The Effect of Verapamil on the Anti-tumour Action of Mitozantrone and Doxorubicin Against Renal Carcinoma Cells in Vitro

Ten renal carcinomas were established in culture and their sensitivity to mitozantrone +/- verapamil, as measured by (75Se) selenomethionine incorporation, was studied. The 5 tumours with spread beyond the kidney were those in which sensitivity to mitozantrone was enhanced by verapamil. With 4 of the 10 tumours and 1 further carcinoma, similar experiments were performed using doxorubicin. This drug was more active, its anti-tumour action being related to concentration. Verapamil was more effective in potentiation of doxorubicin and this action increased in proportion to the concentration of verapamil added.