Asparaginase and amino acids in cancer therapeutics. Cancer and Leukemia Group B Investigators.

Asparaginase was found ineffective in improving induction frequency of acute lymphocytic leukemia of children from vincristine and prednisone, but prolonged remission duration. Prolongation of remission duration was accomplished more effectively and at lower toxic cost by administration of asparaginase after the vincristine and prednisone treatment had been completed. Asparaginase is markedly more effective against human leukemia T-cells in vitro than against several types of B-lymphocytes. This is consistent with in vivo experience. Leukemic T-cells resistant to asparaginase have been induced in vitro. Deficiency of other amino acids causes absolute cessation of RNA biosynthesis, constituting evidence for other amino acid targets critical to leukemic cell survival.