Current perspectives of epothilones in breast cancer

Taxanes have been broadly used in the treatment of breast cancer. However, the majority of initially responsive breast cancer patients eventually develop resistance to taxanes (acquired resistance) and a non-negligible percentage of patients are primarily resistant to these agents (de novo resistance). Additionally, taxanes require pre-medication and may cause important side effects such as febrile neutropenia and neuropathy. Hence, new agents with better efficacy and/or a better toxicity profile and/or are easier to administer need to be developed. Epothilones are a novel class of microtubule-targeting agents sharing a similar mechanism of action to the taxanes and having a more potent antiproliferative activity in various tumour cells lines, particularly in cases of taxane-resistant breast cancer. This review will focus on clinical development of epothilones in breast cancer, particularly ixabepilone which is in the late stages of development, their potential impact in clinical practice, advantages and limitations.