Cytostatic and cytotoxic response of Ehrlich ascites tumor cells in vivo on chronic treatment with cytarabine, bleomycin, and peplomycin.

The cytokinetic response of Ehrlich ascites tumor (EAT) cells in vivo upon chronic treatment at low dosage levels with cytarabine (1-beta-D-arabinofuranosylcytosine, ara-c) bleomycin (BLM) and peplomycin (PEP) was estimated. Bivariate DNA histograms allow the simultaneous evaluation of the cell cycle status of living and killed cells. It could be confirmed that ara-C is cytostatic on cells in S phase. Pronounced cytotoxicity was observed in G1 and G2+M phase. BLM and PEP showed no (or neglectable ) accumulation of vital cells in any cycle phase. Both drugs, however, are cytotoxic on cells, regardless their position within the cell cycle. A successive application of ara-C and BLM (or PEP) in a cell kinetics-directed therapy schedule may be taken into account.