Sensitivity of Bone Marrow Hematopoietic Colony-forming Cells from Mice, Dogs, and Humans to Carminomycin, Marcellomycin, Aclacinomycin A, and A/,/V-Dibenzyldaunorubicin and Its Relationship to Clinical Toxicity1

The sensitivity of bone marrow granulocyte-macrophage col ony-forming cells to 4 anthracyclines, carminomycin, marcellomycin, aclacinomycin A, and A/,A/-dibenzyldaunorubicin, was studied using the agar diffusion chamber technique which allows exposure of target cells to drug metabolized by the chamberbearing host after i.v. injection. Colony-forming cells from mice, dogs, and humans were all found to have exponential doseresponse curves for the agents studied, with variation of the slopes between species and agents. Species sensitivities as determined by the assay related well to the available toxicological and clinical data for specific drugs. The rank order of sensitivity of human marrow colony-forming cells to five anthracyclines tested in this and a previous study related very closely to doses producing moderate leukopenia in Phase I and II clinical studies. A dose of 200 mg/sq m of A/,A/-dibenzyldaunorubicin would be expected to produce moderate leukopenia in future clinical trials. This assay may be useful in predicting human bone marrow toxicity of new agents before actual clinical trial because of the ability to study the survival of human colony-forming cells directly.