Comparison of the activity of arabinosyl-5-azacytosine, arabinosyl cytosine, and 5-azacytidine against intracerebrally implanted L1210 leukemia.

Arabinosyl-5-azacytosine (ara-AC) is a new compound which combines the structural characteristics of arabinosyl cytosine (ara-C) and 5-azacytidine (5-AC). These three compounds, injected intraperitoneally, were evaluated in direct comparison against the intracerebral L1210 leukemia model. 5-AC was active in a non-schedule dependent manner producing increase in life span (ILS) values of 70%. The effects of both ara-C and ara-AC were schedule-dependent with the best activity (ILS ca. 600%; multiple long term survivors) observed using an around-the-clock treatment schedule. In all experiments, ara-AC appeared to be more efficacious than ara-C. In some instances, ara-AC was as active as the positive control compound, BCNU. Excellent activity for ara-AC was also observed against the intracerebral P388 leukemia system.