The immune checkpoint inhibitors, including anti-PD-1 and anti-PD-L1 antibodies (αPD-1 and αPD-L1), have revolutionized tumor immunotherapy. Although αPD-1 and αPD-L1 show excellent efficacy in various tumor types, even in patients with advanced tumors, only 10–30% of patients respond to αPD-1 and αPD-L1 therapy due to primary resistance.