BEBT-209 is an independently developed CDK4 highly selective CDK4/6 inhibitor, primarily intended for the treatment of advanced breast cancer. Distinguished from the already marketed CDK4/6 inhibitors, BEBT-209 enhances the selectivity of CDK4 and reduces CDK6 inhibitory activity through compound structural design. This approach holds promise to reduce hematological and immunosuppressive toxicity caused by CDK6 inhibition. Simultaneously, by increasing maximum compound absorption and human exposure, BEBT-209 aims to achieve improved anti-tumor activity while ensuring safety. BEBT-209's initial indication advancement is in the second-line treatment of HR+/HER2- advanced breast cancer in combination with fulvestrant. It has currently progressed to Phase III clinical trials. In a non-head-to-head comparative analysis, BEBT-209's efficacy data demonstrated an Objective Response Rate (ORR) superior to palbociclib, abemaciclib, and ribociclib. Furthermore, BEBT-209 exhibited lower hematological toxicity compared to palbociclib and ribociclib, as seen in the results. With CDK4/6 inhibitors combined with endocrine therapy becoming the standard treatment for first- or second-line HR+/HER2- advanced breast cancer, the progression resulting from CDK4/6 inhibitor and endocrine therapy resistance has led to unmet treatment needs. The ongoing clinical trial of BEBT-209 in combination with BEBT-908 and either exemestane or fulvestrant for HR+/HER2- advanced breast cancer after progression on CDK4/6 inhibitor and endocrine therapy holds the potential to address this gap. The Phase Ib/II trial of this study is currently in progress. In triple-negative breast cancer(TNBC), CDK4/6 inhibitors combined with chemotherapy can significantly reduce the killing of chemotherapy drugs on bone marrow cells, thereby protecting bone marrow cells and immune system function, and improving the overall survival benefit of patients. The company is also initiating a phase II clinical trial of BEBT-209 combined with carboplatin and gemcitabine for the treatment of advanced triple-negative breast cancer (TNBC), hoping to benefit the majority of patients with relapsed or metastatic TNBC in China.