Indoleamine 2,3-dioxygenase: As a potential prognostic marker and immunotherapeutic target for hepatocellular carcinoma

Tumor cells induce an immunosuppressive microen-vironment which leads towards tumor immune escape. Understanding the intricacy of immunomodulation by tumor cells is essential for immunotherapy. Indoleamine 2,3-dioxygenase(IDO) is an immunosuppressive enzyme which mediates tumor immune escape in various cancers including hepatocellular carcinoma(HCC). IDO up-regulation in HCC may lead to recruitment of regulatory T-cells into tumor microenvironment and therefore inhibit local immune responses and promote metastasis. HCC associated fibroblasts stimulate natural killer cells dysfunction through prostaglandin E2 and subsequently IDO promotes favorable condition for tumor metastasis. IDO up-regulation induces immuno-suppression and may enhance the risk of hepatitis C virus and hepatitis B virus induced HCC. Therefore, IDO inhibitors as adjuvant therapeutic agents may have clinical implications in HCC. This review proposes future prospects of IDO not only as a therapeutic target but also as a prognostic marker for HCC.

Inhibition of allogeneic T-cell response by Kupffer cells expressing indoleamine 2,3-dioxygenase

AIM:To explore the possibility and mechanism of inhibiting allogeneic T-cell responses by Kupffer cells (KC)pretreated with interferon-γ(IFN-γ)in vitro. METHODS:The expressions of indoleamine 2,3-dioxygenase(IDO)mRNA and FasL mRNA in KC pretreated with IFN-γwere studied with real-time polymerase chain reaction(PCR).The catabolism of tryptophan by IDO from KC was analyzed by high performance liquid chromatography.Allogeneic T-cell response was used to confirm the inhibition of KC in vitro.The proliferation of lymphocytes was detected using[ 3 H]thymidine incorporation.Cell cycle and lymphocyte apoptosis were evaluated by flow cytometric assay. RESULTS:Real-time PCR revealed IDO mRNA and FasL mRNA expressions in KC pretreated with IFN-γ,and IDO catabolic effect was confirmed by a decrease in tryptophan and increase in kynurenine concentration. KC expressing IDO and FasL in BABL/c mice acquired the ability to suppress the proliferation of T-cells from C57BL/6,which could be blocked by addition of 1-methyl-tryptophan and anti-FasL antibody.KC expressing IDO could induce allogeneic T-cell apoptosisCONCLUSION:In addition to Fas/FasL pathway,IDO may be another mechanism for KC to induce immune tolerance.

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

Therapeutic manipulation of the immune system in cancer has been an extensive area of research in the field of oncoimmunology.Immunosuppression regulates antitumour immune responses.An immunosuppressive enzyme,indoleamine 2,3-dioxygenase(IDO)mediates tumour immune escape in various malignancies including breast cancer.IDO upregulation in breast cancer cells may lead to the recruitment of regulatory T(T-regs)cells into the tumour microenvironment,thus inhibiting local immune responses and promoting metastasis.Immunosuppression induced by myeloid derived suppressor cells activated in an IDOdependent manner may enhance the possibility of immune evasion in breast cancer.IDO overexpression has independent prognostic significance in a subtype of breast cancer of emerging interest,basal-like breast carcinoma.IDO inhibitors as adjuvant therapeutic agents may have clinical implications in breast cancer.This review proposes future prospects of IDO not only as a therapeutic target but also as a valuable prognostic marker for breast cancer.

Mesenchymal-epithelial Transition Factor Regulates Monocyte Function during Mycobacterial Infection via Indoleamine 2,3-dioxygenase

Objective Mycobacterium tuberculosis(Mtb),the causative agent of tuberculosis(TB),causes an estimated 1.6 million human deaths annually,but the pathogenesis of TB remains unclear.Immunity plays a critical role in the onset and outcome of TB.This study aimed to uncover the roles of innate and adaptive immunity in TB.Methods The gene expression profiles generated by RNA sequencing from human peripheral blood mononuclear cells(PBMCs)stimulated with or without Mtb strain H37Rv antigens were analyzed.A total of 973 differentially expressed mRNAs were identified.Results The differentially expressed genes were enriched in innate immunity signaling functions.The mesenchymal-epithelial transition factor(MET)gene was significantly upregulated in CD14^(+)monocytes.A MET inhibitor improved the uptake of the BCG strain by monocytes and macrophages as well as inhibited the expression of indoleamine 2,3-dioxygenase(IDO).The expression of IDO was increased in PBMCs stimulated with Mtb antigens,and the IDO inhibitor promoted the expression of CD40,CD83,and CD86.Conclusion Our results might provide clues regarding the immunomodulatory mechanisms used by Mtb to evade the host defense system.

Myricetin inhibits interferon-γ-induced programmed death ligand-1 and indoleamine 2,3-dioxygenase 1 expression in lung cancer cells

OBJECTIVE Programmed death ligand-1(PD-L1)and indoleamine 2,3-dioxygenase 1(IDO1)are immune checkpoints which can be induced by interferon-γ(IFN-γ)in the tumor microenvironment,leading to immune escape of tumors.Myricetin(MY)is a flavonoid distributed in many edible and medicinal plants.The aim of this study is to clarify the effect and the mechanism of MY on inhibiting IFN-γ-induced PD-L1 and IDO1 in lung cancer cells.METHODS Expressions of PD-L1 and major histocompatibility complex-I(MHC-I)were evaluated by flow cytometry and Western blotting,and the expression of IDO1 was measured by Western blotting.qRT-PCR was used to detect their mRNA levels.The function of T cells was evaluated using a co-culture system consist of lung cancer cells and the Jurkat-PD-1 T cell line that overexpressing PD-1.Molecular docking analysis,Western blotting and immunofluorescence were used for mechanism study.RESULTS MY potently inhibited IFN-γ-induced PD-L1 and IDO1 expression in human lung cancer cells,while didn't show obvious effect on the expression of MHC-I.In addition,MY restored the survival,proliferation,CD69 expression and interleukin-2(IL-2)secretion of Jurkat-PD-1 T cells suppressed by IFN-γ-treated lung cancer cells in the co-culture system.Mechanistically,IFN-γup-regulated PD-L1 and IDO1 at the transcriptional level through the JAK-STAT-IRF1 axis,which was targeted and inhibited by MY.CONCLUSION Our research revealed a new insight into the anti-tumor effects of MY which inhibited IFN-γ-induced PD-L1 and IDO1 expression,supporting the potential of MY in anti-tumor immunotherapy.

Molecular Cloning and Characterization of Porcine Indoleamine 2,3-Dioxygenase and Its Expression in Various Tissues

In order to confirm the existence of indoleamine 2,3-dioxygenase(IDO) gene in swine,and to clone the novel gene followed by the molecule structure properties and expression pattern analysis,the porcine mRNA sequences homologous to human IDO were obtained from GenBank database by bioinformatics method.By using RT-PCR,the IDO gene was cloned from porcine endothelial cell line and the accuracy of the nucleic acid sequence was confirmed,and the expression pattern of the gene was detected.The three-dimensional structure model of porcine IDO was built referring to the tertiary structure of human IDO using biological sequence analysis software and database.The results showed that the porcine IDO was identified by sequencing.The nucleotide sequences were confirmed as a novel gene after submitted to Genbank.Porcine IDO was expressed in the lung,thymus,epididymis and anterior chamber with a basic level,however in peripheral blood mononuclear cells(PBMCs) the IDO gene was highly expressed.The three-dimensional structure model of porcine IDO was similar to that of human IDO.It was suggested that identification of the structure information of porcine IDO is essential to further investigate the immunologic function of the gene.Study of IDO on NK cells-mediated xenograft rejection will be a novel therapeutic target for the development of xenotransplantation.

Forkhead box P3 and indoleamine 2,3-dioxygenase co-expression in Pakistani triple negative breast cancer patients

BACKGROUND Forkhead box P3(FOXP3)is a specific marker for immunosuppressive regulatory T(T-reg)cells.T-regs and an immunosuppressive enzyme,indoleamine 2,3-dioxygenase(IDO),are associated with advanced disease in cancer.AIM To evaluate the co-expression of FOXP3 and IDO in triple negative breast cancer(TNBC)with respect to hormone-positive breast cancer patients from Pakistan.METHODS Immunohistochemistry was performed to analyze the expression of FOXP3,IDO,estrogen receptor,progesterone receptor,and human epidermal growth factor receptor on tissues of breast cancer patients(n=100):Hormone-positive breast cancer(n=51)and TNBC(n=49).A total of 100 patients were characterized as FOXP3 negative vs positive and further categorized based on low,medium,and high IDO expression score.Univariate and multivariate logistic regression models were used.RESULTS Out of 100 breast tumors,25%expressed FOXP3 positive T-regs.A significant coexpression of FOXP3 and IDO was observed among patients with TNBC(P=0.01)compared to those with hormone-positive breast cancer.Two variables were identified as significant independent risk factors for FOXP3 positive:IDO expression high(adjusted odds ratio(AOR)5.90;95%confidence interval(CI):1.22-28.64;P=0.03)and TNBC(AOR 2.80;95%CI:0.96-7.95;P=0.05).CONCLUSION Our data showed that FOXP3 positive cells might be associated with high expression of IDO in TNBC patients.FOXP3 and IDO co-expression may also suggest its involvement in disease,and evaluation of FOXP3 and IDO expression in TNBC patients may offer a new therapeutic option.

Relationship of Abortion and the Expression of Indoleamine 2,3- dioxygenase (IDO) in Villus and Syncytiotrophoblasts

Objective To study the relationship of abortion and the expression of indoleamine 2, 3- dioxygenase （IDO） in villus and syncytiotrophoblast in vitro. Methods RT-PCR was applied to analyze the mRNA transcription of lDO in villus of normal pregnancy and inevitable abortion and JAR cells as well. Immunohistochemistry was applied to analyze the expression of IDO protein in villus. Western blot was applied to determinate the expression of IDO protein on cultured syncytiotrophoblast. Highperformance liquid chromatography was applied to determinate whether there was kynurenine in cell culture medium of syncytiotrophoblast. Results The expression of IDO mRNA and protein in villus of inevitable abortion was lower than that of normal pregnancy; IDO mRNA did not express in JAR cells. IDO protein expressed on cultured syncytiotrophoblast, and there was kynurenine in cell culture medium of syncytiotrophoblast. Conclusion Appropriate expression of IDO in villus is necessary.for maintenance of normal pregnancy and an active IDO protein expresses in syncytiotrophoblast.

Indoleamine 2,3-dioxygenase in tumor induced tolerance

Objective To review the recent studies about the role of indoleamine 2,3-dioxygenase （IDO） in tumor induced tolerance. Data sources Published articles （1978-2009） on IDO and tumor induced tolerance were selected from Medline. Study selection Articles selected were relevant to development of IDO in tumor induced tolerance. Of all originally identified articles, 50 specially addressed the stated purpose. Results Recent work has revealed IDO at high levels in tumors and in tumor-draining lymph nodes and a close relationship between IDO activity and the regulatory T cells. Conclusion Up-regulation of IDO is proven to be a mechanism of acquired tolerance in tumors, in which the closely coupled positive feedback system between IDO and reclulatorv T cells may be considered to play an important role.

Indoleamine 2,3-dioxygenase and regulatory dendritic cells contribute to the allograft protection induced by infusion of donor-specific splenic stromal cells

It has been reported that splenic stromal cells(SSCs)are capable of directly supporting the development of CD11c ^(lo)CD45RB^(+) IL-10-producing dendritic cells(DCs)from lineage-negative c-kit^(+) progenitor cells in the absence of exogenous cytokines.In vitro,DCs that differentiate on stromal cells suppress mixed leukocyte reaction responses and induce primary alloreactive CD4^(+) T cells to differentiate into IL-10-producing Tr1 cells.However,the precise mechanisms by which these SSCs exert their regulatory functions in vivo remain undefined.Furthermore,their possible contribution to the development of allograft transplantation tolerance has yet to be examined.Here,we have used both murine skin and cardiac allograft transplantation models to explore whether in vivo alloresponses can be regulated by infusion with donor-derived SSCs and to investigate the possible mechanisms by which SSCs exert regulatory effects to prevent allograft rejection.We show that intravenous SSC infusion prolonged murine skin allograft survival.The prolonged graft survival is associated with augmentation of the generation of regulatory DC subsets and CD4^(+) CD25^(+) Foxp3^(+) regulatory T cells(Tregs),as well as upregulation of the production of suppressive cytokines IL-10 and transforming growth factor(TGF)-b.Moreover,we found that indoleamine 2,3-dioxygenase and SSC-derived regulatory DCs contribute to allograft protection by infusion of donor-specific SSCs.Our data suggest that donor-derived SSCs could be used as a therapeutic target to promote transplantation tolerance.

Indoleamine 2,3-Dioxygenase in Endometriosis

Endometriosis(EMS)is a chronic inflammatory and estrogen-dependent gynecological disease characterized by the presence of endometrial tissue outside the uterine cavity.Although it is a benign disease,EMS is tumor-like in several aspects,which include unrestrained growth,decreased apoptosis,and aggressive invasion.EMS involves endocrine disorders and immunological factors.Indoleamine 2,3-dioxygenase(IDO)is an intracellular enzyme that catalyzes the initial and rate-limiting step of the metabolism of tryptophan.IDO is a potential candidate facilitating EMS development.Increased IDO expression in both eutopic and ectopic endometria of women with EMS is biologically important in aspects,which include regulation of endometrial stromal cell function and modulation of adjacent local immunocytes to generate a supportive microenvironment.In turn,the expression of IDO can be regulated by the complex endocrine-immune microenvironment networks in endometrial lesions.Here,we systematically review the roles of IDO in EMS to explore its pathological implications and treatment potential.

基于虚拟筛选的新型吲哚胺2,3-双加氧酶抑制剂的发现及活性评价

目的应用药效团模型及分子对接的综合虚拟筛选策略,对Specs及Chembridge数据库进行筛选并进行生物学活性评价,以期发现新型吲哚胺2,3-双加氧酶(IDO1)抑制剂。方法基于已报道IDO1抑制剂,利用Discovery Studio 2019软件的Pharmacophores(Hiphop)模块构建药效团模型。通过最优药效团模型初步筛选了Specs及Chembridge数据库,后采用LibDock及CDOCKER程序靶向IDO1活性位点进行层级分子对接,最终保留了40个苗头化合物,并在100μmol/L浓度下进行了细胞水平IDO1酶抑制活性初筛。选取初筛抑制率大于50%的11个化合物进行细胞水平及生化水平抑酶活性的进一步测定。采用SPR及分子对接模型进一步确证及阐明化合物与IDO1酶之间的相互作用方式。结果发现羟基嘧啶类化合物29在细胞水平及生化水平上均呈现了IDO1酶抑制活性,EC50和IC50分别为(53.93±1.22)μmol/L和(179±8.12)μmol/L。SPR研究进一步确证了化合物29与IDO1之间的直接结合(KD=65.92μmol/L)。分子对接模型研究显示羟基嘧啶基团与IDO1的卟啉环之间存在较为丰富的相互作用,是靶向识别的关键基团。结论羟基嘧啶类化合物29是一类新型IDO1抑制剂,可作为IDO1酶抑制剂的先导物,通过进一步结构改造及优化,有望获得高效、结构新颖的IDO1抑制剂及新型肿瘤免疫治疗药物。

AncPhore: A versatile tool for anchor pharmacophore steered drug discovery with applications in discovery of new inhibitors targeting metallo-β-lactamases and indoleamine/tryptophan 2,3-dioxygenases

We herein describe AncPhore,a versatile tool for drug discovery,which is characterized by pharmacophore feature analysis and anchor pharmacophore(i.e.,most important pharmacophore features)steered molecular fitting and virtual screening.Comparative analyses of numerous protein-ligand complexes using AncPhore revealed that anchor pharmacophore features are biologically important,commonly associated with protein conservative characteristics,and have significant contributions to the binding affinity.Performance evaluation of AncPhore showed that it had substantially improved prediction ability on different types of target proteins including metalloenzymes by considering the specific contributions and diversity of anchor pharmacophore features.To demonstrate the practicability of AncPhore,we screened commercially available chemical compounds and discovered a set of structurally diverse inhibitors for clinically relevant metallo-β-lactamases(MBLs);of them,4 and 6 manifested potent inhibitory activity to VIM-2,NDM-1 and IMP-1 MBLs.Crystallographic analyses of VIM-2:4 complex revealed the precise inhibition mode of 4 with VIM-2,highly consistent with the defined anchor pharmacophore features.Besides,we also identified new hit compounds by using AncPhore for indoleamine/tryptophan 2,3-dioxygenases(IDO/TDO),another class of clinically relevant metalloenzymes.This work reveals anchor pharmacophore as a valuable concept for target-centered drug discovery and illustrates the potential of AncPhore to efficiently identify new inhibitors for different types of protein targets.

Expression and Prognostic Value of Indoleamine 2,3-dioxygenase in Pancreatic Cancer

Background： Indoleamine 2,3-dioxygenase （IDO）, an enzyme for tryptophan metabolism through the kynurenine pathway, exhibits an immunosuppressive effect and induces immune tolerance in tumor cells. The effects of IDO on pancreatic cancer are poorly understood. This study aimed to investigate the expression and prognostic significance of IDO in pancreatic cancer. Methods： We evaluated the protein expression of IDO in PANC-1, CFPAC-I, and BxPC-3 cell lines with or without 48 11 treatment by 500 U/ml interferon-,/（IFN-y）. We performed immunollistochemical staining and Western blot analysis lbr IDO expression in both pancreatic cancer and normal pancreas tissues obtained from Chinese PLA General Hospital from July 2012 to December 2013. Survival analysis was performed to correlate IDO expression and histopathologic parameters with overall survival. The Kaplan-Meier method and Cox proportional hazards regression model were conducted. Results＂ PANC-I, CFPAC-I, and BxPC-3 cell lines expressed IDO at the protein level, and the relative expression amount increased after stimulation with 500 U/ml IFN-y. Immunohistochemical analysis results revealed that high IDO expression was observed in 59% of pancreatic adenocarcinoma tissues. Compared with normal pancreatic tissues, pancreatic adenocarcinoma showed significantly higher IDO expression levels, especially among patients with high tumor node metastasis （TNM） stages （X2= 4.550, P = 0.030）, poor histological differentiation （X2=5.690, P = 0.017）, and lymph node metastasis （X2=4.340 P = 0.037）. Kaplan-Meier survival curves showed that high 1DO expression was correlated with low survival rates （hazard ratio [HR] = 0.49 P = 0.009）. Multivariate analysis using Cox proportional hazards model indicated that lymph node metastasis （HR = 0.35 P= 0.010） and IDO expression （HR = 0.42 P = 0.020） were two independent prognostic predictors of pancreatic adenocarcinoma. Conclusions： The study confirmed that high IDO expression in pancreatic adenocarcinoma was related to poor prognosis of patients. These findings provided evidence that IDO was involved in pancreatic adenocarcinoma progression and might serve as a relevant therapeutic target.

吲哚胺2,3二氧化酶与肿瘤免疫耐受

肿瘤免疫耐受是一个获得性免疫应答的过程，许多机制参与调节。吲哚胺2，3-二氧化酶（IDO）是体内肝外色氨酸沿犬尿氨酸代谢的限速酶。其通过诱导“色氨酸删除”环境、色氨酸代谢产物的细胞毒性作用和调节Tregs等抑制T淋巴细胞增殖、活化，共同诱导肿瘤免疫耐受。抑制IDO可为今后肿瘤临床治疗提供新思路和方法。

吲哚胺2,3-二氧化酶在病毒性肝炎中的研究进展

病毒性肝炎具有强传染性、高流行性,其传播途径复杂、发病率高、对人体危害性大,已成为社会普遍关注的一类重要的传染性疾病。随着科学社会的进步,目前对于肝炎的治疗有一定的进展,主要应用干扰素、核苷类、基因疗法等抗病毒药物,但这些治疗适用范围局限,副作用大,易产生病毒变异和耐药现象,使病情反复,治疗出现"瓶颈"。近几年,吲哚胺2,3-二氧化酶(indoleamine 2,3-dioxygenase,IDO)在病毒性肝炎中的作用日益受到关注,其与肝炎患者免疫耐受、病毒的复制、肝细胞的损伤程度密切相关。这将为病毒性肝炎的治疗提供新的思路。本文针对IDO在病毒性肝炎中的进展作一概述。

新型吲哚2,3双加氧酶抑制剂对小鼠肺癌细胞系的体外影响

目的 IDO1作为肿瘤治疗策略的新靶点依据有限。本研究探讨新恶二唑基-N-羟基苯甲脒对鼠LLTC肺癌细胞系吲哚2,3双加氧酶1(indoleamine 2,3-dioxygenase,IDO1)的抑制活性,拟为其提供实验依据。方法构建转染人和鼠的IDO1的LLTC细胞系(LLTC-hIDO1和LLTC-mIDO1),加入0、5、10、100 ng/mL IFN-γ,检测该细胞系IDO1的表达;用4-苯基咪唑、维生素K、新型IDO1抑制剂恶二唑基-N-羟基苯甲脒作用于细胞系,检测对IDO1的抑制能力和细胞毒性。结果 LLTC野生细胞株在IFN-γ刺激前后均不表达IDO1、LLTC-hIDO1、LLTC-mIDO1,可以持续性表达IDO1,但不受IFN-γ的诱导,与其剂量无相关性。4-苯基咪唑对LLTC-hIDO1、LLTC-mIDO1的IDO1抑制活性分别为IE50=419.000±60.260μM(n=3)、IE50=21.040±3.140μM(n=3),酶的抑制活性在两个细胞系存在显著性差异(P<0.05);维生素K苯基咪唑对LLTC-hIDO1、LLTC-mIDO1的IDO1抑制能力不具有统计学意义(P>0.05),IE50分别为(14.010±1.140)μM(n=3)、(17.480±1.080)μM(n=3);恶二唑基-N-羟基苯甲脒在LLTC-hIDO1和LLTC-mIDO1细胞系IDO1的活性,不存在显著性差异(P>0.05)。IE50分别是(0.024±0.004)μM(n=3)、(0.074±0.006)μM(n=3)。实验中的4-苯基咪唑和新型恶二唑基-N-羟基苯甲脒对细胞没有细胞毒性,但维生素K对LLTC-hIDO1、LLTC-mIDO1细胞具有一定的细胞毒作用,IC50分别为(63.420±0.740)μM(n=3)、(25.660±6.160)μM(n=3),不存在显著性差异(P>0.05)。结论新型恶二唑基-N-羟基苯甲脒抑制剂具有良好的IDO1抑制活性,且对LLTC-hIDO1和LLTC-mIDO1细胞系无细胞毒作用,为IDO1作为肿瘤治疗策略的新靶点提供了依据。

吲哚胺2,3-双加氧酶1抑制剂的研究进展

吲哚胺2,3-双加氧酶1(indoleamine 2,3-dioxygenase 1,IDO1)是介导色氨酸沿犬尿氨酸途径分解代谢的限速酶。IDO1在肿瘤细胞和抗原呈递细胞(antigen presenting cells,APC)中存在过度表达现象,通过色氨酸的消耗及其代谢产物的聚积抑制局部免疫应答,使肿瘤细胞逃避免疫系统的监测,这与多数肿瘤治疗的不良预后有关。因此,IDO1是肿瘤免疫疗法的重要靶点。目前有多种骨架的IDO1抑制剂正在研究当中,其中3个已经进入了临床研究阶段。本文介绍了IDO1在肿瘤免疫耐受中的作用,并按结构分类,综述了IDO1抑制剂的研究进展。

IDO抑制剂LPM3480226联合不同化疗药物抗小鼠结肠癌CT26

研究吲哚胺2,3-双加氧酶(IDO)抑制剂LPM3480226与不同化疗药物联合使用对小鼠结肠癌CT26移植瘤生长的抑制作用,为IDO抑制剂的应用提供临床前药效学依据。采用CT26皮下移植瘤小鼠模型,通过观察荷瘤小鼠体重、肿瘤体积、肿瘤重量等指标,考察LPM3480226分别与紫杉醇、伊立替康、力扑素(紫杉醇脂质体注射液)、氟尿嘧啶联合使用的抗肿瘤作用。研究结果表明,LPM3480226与各化疗药物联用时,对荷瘤小鼠体重影响较小;紫杉醇、力扑素、伊立替康、氟尿嘧啶单用及与LPM3480226联用后的肿瘤抑制率分别为42.3%vs 54.1%,38.8%vs 61.5%,36.8%vs 55.1%,53.6%vs 78.8%。上述研究结果提示,LPM3480226可显著增强常用化疗药物的抗肿瘤作用,支持在临床试验中进一步考察LPM3480226与上述化疗药物联用的抗肿瘤作用。

以吲哚胺-2,3双加氧酶为靶点的肿瘤治疗研究进展

免疫逃逸已经成为肿瘤研究的一个新思路,吲哚胺-2,3双加氧酶(indoleamine-2,3 dioxygenase,IDO)是涉及色氨酸分解代谢的生物酶,在肿瘤中具有免疫逃逸的功能。IDO表达于不同肿瘤细胞中,并且和肿瘤的预后存在关联。目前,已有学者对IDO在癌症中的作用及IDO抑制剂进行深入探讨,发现在临床试验中IDO抑制剂显示出较好的药物代谢动力学特征和治疗效果,以及在癌症免疫治疗中的临床应用价值及意义。