The mechanism of the PD-1/PD-L1 pathway is to inhibitexcessive tissue destruction during inflammatory disease and act asan immune checkpoint.87 Some cancer cellsexploit this checkpoint to bypass the immune response against it.One of the more advanced and promising immunotherapy strategies isthe inhibition interaction between PD-1 and PD-L1.88 Studies show that PROTAC molecules can be used as an effectivetreatment against cancer.85 PROTAC 21 hasshown that it effectively improved the degradation of PD-L1 in manycancer cells by the proteasome. Here, PDCD1 is linked to cancer.