Efficacy & Safety Study of Relugolix in Women With Heavy Menstrual Bleeding Associated With Uterine Fibroids

The goal of this clinical trial is to determine the benefit of relugolix 40 milligrams (mg) once a day compared with placebo in heavy menstrual bleeding associated with uterine fibroids. The main question\[s\] it aims to answer are:

* the benefit of relugolix 40 mg once daily in women with heavy menstrual bleeding associated with uterine fibroids
* the safety of relugolix 40 mg once daily in women with heavy menstrual bleeding associated with uterine fibroids

This study is a phase 3 multicenter, randomized, double-blind, placebo-controlled, parallel-designed efficacy and safety study to evaluate 12 weeks of oral daily relugolix 40 mg co-administered with megestrol acetate 1 mg and medroxyprogesterone acetate 2 mg (the treatment group) or 12 weeks of daily oral relugolix 40 mg placebo (the placebo group) followed by 12 weeks of daily oral relugolix 40 mg co-administered with megestrol acetate 1 mg and medroxyprogesterone acetate 2 mg.

Approximately 120 women with heavy menstrual bleeding associated with uterine fibroids will be enrolled and randomized 2:1 to the treatment group (N=80) or placebo group (N=40).

Stratification variables will include mean screening menstrual blood loss volume (\< 225 mL versus ≥ 225 mL) by the alkaline hematin method.

The study consists of a screening period (up to \~13 weeks), a double-blind treatment period (12 weeks), an open-label treatment period (12 weeks) and a follow-up period (4w).

Safety will be assessed throughout the study by monitoring adverse events, vital signs, physical examinations, clinical laboratory tests, 12-lead electrocardiograms, and assessments of bone mineral density.

Eligibility Criteria:
Inclusion Criteria:

* Premenopausal female aged 18 to 50 years old (inclusive)
* Diagnosis of uterine fibroids confirmed by transvaginal ultrasound during the screening period
* Heavy menstrual bleeding caused by uterine fibroids
* Breast ultrasound results during the screening period meet the BI-RADS classification of 1 to 3
* Able to understand and comply with the study procedures and methods, voluntarily participate in this trial, and sign the informed consent form in writing

Exclusion Criteria:

* History of bilateral oophorectomy, or planned to undergo hysterectomy, bilateral oophorectomy, or other surgical procedures during the study period.
* Previous treatment with gonadotropin-releasing hormone (GnRH) agonists or GnRH antagonists for uterine fibroids has failed.
* History of or current osteoporosis or other metabolic bone disease.
* History of malignant tumor within 5 years prior to screening, except for cured skin cancer, basal cell carcinoma, and other localized malignant tumors.
* History of drug abuse, alcohol abuse, or drug dependence within 2 years prior to screening.
* Presence of an in situ copper intrauterine device (IUD) or a progestin-containing IUD implant/subdermal contraceptive implant during the screening period; subjects who can remove the IUD/subdermal contraceptive implant at least 1 month before enrollment may be allowed to participate.
* Baseline bone mineral density Z-score of \< -2.0 at the lumbar spine, total hip, or femoral neck during the screening period.
* Any other factors that the investigator deems unsuitable for participation in this trial.