Selective treatment of leukemia L1210 with combination of deoxycytidine and lethal doses of cytosine arabinoside

Peroral administration of deoxycytidine (dC) to mice with leukemia L1210 simultaneously with intraperitoneal injections of toxic doses of cytosine arabinoside (araC) reduces the severity of toxicosis and prevents the death of the animals by poisoning. A marked antitumor effect is observed in these animals. The mean life span of such mice is much longer than that of untreated mice and also of mice receiving dC or araC alone. With the optimal scheme of treatment about 23% of mice live longer than 60 days. Protection with dC weakens the antileukemic effect of araC when the latter is given in nontoxic doses. This combination is not effective against transplantable myeloid leukemia of mice.