling donor had a 5-year overall survival rate of 61%. This was significantly higher compared to those without donors (46%). They also had a lower relapse rate (25%) compared to those without donors (51%). Overall, of the 123 T-ALL patients who relapsed, only 8 survived the study period. 

Researchers concluded that certain genetic changes can affect survival outcomes in T-ALL patients. A stem cell transplant from a sibling donor should be considered for high-risk patients. Researchers also advised that these are preliminary results and further clinical trials are needed.

Only a subset of patients were thoroughly tested for genetic changes. More studies are needed to confirm the effects of specific genetic changes on T-ALL treatment outcomes.