To further validate potential CDK4/6 inhibitor sensitivity conferred by CNVs of CDKN2A and CDKN2B, two CDK4/6 inhibitors, palbociclib (PD-0332991) and ribociclib (LEE011), approved for clinical breast cancer use, were used to perform an analysis on the sensitivity of eight PDCs. The gene discussed is CDKN2A; the disease is breast cancer.