The primary objective of this study is to assess the safety, tolerability, pharmacokinetics and pharmacodynamics of SHR7280 tablets in premenopausal subjects with endometriosis. In addition, this study will provide information on efficacy of SHR7280 tablets in premenopausal subjects with endometriosis.

Endometriosis is a common disease, affecting 5-10% of women of reproductive age . It is an estrogen-dependent and estrogen-driven disease and so hormonal manipulation and suppression of estrogen production form the basis of the majority of medical treatment. The primary objective of this study is to assess the safety, tolerability, pharmacokinetics and pharmacodynamics of SHR7280 tablets in premenopausal subjects with endometriosis. In addition, this study will provide information on efficacy of SHR7280 tablets in premenopausal subjects with endometriosis.

Inclusion Criteria:

Phase I/II

1. premenopausal females, aged 18-45
2. History of regular menstrual cycles
3. Endometriosis participant diagnosed by surgical (e.g., laparoscopy or laparotomy) or by magnetic resonance imaging or ultrasonography.
4. Participant must agree to use only protocol specified rescue analgesics during the Screening and Treatment Periods for endometriosis-associated pain.
5. Participant in general good health. No clinically significant findings in laboratory parameters or clinically significant abnormality on X-ray Phase I (only) Participant has mild or moderate pelvic pain associated with endometriosis at Screening.

Phase II(only) Participant has moderate or severe pelvic pain associated with endometriosis at Screening.

Exclusion Criteria:

Phase I/II

1. Subjects with severe trauma or surgery within 6 months prior to the screening；
2. Known blood donation within 30 days pre-dose; donating≥200 ml of blood 2 months pre-dose;
3. Pregnant or Serum β-human chorionic gonadotropin (hCG)> 5 Million International Units(mIU)/mL at screening or baseline
4. Pregnant or breast feeding ;
5. Have pelvic pain that is not caused by endometriosis
6. Abnormal uterine bleeding
7. Are currently receiving gonadotropin-releasing hormone (GnRH) agonist, a GnRH antagonist or danazol or have received any of these agents within 6 months of the start of screening.
8. Are currently receiving subcutaneous medroxyprogesterone acetate (DMPA-SC) or intramuscular medroxyprogesterone acetate (DMPA-IM) or have received any of these agents within 3 months of the start of screening.
9. Are currently using hormonal contraception or other forms of hormonal therapy or received such treatment within 2 months of the start of screening.

Phase I (only) one month prior to screening involved in any drug or medical device clinical subjects, or within 5 half-life of drugs before screening; Phase II (only) Screening dual-energy x-ray absorptiometry (DXA) scan results of the lumbar spine, femoral neck, or total hip bone mineral density corresponding to 1.5 or more standard deviations below normal (T-score at or below -1.5)