K2 Medicines (Nanjing) Co. Ltd. has identified new proteolysis targeting chimera (PROTAC) compounds comprising an E3 ubiquitin ligase-binding moiety coupled to a cyclin-dependent kinase 4 (CDK4)- and/or CDK4/6 dual-targeting moiety. They are designed for use in the treatment of cancer, neurodegeneration, viral infection, cardiovascular and inflammatory disorders.