Single weekly cytosine arabinoside and oral 6-thioguanine in patients with myelodysplastic syndrome and acute myeloid leukemia.

Older patients with RAEB-T or AML are extremely difficult to treat. They are at high risk of infection and/or bleeding complications and have a low probability of cure and short overall survival with conventional treatments. We treated 12 patients with an outpatient low-dose chemotherapy regimen consisting of Ara-C 100 mg subcutaneously on day 1, and 6-thioguanine 80 mg orally on days 2-5, repeated every week. Nine patients had MDS, six RAEB-T, and three RAEB (median age 57 years) and three had de novo AML (median age 73 years). All patients were transfusion dependent. The mean peripheral blast count at the beginning of treatment was 29% (4-51%). The median follow-up is 13 months (2-34 months) for all the patients and 14 months (2-34 months) for those with RAEB-T. Nine of the 12 patients are alive, including seven RAEB-T patients with a median of 18 months (range 6-34+ months). During treatment, the peripheral blast count was markedly reduced to a mean of 5% (0-23%). The mean pre-therapy platelet count, with transfusion support, was 24.0 x 10(9)/l, while the mean post-therapy platelet count without transfusion support is 95.0 x 10(9)/l. All patients except two became transfusion independent at some time. Treatment for 6-10 weeks was required to show reduction of blast number and increase in hemoglobin, platelet, and WBC counts. Initial cytopenias were the only side effects of this regimen. One patient had granulocytopenic fever. In conclusion, this low-dose regimen is effective and well tolerated for outpatient palliation in high-risk or elderly patients with RAEB-T or AML.