In Merkel cell carcinoma, clinical responses are associated with cells that highly express PD1 and PD-L1, with the former being expressed in a variety of TME-associated immune cells.[14] Antibodies targeting PD1 or PD-L1 are capable of reinstating T-cell activity to trigger an immune reaction against cancerous cells. This evidence concerns the gene PDCD1 and Merkel cell skin cancer.