FULVESTRANT: A REVIEW OF ITS DEVELOPMENT, PRE‐CLINICAL AND CLINICAL DATA

Hormone therapy is the most important systemic treatment of hormone receptor-positive breast cancer at all stages. Selective oestrogen receptor modulators (SERMs), such as tamoxifen, the mainstay of hormone receptor positive breast cancer manipulation for many years, are limited by their agonist actions. Oestrogen-like activity of these drugs may stimulate cancer growth such as in the endometrium and is a mechanism of resistance in breast cancer. Fulvestrant, the first of a new class of drugs, an oestrogen receptor down regulator, may have advantages over tamoxifen in the treatment of oestrogen-dependent disease. The pre-clinical development and early clinical data of fulvestrant are reviewed. Fulvestrant was as effective as the aromatase inhibitor anastrazole in second-line advanced breast cancer. The phase III trial of fulvestrant versus tamoxifen, as first-line treatment for metastatic breast cancer, has completed accrual and is maturing. Fulvestrant has useful activity against breast cancer as well as a favourable side-effect profile and is likely to represent a useful addition to the fight against hormone dependent breast cancer. Its place will be better defined by ongoing clinical trials.