A study to find out how safe long-term treatment with fezolinetant is in women with hot flashes going through menopause

This study was for women in menopause with hot flashes. Menopause, a normal part of aging, was the time of a woman’s last period. Hot flashes can interrupt a woman’s daily life.

The purpose of this study was to find out how safe it is for these women to take fezolinetant in long term (up to 52 weeks). To do that, the study looked at the number and severity of the “adverse events.” Those were the side effects that study participants had while they were in the study.

The study treatments were fezolinetant 30 milligrams (mg) (1 tablet of fezolinetant and 1 placebo tablet) once a day, fezolinetant 45 mg (2 tablets of fezolinetant) once a day or placebo (2 tablets) once a day. (Placebo was a dummy treatment that looked like medicine but did not have any medicine in it.) Women in this study were picked for 1 of the 3 study treatments by chance alone. The study participants took study treatment for 52 weeks.

This study was “double-blinded.” That means that the study participants and the study doctors did not know who took which of the study treatments (fezolinetant 30 mg, fezolinetant 45 mg or placebo).

At weeks 2 and 4 and then once a month, the study participants went to the hospital or clinic for a check-up. They were asked about medications, side effects and how they felt. Other checks included physical exam and vital signs (heart rate, temperature and blood pressure). Blood and urine were collected for laboratory tests. At some study visits, study participants completed questionnaires that were about their quality of life. At the first and last study visits, they had a dual-energy x-ray absorptiometry (DXA for short) test done. To measure bone loss in the hips and spine, DXA created pictures of the inside of these areas with low-dose x-rays. (The dose was approximately one-tenth of the amount of a normal chest x-ray.) Study participants who still had their uterus had 2 more tests done at the first and last study visits. One of the 2 tests was endometrial biopsy. This test involved removing a small amount of tissue from the inside lining of the uterus. The tissue was then checked under a microscope. The other test was transvaginal ultrasound. It used sound waves to create pictures of the organs in the pelvis. The sound waves were transmitted by a probe (transducer), which was placed inside the vagina. Study participants might have had a screening mammogram done at the first and/or last study visit. A mammogram is an x-ray picture of the breasts used to screen for breast cancer. Study participants who did not had this test done in the last 12 months had it done at the first study visit. They had done at the last study visit if they were due for their screening mammogram and their own doctor agreed.

The last check-up at the hospital or clinic was at 3 weeks after the last dose of study treatment.