RELATIVE CYTOTOXICITIES OF ADRIAMYCIN AND EPIRUBICIN IN COMBINATION WITH LONIDAMINE AGAINST HUMAN BLADDER-CANCER CELL-LINES

We have used a panel of bladder cancer cell lines to compare the toxic ities of Adriamycin and epirubicin, two drugs used intravesically to t reat superficial transitional cell cancer (TCC) of the bladder, alone and in combination with lonidamine, an agent known to be active agains t anthracycline-resistant disease. Comparing concentrations reducing c olony-forming ability by 50%, epirubicin and Adriamycin were similar i n their cytotoxicities, although epirubicin was more potent against ev ery line except an Adriamycin-resistant subline. Combinations of the t wo drugs with a non-cytotoxic concentration (1 mu g/ml) of lonidamine were tested using the Adriamycin-resistant subline MGH-U1R and its sen sitive parental line MGH-U1. The addition of lonidamine caused a twofo ld increase in the,sensitivity of the resistant subline to both drugs, while having no effect on the sensitivity of the parental line. The d ata indicate that this combination might be of value in anthracycline- resistant disease.