The inhibition of cyclin-dependent kinase 4 (CDK4) and CDK6 is a useful strategy to treat hormone receptor (HR)+/HER2+ breast cancer, but patients may develop resistance through different mechanisms. As reported at the recent San Antonio Breast Cancer Symposium, researchers from Biotheryx Inc. have synthesized a new CDK4/6 degrader – BTX-9341 – to address the problem of therapeutic resistance in breast cancer.