Interleukin-2 priming chemotherapy: a strategy to improve the remission of refractory/relapsed T cell acute lymphoblastic leukemia.

Regardless of the salvage therapy used, primary induction failure in acute lymphoblastic leukemia (refractory ALL) and relapse after a complete remission (CR) are associated with dismal outcomes. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) may be the best treatment option for relapsed/refractory ALL. However, the outcome of allo-HSCT is very poor when a patient is not in CR. Quiescent leukemia cells protect them from the commonly used cell cycle-specific chemotherapeutic agents. Interleukin-2 (IL-2), a very well characterized T cell growth factor, is responsible for the progression of T lymphocytes from the G0 to the S phase of the cell cycle. IL-2 receptors are present on malignant T cells. Interaction of IL-2 with the IL-2 receptor triggers T cell proliferation, but T cells must change from a resting to an activated state, which leads to the de novo synthesis of IL-2 and expression of the IL-2 receptor. Thus, exogenous IL-2 administration is pivotal for the activation of T cells. Based on the findings above mentioned, we hypothesized that IL-2 priming chemotherapy improves the remission of refractory/relapsed T cell acute lymphoblastic leukemia.