Treatment of acute myeloblastic leukemia

39 adults with acute myeloblastic leukemia were entered on the 'L-6' protocol which consists of repeated courses of arabinosylcytosine (Ara-C) 3 mg/kg by i.v. injection plus 6-thioguanine (TG) 2.5 mg/kg orally, both every 12 hr until induction of remission, and then followed by multiple drugs given in a complex sequence. Of 24 previously untreated patients, 16 had remissions, 3 died during attempted induction, 1 withdrew from the study, 1 failed after adequate therapy, and 3 are presently being untreated. 2 patients died while in remission, 2 relapsed after 2 mth, and the other 12 are still in remission. 20 trials were started in 17 previously treated patients, most of whom had previously received Ara-C and TG. 6 had remissions; 3 relapsed within several months, 1 died in remission, and 2 are still in remission. There were 11 failures; 7 died during attempted induction, 2 subsequently had remissions on other drugs, and 2 are receiving other chemotherapy. 3 other patients are presently being treated. The results so far in previously untreated patients are superior to those in other regimens tried. Previous inadequate therapy with Ara-C and TG appears to greatly reduce both the rate and duration of response.