Do you or a loved one suffer
from moderate to severe
vasomotor symptoms
(hot flashes) associated
with menopause?

Then you may be interested in the SKYLIGHT clinical study. It will test how well an investigational drug works and how safe it is. This website will tell you what you need to know about being in the study. It will also tell you where the study takes place.

About the SKYLIGHT study

Who is this clinical study for?

Postmenopausal women with vasomotor symptoms (hot flashes)

This website is for US residents only. Residents outside the US please go to for more information.

Study Title

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

Identifier: NCT04003389

Please note that if you decide to participate in the study you can also choose to stop at any time.

Things to think about before taking part in a clinical study:

Being part of a clinical study takes time and effort for the people in it and their caregivers. Here is important information you should know about the SKYLIGHT study:

Clinic Visits
The number of clinic visits. Number of visits may be different for each participant. You can talk to the study doctor to learn more.

Number of Skylight clinical visits

What do you need to know about the study?

Purpose of the study

Conditions being studied
The disease, disorder, syndrome, illness, or injury that is being studied.

  • Hot Flashes

Drugs being tested in the study

  • placebo
  • fezolinetant

Facts about the study
Clinical studies happen in phases. Each phase has a different goal that helps researchers answer specific questions. For example, in Phase 2, the goal is to find out if the medicine works and learn more about its safety. In Phase 3, the goal is to test the medicine compared to different treatments. Also, researchers can learn more about the medicine's side effects and how to use it safely.

Trial phase


Searching for



What can you expect from being in this study?

Being part of the SKYLIGHT study takes time and effort for the person in it and their caregiver. You may:

  • be in the study for up to 13 months
  • need to travel to the closest clinical trial site location every 4 or 6 weeks
  • receive pills you take by mouth once or twice daily
  • need blood taken or other tests such as heart monitoring. This helps researchers learn how the medicine is working
  • receive placebo. Placebo is something that looks like the drug but does not contain any drug

This drug is experimental. Because of that, not all risks are known before starting a clinical trial. People who are in the study may stop at any time.

Why is this study being done?

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

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

The study treatments are fezolinetant low dose (1 tablet of fezolinetant and 1 placebo tablet) once a day, fezolinetant high dose (2 tablets of fezolinetant) once a day or placebo (2 tablets) once a day. (Placebo is a dummy treatment that looks like medicine but does not have any medicine in it.)

Women in this study will be picked for 1 of the 3 study treatments by chance alone. The study participants will take study treatment for 52 weeks.

This study is “double-blinded.” That means that the study participants and the study doctors do not know who takes which of the study treatments (fezolinetant low dose, fezolinetant high dose or placebo).

At weeks 2 and 4 and then once a month, the study participants will go the hospital or clinic for a check-up. They will be asked about medications, side effects and how they feel. Other checks will include physical exam and vital signs (heart rate, temperature and blood pressure). Blood and urine will be collected for laboratory tests. At some study visits, study participants will complete questionnaires that are about their quality of life. At the first and last study visits, they will have a dual-energy x-ray absorptiometry (DXA for short) test done. To measure bone loss in the hips and spine, DXA creates pictures of the inside of these areas with low-dose x-rays. (The dose is approximately one-tenth of the amount of a normal chest x-ray.) Study participants who still have their uterus will have 2 more tests done at the first and last study visits. One of the 2 tests is endometrial biopsy. This test involves removing a small amount of tissue from the inside lining of the uterus. The tissue is then checked under a microscope. The other test is transvaginal ultrasound. It uses sound waves to create pictures of the organs in the pelvis. The sound waves are transmitted by a probe (transducer), which is placed inside the vagina. Study participants may have 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 have this test done in the last 12 months will have it done at the first study visit. They will have it done at the last study visit if they are due for their screening mammogram and their own doctor agrees.

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

Could you be a candidate
for this study?

Answer these questions to learn more.

Are you a woman between the ages of 40 and 65?
Around how many hot flashes do you experience per 24 hour period?
Are you currently taking any hormonal treatments for hot flashes?
Would you be willing to stop in order to join this study?
Have you been previously diagnosed with cancer other than basal cell carcinoma?

Based on your answers, you may be a candidate for this study.
To find the study center closest to you, enter your location below.

Based on your answers, this study may not be right for you. Please talk to your doctor if you still have questions about the SKYLIGHT study. You can also search for other clinical studies that may be of interest to you.

Clinical study centers
closest to you

Invalid address or ZIP code.
  • 10 miles
  • 25 miles
  • 50 miles
  • 100 miles
  • 200 miles

Please fill in your required information to request a call back from our call center or from a study center of your choice

All fields are required.

Best time to contact you (normally within two business days):

Thank you for your interest.
We will submit your information
the SKYLIGHT Patient
Recruitment Call Center.

The Call Center will call you to
confirm within 2 business days.
They will then connect you
with a local site currently
conducting the study.

There was an error trying to submit the form. Please try again.

If you have questions, please call the Astellas Medical Information team at 1 (800) 727‑7003.
We are available Monday–Friday,
8:00 AM–4:30 PM CT.