PDCD1 and neoplasm: A considerable number of studies have analyzed immune cell phenotypes in both tumor tissue and blood after ICI treatment with the aim to identify markers associated with response—for example, in clear cell renal cell carcinoma patients, the response to anti-PD-1 treatment (nivolumab) was associated with a higher expression of CD3E, CD8A, Granzyme B (GZMB), and TCF7 in T cells from responders’ versus non-responders’ tumor samples (7).