Hematological aspects of a novel 9-aminoanthracycline, amrubicin.

Our previous study showed that the myelosuppression induced by a single-bolus intravenous injection of amrubicin into mice was more severe, even at half the maximum tolerated dose (MTD), than that induced by adriamycin (ADR) at the MTD, but that the recovery was more rapid than that after ADR. The present study shows that the administration of amrubicin significantly decreased the number of colony-forming units of granulocytes and monocytes (CFU-GM) from day 1, but that the CFU-GM numbers recovered by day 3. In contrast, the administration of ADR induced a continuous decrease in the numbers of CFU-GM until day 10. The early myelosuppression and rapid recovery of white blood cells (WBC) induced by amrubicin may depend upon the early decrease in the number of CFU-GM and the rapid recovery of CFU-GM. These data suggest that the toxic effects on the peripheral blood and bone marrow induced by amrubicin are more reversible and more controllable than those induced by ADR.