Use of cell-cycle information in the preparation of drug combinations: results with cytosine arabinoside plus actinomycin D1,2.

Cytosine arabinoside (ara-C) plus actinomycin D acted synergistically in killing L1210 and DON cells. The time course of cell-kill by the combination was different from that seen for either drug alone. The results obtained (both with L1210 and synchronous DON cells) suggest that cells blocked in G1/S with continuing unbalanced growth are particularly sensitive to the combined action of ara-C and actinomycin D.