Table 2.

Exosomes in predicting the efficacy of immunotherapy.

Detection Method
Traditional detection technology	Use ultracentrifugation to separate the exosomes; use RT-PCR to evaluate the exosomal miRNA; use mass spectrometry or ELISA to assess exosomal protein
Novel detection technology	Use acoustic tweezer techniques in combination with microfluidics or commercial kits to isolate the exosomes
Potential samples for detection
Source of body fluids	Blood (plasma or serum), ascites, and bile (may be the most appropriate), etc.
Possible predictive biomarkers
Exosomal PD-L1	Has been demonstrated in other tumors and exosomal PD-L1 may better than other forms of extracellular PD-L1
Exosomal genes MYL6B and THOC2	Influence the expression of immune checkpoint genes
Exosomal miR-143-3p	Upregulate the expression of MARCKS in TAMs
Exosomal HMGB1	The prediction of HGMB1 for HCC prognosis has been clinically confirmed

PD-L1, programmed cell death ligand 1; ELISA, enzyme-linked immunosorbent assay; TAMs, tumor-associated macrophages; HCC, hepatocellular carcinoma.