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Hot FlashesPhase 3Starlight 3NCT06206421

A Study to Assess Long-term Safety of Fezolinetant Given to Japanese Women Going Through Menopause

A Phase 3 study testing Fezolinetant in people with Hot Flashes, run by Astellas Pharma Inc at 24 sites in Japan.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
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Trial summary

Hot flashes are the most common reason women going through menopause seek medical attention. Hormone replacement therapy, or HRT, is most often prescribed to treat hot flashes. However, HRT can't be used by all women or for as long as may be needed. Researchers want to find other ways to treat hot flashes. Read more about this study

Who is it for?
Ages 40 to 65 years, women only
Conditions the study is for
Hot Flashes
What is being tested?
Fezolinetant
Type of treatment
Pill or oral medicine
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
277 participants
Where
24 sitesJapan
Study dates
22 Feb 2024to 19 Mar 2026
Phase
Phase 3
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 40 to 65 years
  • Women only
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • Participant confirmed as menopausal per one of the following criteria at the screening visit (visit 1):
  • For a post-menopausal participant: Spontaneous amenorrhea for >/=12 consecutive months; Spontaneous amenorrhea for >/=6 months with biochemical criteria of menopause (follicle-stimulating hormone (FSH) > 40 IU/L); Having had bilateral oophorectomy >/=6 weeks prior to the screening visit (visit 1) (with or without hysterectomy); Having had hysterectomy without bilateral oophorectomy with the biochemical criteria of menopause (FSH > 40 IU/L); or Having been confirmed to be post-menopausal in the 2693-CL-0310 study.
  • For a peri-menopausal participant: Spontaneous amenorrhea for >/=60 days but < 6 consecutive months 2 times in the 2 most recent menstrual cycles with biochemical criteria of peri-menopause (FSH > 25 IU/L); or Spontaneous amenorrhea for >/=6 months but < 12 consecutive months with biochemical criteria of peri-menopause (FSH > 25 IU/L and ≤ 40 IU/L); Having had hysterectomy without bilateral oophorectomy with the biochemical criteria of peri-menopause (FSH > 25 IU/L and ≤ 40 IU/L).
  • Participant is seeking treatment for relief of vasomotor symptoms (VMS) associated with menopause.
  • Female participant:
  • Is not pregnant and at least 1 of the following conditions apply: Not a women of childbearing potential (WOCBP); WOCBP who has a negative urine pregnancy test day 1 (visit 2) and agrees to follow the contraceptive guidance from the time of informed consent through at least 21 days after final study intervention administration.
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  • Must not be breastfeeding or lactating starting at screening and throughout the investigational period and for 21 days after final study intervention administration.
  • Must not donate ova starting at first administration of study intervention and throughout the investigational period and for 21 days after final study intervention administration
  • Participant agrees not to participate in another interventional study while participating in the present study.

Who cannot join

  • Participant has a history of an undiagnosed uterine bleeding within the 6 months prior to the screening visit (visit 1).
  • Participant has a current malignant tumor or history (except for a participant who has not received treatment for malignant tumors for at least 5 years before informed consent acquisition and was not considered to have recurrence) of a malignant tumor except for non-metastatic basal cell carcinoma of the skin.
  • Participant has a medical condition or chronic disease (including history of neurological [including cognitive], hepatic, renal, cardiovascular, gastrointestinal, pulmonary [e.g., moderate asthma], endocrine, or gynecological disease) that could confound interpretation of the study outcome.
  • Participant uses a prohibited therapy (hormone therapy, hormone replacement therapy (HRT), hormonal contraceptive, any treatment for VMS [prescription medications, over-the-counter, or herbal/Kampo medicines] or strong or moderate cytochrome P450 1A2 (CYP1A2) inhibitors and is not willing to wash out or discontinue use of such drugs from screening visit (visit 1) through the follow-up visit (visit 16) or it is not medically appropriate to discontinue such drugs for the duration of the study.
  • Participant has been randomized/registered in a clinical trial with fezolinetant previously or had previous exposure to marketed fezolinetant elsewhere.
  • Participant has a present or previous history of participation in this study.
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  • Participant has received any investigational therapy within 28 days or 5 half-lives, whichever is longer, prior to screening visit (visit 1).
  • Participant has an unacceptable result from the transvaginal ultrasound (TVU) assessment at screening (i.e., full length of endometrial cavity cannot be visualized or presence of clinically significant abnormal findings).
  • Participant has documentation of a clinically significant abnormal Papanicolaou (Pap) test (or equivalent cervical cytology) within 12 months prior to the screening visit (visit 1) or at screening.
  • Participant has active liver disease, jaundice, or elevated liver aminotransferases (alanine aminotransferase (ALT) or aspartate aminotransferase (AST)), elevated total bilirubin (TBL) or direct bilirubin (DBL), elevated international normalized ratio (INR), or elevated alkaline phosphatase (ALP) at screening. A participant with mildly elevated ALT or AST up to < 1.5 × upper limit of normal (ULN) can be enrolled if TBL and DBL are normal. Participant with mildly elevated ALP (up to < 1.5 × ULN) can be enrolled if cholestatic liver disease is excluded and no cause other than fatty liver is diagnosed. Participant with Gilbert's syndrome with elevated TBL may be enrolled as long as DBL, hemoglobin and reticulocytes are normal.
  • Participant has creatinine > 1.5 × ULN or estimated glomerular filtration rate using the Modification of Diet in Renal Disease formula </=30 mL/min/1.73 m^2 at screening.
  • Participant has positive hepatitis serology panel (i.e., positive hepatitis B surface (HBs) antigen and/or positive hepatitis C virus (HCV) antibody) at screening. If HCV antibody test result is equivocal, hepatitis C virus ribonucleic acid (HCV RNA) test at study site is allowed. Participant can be enrolled if that result is normal or not abnormal.
  • Participant is not in good general health as determined on the basis of medical history and general physical examination performed at the screening; hematology parameters, biochemistry parameters, pulse rate, blood pressure, electrocardiogram (ECG) outside the reference range for the population studied, or is showing clinically relevant deviations.
  • Participant has a history of suicide attempt or suicidal behavior within 12 months prior to study enrollment or suicidal ideation within 12 months prior to study enrollment (a response of "yes" to question 4 or 5 on the suicidal ideation portion of the Columbia Suicide Severity Rating Scale (C-SSRS)), or is at significant risk to commit suicide at day 1 (visit 2).
  • Participant is unable or unwilling to complete the study procedures.
  • Participant has any condition which makes the participant unsuitable for study participation.
  • Participant has a known or suspected hypersensitivity to fezolinetant or any components of the formulation used.
  • Participant is the investigator or a member of the study site staff.
  • Participant is an employee of Astellas, the study-related contract research organizations (CROs) or site management organizations.

Trial locations and contacts

24 sites in 1 country.

24 sites in 1 country

Japan24 sites

  • Marunouchi no Mori Ladies Clinic

    Chiyoda-ku, Tokyo

  • Ginza Yoshida Medical Clinic

    Chuo-ku, Tokyo

  • Medical Corporation Asbo Tokyo Asbo Clinic

    Chuo-ku, Tokyo

  • Mori Ladies Clinic

    Fukuoka, Fukuoka

  • Medical Corp.SEIKOUKAI New Medical Research System Clinic

    Hachioji-shi, Tokyo

  • Juno Vesta Clinic hatta

    Matsudo-shi, Chiba

  • Kichijyoji Ladies Clinic

    Musashino-shi, Tokyo

  • Daido Clinic

    Nagoya, Aichi-ken

  • Shimamura Memorial Hospital

    Nerima-ku, Tokyo

  • Yukawa Women'S Clinic

    Nishi-Tokyo-shi, Tokyo

  • GyNet Medical Corporation Minamimorimachi Ladies' Clinic

    Osaka, Osaka

  • Ninomiya Ladies Clinic

    Osaka, Osaka

  • Rikako Ladies Clinic

    Osaka, Osaka

  • Tennoji Chihiro Women's Clinic

    Osaka, Osaka

  • Shimizu Ladies Clinic

    Sakai-shi, Osaka

  • Kotoni Ladies Clinic

    Sapporo, Hokkaido

  • M's Ladies Clinic

    Sapporo, Hokkaido

  • NISHIKAWA Women's Health Clinic

    Sapporo, Hokkaido

  • Chieko Yukika Lady's Clinic

    Sendai, Miyagi

  • Shimodaira Ladies Clinic

    Suginami-ku, Tokyo

  • jMOG Medical Corporation Tanabe Ladies' Clinic

    Takatsuki-shi, Osaka

  • Medical Corporation Associa Tamacenter Ladies Clinic

    Tama-Shi, Tokyo

  • Motomachi Ladies Clinic

    Yokohama, Kanagawa

  • Women's Clinic LUNA Yokohama Motomachi

    Yokohama, Kanagawa

Other trials in Japan

About this study

Official title: A Phase 3, Randomized, Placebo-controlled, Double-blind Study to Investigate the Long Term Safety of Fezolinetant in Japanese Women Suffering From Vasomotor Symptoms (Hot Flashes) Associated With Menopause

Hot flashes are the most common reason women going through menopause seek medical attention. Hormone replacement therapy, or HRT, is most often prescribed to treat hot flashes. However, HRT can't be used by all women or for as long as may be needed.

Researchers want to find other ways to treat hot flashes. Fezolinetant is a medicine to treat hot flashes in women going through menopause. Fezolinetant is an approved medicine in the US. Further studies are needed before it is available in other regions such as Asia.

Read more

In this study fezolinetant will be used to treat hot flashes in Japanese women going through menopause. This study will confirm the safety of fezolinetant and how well the women tolerate the treatment.

Women will either take fezolinetant or a placebo. This is decided by chance alone. The placebo looks like fezolinetant but will not have any medicine in it.

The women will take 1 tablet of the study medicine (fezolinetant or the placebo) once a day for up to 52 weeks.

During the study, the women will visit their study clinic for a check-up about every 4 weeks for up to 52 weeks (1 year). At each visit they will be asked if they had any medical problems. Other checks will include a medical examination and vital signs (temperature, blood pressure and pulse). At some visits, the women will have an ECG to check their heart rhythm and some blood and urine samples will be taken for laboratory tests. During a couple of visits, women who have a womb (uterus) will also have a test called a transvaginal ultrasound. A probe is gently placed inside the vagina. Sound waves will create a picture of the organs in the pelvis. This will allow the study doctor to look more closely at the uterus and surrounding organs.

The last clinic visit will be 3 weeks after the women take their final tablet of the study medicine (fezolinetant or the placebo).

Conditions
Hot Flashes
Being tested
Fezolinetant, Placebo
Keywords
menopause;, ESN364;, vasomotor symptoms;, fezolinetant;, VEOZAH™
Medical subject headings
Hot Flashes

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • FezolinetantDrug

    Also called ESN364;, VEOZAH™

    oral

  • PlaceboDrug

    oral

Study groups in NCT06206421
Study groupRoleWhat they receive
FezolinetantExperimentalParticipants will receive fezolinetant once daily for 52 weeks.
Receives: Drug: Fezolinetant
PlaceboExperimentalParticipants will receive matching placebo once daily for 52 weeks.
Receives: Drug: Placebo

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Number of participants with Adverse Events (AEs)

    An AE is any untoward medical occurrence in a patient or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention.

    An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of study intervention. This includes events related to the comparator, if applicable, and events related to the (study) procedures.

    Measured: Up to Week 55

Secondary outcomes (6)

  1. Change from baseline in endometrial thickness in post-menopausal participants

    Endometrial thickness is a measure of how thick the lining of the uterus is. Endometrial thickness will be measured by transvaginal ultrasound (TVU).

    Measured: Baseline and up to Week 52

  2. Number of participants with laboratory value abnormalities and/or AEs

    Number of participants with potentially clinically significant laboratory values.

    Measured: Up to Week 55

  3. Number of participants with vital sign abnormalities and/or AEs

    Number of participants with potentially clinically significant vital sign values.

    Measured: Up to Week 55

  4. Number of participants with electrocardiogram (ECG) abnormalities and/or AEs

    Number of participants with potentially clinically significant ECG values.

    Measured: Up to Week 52

  5. Pharmacokinetics (PK) of fezolinetant in plasma: Concentration

    Concentration will be recorded from the PK plasma samples collected.

    Measured: Up to Week 52

  6. Pharmacokinetics (PK) of metabolite ES259564 in plasma: Concentration

    Concentration will be recorded from the PK plasma samples collected.

    Measured: Up to Week 52

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted16 Jan 2024
  2. Study start22 Feb 2024
  3. Primary completion19 Mar 2026
  4. Study completion19 Mar 2026

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 3
Primary purpose
Treatment
Allocation
Randomised
Intervention model
Parallel groups
Masking
Triple blind
Who is masked
Participant, Investigator, Outcomes assessor
Enrolment
277 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT06206421
Sponsor's protocol ID
2693-CL-0311
Other IDs
jRCT2031230584
Acronym
Starlight 3
Status last verified
Mar 2026
First submitted
4 Jan 2024
Last updated
8 Apr 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
Yes: Access to anonymized individual participant level data collected during the study, in addition to study-related supporting documentation, is planned for studies conducted with approved product indications and formulations, as well as products terminated during development. Studies conducted with product indications or formulations that remain active in development are assessed after study completion to determine if Individual Participant Data can be shared. Further details on Astellas' data sharing policy can be found at https://www.clinicaltrials.astellas.com/transparency/.

Questions about this trial

What is this clinical trial studying?

A Phase 3 study testing Fezolinetant in people with Hot Flashes, run by Astellas Pharma Inc at 24 sites in Japan.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 9 inclusion and 19 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 8 Apr 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 24 sites in Japan. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Number of participants with Adverse Events (AEs) (time frame: Up to Week 55). It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT06206421.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 8 Apr 2026.

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