TABLE 1.

Different biomarkers utilized in cancer immunology investigations.

Category	Biomarkers	Measurement	Cancer types	Immunotherapies
Surface proteins	PD‐L1	IHC	NSCLC, 34 RCC, 35 Melanoma, 35 etc.	Anti‐PD‐1 35
	LAG‐3	Flow cytometer, IHC	NSCLC 36	Anti‐PD‐1 36
	Tumor neoantigen	Epitope discovery, NGS	Melanoma, 37 Sarcoma 38	Anti‐PD‐1, 38 anti‐CTLA‐4, 37 ACT 39
Genetic features	TMB	NGS	NSCLC, 7 UC, 40 HNSCC, 41 etc.	Anti‐PD‐1, 7 anti‐CTLA‐4 42
	dMMR/MSI‐H	NGS	CRC, 43 NSCLC, 44 GC, 45 etc.	Anti‐PD‐1, 43 anti‐CTLA‐4 46
	DNA methylation	Sulfite sequencing	CRC, 47 EC, 48 Melanoma, 49 etc.	Anti‐PD‐1, 50 anti‐CTLA‐4 49
	MHC–TCR axis mutation	Targeted sequencing	NSCLC, 51 Melanoma 52	Anti‐PD‐1, 52 anti‐CTLA‐4 52
	RNA signatures	RNA sequencing	BC, 53 NSCLC, 54 CRC, 55 etc.	Anti‐PD‐1, 56 CAR‐T 55
TILs	CD8+ T cells	Flow cytometer	NSCLC, 57 RCC, 58 UC, 59 etc.	Anti‐PD‐1 59
	CD4+ T cells	Flow cytometer	Melanoma, 60 BC, 61 GC, 62 etc.	Anti‐PD‐1, 63 anti‐CTLA‐4 60
	Exhausted T cells	Flow cytometer	NSCLC, 64 Melanoma 65	Anti‐PD‐1 64
	B cells	Flow cytometer	Melanoma, 66 RCC, 67 BC 68	Anti‐PD‐1 66
Liquid biopsy	ctDNA	NGS, sulfite sequencing	NSCLC, 69 UC, 69 GC, 69 etc.	Anti‐PD‐1, 69 anti‐CTLA‐4 69
	CTC	Flow cytometer	NSCLC, 70 OC, 71 Melanoma 72	Anti‐PD‐1, 70 anti‐CTLA‐4 72
	tdEV	MS, NGS	NSCLC, 73 Melanoma 74	Anti‐PD‐1 74

Abbreviations: ACT, adoptive cell therapy; BC, breast cancer; CAR‐T, chimeric antigen receptor T cell immunotherapy; CRC, colorectal cancer; CTC, circulating tumor cell; ctDNA, circulating tumor DNA; dMMR, mismatch repair system deficiency; EC, esophagus carcinoma; GC, gastric cancer; HNSCC, head and neck squamous cell carcinoma; IHC, immunohistochemistry; MHC, major histocompatibility complex; MS, mass spectrometry.; MSI‐H, high microsatellite instability; NGS, next‐generation sequencing; NSCLC, non‐small cell lung cancer; RCC, renal cell carcinoma; tdEV, tumor‐derived extracellular vesicle; TMB, tumor mutation burden; UC, urothelial cancer.