Study Evaluating Hemay022 in Combination With Endocrine Therapy In Subjects With ER Positive and HER2 Positive Advanced Breast Cancer

The purpose of this study is to evaluate the safety and tolerability of Hemay022 combined with endocrine therapy in the treatment of ER and HER2-positive metastatic or advanced breast cancer, and to establish OTR (best tolerated regimen). The second purpose of this study is to evaluate the pharmacokinetics and efficacy of Hemay022 in combination with exemestane, and the safety of Hemay022 in combination with letrozole or fulvestrant. The research will be divided into two parts. In the first part, 15 to 24 subjects will be enrolled to determine the safety and tolerability of combining Hemay022 with exemestane in patients with HER2-positive advanced breast cancer. The second part will enroll about 24-36 other subjects with ER and HER2-positive advanced breast cancer to better determine the tolerability and preliminary efficacy of Hemay022.