thioinosine and Leukemia--Lymphoid

In order to analyze the cellular determinants that mediate the action of 2',3'-dideoxycytidine, the growth inhibitory and cytotoxic effects and the metabolism of the dideoxynucleoside were examined in wild type human CEM T lymphoblasts and in mutant populations of CEM cells that were genetically deficient in either nucleoside transport or deoxycytidine kinase activity. Whereas 2',3'-dideoxycytidine at a concentration of 5 microM inhibited growth of the wild type CEM parental strain by 50%, two nucleoside transport-deficient clones were 4-fold resistant to the pyrimidine analog. The deoxycytidine kinase-deficient cell line was virtually completely resistant to growth inhibition by the dideoxynucleoside at a concentration of 1024 microM. An 80% diminished rate of 2',3'-[5,6-3H]dideoxycytidine influx into the two nucleoside transport-deficient lines could account for their resistance to the dideoxynucleoside, while the resistance of the deoxycytidine kinase-deficient cells to 2',3'-dideoxycytidine toxicity could be explained by a virtually complete failure to incorporate 2',3'-[5,6-3H]dideoxycytidine in situ. Two potent inhibitors of mammalian nucleoside transport, 4-nitrobenzylthioinosine and dipyridamole, mimicked the effects of a genetic deficiency in nucleoside transport with respect to 2',3'-dideoxycytidine toxicity and incorporation. These data indicate that the intracellular metabolism of 2',3'-dideoxycytidine in CEM cells is initiated by the nucleoside transport system and the cellular deoxycytidine kinase activity.

Topics: Acquired Immunodeficiency Syndrome; Biological Transport; Cell Division; Cell Survival; Deoxycytidine; Deoxycytidine Kinase; Dipyridamole; Humans; Kinetics; Leukemia, Lymphoid; Mutation; Nucleosides; Phosphorylation; Phosphotransferases; T-Lymphocytes; Thioinosine; Tumor Cells, Cultured; Zalcitabine

The intracellular half-life for retention of the active triphosphate metabolite 1-beta-D-arabinofuranosylcytosine 5'-triphosphate (araCTP) of 1-beta-D-arabinofuranosylcytosine was measured in vitro in blast cells from patients with acute myeloblastic leukemia, acute lymphoblastic leukemia, and T-cell lymphoblastic lymphoma. araCTP accumulation from 1 microM 1-beta-D-arabinofuranosylcytosine in leukemic blast cells was closely correlated with the nucleoside transport capacity as measured by equilibrium binding of [3H]nitrobenzylthioinosine. The half-life of araCTP retention was related to araCTP accumulation only when the level of araCTP was expressed as a percentage of total intracellular 1-beta-D-arabinofuranosylcytosine metabolites. Accumulation of 1-beta-D-arabinofuranosyluracil 5'-monophosphate was inversely related to the half-life of araCTP retention and directly related to dCMP deaminase activity in cell free extracts. No conversion of 1-beta-D-arabinofuranosyluracil to 1-beta-D-arabinofuranosyluracil 5'-monophosphate was detectable in intact cells. The end product of araCTP degradation was 1-beta-D-arabinofuranosyluracil and it is proposed that conversion of 1-beta-D-arabinofuranosylcytosine 5'-monophosphate to 1-beta-D-arabinofuranosyluracil 5'-monophosphate is a step in the degradative pathway of araCTP. However, it is the cells' nucleoside transport capacity which primarily determines the level of intracellular araCTP accumulation.

Topics: Arabinofuranosylcytosine Triphosphate; Arabinonucleotides; Cytarabine; DCMP Deaminase; Guanosine; Half-Life; Humans; Kinetics; Leukemia, Lymphoid; Leukemia, Myeloid, Acute; Lymphocytes; Phosphorylation; Thioinosine; Thionucleosides

Topics: Adolescent; Child; Child, Preschool; Humans; Infusions, Parenteral; Inosine; Leukemia, Lymphoid; Mercaptopurine; Thioinosine

The case histories of 293 adolescent and adult patients with acute lymphoblastic leukemia (ALL) first seen and treated between 1969 and 1979 are reviewed. A complete remission (CR) was achieved in 79% of cases. Male sex, advanced age (greater than or equal to 30 yr old), and early CNS involvement were the major determinants of remission failure. Median duration of first CR was 16 mo, with 23 patients (actuarial proportion 25%) alive and relapse-free at 5 yr. The major determinant of first CR length was white blood cell (WBC) count (best cut-off value at 35 X 10(9)/liter). First CR length was also negatively affected by early CNS involvement, morphological FAB L3 subtype, and B-cell (Smlg+) leukemia, but these features were significantly associated with a high WBC count. First CR length in patients 11-15 yr old did not differ significantly from that of patients 16-59 yr old. The negative prognostic value of T-cell (E+) leukemia was not confirmed in this adult series. CNS prophylaxis provided an effective protection against CNS relapse. Maintenance chemotherapy was apparently more effective when 4 or more than 4 drugs were employed. "Low risk" patients (WBC count less than 35 X 10(9)/liter still relapsed rather frequently (32% at 1 yr, 49% at 2 yr), with 33% of them alive and relapse-free at 5 yr. "High risk" patients (WBC count greater than or equal to 35 X 10(9)/liter +/- early CNS involvement +/- morphological L3 subtype +/- B-cell leukemia) relapsed very quickly (50% at 6 mo. 70% at 1 yr), with only 6% of them relapse-free at 5 yr.

Topics: Actuarial Analysis; Adolescent; Adult; Aging; Bacterial Infections; Child; Drug Therapy, Combination; Female; Humans; Leukemia, Lymphoid; Leukocyte Count; Male; Methotrexate; Middle Aged; Prednisone; Prognosis; Receptors, Antigen, B-Cell; Retrospective Studies; Thioinosine; Vincristine

Xanthine oxidase deficiency was identified in a 16-year-old girl with acute lymphocytic leukemia (ALL). Despite the enzyme deficiency, the patient tolerated high doses of 6-mercaptopurine (6-MP), a drug which is normally inactivated by the action of xanthine oxidase. This rate clinical situation may be analogous in the practice to that of the patient receiving 6-MP who is also given allopurinol, which inhibits xanthine oxidase activity. The implications of these observations on the determination of appropriate drug dosages for patients receiving these two agents are discussed.

Topics: Adolescent; Allopurinol; Asparaginase; Female; Humans; Leukemia, Lymphoid; Methotrexate; Prednisone; Thioinosine; Uric Acid; Vincristine; Xanthine Oxidase

Topics: Acute Disease; Bacterial Infections; Child; Child, Preschool; Humans; Leukemia; Leukemia, Lymphoid; Methotrexate; Prednisolone; Thioinosine; Vincristine

Survival and response to chemotherapy were evaluated in 84 adults with granulocytic leukemia (AGL) and 22 with acute lymphocytic leukemia (ALL). Twenty-two of the 84 patients with AGL reveived no chemotherapy (untreated group). The median survival for patients with AGL who achieved complete remission (CR) was 17.1 months, compared to 6.5 months for those who achieved partial remission (PR (p less than 0.05), 2.8 months for those who failed chemotherapy (p less than 0.01), and 2.1 months for the untreated group (p less than 0.01). The median survival for patients with ALL who achieved a CR was 18.2 months, compared to 7.3 months for those who achieved a PR and 7.0 months for those who failed chemotherapy. Of patients with AGL who reveived an adequate trial of chemotherapy, 43% achieved a CR and 16% a PR; 75% of patients with ALL achieved a CR and 13% a PR. Improved survival depends on the induction of a complete or partial remission with the use of aggressive chemotherapy.

Topics: Acute Disease; Adolescent; Adult; Aged; Child; Cyclophosphamide; Daunorubicin; Drug Therapy, Combination; Humans; Leukemia, Lymphoid; Leukemia, Myeloid; Mercaptopurine; Methotrexate; Middle Aged; Prednisone; Thioguanine; Thioinosine; Vincristine