CD8A and cancer: Previous studies have reported, that metastases show higher expressions of tumor-associated antigens (TAA) compared to primary lesions.46 TAA, such as TRP-2,47 and melanoma antigen reactive with T cells,48 can be recognized by TCRs of tumor-infiltrating CD8+ T lymphocytes, which contribute to the efficacy of most cancer immunotherapies.49 Therefore, characterization of the TCR repertoire and its antigen specificity within tumors is appropriate for assessing treatment efficacy.