Effect of mitoxantrone on human chronic myeloid leukemia cells in vitro, combined with hyperthermia

Mitoxantrone, a new anticancer drug has DNA-binding properties similar to anthracycline antibiotics. In the present studies, effect of the drug has been tested in vitro on human chronic myeloid leukemia cells at 37 degrees C and 42 degrees C. Inhibition of 3H-tritiated thymidine incorporation in the drug-treated cells compared with untreated cells has been used as the parameter of cytotoxicity of the drug and hyperthermia. Cell samples from 11 CML patients who did not receive any chemotherapy showed less response to the drug at 0.5 micrograms/ml and 1 microgram/ml at 37 degrees C. Exposure of CML cells to 42 degrees C for 2 h indicated 13 to 44% inhibition in 3H-TdR incorporation. However, when CML cells were exposed to mitoxantrone for 2 h at 42 degrees C the 3H-thymidine incorporation was inhibited to the extent of 27 to 71%, indicating greater cellular damage with this combination.