Background:~Breast cancer is a collective term for a variety of malignant breast tumors.According to the World Cancer Report newly released by the World Health Organization in February 2020, breast cancer ranks first in the causes of death among women due to cancer worldwide, with about 2.1 million new cases and 627,000 deaths in 2018. At present, the main treatments for breast cancer are surgery, chemotherapy, and endocrine therapy, but the therapeutic effect is limited. The 5-year survival rate for patients with advanced breast cancer is only 20%, and the overall survival (OS) is 2 ~ 3 years.~Research basis:~Tumor cells can activate their own DNA repair machinery to repair DNA damage caused by drugs and thus become resistant to radiotherapy and chemotherapy, while there is overexpression of DNA repair enzymes in a variety of tumor cells. Therefore, reducing the expression of DNA repair enzymes or inhibiting their activity may exert latent anti-tumor effects.~Specific aims:~To evaluate the objective response rate at least 4 weeks later,disease control rate,duration of response,progression-free survival and objective response rate and overall survival in patients withHER2-negative locally advanced or metastatic breast cancer patients with germline BRCA mutations. Also we plan to estimate safety endpoints and PK endpoints in this subject population.~Treatment plan:~Patients will be randomized in three arms. In arm A , patients will be treated with low dose TSL-1502 capsules, 350 mg each time, orally administered QD, every 3 weeks as a treatment cycle. In arm B , patients will be treated with the same interference with high dose,500 mg each time, orally administered QD, every 3 weeks as a treatment cycle. In arm B , patients will be treated with investigator's choice of chemotherapy.
This research study is evaluating the efficacy and safety of TSL-1502 capsules in patients with breast cancer, will be included HER2-negative locally advanced or metastatic breast cancer patients with germline BRCA mutations.