We studied the feasibility, toxicity, and efficacy of a 2-step approach to autologous stem cell transplantation for patients with acute myeloid leukemia in first remission. Step 1 consisted of consolidation chemotherapy including cytarabine 2000 mg/m2 twice daily for 4 days concurrent with etoposide 40 mg/kg by continuous infusion over 4 days. During the recovery from this chemotherapy, peripheral blood stem cells were collected under granulocyte colony-stimulating factor stimulation. Step 2, autologous stem cell transplantation, involved the preparative regimen of busulfan 16 mg/kg followed by etoposide 60 mg/kg and reinfusion of unpurged peripheral blood stem cells. A total of 128 patients were treated. During step 1, there was 1 treatment-related death. A median CD34+ cell dose of 14 (x10(6)/kg) was collected in 3 aphereses. Ten patients suffered relapse before transplantation, and 117 patients (91%) proceeded to transplantation. During step 2, there were 2 treatment-related deaths, and 35 patients subsequently suffered relapse. With median follow-up of 30 months, 5-year disease-free survival for all patients entered in the study is projected to be 55%. By cytogenetic risk group, 5-year disease-free survival is 73% for favorable-risk patients, 51% for intermediate-risk patients, and 0% for poor-risk patients. We conclude that this 2-step approach to autologous transplantation produces excellent stem cell yields and allows a high percentage of patients to receive the intended therapy. Preliminary efficacy analysis is very encouraging, with outcomes that appear superior to those of conventional chemotherapy.

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The initial changes in lymphocyte RNA metabolism produced by treatment with phytohemogglutinin (PHA) are described. The earliest change was a decrease in total RNA (i-RNA), detectable after 30 minutes of exposure to PHA. This loss could not be localized to any of the major types of cellular RNA. After 1 hour, accelerated synthesis of RNA, shown by incorporation of u-H3, was detected, and a progressive increase in rate of synthesis continued for 24 hours. The significance of the early loss of RNA as related to the onset of lymphocyte growth is discussed.