Group 1 - The HR+/HER2- breast cancer subtype accounts for approximately 70% of all breast cancer cases globally, with over 2.2 million new cases annually, including about 1.5 million HR+/HER2- cases [1] - Current first-line treatment involves CDK4/6 inhibitors combined with endocrine therapy, but nearly all patients eventually develop resistance, with a median resistance duration of 12-18 months [1] - There are currently no approved targeted therapies for patients who have developed resistance to CDK4/6 inhibitors, and existing second-line options show limited efficacy, with an objective response rate of only 5-10% and median progression-free survival of 3-6 months [1] Group 2 - TY-00540 is a globally leading dual-target CDK2/4 inhibitor that addresses the key mechanism of resistance to CDK4/6 inhibitors by upregulating CDK2 activity [2] - Preclinical studies indicate that TY-00540 demonstrates nanomolar-level inhibitory activity against both CDK2/cyclin E and CDK4/cyclin D1, significantly outperforming single-target CDK4/6 inhibitors or chemotherapy [2] - By simultaneously inhibiting CDK4/6 and CDK2, TY-00540 effectively blocks tumor cell cycle progression, overcoming resistance to CDK4/6 inhibitors [2] Group 3 - The ESMO 2025 conference will present specific data from the Phase I clinical trial of TY-00540, led by Professor Zhang Jian from Fudan University Shanghai Cancer Center [3] - Preliminary results suggest that TY-00540 shows significant anti-tumor activity and manageable safety in patients who have developed resistance to first-line CDK4/6 inhibitors, with objective response rates and disease control rates superior to existing second-line options [3] - The overall safety profile of TY-00540 is favorable, with most treatment-related adverse events being mild to moderate [3]