Antineoplastic activity of combinations of 6-chloropurine and azaserine.

Simultaneous administration of 6-chloropurine and azaserine in the therapy of mice bearing the ascites cell forms of Sarcoma 180 or the Ehrlich carcinoma resulted in a potentiation of tumor inhibition as measured by increases in survival time. The 6C3HED and the Mecca ascites lymphosarcomas proved resistant to the combination of chloropurine and azaserine employed. Hepatoma 134 was sensitive to azaserine therapy; addition of chloropurine to this regimen did not elicit a further therapeutic response. Cytological examination of Sarcoma 180 ascites cells treated with the combination of 6-chloropurine and azaserine revealed the presence of extensive vacuolation, pro nounced nucleoli, and both nuclear and cytoplasmic enlargement. These alterations were not present in 6C3HED lymphosarcoma ascites cells treated with the drug combination. The total packed cell volume was markedly decreased in both Sarcoma 180 and 6C3HED lymphosarcoma ascites cells treated with azaserine. 6-Chloropurine did not decrease the total packed cell volume of either tumor line, while combination of these two agents yielded a decrease similar to that obtained with azaserine in both neo plasms.