EndometriosisEarly Phase 1NCT03746535

Cardiovascular Disease Risk in Women With Endometriosis

A Early Phase 1 study testing Elagolix in people with Endometriosis, run by Yale University at 1 site in United States.

Completed

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

Trial summary

To test the hypothesis that estrogen suppression impairs endothelial dysfunction in endometriosis. Read more about this study

Who is it for?: Ages 18 to 45 years, women onlyHealthy volunteers can take part
Conditions the study is for: Endometriosis
What is being tested?: Elagolix
Type of treatment: Pill or oral medicine
Could I receive a placebo?: No, everyone receives an active treatment
How many people: 21 participants
Where: 1 siteUnited States
Study dates: 1 Jul 2022to 27 May 2025
Phase: Early Phase 1
Are there results?: Yes, posted in the registrySummary in the doctors' view

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 18 to 45 years
Women only
Healthy volunteers accepted
Adult

Who may be able to join

Young women between the ages of 18 and 45 years (Controls);
Young women between the ages of 18 and 45 years with endometriosis.

Who cannot join

Subjects who smoke
Subjects who have diabetes,
Subjects with sleep apnea or BP>140/90 will be excluded.
Women with endometriosis and severe acute pain requiring immediate treatment will be excluded.

Trial locations and contacts

1 site in 1 country.

United States1 site

Yale School of Medicine
New Haven, Connecticut, 06519

Other trials in United States

About this study

Official title: Mechanisms and Interventions Addressing Accelerated Cardiovascular Disease Risk in Women With Endometriosis

To test the hypothesis that estrogen suppression impairs endothelial dysfunction in endometriosis.

Read the detailed description

Our scientific premise is that in women with endometriosis, elevated cardiovascular disease risk is the result of endothelial dysfunction and chronic systemic inflammation through lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) receptor activation. This cardiovascular disease risk is exacerbated by standard estrogen suppression treatments.

Conditions: Endometriosis
Being tested: Elagolix
Keywords: endometriosis, elagolix, ntradermal microdialysis, GnRH antagonist, flow mediated vasodilation
Medical subject headings: Endometriosis

What participants receive

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

ElagolixDrug
Elagolix, 400 mg/day oral, 2X200 mg tablets/day for 4 days.

Study groups in NCT03746535
Study group	Role	What they receive
patients without endometriosis	Active comparator	Control subjects will be healthy women, with regular menses every 26-34 days. Subjects will be excluded if they have any symptoms of endometriosis, including severe dysmenorrhea or progressive cyclic pelvic pain or prior surgery showing evidence of endometriosis Receives: Drug: Elagolix
patients with endometriosis	Experimental	Endometriosis will be diagnosed by history of the disease seen at the time of prior surgery or will be diagnosed by classic clinical symptoms of the disease (cyclic progressive pelvic pain) using prior surgical report reviewed by Dr. Taylor. Receives: Drug: Elagolix

What is being measured

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

Flow Mediated Vasodilation
Blood flow velocity measured using the Sonoscope S2 ultrasound imaging system. Percent change is measured pre and post cuff inflation at baseline and during intervention
Measured: Baseline and during intervention (1 month)
Microdialysis Perfusions of Acetylcholine ED50
Skin blood responses to perfusion of acetylcholine at baseline and during intervention
Measured: Baseline and during intervention (1 month)
Microdialysis Perfusions of Acetylcholine Hill Slope
hill slope of skin blood flow dose perfusions of acetylcholine into skin
Measured: baseline and during intervention (1 month)
Microdialysis Perfusions of Estradiol ED50
Skin blood responses to perfusion of estradiol at baseline and during intervention
Measured: Baseline and during intervention (1 month)
Microdialysis Perfusions of Estradiol- Hill Slope
hill slope of skin blood flow dose perfusions of estradiol into skin
Measured: Baseline and during intervention (1 month)

Secondary outcomes (3)

Plasma Estrogen Concentration
blood draw, this is done on baseline and during intervention
Measured: Baseline and during intervention (1 month)
Serum Concentration Progesterone
Serum concentration progesterone at baseline and during intervention
Measured: Baseline and During intervention (1 month)
Serum Sex Hormone Binding Globulin Concentration
Serum concentration of sex hormone binding globulin concentration taken a baseline and during intervention
Measured: Baseline and During intervention (1 month)

Timeline

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

1 Jul 202227 May 2025

First posted19 Nov 2018
Study start1 Jul 2022
Primary completion27 May 2025
Study completion27 May 2025

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
Other trials for EndometriosisStudies of the same condition, open and under way.
More trials run by Yale UniversityThe sponsor's other registered studies.
What the trial phases meanHow a treatment moves from first tests in people to approval.

More details

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

Study design

Study type: Interventional
Phase: Early Phase 1
Primary purpose: Treatment
Allocation: Non-randomised
Intervention model: Parallel groups
Model description: 2 cohort clinical trial
Masking: None (open label)
Enrolment: 21 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT03746535
Sponsor's protocol ID: 2000022193
Other IDs: 1R01HL161000-01
Status last verified: Sep 2026
First submitted: 17 Oct 2018
Last updated: 16 Oct 2026
Results posted: Yes, on ClinicalTrials.gov
Data monitoring committee: Yes
FDA-regulated drug: Yes
FDA-regulated device: No

Want to know more?

The sponsor has not listed a contact. The official record may have more details.

Talk to your doctor first and take this page with you. Only the study team can confirm whether you can join.

Questions to ask the study team

What is the study trying to find out?
What would I need to do, and how often would I visit?
Could I receive a placebo instead of the treatment?
What are the possible risks and benefits for me?
Will it cost me anything? Are travel or time paid for?
Can I keep seeing my own doctor during the study?
What happens when the study ends?

See locations

RecruitingPhase 1
Phase Ia Trial of HHK001 Compared With Enantone in Patients With Endometriosis
Endometriosis
Active, not recruiting
Feasibility of a Mindfulness Intervention for Endometriosis Surgery
Endometriosis, Pain
Recruiting
Trial Evaluating Nutritional Fiber in Digestive Symptoms of Endometriosis
Endometriosis, Microbiome Dysbiosis
RecruitingObservational study
Retinal Imaging for Systemic Inflammation in Endometriosis
Endometriosis
Active, not recruiting
Nutritional Intervention for Endometriosis
Endometriosis

All Endometriosis trials

Study at a glance

From the registry record, last updated by the sponsor on 16 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: Mechanisms and Interventions Addressing Accelerated Cardiovascular Disease Risk in Women With Endometriosis
ClinicalTrials.gov ID: NCT03746535
Acronym / sponsor ID: 2000022193
Conditions: Endometriosis
Keywords: endometriosis, elagolix, ntradermal microdialysis, GnRH antagonist, flow mediated vasodilation
Phase: Early Phase 1
Study type: Interventional
Recruitment status: Completed
Enrolment: 21 participants (actual)
Lead sponsor: Yale UniversityUniversity, hospital or other
Collaborators: National Heart, Lung, and Blood Institute (NHLBI)
Study start: 1 Jul 2022 (actual)
Primary completion: 27 May 2025 (actual)
Study completion: 27 May 2025 (actual)
First posted: 19 Nov 2018 (actual)
Results: Posted 16 Oct 2026

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

To test the hypothesis that estrogen suppression impairs endothelial dysfunction in endometriosis.

Detailed description

Study design

Primary purpose: Treatment
Allocation: Non-randomised
Intervention model: Parallel groups
Masking: None (open label)
Number of arms: 2
Model description: 2 cohort clinical trial

Arm	Type	Receives
patients without endometriosis	Active comparator	Drug: ElagolixControl subjects will be healthy women, with regular menses every 26-34 days. Subjects will be excluded if they have any symptoms of endometriosis, including severe dysmenorrhea or progressive cyclic pelvic pain or prior surgery showing evidence of endometriosis
patients with endometriosis	Experimental	Drug: ElagolixEndometriosis will be diagnosed by history of the disease seen at the time of prior surgery or will be diagnosed by classic clinical symptoms of the disease (cyclic progressive pelvic pain) using prior surgical report reviewed by Dr. Taylor.

Who may qualify

Ages: 18 to 45 years
Sex: Female only
Healthy volunteers: Accepted
Age groups: Adult

Key inclusion criteria (2 listed)

Young women between the ages of 18 and 45 years (Controls);
Young women between the ages of 18 and 45 years with endometriosis.

Key exclusion criteria (4 listed)

Subjects who smoke
Subjects who have diabetes,
Subjects with sleep apnea or BP>140/90 will be excluded.
Women with endometriosis and severe acute pain requiring immediate treatment will be excluded.

Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.

Interventions

Intervention	Type	Arms
ElagolixElagolix, 400 mg/day oral, 2X200 mg tablets/day for 4 days.	Drug	patients with endometriosis, patients without endometriosis

Primary outcome

Flow Mediated Vasodilation
Time frame: Baseline and during intervention (1 month)
Blood flow velocity measured using the Sonoscope S2 ultrasound imaging system. Percent change is measured pre and post cuff inflation at baseline and during intervention
Microdialysis Perfusions of Acetylcholine ED50
Time frame: Baseline and during intervention (1 month)
Skin blood responses to perfusion of acetylcholine at baseline and during intervention
Microdialysis Perfusions of Acetylcholine Hill Slope
Time frame: baseline and during intervention (1 month)
hill slope of skin blood flow dose perfusions of acetylcholine into skin
Microdialysis Perfusions of Estradiol ED50
Time frame: Baseline and during intervention (1 month)
Skin blood responses to perfusion of estradiol at baseline and during intervention
Microdialysis Perfusions of Estradiol- Hill Slope
Time frame: Baseline and during intervention (1 month)
hill slope of skin blood flow dose perfusions of estradiol into skin

3 secondary outcomes

Plasma Estrogen Concentration
Time frame: Baseline and during intervention (1 month)
Serum Concentration Progesterone
Time frame: Baseline and During intervention (1 month)
Serum Sex Hormone Binding Globulin Concentration
Time frame: Baseline and During intervention (1 month)

Results and safety

Results posted to the registry on 16 Oct 2026, as reported by the sponsor. Figures are copied from the record, not re-analysed. Full results on ClinicalTrials.gov.

Participant flow

Group	Started	Completed
Patients Without Endometriosis	13	12
Patients With Endometriosis	8	8

Primary outcome: Flow Mediated Vasodilation

Time frame: Baseline and during intervention (1 month). Mean (Standard Deviation). Unit: percent change

Measure	Patients Without Endometriosis n = 12	Patients With Endometriosis n = 8
Baseline	12.5 (4.25)	9.49 (4.17)
During intervention	9.57 (4.57)	7.62 (4.19)

Patients Without Endometriosis vs Patients With Endometriosis: Mean Difference (Final Values): 4, p = 0.05, ANOVA

Primary outcome: Microdialysis Perfusions of Acetylcholine ED50

Time frame: Baseline and during intervention (1 month). Mean (Standard Deviation). Unit: log M

Measure	Patients Without Endometriosis n = 12	Patients With Endometriosis n = 8
Baseline	-3.38 (1.08)	-2.83 (1.20)
During intervention	-2.49 (0.89)	-3.49 (1.50)

Primary outcome: Microdialysis Perfusions of Acetylcholine Hill Slope

Time frame: baseline and during intervention (1 month). Mean (Standard Deviation). Unit: Moles/%variability

Measure	Patients Without Endometriosis n = 12	Patients With Endometriosis n = 8
Baseline	1.38 (2.20)	2.35 (1.80)
During intervention	2.31 (1.85)	2.78 (1.43)

Primary outcome: Microdialysis Perfusions of Estradiol ED50

Time frame: Baseline and during intervention (1 month). Mean (Standard Deviation). Unit: nanoMolar

Measure	Patients Without Endometriosis n = 12	Patients With Endometriosis n = 8
Baseline	1.88 (0.08)	1.95 (0.24)
During interventions	1.80 (0.13)	2.90 (0.27)

3 secondary outcomes are reported in the full results.

Adverse events

Time frame: 1 month. Other adverse events reported at 0% frequency or more

Group	Serious adverse events	Other adverse events	Deaths
Patients Without Endometriosis	0 of 13 (0%)	0 of 13 (0%)	0 of 13
Patients With Endometriosis	0 of 8 (0%)	0 of 8 (0%)	0 of 8

Limitations and caveats (from the sponsor): This was a difficult study to recruit subjects into because many women with endometriosis are already taking hormonal treatments so had to be excluded. Thus, completing the study took longer than expected.

Loading the posted results from ClinicalTrials.gov…

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 16 Oct 2026.
Posted resultsParticipant flow, baseline, all outcome measures and adverse events.

Related trials for Endometriosis

RecruitingPhase 1
Phase Ia Trial of HHK001 Compared With Enantone in Patients With Endometriosis
Endometriosis
Active, not recruiting
Feasibility of a Mindfulness Intervention for Endometriosis Surgery
Endometriosis, Pain
Recruiting
Trial Evaluating Nutritional Fiber in Digestive Symptoms of Endometriosis
Endometriosis, Microbiome Dysbiosis
RecruitingObservational study
Retinal Imaging for Systemic Inflammation in Endometriosis
Endometriosis
Active, not recruiting
Nutritional Intervention for Endometriosis
Endometriosis

Referral and contact

AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.

Nina Stachenfeld, MD principal investigator

Yale University

1 site in 1 country: see every site and its status.

Questions about this trial

What is this clinical trial studying?

A Early Phase 1 study testing Elagolix in people with Endometriosis, run by Yale University at 1 site in United States.

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 2 inclusion and 4 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 16 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in United States. 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?

Early Phase 1 (sometimes called Phase 0) studies give a very small amount of a treatment to a few people, mainly to see how the body handles it.

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

Are results available for this study?

Yes. Results are posted in the registry (first posted 16 Oct 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.

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?

Flow Mediated Vasodilation (time frame: Baseline and during intervention (1 month)). The study lists 5 primary outcomes in all. 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 NCT03746535.

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 16 Oct 2026; AzTrials last refreshed its copy on 26 Oct 2026.