264Tip TACTIVE-K: Phase Ib/II Study of Vepdegestrant, a Proteolysis Targeting Chimera (PROTAC) Estrogen Receptor (ER) Degrader, in Combination with PF-07220060, a Cyclin-Dependent Kinase (CDK)4 Inhibitor, in ER+/human Epidermal Growth Factor Receptor 2 (HER2)- Advanced Breast Cancer