CDK4 and breast carcinoma: Inavolisib combined with CDK4/6 inhibitors demonstrates a significant synergistic effect in a PIK3CA-mutated breast cancer model: in vitro experiments show an 89% inhibition rate in mutant cells (CI = 0.45), a 68% reduction in tumor volume in vivo models, and enhanced radiotherapy sensitivity while reshaping the tumor microenvironment (62).