Borrelidin has limited anti-cancer effects in bcl-2 overexpressing breast cancer and leukemia cells and reveals toxicity in non-malignant breast epithelial cells.

Clinically effective anti-cancer drugs have to tread a narrow line between selective cytotoxicity on tumor cells and tolerable adverse effects against healthy tissues. This causes the failure of many potential cancer drugs in advanced clinical trials, hence signifying the importance of a comprehensive initial estimate of the cytotoxicity of prospective anti-cancer drugs in preclinical studies. In this study, the cytotoxicity of borrelidin, a macrolide antibiotic with a high cytotoxic selectivity for proliferating endothelial cells and leukemia cells, was tested on malignant and non-malignant breast cells.