CDK4 and breast cancer: Apart from angiogenesis inhibitors, various targeted therapies combined with anti-PD-1/PD-L1 are undergoing clinical trials, such as nivolumab plus erlotinib (EGFR) in NSCLC patients (NCT01454102), tislelizumab plus pamiparib (PARP) in solid tumor patients (NCT02660034), cobimetinib (MEK) plus atezolizumab in colorectal cancer patients (NCT02788279), nivolumab plus copanlisib (PI3K) in lymphoma and solid tumor patients (NCT03502733), and pembrolizumab plus abemaciclib (CDK4/6) in NSCLC and breast cancer patients (NCT02779751).