Liquid biopsy and tumor heterogeneity in metastatic solid tumors: the potentiality of blood samples

Table 3 Tumor heterogeneity: potentiality of TCR profiling and circulating leukocytes

Tumor type	Findings	References
Pancreatic Ductal Adenocarcinoma	TCR features are correlated with survival in immunotherapy treated patients	[41]
Melanoma	TCR repertoire profiling is associated with immunotherapy response	[42,43,44]
	Baseline frequency of CD14 + CD16-HLA-DRhi monocytes, CD69 + MIP-1β + NK cells, and PD-1 + CD56+ T cells are potential predictors of clinical response in patients treated with immunotherapy	[45,46,47]
	The increase of central memory CD4+ T cells and the decrease of dysfunctional PD-1 + CD38hi CD8+ cells during immunotherapy are correlated with response.	[48, 49]
	Levels of circulating CD33 + CD11b + HLA-DR- myeloid derived suppressor and distinct CD4+ and CD8+ memory T cell subsets are correlated with survival of immunotherapy treated patients.	[46, 50]
Lung Cancer	TCR repertoires of PD-1+ CD-8+ lymphocytes are correlated with clinical outcomes of immunotherapy treated patients	[51, 52]
Lung Cancer	Baseline percentage of HLA-DR monocytes and dendritic cells are correlated to immunotherapy response	[53]
Melanoma and Lung Cancer	Elevated frequencies of CD4 + Foxp3- T cells, at baseline and/or during immunotherapy, are associated with a higher risk of death	[54]

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