One hundred and forty-seven adults with acute nonlymphocytic leukemia were randomized to one of two treatment regimens utilizing cytosine arabinoside and 6-thioguanine. In regimen A the drugs were administered every 12 hours until marrow cellularity was reduced by at least 50%. In regimen B the drugs were administered every 12 hours for 5 days with five to 7 days rest intervals between courses. Decisions to continue or reinstitute therapy were based solely on marrow cellularity and marrow ratings. The overall response in refereeverified cases in both groups was similar (41%); regimen B proved to be the easier protocol to administer but required greater support. Younger patients or those with an initial high hemoglobin count responded best to these drug regimens. Only 36% of our patients experienced Severe marrow hypoplasia (i.e., a 75% or greater reduction in marrow cellularity) prior to complete remission, suggesting that cytosine arabinoside and 6-thioguanine in combination may selectively suppress leukemic cells while sparing normal hematopoietic elements.
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3911387-1396, 1977.
N LATE 1971 THE WESTERN CANCER STUDY data on regimens that would yield a high pro-I Group (WCSG) began developing a series of portion of complete remissions. The regimen of protocols to investigate the role of maintenance Gee, Yu, and Clarkson, 'modified and published chemotherapy on prolongation of life in adults later by Clarkson,' was selected since it had with acute nonlymphocytic leukemia. In prepa-been reported to yield 65% complete and partial ration for instituting these studies, we sought responses. This regimen required continuous