What is the prospect of indoleamine 2,3-dioxygenase 1 inhibition in cancer? Extrapolation from the past

Table 6 TRP and KYN changes in human cancers^a

Tumor type	No. of patients	Source	TRP	KYN	KYN/TRP ratio	Ref
CRC	66	serum	↓	−	↑	[39]
Melanoma	87	serum	↓	−	↑	[40]
Lung	123	serum	↓	↑	↑	[41]
Lung	36	serum	↓	−	↑	[43]
Ovarian carcinoma	20	serum	↓	−	↑	[44]
Gynecologic cancers^b	109	serum	−	↑	↑	[45]
CRC	69	serum	?	↑	?	[116]
Lung	33	serum	?	?	↑	[46]
ATL	96	serum	−	↑	↑	[42]
Glioblastoma	10	serum	↓	↓^c	−	[47]
Cervical cancer	27	tumor	↓	↑	↑	[117]

^a symbols used: ↑ increase, ↓ decrease, - no change, ? not reported (defined as statistically significant change). ^b include endometrial, ovarian, and vulvar cancer. ^c KYN serum level was significantly decreased in glioblastoma patients compared to healthy controls

ISSN: 1756-9966