Chidamide/Everolimus for PIK3CA Wild-type/Mutant HR+/HER2- Advanced Breast Cancer

This study is an open, multi center, prospective cohort, and Phase II exploratory research. According to the PIK3CA gene mutation status of patients, the study is divided into two cohorts. The PIK3CA Mutant uses everolimus combined with endocrine therapy as the cohort A, and the PIK3CA wild type uses chidamide combined with endocrine therapy as the cohort B, until the disease progresses or the toxicity is intolerable. According to the judgment of the researchers, whether to enter the second stage of cross design, Queue A was cross administered with chidamide in combination with endocrine therapy. Cohort B cross used everolimus combined with endocrine until the disease progressed or the toxicity was intolerable.