The primary objective of this study is to demonstrate the superior efficacy versus placebo of OBE2109 alone and in combination with add-back therapy for the reduction of heavy menstrual bleeding associated with uterine fibroids in premenopausal women.

The study is a prospective, randomized, parallel group, double-blind, placebo-controlled phase 3 study investigating the efficacy and safety of OBE2109 alone and in combination with add-back therapy for the treatment of uterine fibroids.

Subjects will be randomized to one of 5 treatment groups in a 1:1:1:1:1 ratio.

Key Inclusion Criteria:

• Premenopausal woman at screening.
• Body Mass Index ≥ 18 kg/m2.
• Menstrual cycles ≥ 21 days and ≤ 40 days.
• Presence of uterine fibroids.
• Heavy menstrual blood loss for each of the 2 menstrual periods assessed at screening using the alkaline hematin method.

Key Exclusion Criteria:

• The subject is pregnant or breast-feeding or is planning a pregnancy within the duration of the treatment period of the study.
• History of uterus surgery that would interfere with the study.
• The subject's condition is so severe that she will require surgery within 6 months regardless of the treatment provided.
• Undiagnosed abnormal uterine bleeding.
• Significant risk of osteoporosis or history of, or known osteoporosis or other metabolic bone disease.