Table 1.
Sample | Biomarker | Clinical Significance |
---|---|---|
Tumor Tissue | PD-L1 | Increased expression in tumor cells is associated with a positive clinical response to anti-PD-1/PD-L1 antibodies [16,21,22,23,24,25]. |
TMB | High TMB is associated with an improved response to ICIs [26,27]. | |
MMR | MMR deficiency, regardless of tumor types, correlates with a clinical response to pembrolizumab [28,29,30,31,32,33]. | |
TIL | The presence of tumor-infiltrating CD8+ T cells is associated with a better prognosis [34,35,36,37,38,39]. | |
Tregs/ MDSCs | The presence of tumor-infiltrating Tregs and MDSCs is associated with a poor prognosis [40,41,42,43,44,45,46]. | |
Peripheral Blood | Neutrophils/leukocytes | Elevated NLR is associated with a poor response [7,47,48,49,50]. |
Low % of lymphocytes | Patients with a lymphocyte count less than 15% should be excluded from immunotherapy [7]. | |
LDH | Elevated pretreatment levels are correlated with a worse OS [51,52,53,54,55,56,57,58,59]. | |
CRP | High level of CRP is associated with an increased risk of OS [60]. | |
miRNA | Expression of several miRNAs is associated with clinical outcomes [61,62]. | |
Tregs/ MDSCs | Decreased level of circulating Tregs and MDSCs after treatment correlated with improved prognosis [6,60,63]. | |
Ki-67 expression | Increased Ki-67 expression in PD1+ CD8+ T cells is associated with a good response [64,65]. | |
Feces | Microbiome | The presence of Ruminococcaceae/Faecalibacterium in melanoma patients and Akkermansia muciniphila in NSCLC and RCC is associated with a clinical response to anti-PD-1 antibody [66,67]. |
PD-L1, programmed cell death-1 ligand 1; PD-1, programmed cell death receptor-1; TMB, tumor mutation burden; ICIs, immune checkpoint inhibitors; MMR, mismatch repair; TIL, tumor-infiltrating lymphocyte; Treg, regulatory T cells; MDSC, myeloid-derived suppressor cells; NLR, neutrophil-to-lymphocyte ratio; LDH, lactate dehydrogenase; OS, overall survival; CRP, C-reactive protein; miRNA, micro ribonucleic acid; NSCLC, non-small-cell lung carcinoma; RCC, renal cell cancer.