Phase I Study of BEBT-209 in Women With Advanced Breast Cancer

BEBT-209 capsules, 25mg once daily, or 25mg, 50mg, 75mg, 100mg, 150mg each time, twice daily, were administered continuously for 3 weeks and discontinued for 1 week, and 4 weeks were used as a treatment cycle.

Letrozole tablets, 2.5mg each time, once a day for 4 weeks, 4 weeks as a treatment cycle.

Fulvestrant, injection, 500mg each time, 1 time on day 1 and day 15 of the first cycle, and once on the first day of each cycle from the second cycle, 4 weeks as a treatment cycle