Quinidine as a resistance modulator of epirubicin in advanced breast cancer: mature results of a placebo-controlled randomized trial.

Abstract

Quinidine at this dose does not significantly alter the toxicity profile, response rate, or survival after epirubicin chemotherapy in patients with advanced breast cancer. This may be due to ineffective modulation of P-glycoprotein by quinidine or the lack of expression of mdr-1 in a sufficient proportion of cells in these tumors, or alternative mechanisms underlying resistance to epirubicin.