Dallas, TX—Heavy menstrual bleeding from fibroid tumors was successfully reduced with a new oral gonadotropin-releasing hormone receptor antagonist.

Benign fibroids are the most common gynecologic tumors in the United States and disproportionately affect African-Americans, according to results of an international clinical trial published in the journal Obstetrics & Gynecology.

University of Texas Southwestern–led researchers point out that, in the five-country study, elagolix reduced bleeding in more than 90% percent of premenopausal women who had heavy menstrual bleeding associated with uterine leiomyomas that often appear during childbearing years.

Lead author Bruce Carr, MD, professor of Obstetrics and Gynecology at UT Southwestern Medical Center, suggested that a nonsurgical option should be well-received for a condition for which surgery has been the best option for some patients, resulting in hysterectomy or myomectomy.

“There are no orally approved drugs to decrease bleeding and prevent anemia in women with these tumors,” explained Carr. “Now, there is a medical option for this devastating disease that affects up to 75 percent of women.”

The study notes that prescribing hormone therapy together with the new drug prevented estrogen-deficiency induced side effects, such as hot flashes and bone loss.

About 80% percent of African-American women and approximately 70% of white women will have uterine fibroids by age 50 years, although the tumors cause symptoms in only about a quarter to half of women who have them, according to background information in the article.

The double-blind, randomized, placebo-controlled, parallel-group study, conducted from April 8, 2013, to December 8, 2015, and enrolling 571 women, evaluated efficacy and safety of elagolix in cohorts 1 (300 mg twice daily) and 2 (600 mg daily) with four arms per cohort: placebo, elagolixalone, elagolix with 0.5 mg estradiol/0.1 norethindrone acetate, and elagolix with 1.0 mg estradiol/0.5 mg norethindrone acetate.

The primary end point was defined as the percentage of women, mean age 43 years and 70% African-American, who had less than 80 mL menstrual blood loss and 50% or greater reduction in menstrual blood loss from baseline to the last 28 days of treatment. Assessed for safety were issues such as changes in bone mineral density.

Results from 86 sites in the United States and other countries indicate that primary end point responder rates in cohort 1 (cohort 2) were:
• 92% (90%) for elagolix alone
• 85% (73%) for elagolix with 0.5 mg estradiol/0.1 mg norethindrone acetate
• 79% (82%) for elagolix with 1.0 mg estradiol/0.5 mg norethindrone acetate
• 27% (32%) for placebo (all P <.001 vs placebo) 

On the downside, researchers report that elagolix groups had significant decreases compared with placebo in lumbar-spine bone mineral density, which was attenuated by adding 1.0 mg estradiol/0.5 mg norethindrone acetate.

“Elagolix with and without add-back significantly reduced menstrual blood loss in women with uterine leiomyomas,” study authors conclude. “Add-back therapy reduced hypoestrogenic effects on bone mineral density.”

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