ESR1 and B-cell chronic lymphocytic leukemia: Currently, the PROTAC drug Vepdegestrant, which targets estrogen receptors in breast cancer, has completed phase III clinical trials (Campone et al., 2025), and PROTAC drugs such as BGB-16673, which target BTK in chronic lymphocytic leukemia, have entered phase III clinical trials (Li Z. et al., 2025).