Study to Evaluate the Long-Term Safety and Efficacy of Elagolix in Subjects With Moderate to Severe Endometriosis-Associated Pain

• Endometriosis Associated Pain [ Time Frame: Month 6 of Treatment Period ] [ Designated as safety issue: No ]
  Proportion of responders based on reduction from baseline in study M12-665 (NCT01620528)
  
  
• Bone Mineral Density (DXA Scan) [ Time Frame: Month 6 of Treatment Period ] [ Designated as safety issue: Yes ]
  Change from baseline in study M12-665 (NCT01620528)
  
  
• Bone Mineral Density (DXA Scan) [ Time Frame: Month 6 of Follow-up Period ] [ Designated as safety issue: Yes ]
  Change from baseline in study M12-665 (NCT01620528)
  
  
• Bone Mineral Density (DXA Scan) [ Time Frame: Month 12 of Follow-up Period ] [ Designated as safety issue: Yes ]
  Change from baseline in study M12-665 (NCT01620528)
  
  
• Endometrial Biopsy [ Time Frame: Month 6 of Treatment Period ] [ Designated as safety issue: Yes ]
  Percent of subjects in each diagnostic category
  
  
• Transvaginal Ultrasound (TVU) [ Time Frame: Month 6 of Treatment Period ] [ Designated as safety issue: Yes ]
  Change from baseline in study M12-665 (NCT01620528) in endometrial thickness; percent of subjects with ovarian cyst.
  
  

• Clinical Laboratory Tests (standard laboratory values including hormones) [ Time Frame: Month 3 of Treatment Period ] [ Designated as safety issue: Yes ]
  Change from baseline in study M12-665 (NCT01620528)
  
  
• Clinical Laboratory Tests (standard laboratory values including hormones) [ Time Frame: Month 6 of Treatment Period ] [ Designated as safety issue: Yes ]
  Change from baseline in study M12-665 (NCT01620528)
  
  
• Clinical Laboratory Tests (standard laboratory values including hormones) [ Time Frame: Month 3 of Follow-up Period ] [ Designated as safety issue: Yes ]
  Change from baseline in study M12-665 (NCT01620528)
  
  
• Number of study subjects with Adverse Events [ Time Frame: Up to Month 18 ] [ Designated as safety issue: Yes ]
  Proportion of subjects reporting Adverse Events
  
  

This is a Phase 3 multicenter, double blind randomized study to assess the continued safety and efficacy of two doses of elagolix (Dose 1 and Dose 2) in premenopausal women with moderate to severe endometriosis-associated pain who completed the 6 month treatment period in the pivotal study M12-665 (NCT01620528). Approximately 500 subjects are expected to enroll at approximately 170 sites. The study consists of 2 periods: 1.) a 6 month Treatment Period and 2.) a post treatment Follow-up period of up to 12 months (if applicable). An electronic diary will be used to collect endometriosis-associated pain, uterine bleeding, and analgesic medication use for endometriosis associated pain on a daily basis. Pregnancy testing will be performed monthly throughout the study. Subjects will be required to use non-hormonal dual contraceptive during the study and will be counsel on appropriate and effective forms of birth control to promote pregnancy prevention.