In addition to ESR1 mutations, the following miRNAs have shown to be promising predictors for CDK4/6 inhibitor response or resistance in BC: miR-326, miR-29b-3p, miR-126, miR3613-3p, miR-432-5p, miR-223, and miR-106b [60]. This evidence concerns the gene ESR1 and breast cancer.