Study of Efficacy, Safety, and Pharmacokinetics of FCN-437c in Combination With Fulvestrant or Letrozole+Goserelin

FCN-437c 200mg, oral administration under fasting conditions, QD, for 21 days, with 7-day discontinuation, 28 days for 1 cycle; Fulvestrant, C1D1 and C1D15 and Day 1 of each cycle, 500mg/day, intramuscularly.

FCN-437c 200mg, oral administration under fasting conditions, QD, for 21 days, with 7-day discontinuation, 28 days for 1 cycle; Letrozole 2.5 mg, QD, for continuous dosing; Goserelin 3.6 mg, subcutaneously, once every 28 days.