A Phase 3b Study to Evaluate the Safety and Efficacy of Elagolix in Combination With Combined Oral Contraceptives in Premenopausal Women With Documented Endometriosis and Associated Moderate to Severe Pain

  • End date
    Feb 23, 2026
  • participants needed
  • sponsor
Updated on 28 October 2022
combined oral contraceptives


Endometriosis is a painful disorder of the uterus affecting 6-10% of women of childbearing age. Endometriosis affects daily activities, social relationships, sexuality and sexual activity, and mental health. This study will evaluate how well elagolix in combination with combined oral contraceptives (COC) works within the body and/or how safe it is compared to placebo (does not contain treatment drug). This study will assess the dysmenorrhea (painful periods) response in participants with endometriosis and associated pain.

Elagolix is an approved drug for the management of moderate to severe pain associated with endometriosis. Participants are randomly put in 1 of 3 groups, called treatment arms. Each group receives a different treatment. There is a 1 in 3 chance that participants will be assigned to placebo. Adult female participants who still have periods with a diagnosis of endometriosis will be enrolled. Around 800 participants will be enrolled in the study at multiple sites in the United States, including Puerto Rico.

Participants will receive oral elagolix or placebo tablets in combination with combined oral contraceptive (COC) or placebo capsules for 3 months. All the participants will receive elagolix tablets in combination with COC tablets from Month 4 through Month 18.

There will be higher treatment burden for participants in this trial compared to their standard of care. Participants will attend regular visits during the course of the study at a hospital or clinic. The effect of the treatment will be checked by medical assessments, blood tests, checking for side effects and completing questionnaires.

Condition Endometriosis
Treatment Elagolix, Placebo for Elagolix, Combined Oral Contraceptive (COC), Placebo for COC
Clinical Study IdentifierNCT04333576
Last Modified on28 October 2022


Yes No Not Sure

Inclusion Criteria

Documented surgical confirmation of endometriosis and associated moderate to severe pain
Participants must agree to use dual non-hormonal methods of contraception consistently during washout (if applicable), screening, and 3-month double-blind placebo-controlled treatment periods of the study
Participant, in the investigator's opinion must be an appropriate candidate to receive combined oral contraceptives (COCs)

Exclusion Criteria

Pregnant or breastfeeding or planning a pregnancy until completion of the study
Surgical history of hysterectomy or bilateral oophorectomy
Participant has osteoporosis or other metabolic bone disease or clinically significant gynecological findings from Screening
Participant has any other active chronic pain condition that would interfere with their assessment of endometriosis-related pain
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If you are confirmed eligible after full screening, you will be required to understand and sign the informed consent if you decide to enroll in the study. Once enrolled you may be asked to make scheduled visits over a period of time.

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