Relugolix for Endometriosis Associated Pain (RELAX)

An Ambispective, Single-center Observational Study Evaluating the Effectiveness of Relugolix Combination Therapy in Reducing Endometriosis-associated Pain Over 24 Weeks in a Real-world Clinical Setting

Endometriosis is a chronic, estrogen-dependent condition frequently associated with pelvic pain and reduced quality of life. Relugolix combination therapy (CT), an oral GnRH receptor antagonist-based treatment, has demonstrated efficacy in randomized clinical trials, but real-world data remain limited.

The RELAX study is a single-center, ambispective observational study evaluating the effectiveness of relugolix CT in reducing endometriosis-associated pain over 24 weeks in routine clinical practice. The primary endpoint is the change from baseline in pelvic pain measured by the Visual Analog Scale (VAS). Secondary outcomes include changes in pain-related symptoms, ultrasonographic findings, patient satisfaction, and safety.

Study Overview

• Status: Not yet recruiting
• Conditions: Endometriosis; Endometriosis-related Pain; Pelvic Pain Syndrome
• Intervention / Treatment: Other: Patients with a diagnosis of endometriosis receiving treatment with Relugolix CT, according to clinical practice,

Detailed Description

Endometriosis is a chronic, estrogen-dependent condition frequently associated with pelvic pain and impaired quality of life. Despite available hormonal treatments, unmet clinical needs remain in terms of long-term efficacy and tolerability. Relugolix combination therapy (CT), an oral GnRH receptor antagonist combined with estradiol and norethisterone acetate, has shown efficacy in randomized trials, but real-world data are limited.

The RELAX study is a single-center, ambispective observational study evaluating the effectiveness of relugolix CT in routine clinical practice. Women aged 18-50 years with laparoscopically or radiologically confirmed endometriosis receiving relugolix CT will be included. Both retrospective and prospective data will be collected.

The primary objective is to assess the change from baseline in chronic pelvic pain measured by the Visual Analog Scale (VAS) after 24 weeks of treatment. Secondary outcomes include changes in dyspareunia, dyschezia, and dysuria; the proportion of patients achieving ≥30% and ≥50% reduction in VAS pain score; changes in transvaginal ultrasound findings; patient satisfaction; and safety.

This study aims to provide real-world evidence to support clinical decision-making in the management of endometriosis-associated pain.

• Study Type: Observational
• Enrollment (Estimated): 33

Contacts and Locations

• Study Contact: Name: Cristiano Rossitto; Phone Number: +390630155701; Email: cristiano.rossitto@policlinicogemelli.it

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Patients with a diagnosis of endometriosis who have been receiving treatment with Relugolix CT according to clinical practice for at least one month.

Description

Inclusion Criteria:

• Female aged between 18 and 50 years
• Endometriosis confirmed laparoscopically or radiologically (via ultrasound or MRI)
• Receiving treatment with Relugolix CT according to clinical practice for at least one month
• Pain score ≥40 on the VAS scale
• Regular menstrual cycles, (i.e., not in a menopausal or perimenopausal state)
• Signed informed consent

Exclusion Criteria:

- Menopausal status (natural or surgical)

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Evaluation of reduction of endometriosis associated pelvic pain	To evaluate the reduction of endometriosis-associated pain after a 24-week treatment period with Relugolix CT used according to current clinical practice.	24 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Evaluation of reduction in other endometriosis-associated symptoms	Change from baseline in dyspareunia, dyschezia, and dysuria after a 24-week treatment period with Relugolix CT.	24 weeks
Evaluation of reduction in VAS score	The proportion of participants achieving ≥30% and ≥50% reduction in VAS pain score after 24 weeks of treatment compared with baseline.	24 weeks
Changes in ultrasound findings.	Changes in findings from transvaginal ultrasound examinations.	24 weeks
Evaluation of patient satisfaction	Patient satisfaction with treatment, assessed using a five-category scale (very satisfied, satisfied, neither satisfied nor dissatisfied, dissatisfied, very dissatisfied) administered at the end of the 24-week period.	24 weeks

Collaborators and Investigators

• Sponsor: Fondazione Policlinico Universitario Agostino Gemelli IRCCS
• Investigators: Principal Investigator: Cristiano Rossitto, Fondazione Policlinico Universitario A. Gemelli, IRCCS

Study record dates

Study Major Dates

• Study Start (Estimated): February 25, 2026
• Primary Completion (Estimated): December 25, 2026
• Study Completion (Estimated): February 28, 2027

Study Registration Dates

• First Submitted: February 23, 2026
• First Submitted That Met QC Criteria: February 23, 2026
• First Posted (Actual): February 27, 2026

Study Record Updates

• Last Update Posted (Actual): February 27, 2026
• Last Update Submitted That Met QC Criteria: February 23, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Urogenital Diseases; Genital Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Genital Diseases, Female; Endometriosis
• Other Study ID Numbers: 26987

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No