Intarcia Announces Phase III Clinical Trial for Advanced Breast Cancer

Intarcia Therapeutics has initiated its CAT (Combined Anti-estrogen Therapy) study, a global, randomized Phase III study of combination hormonal therapy for the first-line treatment of advanced breast cancer.

Intarcia's objective is to test the hypothesis that its combination of atamestane plus toremifene (Fareston) will be more active than single agent therapy with letrozole (Femara) alone. This international Phase III trial, being conducted in the U.S. and Europe, is a randomized, double-blind, placebo-controlled study that will involve approximately 420 patients in each of two treatment groups. One group will receive atamestane and toremifene, and the other group will receive letrozole and placebo. Intarcia's primary goal will be to determine whether the combination therapy will increase the time to disease progression and the rate of objective response when compared to the single agent therapy.

An earlier Phase II study showed that atamestane alone is active in postmenopausal women with recurrent hormone dependent breast cancer who had failed previous tamoxifen therapies. The drug significantly lowered estrogen levels and prevented tumor growth for a median of seven months, suggesting significant antitumor activity. Toremifene was selected by Intarcia as the estrogen receptor blocker to be used with atamestane because it has been shown to be as active as tamoxifen in first line treatment of metastatic breast cancer and has 40-fold less intrinsic estrogenic activity than tamoxifen.