CLINICAL-STUDIES WITH THE SPECIFIC PURE ANTIESTROGEN ICI-182780

We have shown that ICI 182780 inhibits the growth of metastatic tumour cells derived from patients failing treatment with tamoxifen when gro wn in vitro. In this system tamoxifen stimulates growth of tumour cell s which can be reversed by addition of ICI 182780 to tamoxifen in cult ure. In a phase I study we have demonstrated that treatment of patient s for 7 days before surgical excision of the tumour resulted in marked down regulation of ER, inhibition of growth and oestrogen-induced gen e expression. More recently we demonstrated that treatment of advanced breast cancer patients with ICI 182780, after tamoxifen failure, resu lted in a high remission rate and prolonged periods of remission with very few side-effects. These data indicate that further clinical trial s of ICI 182780 are warranted. We expect that it will show superiority over conventional endocrine therapy.