Indoleamine 2,3-dioxygenase Inhibitor Research Articles

A polymeric IDO inhibitor based on poly(ethylene glycol)-b-poly(l-tyrosine-co-1-methyl-d-tryptophan) enables facile trident cancer immunotherapy

Indoleamine 2,3-dioxygenase (IDO), with an immunoregulatory effect related to tryptophan metabolism, has emerged as an attractive target for cancer immunotherapy. Here, a polymeric IDO inhibitor based on the poly(ethylene glycol)-b-poly(L-tyrosine-co-1-methyl-D-tryptophan) copolymer (PEG-b-P(Tyr-co-1-MT)) was developed for facile trident cancer immunotherapy. PEG-b-P(Tyr-co-1-MT) could self-assemble into nanoparticles (NPs), which were subject to enzyme degradation and capable of retarding the metabolism of L-tryptophan (TRP) to L-kynurenine (KYN) in B16F10 cancer cells. Notably, cRGD-functionalized NPs showed efficient encapsulation and an enzyme-responsive release of doxorubicin (DOX) and the BET bromodomain inhibitor JQ1. DOX in drug-loaded nanoparticles (cRGD-NPDJ) could activate immunization by inducing the discernible immunogenic cell death (ICD) of cancer cells and promoting the secretion of interferon-γ (IFN-γ), which besides activating the antitumor cellular immunity often upregulates the expression of PD-L1 and IDO to accelerate tumor progression. The encapsulated JQ1 and polymeric 1-MT in cRGD-NPDJ could reverse the expression by disrupting the binding of BET proteins with chromatin and elevating the TRP/KYN ratio. In B16F10 tumor-bearing C57BL/6 mice, cRGD-NPDJ displayed significantly increased CD8+ T cells, matured dendritic cells (mDCs), and cytokines (IFN-γ, TNF-α), as well as reduced regulatory T cells and downregulated PD-L1 expression at tumor sites, generating immune cascade reactions and a distinct improvement of the tumor microenvironment (TME), leading to significant tumor suppression and survival prolongation. The polymeric IDO inhibitor provides a facile strategy for the co-delivery of chemotherapeutics and inhibitors for efficient and safe combination cancer immunotherapy.

Discovery and development of a novel N-(3-bromophenyl)-{[(phenylcarbamoyl)amino]methyl}-N-hydroxythiophene-2-carboximidamide indoleamine 2,3-dioxygenase inhibitor using knowledge-based drug design

Indoleamine 2,3-dioxygenase-1 (IDO1) is a potential target for the next generation of cancer immunotherapies. We describe the development of two series of IDO1 inhibitors incorporating a N-hydroxy-thiophene-carboximidamide core generated by knowledge-based drug design. Structural modifications to improve the cellular activity and pharmacokinetic (PK) properties of the compounds synthesized, including extension of the side chain of the N-hydroxythiophene-2-carboximidamide core, resulted in compound 27a, a potent IDO1 inhibitor which demonstrated significant (51%) in vivo target inhibition on IDO1 in a human SK-OV-3 ovarian xenograft tumor mouse model. This strategy is expected to be applicable to the discovery of additional IDO1 inhibitors for the treatment of other diseases susceptible to modulation of IDO1.

Indoleamine 2, 3 Dioxygenase 1 Impairs Chondrogenic Differentiation of Mesenchymal Stem Cells in the Joint of Osteoarthritis Mice Model.

Osteoarthritis (OA) is a serious joint inflammation that leads to cartilage degeneration and joint dysfunction. Mesenchymal stem cells (MSCs) are used as a cell-based therapy that showed promising results in promoting cartilage repair. However, recent studies and clinical trials explored unsatisfied outcomes because of slow chondrogenic differentiation and increased calcification without clear reasons. Here, we report that the overexpression of indoleamine 2,3 dioxygenase 1 (IDO1) in the synovial fluid of OA patients impairs chondrogenic differentiation of MSCs in the joint of the OA mice model. The effect of MSCs mixed with IDO1 inhibitor on the cartilage regeneration was tested compared to MSCs mixed with IDO1 in the OA animal model. Further, the mechanism exploring the effect of IDO1 on chondrogenic differentiation was investigated. Subsequently, miRNA transcriptome sequencing was performed for MSCs cocultured with IDO1, and then TargetScan was used to verify the target of miR-122-5p in the SF-MSCs. Interestingly, we found that MSCs mixed with IDO1 inhibitor showed a significant performance to promote cartilage regeneration in the OA animal model, while MSCs mixed with IDO1 failed to stimulate cartilage regeneration. Importantly, the overexpression of IDO1 showed significant inhibition to Sox9 and Collagen type II (COL2A1) through activating the expression of β-catenin, since inhibiting of IDO1 significantly promoted chondrogenic signaling of MSCs (Sox9, COL2A1, Aggrecan). Further, miRNA transcriptome sequencing of SF-MSCs that treated with IDO1 showed significant downregulation of miR-122-5p which perfectly targets Wnt1. The expression of Wnt1 was noticed high when IDO1 was overexpressed. In summary, our results suggest that IDO1 overexpression in the synovial fluid of OA patients impairs chondrogenic differentiation of MSCs and cartilage regeneration through downregulation of miR-122-5p that activates the Wnt1/β-catenin pathway.

Discovery of the First Potent IDO1/IDO2 Dual Inhibitors: A Promising Strategy for Cancer Immunotherapy.

Indoleamine 2,3-dioxygenase-1 (IDO1) plays an important role in tumor immune escape. However, unsatisfactory clinical efficacies of selective IDO1 inhibitors have impeded their further development, suggesting that they do not exert sufficient antitumor effects by selectively inhibiting IDO1. IDO2, an isoenzyme of IDO1, is overexpressed in some human tumors, and emerging evidence suggests that concomitant inhibition of IDO1/2 may have synergistic effects in cancer treatment, revealing a promising cancer immunotherapeutic strategy. Herein, we describe the discovery of compound 4t, the first inhibitor targeting both IDO1/2 that has excellent in vitro inhibitory activity (IDO1 IC50 = 28 nM and IDO2 IC50 = 144 nM). Notably, 4t (TGI = 69.7%) exhibited significantly stronger in vivo antitumor potency than epacadostat (TGI = 49.4%) in CT26 xenograft mouse models, highlighting the advantages of IDO1/2 dual inhibitors for tumor immunotherapy. Preliminary mechanistic studies in vivo further identified that 4t exerts its antitumor effect by inhibiting IDO1/2.

IDO1/TDO dual inhibitor RY103 targets Kyn-AhR pathway and exhibits preclinical efficacy on pancreatic cancer.

Indoleamine 2,3-dioxygenase 1 (IDO1) catalyzing the conversion of tryptophan (Trp) to kynurenine (Kyn) in kynurenine pathway (KP) is involved in the immunosuppression in pancreatic cancer (PC), but the value of IDO1 as an independent prognostic marker for PC is uncertain. Moreover, the correlation between tryptophan 2,3-dioxygenase (TDO), an isozyme of IDO1, and PC is largely unknown. Using TCGA database, the correlation between IDO1 and/or TDO expression and PC patients' survival was analyzed. The expressions of IDO1 and TDO in PC cells and PC mice were examined. The effects of IDO1, TDO or dual inhibition on IDO1 and TDO effector pathway (Aryl hydrocarbon receptor, AhR) and on migration and invasion of PC cells were investigated. The block effect of IDO1/TDO dual inhibitor RY103 on KP was evaluated. The preclinical efficacy of RY103 and its immunomodulatory effect on KPIC orthotopic PC mice and Pan02 tumor-bearing mice were explored. Results showed that IDO1/TDO co-expression is an independent prognostic marker for PC. RY103 can significantly block KP and target Kyn-AhR pathway to blunt the migration and invasion of PC cells, exhibit preclinical efficacy and ameliorate IDO1/TDO-mediated immunosuppression in PC mice.

Coordination Polymer-Coated CaCO3 Reinforces Radiotherapy by Reprogramming the Immunosuppressive Metabolic Microenvironment.

Radiotherapy is widely exploited for the treatment of a large range of cancers in clinic, but its therapeutic effectiveness is seriously crippled by the tumor immunosuppression, mainly driven by the altered metabolism of cancer cells. Here, a pH-responsive nanomedicine is prepared by coating calcium carbonate (CaCO3 ) nanoparticles with 4-phenylimidazole (4PI), an inhibitor against indoleamine 2,3-dioxygenase 1 (IDO-1), together with zinc ions via the coordination reaction, aiming at reinforcing the treatment outcome of radiotherapy. The obtained pH-responsive nanomedicine, coined as acidity-IDO1-modulation nanoparticles (AIM NPs), is able to instantly neutralize protons, and release 4PI to suppress the IDO1-mediated production of kynurenine (Kyn) upon tumor accumulation. As a result, treatment with AIM NPs can remarkably enhance the therapeutic efficacy of radiotherapy against both murine CT26 and 4T1 tumors by eliciting potent antitumor immunity. Furthermore, it is shown that such combination treatment can effectively suppress the growth of untreated distant tumors via the abscopal effect, and result in immune memory responses to reject rechallenged tumors. This work highlights a novel strategy of simultaneous tumor acidity neutralization and IDO1 inhibition to potentiate radiotherapy, with great promises to suppress tumor metastasis and recurrence by eliciting robust antitumor immunity.

CTIM-05. A PHASE 1/2 STUDY OF THE COMBINATION OF INDOXIMOD AND TEMOZOLOMIDE FOR ADULT PATIENTS WITH TEMOZOLOMIDE-REFRACTORY PRIMARY HIGH-GRADE GLIOMAS

Abstract BACKGROUND Optimal management of progressive high-grade gliomas (HGG) is not fully defined and outcomes are poor. Indoleamine 2,3-dioxygenase 1 (IDO1) is an enzyme which converts tryptophan to kynurenines, which contribute to the immunosuppresive tumor microenvironment (TME). Targeting the TME by inhibiting IDO1 is a strategy for potential improvement in survival in HGG. METHODS A phase 1/2 trial using the IDO1 inhibitor indoximod was conducted in progressive grade 3 and 4 gliomas. The phase 1 cmponent used a 3 + 3 design escalating indoximod from 600mg po BID to 1200mg po BID in conjunction with temozolomide (150 mg/m2, 5/28 days). The phase 2 component consisted of 3 cohorts: A) indoximod+temozolomide B) indoximod+temozolomide+bevacizumab (patients already on bevacizumab) C) indoximod+temozolomide+stereotactic radiosurgery (SRS). Patients were treated until progression or toxicity. RESULTS 33.3% of patients developed indoximod TEAEs. There were no dose limiting toxicities in the phase 1 component (n=12). 1200 mg BID was established as the phase 2 dose of indoximod. In the phase 2 component (n=148) PFS6 was 74% (A), 93% (B), 70% (C). Median OS was 289 days [10.3 months](A), 159 days [5.7 months](B), 285 days [10.2 months](C). Correlative study results will be available for meeting presentation. CONCLUSIONS The IDO1 inhibitor indoximod proved safe and tolerable in conjunction with temozolomide, bevacizumab, and SRS in patients with progressive HGG. There was a trend toward better survival outcomes when indoximod was combined with temozolomide alone or temozolomide+SRS.

CTIM-12. A PHASE 1 TRIAL OF IMMUNORADIOTHERAPY WITH THE IDO ENZYME INHIBITOR (BMS-986205) AND NIVOLUMAB IN PATIENTS WITH NEWLY DIAGNOSED MGMT PROMOTER UNMETHYLATED IDHwt GLIOBLASTOMA

Abstract BACKGROUND IDHwt glioblastoma with unmethylated MGMT gene promoter carries a poor prognosis. Preclinical studies have shown that combination of radiotherapy and dual immunotherapy with nivolumab and IDO inhibition significantly prolongs survival of mice with an orthotopic glioblastoma [Ladomersky, et al. CCR 2018;24(11):2559-2573]. In a clinical trial in patients with newly diagnosed glioblastoma with unmethylated MGMT we substituted temozolomide for dual immunotherapy combination. METHODS Phase 1 trial [NCT04047706] using a 3 + 3 dose-escalation design. All received standard radiotherapy (30 x 2 Gy) with addition of once daily oral BMS-986205 and intravenous nivolumab (240mg every 2 weeks) begining on day 1 of radiotherapy and continuing until disease progression or intolerance. BMS-986205 dosing was increased from 50 mg to 100 mg. DLT period encompasses 6 weeks of radiotherapy and the 4 subsequent weeks. Immunocorrelatives being conducted before and after treatment include mass spectrometry for tryptophan and kynurenine levels, immunohistochemistry of resected tumor, and RNA-sequencing and flow cytometric analysis of PBMCs. RESULTS Twelve patients were treated on 2 dose levels of BMS-986205 (50, 100 mg). Treatment-emergent toxicity was as expected for this population. Three (25%) treatment-related SAEs were reported. Dose limiting toxicity of grade 3 transaminase elevation was observed in 2 patients at the 100 mg dose level, while at lower doses of BMS-986205 no substantial alterations of liver enzymes was observed. No other relevant treatment related toxicity occured. Ongoing immunocorrelative profiling and preliminary outcome data (all patients minimal follow-up >12 months) will be available at the time of the meeting. CONCLUSIONS Dose limiting toxicity of BMS-986205 in combination with nivolumab and radiotherapy is hepatic (reversible) transaminitis. The recommended dose for further investigation is 50 mg. Accrual is ongoing for the MGMT promoter methylated cohort using the same regimen without withholding temozolomide. A randomized phase 2/3 trial is approved within the NRG network.

A Targetable Bone Marrow-Niche Axis for the Treatment of Acute Myeloid Leukemia

Converging lines of evidence show that the endosteal niche within the bone marrow (BM) microenvironment plays a crucial role in the pathogenesis and chemoresistance of myeloid malignancies. Dysplastic cells can exploit niche-dependent, cell non-autonomous pathways to favor their growth. Molecular delineation and targeting of those pathways may help overcome resistance to targeted therapies. In particular, acute myeloid leukemia (AML) remains recalcitrant to conventional chemo- and targeted-therapies leading to relapse and low overall survival rates (5-year survival rate <30%). These shortcomings highlight the urgency of proposing novel and adapted therapies for the disease.Leveraging genetic mouse models, patient-derived xenografts (PDX), and patient samples, herein we show the mechanism and therapeutic targeting of a cell non-autonomous progression pathway in AML. Specifically, we show that conditional ablation of serotonin receptor 1b (HTR1B) in osteoblasts -during or after AML engraftment- hampers or even prevents AML progression, increasing overall survival. Mass spectrometry-based untargeted metabolomics identified the tryptophan catabolite kynurenine (Kyn) as an oncometabolite secreted by AML cells. Remarkably, the AML proliferative pathway that exploits peripheral serotonin signaling in osteoblasts, is not driven by serotonin but by Kyn, which acts as a previously unrecognized HTR1B ligand.To explore in vivo the significance of Kyn for leukemia progression, we inhibited its synthesis by suppressing indoleamine 2,3-dioxygenase-1 (IDO1) activity in mouse and human AML cells. CRISPR-Cas9-mediated Ido1 targeting suppressed AML growth in a dose-dependent manner. Next, we sought to identify the downstream molecular targets of Kyn in human osteoblasts that render the BM niche permissive to AML engraftment and support proliferation of leukemia cells. RNAseq analysis of co-cultures between primary human osteoblasts and leukemia cells shows that AML cells induce a pro-inflammatory remodeling of the osteoblastic niche that depends on HTR1B engagement by Kyn. Among the plethora of secreted pro-inflammatory molecules induced in osteoblasts, AML-secreted Kyn (but not the canonical HTR1B ligand serotonin) induces secretion of the acute-phase protein serum amyloid-A (SAA), which in turn acts in a positive feedback-loop on leukemia cells by increasing IDO1 expression, the rate-limiting enzyme for Kyn synthesis. Acting in an autocrine manner -in a mode distinct from its established immunomodulatory properties in cancer- Kyn activates the aryl hydrocarbon receptor (AHR), thereby supporting further AML proliferation.Highlighting a clinical relevance of these findings, the Kyn-HTR1B-SAA-IDO1 AML-promoting axis identified in leukemia mouse models, is recapitulated in PDX as well as myelodysplastic syndromes (MDS) and AML patients. Preferential and progressive production of Kyn over serotonin by leukemic cells, as well as increased levels of SAA1 in the BM plasma, occur as the disease pathogenesis proceeds from MDS to AML in patients. Moreover, genetic or pharmacological (Epacadostat) IDO1 inhibition hinders AML progression in PDX models. Of note, inhibition of IDO1 synergizes with chemotherapy to reduce AML burden. Overall, these data suggest that the leukemia-osteoblast crosstalk conferred by the Kyn-HTR1B-SAA-IDO1 axis has potential as a therapeutic target. This niche-dependent, cell non-autonomous AML axis, may impact the management of myeloid malignancies, opening also new opportunities for cancer treatment in conjunction with chemo/immunotherapies. DisclosuresBorot: Vor Biopharma: Consultancy, Patents & Royalties: coinventor on issued and pending patent applications licensed to Vor Biopharm. Ali: Vor Biopharma: Consultancy, Patents & Royalties: coinventor on issued and pending patent applications licensed to Vor Biopharm. Roth: UNC: Patents & Royalties: UNC has licensed a patent with B.L.R. listed as an inventor on biased opioid compounds. . Mukherjee: Vor Biopharma: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties: coinventor on issued and pending patent applications licensed to Vor Biopharma. S.M. has equity ownership and is on the Scientific Advisory Board of Vor Biopharma., Research Funding. Rabadan: AimedBio: Membership on an entity's Board of Directors or advisory committees; Genotwin: Other: Raul Rabadan is founder of Genotwin. Carroll: Incyte Pharmaceuticals: Research Funding; Janssen Pharmaceutical: Consultancy. Raza: Celgene Inc: Research Funding, Speakers Bureau; Novartis: Speakers Bureau; Genoptix: Speakers Bureau; Kura Oncology: Research Funding; Janssen R&D: Research Funding; Syros Pharmaceuticals: Research Funding; Onconova Therapeutics: Research Funding, Speakers Bureau.

Characterizing the distributions of IDO-1 expressing macrophages/microglia in human and murine brains and evaluating the immunological and physiological roles of IDO-1 in RAW264.7/BV-2 cells.

Indoleamine 2,3-dioxygenase 1 (IDO-1) is an immunosuppressive enzyme expressed in the placenta, neoplastic cells, and macrophages to reject T cells by converting tryptophan into kynurenine. However, the role of IDO-1 in brain immunity, especially in the meninges, is unclear. We aim to elucidate the distribution pattern of IDO-1+ macrophages/microglia in the human brain tissues, human glioblastoma, APP/PS1 mouse brains, and quinolinic acid model brains and explore the physiological and immunological roles of IDO-1+ macrophages/microglia. Here, we find that both human and mouse macrophages/microglia of the perivascular and subarachnoid space and in glioblastoma (GBM) expressed IDO-1 but not macrophages/microglia of parenchyma. Using IDO-1 inhibitors including 1-MT and INCB24360, we observed that inhibiting IDO-1 reduced the cellular size and filopodia growth, fluid uptake, and the macropinocytic and phagocytic abilities of human blood monocytes and RAW264.7/BV-2 cells. Inhibiting IDO-1 with 1-MT or INCB24360 increased IL-1β secretion and suppressed NLRP3 expression in RAW264.7/BV-2 cells. Our data collectively show that IDO-1 expression in perivascular and meninges macrophages/microglia increases cellular phagocytic capacity and might suppress overactivation of inflammatory reaction.

The Function of the Kynurenine Pathway in the Placenta: A Novel Pharmacotherapeutic Target?

(L-)tryptophan is metabolized via the kynurenine pathway into several kynurenine metabolites with distinct functions. Dysfunction of the kynurenine pathway can lead to impairments in vascular regulation, immune regulation, and tolerance. The first and rate limiting enzyme of this pathway, indoleamine 2,3-dioxygenase (IDO), is highly expressed in the placenta and reduced in placentas from complicated pregnancies. IDO is essential during pregnancy, as IDO inhibition in pregnant mice resulted in fetal loss. However, the exact function of placental IDO, as well as its exact placental localization, remain controversial. This review identified that two isoforms of IDO; IDO1 and IDO2, are differently expressed between placental cells, suggesting spatial segregation. Furthermore, this review summarizes how the placental kynurenine pathway is altered in pregnancy complications, including recurrent miscarriage, preterm birth, preeclampsia, and fetal growth restriction. Importantly, we describe that these alterations do not affect maternally circulating metabolite concentrations, suggesting that the kynurenine pathway functions as a local signaling pathway. In the placenta, it is an important source of de novo placental NAD+ synthesis and regulates fetal tryptophan and kynurenine metabolite supply. Therefore, kynurenine pathway interventions might provide opportunities to treat pregnancy complications, and this review discusses how such treatment could affect placental function and pregnancy development.

Indoleamine 2,3-dioxygenase 1 (IDO1) inhibitors and PROTAC-based degraders for cancer therapy

Indoleamine 2,3-dioxygenase 1 (IDO1), a known immunosuppressive enzyme that catalyzes the rate-limiting step in the oxidation of tryptophan (Trp) to kynurenine (Kyn), has received increasing attention as an attractive immunotherapeutic target for cancer therapy. Up to now, eleven small-molecule IDO1 inhibitors have entered clinical trials for the treatment of cancers. In addition, proteolysis targeting chimera (PROTAC) based degraders also provide prospects for cancer therapy. Herein we present a comprehensive overview of the medicinal chemistry strategies and potential therapeutic applications of IDO1 inhibitors in nonclinical trials and IDO1-PROTAC degraders.

Indoleamine 2,3-dioxygenase-1, a Novel Therapeutic Target for Post-Vascular Injury Thrombosis in CKD.

CKD, characterized by retained uremic solutes, is a strong and independent risk factor for thrombosis after vascular procedures . Urem ic solutes such as indoxyl sulfate (IS) and kynurenine (Kyn) mediate prothrombotic effect through tissue factor (TF). IS and Kyn biogenesis depends on multiple enzymes, with therapeutic implications unexplored. We examined the role of indoleamine 2,3-dioxygenase-1 (IDO-1), a rate-limiting enzyme of kynurenine biogenesis, in CKD-associated thrombosis after vascular injury. IDO-1 expression in mice and human vessels was examined. IDO-1-/- mice, IDO-1 inhibitors, an adenine-induced CKD, and carotid artery injury models were used. Both global IDO-1-/- CKD mice and IDO-1 inhibitor in wild-type CKD mice showed reduced blood Kyn levels, TF expression in their arteries, and thrombogenicity compared with respective controls. Several advanced IDO-1 inhibitors downregulated TF expression in primary human aortic vascular smooth muscle cells specifically in response to uremic serum. Further mechanistic probing of arteries from an IS-specific mouse model, and CKD mice, showed upregulation of IDO-1 protein, which was due to inhibition of its polyubiquitination and degradation by IS in vascular smooth muscle cells. In two cohorts of patients with advanced CKD, blood IDO-1 activity was significantly higher in sera of study participants who subsequently developed thrombosis after endovascular interventions or vascular surgery. Leveraging genetic and pharmacologic manipulation in experimental models and data from human studies implicate IS as an inducer of IDO-1 and a perpetuator of the thrombotic milieu and supports IDO-1 as an antithrombotic target in CKD.

Design, synthesis and biological evaluation of exiguamine A analogues as IDO1 inhibitors.

A series of exiguamine A analogues were designed and synthesized via 15 steps. Their inhibitory activities against IDO1 were tested and the structure-activity relationships were studied. Most compounds exhibited potent IDO1 inhibitory activities with IC50 values at the level of 10-7-10-8M. Compound 21f was the most potent IDO1 inhibitor with an IC50 value of 65.3nM, which was comparable with the positive control drug epacadostat (IC50=46nM). Moreover, compound 21f showed higher selectivity for IDO1 over tryptophan 2,3-dioxygenase (TDO) and no cytotoxicity at its effective concentration, rending it justifiable for further optimization and evaluation.

Peritumoral CD90+CD73+ cells possess immunosuppressive features in human non-small cell lung cancer.

SummaryBackgroundAlthough T cell abundance in solid tumours is associated with better outcomes, it also correlates with a stroma-mediated source of immune suppression driven by TGFβ1 and poor overall survival. Whether this also is observed in non-small cell lung cancer (NSCLC) is unknown.MethodsWe utilized molecular analysis of The Cancer Genome Atlas (TCGA) NSLCC cohort to correlate immune activation (IA) gene expression and extracellular matrix/stromal (ECM/stromal) gene expression with patient survival. In an independent cohort of NSCLC samples, we used flow cytometry to identify mesenchymal subsets and ex vivo functional studies to characterize their immune regulatory function.FindingsWe observed a high enrichment in a core set of genes defining an IA gene expression signature in NSCLC across TCGA Pan-cancer cohort. High IA signature score correlates with enrichment of ECM/stromal gene signature across TCGA NSCLC datasets. Importantly, a higher ratio of ECM/stromal to IA gene signature score was associated with shorter overall survival. In tumours resected from a separate cohort of NSCLC patients, we identified CD90+CD73+ peritumoral cells that were enriched in the ECM/stromal gene signature, which was amplified by TGFβ1. IFNγ and TNFα-primed peritumoral CD90+CD73+ cells upregulate immune checkpoint molecules PD-L1 and IDO1 and secrete an array of cytokines/chemokines including TGFβ1. Finally, immune primed peritumoral CD90+CD73+ cells suppress T cell function, which was relieved following combined blockade of PD-L1 and TGFβ1 with IDO1 inhibition but not PD-L1 or anti-CD73 alone.InterpretationOur findings suggest that targeting PD-L1 together with independent biological features of the stroma may enhance host antitumor immunity in NSCLC.FundingLW and HY are supported by a 4-year China Scholarship Council award. This work was funded, in part, by a grant from the Cancer League of Bern, Switzerland to SRRH. Laser scanning microscopy imaging was funded by the R'Equip grant from the Swiss National Science Foundation Nr. 316030_145003.

Adaptable peptide-based therapeutics modulating tumor microenvironment for combinatorial radio-immunotherapy

Radiotherapy is one of the conventional tumor treatments, while its abscopal therapeutic efficacy is severely hampered by the immunosuppressive tumor microenvironment. To address this challenge, we herein report on the morphology-adaptable peptide-based therapeutics for efficiently reversing the immunosuppression in the combinatorial radio-immunotherapy through simultaneous checkpoint blocking and induction of immunogenic cell death. The peptide-based therapeutics were created via co-assembling a pentapeptide containing a 4-amino proline residue with its derivatives containing IDO-1 inhibitor NLG919. The resulting therapeutics underwent pH-adaptable morphological transformation between nanofibrils and nanoparticles and released NLG919 upon GSH cleavage. In vivo studies confirmed that the pH-adaptable morphologies of the therapeutics facilitated their tumor accumulation and retention at tumor sites compared to morphology-persistent counterparts, thus resulting in efficient delivery of IDO-1 inhibitors. Simultaneously treating the tumor-bearing mice with the therapeutics and external γ-ray radiation boosted the tumor immunogenicity via inducing ICD cascade of the tumor cells and reverse the immunosuppressive tumor microenvironment due to the inhibition of IDO-1 for depletion of tryptophan. Our findings strongly demonstrate that the morphology-adaptable peptide-based therapeutics exhibit the capability to reverse the immunosuppressive tumor microenvironment during irradiation, thus providing a new strategy for the combinatorial radio-immunotherapy.

Polymeric Nanoparticles as a Promising Drug Delivery Platform for the Efficacious Delivery of Toll-Like Receptor 7/8 Agonists and IDO-Inhibitor

The current investigation delineates the poly(lactide-co-glycolic acid) nanoparticles (PLGA NPs) formulation as the drug encapsulating assembly using nanoprecipitation method. Specifically, for the first time, 8-fluorotryptanthrin (Try, an IDO1 inhibitor) and 1-benzyl-2-butyl-1H-imidazo[4,5-c]quinolin-4 amine (BBIQ, a TLR7 agonist) have been encapsulated in the PLGA NPs. BBIQ and Try are the immunomodulating agents which have some shortcomings such as their low solubility and dose-related side effects associated with their systematic administration. To overcome these shortcomings, successful loading of the BBIQ and Try has been done in the polymer-based assembly. To confirm the surfactant coating and drug interaction with the NPs, differential scanning calorimetry and fourier transform infrared spectroscopy have been employed. Physicochemical characterization of the blank and loaded NPs has been done using dynamic light scattering, zeta potential, thermogravimetric analysis a high-resolution transmission electron microscope, atomic force microscopy, and X-ray diffraction analysis. To study the drug release behaviour of the NPs, drug release profiles and kinetic modelling was employed. Thus, co-encapsulation of BBIQ and try within the NPs have proven to be a promising assembly that can be investigated further in cancer vaccines.

The Role of Indoleamine 2,3-Dioxygenase in Renal Tubular Epithelial Cells Senescence under Anoxia or Reoxygenation.

Ischemia-reperfusion injury is the commonest form of acute kidney injury (AKI). Tubular epithelial cell senescence contributes to incomplete recovery from AKI and predisposes to subsequent chronic kidney disease. In cultures of primary proximal renal tubular epithelial cells (RPTECs) subjected to anoxia or reoxygenation, we evaluated the role of indoleamine 2,3-dioxygenase 1 (IDO) in cellular senescence. Proteins of interest were assessed with Western blotting or enzyme-linked immunosorbent assay or histochemically. Under anoxia or reoxygenation, IDO expression and activity were increased. Moreover, the two IDO-derived pathways, the general control nonderepressible 2 kinase (GCN2K) pathway and the aryl-hydrocarbon receptor (AhR) pathway, were also activated. A DNA damage response (DDR) took place and led to increased levels of the cell-cycle inhibitors p21 and p16, and senescence-associated β-galactosidase (SA-β-Gal) activity. Cell proliferation was inhibited, and more IL-6 was produced. The IDO inhibitor 1-DL-methyl-tryptophan ameliorated the DDR; decreased p21, p16, and SA-β-Gal activity; restored cell proliferation; and decreased IL-6 production. The AhR inhibitor CH223191 did not affect the above parameters. In conclusion, anoxia and the subsequent reoxygenation upregulate IDO. IDO depletes tryptophan and activates GCN2K. The latter enhances the anoxia- or reoxygenation-induced DDR, resulting in increased p21 and p16 expression and eventually leading to RPTEC senescence. Since cellular senescence affects AKI outcome, the role of IDO in cellular senescence and the possible therapeutic role of IDO inhibitors deserve further investigation.

D-MT prompts the anti-tumor effect of oxaliplatin by inhibiting IDO expression in a mouse model of colon cancer

Colon cancer is one of the most common malignant tumors in the digestive system. Although oxaliplatin, a chemotherapy drug, has been clinically used to treat colon cancer, its therapeutic effect is unsatisfactory. It has been proved that indoleamine dioxygenase 2,3 (IDO) is a tumor immunosuppressive factor for the immune response. Herein, an IDO inhibitor, D-MT (indoximod, 1-Methyl-D-tryptophan), was combined with oxaliplatin to treat colon cancer in mice. T cell infiltration in tumor tissues, the ratios of immune cells in the spleens, and the tumor growth and survival of the mice were detected and recorded. The results showed that the combination of oxaliplatin and D-MT significantly inhibited tumor growth and prolonged the survival of tumor-bearing mice. More importantly, the combination treatment increased the ratios of CD4+ T, CD8+ T and NK cells from the spleen in tumor-bearing mice, and prompted T cell infiltration in tumor tissues. This study provided a new therapeutic strategy for colon cancer treatment in the clinic, especially for patients with oxaliplatin resistance.

Cancer immunogenic cell death via photo-pyroptosis with light-sensitive Indoleamine 2,3-dioxygenase inhibitor conjugate

Immune checkpoint blockade (ICB) therapy currently considered as to be effective way to cure cancer in clinic. However, the insufficient tumor immunogenicity and the immunosuppressive tumor microenvironment always result in diminished efficacy of immunotherapy. Herein, we report the synthesis of an organic photo-immune activator NBS-1MT, the combination of photosensitizer and Indoleamine 2,3-dioxygenase (IDO) inhibitor effectively stimulates lysosomes oxidative stress the releases inflammatory cytokines. This process triggers pyroptosis for the considerable immunogenic cell death (ICD) while reversing suppressive tumor microenvironment. The photo-immune drug shows outstanding potential to activate caspase-1and then remove gasdermin-D (GSDMD), which could stimulate pyroptosis and also inhibit the tumor growth successfully in both primary and distant tumor. Furthermore, pyroptosis activated by photodynamic therapy (PDT) promotes the immune related factors release, and enhance the intratumoral infiltration of cytotoxic T lymphocytes (CTLs) with the induction of ICD of tumor cells and the cascaded synergize with IDO inhibitor, so the general antitumor immune response could be strengthened effectively. Our research confirms that the use of NBS-1MT is a promising strategy to boost the immune response and eventually to inhibit tumor growth.