Biomarkers for response to immune checkpoint inhibitors in gastrointestinal cancers

Table 1 Summary of biomarkers used or worthwhile in gastrointestinal cancers

Classification	Biomarkers	Tumors	Response	OS	PFS	Others	Ref.
Tumor-genome biomarkers	TMB	Multiple GI	Pos/Neg1	14.6/4.0 mo	Unreached/2 mo (CRC)	NA	[19-21]
	dMMR/MSI-H	Multiple GI	Pos	Unreached vs 5.0 mo (CRC)	Unreached vs 2.2 mo (CRC)	Higher DCB (59.1% vs 28.6%, GI tumors)	[30,31]
	CNA	Multiple GI	Neg	Unreached2	Over 10 mo	NA	[31]
	IFN-γ-related	Multiple GI	Pos	Positive correlation (GC)	Positive correlation (GC and ESCA)	NA	[40,42]
	MDM2	HCC	Neg	NA	NA	Correlated with HPD	[50]
TME biomarkers	PD-L1	Multiple GI	Pos	NA	NA	NA	[53,54]
	TIL	Multiple GI	Pos	Prolonged OS (ESCA)	NA	3-yr RFS 71.6% vs 55.3% (CRC)	[67,78]
Liquid-biopsy biomarkers	ctDNA	Multiple GI	Neg	NA	4.9 mo vs 7.4 mo (GC)	2-yr RFS 66% vs 100% (CRC)	[73,74]
	Exosome	GC	Neg	Reduced OS	NA	High level Exosome	[78]

¹In tumor mutation burden (TMB), the Neg means that immune checkpoint inhibitor treatment response of TMB-L patients may be better by epigenetic modifications.

²Represent a wide variety of gastrointestinal tumors and do not refer to any particular type.

OS: Overall survival; PFS: Progression-free survival; TMB: Tumor mutation burden; dMMR: Mismatch repair deficiency; MSI-H: Highly microsatellite instability; CNA: Copy number alteration; TIL: Tumor infiltrating lymphocyte; ctDNA: Circulating tumor DNA; GI: Gastrointestinal; GC: Gastric cancer; CRC: Colorectal cancer; HCC: Hepatocellular cancer; ESCA: Esophageal cancer; HPD: Hyperprogressive disease; DCB: Durable clinical benefit; RFS: Recurrence free survival; Pos: Positive; Neg: Negative; NA: Not applicable; ICI: Immune checkpoint inhibitor.