Mode of Action of Chemotherapy In Vivo on Human Acute Leukemia. I. DAUNOMYCIN

Abstract
The leukocytes of 16 adult patients with acute myeloblastic leukemia were studied by autoradiographic methods to elucidate the mode of action of daunomycin. It was shown that daunomycin, at clinically useful doses, exhibits a cytolytic effect on all leukemic blasts whatever their cell-cycle phase. This cytolytic action affects, however, preferentially S-phase cells. It was shown also that blasts of patients less sensitive to daunomycin or receiving a lesser dose of the drug are temporarily blocked in G2 phase (delayed mitosis) or in G2 phase (prolonged generation time). Finally daunomycin appeared to hamper the passage of G2-blocked blasts from the bone marrow to the blood, while G2-phase cells crossed freely.