Hormone Replacement Therapy

July 15, 2002

The National Institutes of Health has halted a large multicenter trial evaluating estrogen plus progestin due to an increased risk of invasive breast cancer. The randomized, placebo-controlled estrogen/progestin component of the Women's Health Initiative (WHI) included 16,608 women ages 50 to 79 years with an intact uterus. For the estrogen/progestin group versus placebo, results showed a 26% increase in breast cancer, 41% increase in strokes, 29% increase in heart attacks and a doubling of rates of venous thromboembolism. While benefits to estrogen/progestin treatment were reported, including a 37% reduction in cases of colorectal cancer and fewer cases of hip fractures, the overall health risks were found to exceed the benefits. The study -- stopped after an average follow-up of 5.2 years -- was originally scheduled to run until 2005. A separate WHI trial is still ongoing for women without a uterus who are taking estrogen alone.

May 13, 2002

Phase I trial results suggest that Neurocrine Biosciences' orally active gonadotropin-releasing hormone (GnRH) receptor antagonist effectively suppresses leutinizing hormone (LH) levels. The randomized, double-blind, placebo-controlled, single-dose trial included 56 healthy post-menopausal women between 45 and 65 years of age. Positive pharmacokinetic data was obtained, and an initial pharmacodynamic assessment after a single dose indicated rapid suppression of circulating LH up to approximately 60% in a dose-dependent manner. Neurocrine Biosciences is developing the GnRH receptor antagonist for the treatment of women's health disorders and prostate cancer.

February 4, 2002

Study results indicate that Novartis' Femara (letrozole) is more effective than AstraZeneca's Arimidex (anastrozole) in inhibiting total body aromatization and suppressing plasma estrogen levels. The randomized trial included 12 postmenopausal women with metastatic breast cancer whose disease was suitable for treatment with an aromatase inhibitor. Results showed that on-treatment levels of aromatization were detectable in 11 of 12 subjects during treatment with Arimidex; in comparison, they were undetectable in all 12 subjects during treatment with Femara. Femara versus Arimidex treatment also suppressed mean plasma estrogen levels as follows: estrone (84.3% vs. 81.0%), estrone sulfate (98.0% vs. 93.5%) and estradiol (87.8% vs. 84.9%).