[Clinical effect and pharmacokinetics of intermediate dose Ara-C therapy in a patient with acute non-lymphocytic leukemia with two CNS recurrences].

A case of two repeated CNS recurrences of acute non-lymphocytic leukemia (M2) was treated with intermediate dose Ara-C therapy and achieved 2 complete remissions. The clinical effect and pharmacokinetics of intermediate dose Ara-C therapy in this patient were discussed. A 55-year-old male with acute non-lymphocytic leukemia (M2) achieved complete remission by combination chemotherapy of Behenoyl-ara-C, Daunorubicin, 6-Mercaptopurine and Prednisolone in July, 1985. He subsequently received consolidation and intensification therapy with periodical intrathecal injection of Methotrexate (MTX), but 13 months later he developed his first CNS recurrence which was resistant to the intrathecal administration of Ara-C and MTX. As he also relapsed systemically, Ara-C was administered in intermediate dose (1 g/m2 every 12 hrs for 5 days) and he achieved complete remission both in the CNS and systemic manifestations. Six months later he was diagnosed as having a second CNS recurrence and another systemic relapse. Intermediate dose Ara-C was administered again, and he achieved complete remission in the CNS and partial remission in systemic manifestations. Pharmacokinetic study revealed high peaks of Ara-C concentration in plasma (6.2 microM immediately after the end of the infusion) and high degree of its penetration into the CNS (5.6 microM at 3 hr after the end of the infusion) suggesting the effective and perhaps a uniform level of Ara-C is achieved throughout the CNS by this therapy. In 3 other patients without CNS involvement 0.88 +/- 0.44 microM of Ara-C, which is enough concentrations for its cytostatic effect, was detected at 3 hr after the end of infusion, suggesting the efficacy of the therapy for CNS prophylaxis. In this case the relapse occurred after repeated administration of antileukemic drugs, including Behenoyl-ara-C, an analog of Ara-C, and was resistant to the intrathecal administration of Ara-C. These findings suggest that intermediate dose Ara-C therapy was effective to overcome a resistance to antileukemic drugs, including Ara-C, and also, in some cases, more effective than intrathecal injection of antileukemic drugs for the treatment of CNS leukemia.