Review of 10 years of research on breast cancer patients: Focus on indoleamine 2,3-dioxygenase

Table 1 Review of ten years of research on indoleamine 2,3-dioxygenase in breast cancer patients

Year	Ref.	Population	Description
2011	Yu et al[21]	Chinese (n = 26)	IDO upregulation inhibits local immune responses by infiltration of T-regs in the tumour microenvironment and promotes metastasis in breast cancer
2011	Lyon et al[27]	American (n = 33)	Increased tryptophan degradation may occur in women with early-stage breast cancer
2012	Jacquemier et al[31]	French (n = 1749)	Immunodetection of IDO-positive cells may be used for diagnosis of medullary breast cancer. IDO has a prognostic significance in basal like breast cancer
2013	Soliman et al[24]	American (n = 203)	IDO expression was higher in ER+ breast cancer than ER– breast cancer
2013	Yu et al[22]	Chinese (n = 85)	STAT3-dependent IDO expression induces immunosuppressive effects of MDSCs in breast cancer
2014	Bi et al[37]	Chinese (n = 110)	IDO and EGFR may serve as a potential biomarkers for breast cancer prognosis and treatment
2014	Isla Larrain et al[32]	Argentinian(n = 91)	IDO was expressed in a TNBC subgroup and was involved in the tumour immune escape
2015	Salvadori et al[33]	Brazilian (n = 20)	IDO inhibitor when combined with paclitaxel may be used as a new therapeutic strategy for breast cancer
2017	Kim et al[30]	South Korean (n = 200)	IDO might be an effective immunotherapeutic target in TNBC
2017	Dewi et al[25]	German (n = 15)	IDO-1 expression in ER– breast cancer may be associated with poor prognosis. IDO-1 maybe a promising therapeutic target for ER– breast cancer
2017	Carvajal-Hausdorf et al[36]	American (n = 362)	IDO-1 quantification has potential to differentiate a population that might get an advantage from IDO-1 blockade
2017	Li et al[38]	Chinese (n = 46)	Expression of IDO and IL-6 is associated with advanced breast cancer and poor response to neoadjuvant chemotherapy
2018	Ye et al[34]	Chinese (n = 963)	IDO and programmed cell death protein-1 pathways might be an effective therapeutic approach in breast cancer treatment
2018	Wei et al[23]	Chinese (n = 65)	IDO may induce angiogenesis in breast cancer, providing a molecular or gene therapy target for angiogenesis inhibition
2018	Li et al[39]	Chinese (n = 44)	Tumour-infiltrating T-regs, MDSCs and IDO expression may be used as a prognostic marker for the outcome of neoadjuvant chemotherapy
2018	Dill et al[29]	American (n = 281)	IDO expression in high-grade,TNBC is associated with PD-L1 co-expression
2019	Asghar et al[28]	Pakistani (n = 100)	IDO expression in TNBC may suggest its role in disease pathogenesis
2019	Onseti et al[26]	Belgian (n = 202)	Kynurenine/tryptophan ratio in plasma might differentiate breast cancer patients from healthy controls
2019	Asghar et al[35]	Pakistani (n = 100)	IDO expression is associated with COX-2 expression in breast cancer patients
2019	Zhao et al[40]	Chinese (n = 53)	IDO expression and activity is linked with advanced breast cancer and poor response to neoadjuvant chemotherapy
2020	Wei et al[41]	Chinese (n = 77)	IDO and tumour infiltrating immune cells can help to evaluate the prognosis of breast cancer patient

IDO: Indoleamine 2,3-dioxygenase; T-regs: regulatory T cells; ER: Estrogen receptor; TNBC: triple-negative breast cancer; STAT3: Signal transducer and activator of transcription 3; MDSCs: Myeloid-derived suppressor cells; EGFR: Epidermal growth factor receptor; COX-2: Cyclooxygenase-2.