Lethal effect of aclacinomycin A on cultured mouse L cells

The effect of aclacinomycin A on the survival of cultured mouse L cells was studied. The drug showed a characteristic dose-survival response, i.e., an initial exponential responses followed by a sigmoidal inactivation characterized by a broad shoulder. With prolongation of the exposure time, the exponential response seen at a low concentration was remarkably intensified with a progressive decrease of the shoulder width. Two-dose fractional survival studies revealed that at least a portion of the shoulder region relation to an accumulation of sublethal damage which can be repaired during 12 hr after the first dose. The implication of these results for therapeutic scheduling is discussed.