Study of BEBT-209 in Combination With Fulvestrant Versus Placebo in Combination With Fulvestrant in Patients With HR+/HER2- Locally Advanced or Metastatic Breast Cancer Who Have Progressed After Prior Endocrine Therapy

Oral, 75 mg per dose, twice daily, in a 28-day cycle. Continuous dosing from day 1 to day 21, followed by a rest period from day 22 to day 28.

Oral, 75 mg per dose, twice daily, in a 28-day cycle. Continuous dosing from day 1 to day 21, followed by a rest period from day 22 to day 28.

500 mg intramuscular injection, with a 28-day treatment cycle. Administration on day 1 and day 15 of the first cycle, and then on day 1 of each subsequent cycle.