Hormone receptor-positive, HER2-negative breast cancer is the most common subset of breast cancer. The estrogen receptor (ER) in these patients is a key driver of disease progression, and the primary reason for relapse in these patients is that endocrine therapies are only partially effective, typically causing cell cycle arrest rather than cell death. As a result, secondary resistance to endocrine therapy is a major clinical challenge. ZN-c5 is a novel and potent ZN-c5 is a novel and potent selective estrogen receptor degrader with oral bioavailability and strong activity in estrogen-dependent and tamoxifen-resistant tumor models.
The aim of this phase 1b study in Chinese patients with ER+/Her2- advanced breast cancer is to evaluate the safety and tolerability of ZN-c5 at dose of 50 mg and 150 mg QD well tolerance established in the previous oversea study in non-Chinese patients.