Prognostic Significance of Terminal Transferase Activity and other Factors in Childhood Acute Lymphoblastic Leukemia

Abstract

Terminal deoxynucleotidyl transferase (TDT) is an intracellular biochemical marker of certain types of lymphoid precursors. Clinically, TDT serves as a useful marker of malignant lymphoblasts. TDT activity is elevated in 85–95% of cases of non-B, non-T and T-marked acute lymphoblastic leukemias, 5–10% of cases of acute myelogenous leukemia, and 30–40% of cases of chronic myelogenous in blastic phase (reviewed by Coleman and Hutton, 1981). The presence of TDT in leukemic cells is correlated with a favorable response to therapy with drugs cytocidal to lymphoblasts. There is marked variation in the activity of TDT in leukemic cells at diagnosis of acute lymphoblastic leukemia. In our experience values ranged from 0 to 694 units/10⁸ nucleated cells in bone marrow from 118 children and from 0 to 1790 units/10⁸ nucleated cells in peripheral blood from 51 children with acute lymphoblastic leukemia (Hutton et al, 1979). There are no studies testing the prognostic significance of these quantitative variations in level of TDT at diagnosis. Similarly, there are no studies testing whether quantitative measurements of TDT activity during remission of leukemia can predict relapse of disease.