8-azaguanine was suspended in a 10 % glucose solution and delivered intravenously. Four patients received a daily dose of 8-azaguanine between 25 to 1000 mg for 4 to 42 days. Two of the four patients with acute leukemia showed a rapid decrease in the leukocyte count and regression in the size of the lymph nodes, liver, and spleen.

Human epidermoid carcinoma cells (H.Ep.-2) and Adenocarcinoma-755 cells were maintained in SRI-14 tissue culture medium. Effects of 8-Azaguanine on cellular proliferation were determined by following the increase in cell number over a 72 hour period of exponential growth. Cell viability was determined by measurement of clones formed when approximately 100 H.Ep. 2 cells were cultured in 10 ml of medium over a 7- to 14-day period. Approximately 100 H.Ep. 2 S cells were attached to glass by overnight incubation. The cells were then exposed for 1 hour to 8-azaguanine in the presence or absence of 1 mM thymidine. Cells were washed and viability determined. The viability of H.Ep.-2 cells was limited to 35 % and 21 % of control cultures in the presence and absence of thymidine respectively.