Indoleamine 2,3-dioxygenase Inhibitor Research Articles

Abstract 5481: Combination therapy with anti-PD-1 and YH29407, a novel IDO1 inhibitor, enhances T cell-mediated antitumor immunity in MC38 tumor-bearing mice

Abstract Background: The IDO is an enzyme responsible for catabolizing tryptophan (Trp) to kynurenine (Kyn). The kynurenine exert important immunosuppressive functions by activating Treg cells and myeloid-derived suppressor cells. YH29407 is a novel IDO1 inhibitor, improved the pharmacodynamics compared to previous IDO inhibitors. Methods: To evaluate antitumor effects and immune profiles of YH29407, YH29407 was dosed at 50 or 100 mg/kg twice daily (B.I.D.) alone or in combination with anti-PD-1 (10 mg/kg, B.I.W., i.p.) and BMS-986205 was dosed at 125 mg/kg once daily (Q.D.) alone or in combination with anti-PD-1 in a MC38 syngeneic tumor model. The antitumor effects during 11 days of administration of YH29407 alone or combinations and BMS-986205 alone or combination in the MC38 model were measured. Measurements were carried out up to day 50 for survival testing. After 3 days of treatment for each condition, immune cell profiles were evaluated by flow cytometry. Results: The YH29407 at dose of 100 mg/kg B.I.D combination treatment group showed the best effects on tumor size reduction. The group constituting >TGI:70% contained 100% (15/15) of the combination treatment group, whereas 15% (2/13) of competitor BMS-986205 combination group were contained. In addition, in the combination treatment group, most tumors showed an aspect of decrease including complete responses of 5 mice. Moreover, there was a complete response in YH29407 alone group but, not observed in BMS-986205 group. According to flow cytometry analysis, the combination treatment group showed higher CD3+ total T cells compared to the vehicle group (*p<0.05). Also, the effector T cells were respectively increased in the combination treatment group than BMS-986205 alone group. Significantly, helper T cells were increased in the combination treatment group against vehicle group (***p<0.001) and BMS-986205 combination group (*p<0.05). In addition, total macrophages were increased in the combination treatment group than BMS-986205 alone group (*p<0.05). On the other hand, M-MDSC were significantly decreased in the combination treatment group than BMS-986205 combination group (*p<0.05). We evaluated the tumor-infiltrating immune cells by immunohistochemistry, infiltrated CD3+ T cells were increased in the tumor of the combination treatment group than the vehicle group and BMS-986205 combination group (both *p<0.05). Likewise, tumor infiltrated CD8+ T cells were increased in the combination treatment group than vehicle group (**p<0.01) and BMS-986205 combination group (*p<0.05). However, dose-response effect or synergistic effect on immune cell profiles between YH29407 50 mg/kg alone or combination and YH29407 100 mg/kg alone or combination were not observed. Conclusion: Taken together, we suggest that YH29407 is the best combination partner with immune checkpoint inhibitors for solid tumor. Citation Format: Kyoung-Ho Pyo, Dong Kwon Kim, Se-Woong Oh, Gyu-Jin Lee, Ho-Woong Kang, Jae Hwan Kim, Youngseon Byeon, Young Seob Kim, Chun-Bong Synn, Wongeun Lee, Su Hwan Lee, Seul Lee, Seung Min Yang, Soyeon Lee, Yunjoo Joo, Eun Ji Lee, Sun Min Lim, Byoung Chul Cho. Combination therapy with anti-PD-1 and YH29407, a novel IDO1 inhibitor, enhances T cell-mediated antitumor immunity in MC38 tumor-bearing mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5481.

Abstract 2325: Targeting kynurenine pathway using novel IDO/TDO dual inhibitor (AT0174) to modulate tumor microenvironment in platinum resistant non-small cell lung cancer cancer: An immunometabolism compliment markers

Abstract We discovered a crucial change common to all platinum resistant (CR) NSCLC cells, wherein a high level of reactive oxygen species (ROS) modulates tumor metabolism. CR cells activate the kynurenine (KYN) pathway (KP) during excessive oxidative stress to maintain high ROS for proliferation by catabolizing tryptophan (TRP) to KYN via indoleamine 2,3-dioxygenase-1 (IDO1); and by expressing (3-5x) higher levels of programmed death-ligand 1 (PD-L1) compared to platinum sensitive cells (p<0.02; n=8). We detected significant increases in IDO1 activity (3-4x), identified by the KYN/TRP ratio, in CR cells’ culture media (p<0.05; n=8). Extracellular KYN is known to program naïve T-cells to the immune suppressive regulatory T-cell (T-reg) phenotype. Using a human peripheral blood mononuclear cell (PBMC) co-culture system, we found a higher frequency of regulatory T-cells (Tregs; CD4+CD25+Foxp3+) and a lower frequency of effector T-cells (Teffs CD3+CD8+) and NK cell (CD3-CD314+CD335+) activity in co-culture with CR cells compared to cisplatin sensitive cancer cells. Importantly, inhibition of IDO1 and Tryptophan 2,3-Dioxygenase (TDO2), the enzymes involved in the rate limiting step in the KP, with the dual inhibitor AT-0174 at 20µM (48h) suppressed Tregs, but enhanced Teffs and NK cell populations in CR co-cultures. Next, we used a syngeneic mouse model of LLC (Lewis lung cancer) vs cisplatin resistant LLC-CR, to examine the effects of AT-0174 (170 mg/kg; P.O. once daily) in combination with anti-PD1 antibody (10 mg/ml; I.P. once every 3 days). Consistent with the in vitro model, analysis of mice with LLC-CR tumors found higher intratumoral T-reg and lower NK cell populations. Treatment with AT-0174 resulted in higher tumor infiltrating lymphocytes of Teffs and NK and lower Treg frequency in LLC-CR tumors than treatment with a selective IDO1 inhibitor (epacadostat). More importantly, the combination of AT-0174+antiPD1 reversed the immunosuppressive tumor microenvironments with further enhancement in Teffs and NK frequencies and diminished tumor growth in CR allografts with a significant reduction of total tumor weight compared with LLC mouse tumors (n=10, P<0.01). Our new findings support the potential therapeutic efficacy of the dual IDO/TDO inhibitor AT-0174 as an immuno-therapeutic treatment that enhances tumor immune surveillance and blocks tumor metabolism related survival mechanisms in platinum resistant NSCLC tumors. Support by the Dept. of Veterans Affairs. Citation Format: Sydney Spector, Chunjing Wu, Dan Nguyen, George Theodore, Ashley Garcia, Lynn Feun, Niramol Savaraj, Medhi Wangpaichitr. Targeting kynurenine pathway using novel IDO/TDO dual inhibitor (AT0174) to modulate tumor microenvironment in platinum resistant non-small cell lung cancer cancer: An immunometabolism compliment markers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2325.

Abstract 4184: RNA-seq analyses reveal remodeling of tumor microenvironment and reversal of glioma resistance to oncolytic viruses by targeting immunometabolism

Abstract Viroimmunotherapy aims to infect cancer cells to elicit anti-tumor immune responses. In clinical trials, glioma treatment with oncolytic viruses induced durable clinical responses in a small fraction of patients. To improve the percentage of responders, it is necessary to reshape the tumor microenvironment that shields the tumor from the immune system of the patient. Thus, we engineered Delta-24-RGDOX (DNX-2440), an oncolytic adenovirus that carries the cDNA of the T-cell activator, OX40L. In this work, we observed that Delta-24-RGDOX triggered a dramatic reshaping of the tumor microenvironment dominated by strong changes in immune processes as indicated by RNA-sequencing via ingenuity pathway analyses in a murine glioblastoma model. Paradoxically, network analyses revealed that Delta-24-RGDOX also induced robust activation of the cytokine-driven immunosuppressive IDO-Kynurenine-AhR circuitry, indicating a potential mechanism of resistance of the cancer cells to oncolytic virotherapy. To reverse this immunosuppression, we combined Delta-24-RGDOX with clinically relevant IDO inhibitors to treat glioma bearing mice. Importantly, addition of the IDO inhibitor to Delta-24-RGDOX decreased the activation of the IDO network. IDO inhibition did not affect virus infection or replication in human or murine glioma cells. Flow cytometry assays revealed that the combination therapy increased the frequency of activated CD8+ T cells and decreased the presence of the immunosuppressive cell populations, MDSCs and Tregs. Gene set enrichment analyses confirmed the decrease of MDSCs and Tregs in the combination treated glioma-bearing mice compared to the virus alone. Functional co-culture studies showed that the combined therapy activated splenocytes against tumor antigens, and that this activation was reversed by kynurenine. Importantly, the combination treatment eradicated the tumors in a CD4-dependent manner and significantly prolonged the survival of glioma-bearing mice. Altogether, these studies indicate that the combination treatment promotes an adaptive immune response while decreasing immunosuppression caused by virus-induced IDO activation. Furthermore, our data identified the striking role of immunosuppressive pathways in the resistance of gliomas to oncolytic virotherapy. Specifically, the activity of the tumor microenvironment IDO circuitry was responsible, at least partially, for the remodeling of local immunosuppression after tumor infection. Combining molecular and immune-related therapies may improve outcomes in human gliomas treated with virotherapy. Citation Format: Teresa T. Nguyen, Dong Ho Shin, Sagar Sohoni, Sanjay K. Singh, Yisel Rivera-Molina, Hong Jiang, Xuejun Fan, Joy Gumin, Frederick F. Lang, Christopher Alvarez-Breckenridge, Marta M. Alonso, Filipa Godoy-Vitorino, Lijie Zhai, Erik Ladomersky, Kristen L. Lauing, Derek A. Wainwright, Juan Fueyo, Candelaria Gomez-Manzano. RNA-seq analyses reveal remodeling of tumor microenvironment and reversal of glioma resistance to oncolytic viruses by targeting immunometabolism [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4184.

The Kynurenine Pathway and Cancer: Why Keep It Simple When You Can Make It Complicated.

Simple SummaryThe kynurenine pathway has two main physiological roles: (i) it protects specific organs such as the eyes and placenta from strong immune reactions and (ii) it additionally generate in the liver and kidney a metabolite essential to all cells of human body. Abnormal activation of this pathway is recurrently observed in numerous cancer types. Its two functions are hijacked to promote tumor growth and cancer cell dissemination through multiple mechanisms. Clinical assays including administration of inhibitors of this pathway have not yet been successful. The complex regulation of this pathway is likely the reason behind this failure. In this review, we try to give an overview of the current knowledge about this pathway, to point out the next challenges, and to propose alternative therapeutic routes.The kynurenine pathway has been highlighted as a gatekeeper of immune-privileged sites through its ability to generate from tryptophan a set of immunosuppressive metabolic intermediates. It additionally constitutes an important source of cellular NAD+ for the organism. Hijacking of its immunosuppressive functions, as recurrently observed in multiple cancers, facilitates immune evasion and promotes tumor development. Based on these observations, researchers have focused on characterizing indoleamine 2,3-dioxygenase (IDO1), the main enzyme catalyzing the first and limiting step of the pathway, and on developing therapies targeting it. Unfortunately, clinical trials studying IDO1 inhibitors have thus far not met expectations, highlighting the need to unravel this complex signaling pathway further. Recent advances demonstrate that these metabolites additionally promote tumor growth, metastatic dissemination and chemoresistance by a combination of paracrine and autocrine effects. Production of NAD+ also contributes to cancer progression by providing cancer cells with enhanced plasticity, invasive properties and chemoresistance. A comprehensive survey of this complexity is challenging but necessary to achieve medical success.

Neoadjuvant nivolumab with or without IDO inhibitor in head and neck squamous cell carcinoma (HNSCC): Final pathologic and clinical outcomes.

6070 Background: Indoleamine 2,3-dioxygenase (IDO) catalyzes the degradation of tryptophan to kynurenine. In order to improve the clinical efficacy of PD-1 inhibition, we designed a novel neoadjuvant trial to test the immunological and therapeutic effects of nivolumab (nivo) and the IDO inhibitor BMS986205 in combination in previously untreated HNSCC utilizing an interim radiographic assessment to determine response treatment prior to surgery. Methods: We conducted an investigator-initiated, multi-institutional, two-arm, 3:1 randomized neoadjuvant trial in patients with previously untreated HNSCC of any stage who were candidates for complete surgical resection. Patients were stratified by HPV status. Patients in arm A received 480 mg of nivolumab alone. Subjects in arm B received BMS986205 100 mg po qday beginning 1 week prior to nivolumab 480 mg. Both groups were evaluated at week 5 with CT scans. Radiographic response was evaluated at both the primary site and any involved lymph nodes. Patients with at least a 10% reduction in volume at either the primary or lymph nodes with no evidence of progression continued on to a second cycle of the assigned treatment. Patients with stable disease or progression proceeded to surgery at week 5 without additional study treatment. Imaging, blood and tumor were obtained pretreatment and post treatment and used for immunological correlatives. 2 blinded independent pathologist provided pathologic treatment effect (pTE) scores for primary tumor and lymph nodes. The primary endpoint was radiographic response leading to additional study treatment. Results: 42 patients were randomized and completed treatment to the primary endpoint evaluation including 22 HPV+ oropharyngeal HNSCC. Four patients did not proceed with planned surgery: 2 progression, 1 patient preference, and 1 toxicity. 3 patients in Arm B developed hepatitis with 2 subjects having a delay in surgery. 36% of patients (n=4) in Arm A (nivo alone) and 42% of patients (n= 13) in Arm B (nivo+IDO) were considered radiographic responders and continued to a second cycle of therapy (p= 1.0). Pathologic treatment effect (pTE) was significantly higher in subjects who were treated with a second cycle: median of 85% pTE (responders) compared to median of 5% pTE (nonresponders) at the primary site (p=0.018) with 6/16 (38%) subjects in the radiographic responders and 1/20 (5%) in radiographic non-responders demonstrating a CR at the primary site. In the lymph node compartment, the median pTE was 73% compared to 23% in radiographic responders vs non-responders (p=0.04). Conclusions: In previously untreated HNSCC, nivolumab +/- IDO inhibitor demonstrated a significantly greater pTE after a second dose in radiographic responders. The addition of IDO-inhibitor to anti-PD1 did not result in a significant increase in radiographic or pathologic response over nivolumab alone. NCT03854032. Clinical trial information: NCT03854032.

IDO1 plays a tumor-promoting role via MDM2-mediated suppression of the p53 pathway in diffuse large B-cell lymphoma

With the intensive therapeutic strategies, diffuse large B-cell lymphoma (DLBCL) is still a fatal disease due to its progressive characteristics. Indoleamine 2,3-dioxygenase 1 (IDO1) is a key regulator that catalyzes the commitment step of the kynurenine pathway in the immune system, its aberrant activation may contribute to malignant cell escape eradication. However, the role of IDO1 in DLBCL progression remains elusive. Our study showed IDO1 expression was upregulated in DLBCL and was associated with a poor prognosis and low overall survival. Inhibition of IDO1 suppressed DLBCL cell proliferation in vitro and impeded xenograft tumorigenesis in vivo. RNA-seq analyses revealed MDM2 was downregulated while TP53 was upregulated in IDO1 inhibition OCI-Ly10 cells. Mechanistically, IDO1 inhibition decreased the expression of MDM2, a major negative regulator of p53, and restored p53 expression in OCI-Ly3 and OCI-Ly10 cells, resulting in cell cycle arrest and apoptosis. IDO1 inhibition induced cell apoptosis coupled with PUMA and BAX upregulation, as well as BCL2 and BCL-XL downregulation. In addition, p21, a p53 transcriptional target, was upregulated in cell cycle arrest. Taken together, this study revealed IDO1 is essential for the proliferation of DLBCL cells and may be a potential therapeutic target for the treatment of DLBCL.

Protective effects of Zuogui Jiangtang Jieyu Formula on hippocampal neurons in rats of diabetes complicated with depression via the TRP/KYN metabolic pathway

ObjectiveTo explore the protective effects and mechanism of Zuogui Jiangtang Jieyu Formula (左归降糖解郁方, ZGJTJYF) on hippocampal neurons in rats of diabetes complicated with depression (DD) via the TRP/KYN metabolic pathway. Methods(i) In vivo experiments: 60 specified pathogen free (SPF) grade male Sprague-Dawley (SD) rats were randomly divided into six groups with 10 rats in each groups: control, DD model, positive (1.8 mg/kg fluoxetine + 0.18 g/kg metformin), high-dose ZGJTJYF (ZGJTJYF-H, 40.500 g/kg ZGJTJYF), middle-dose ZGJTJYF (ZGJTJYF-M, 20.250 g/kg ZGJTJYF), and low-dose ZGJTJYF (ZGJTJYF-L, 10.125 g/kg ZGJTJYF) groups. Except for the control group, other groups were established DD model by high-fat emulsion intake with single tail vein streptozotocin (STZ) and four weeks of chronic unpredictable mild stress (CUMS). All drug administration groups were treated by gavage during CUMS modeling, and the control and model groups were given equal amount of distilled water. After four weeks, the serum levels of blood glucose and glycosylated hemoglobin were measured to determine the hypoglycemic effect of ZGJTJYF. Moreover, the open field test and Morris water maze test were performed to evaluate the antidepressant effect of ZGJTJYF. Changes in 5-hydroxytryptamine (5-HT) level were detected via high-performance liquid chromatography with electrochemical detection (HPLC-ECD); the levels of tryptophan (TRP), kynurenine (KYN), and indoleamine 2,3-dioxygenase (IDO) in the hippocampus were detected using enzyme-linked immunosorbent assay (ELISA); the protein expression levels of synaptophysin (SYN) and postsynaptic density material-95 (PSD-95) were detected via immunohistochemistry (IHC); and the protein expression levels of N-methyl-D-aspartate receptor (NR) 2A and NR2B were detected using Western blot. (ii) In vitro experiments: five SPF grade SD pregnant rats (E16 – 18) were used to obtain primary hippocampal neurons (Ne), six SD new-born rats were used to collected primary astrocytes (As) and microglia (MG), and to establish a Ne-As-MG co-culture system. All co-culture systems were divided into six groups: control (PBS), model [150 mmol/L glucose + 200 μmol/L corticosterone (G&P) + PBS], blank (G&P + blank serum), positive (G&P + positive drug-containing serum), ZGJTJYF (G&P + ZGJTJYF serum), and 1-methyl-D-tryptophan (1-MT, IDO inhibitor) (G&P + 1-MT) groups. After 18 h of intervention by corresponding treatment, immunofluorescence was used to analyze the protein expression levels of SYN, PSD-95, NR2A, and NR2B; ELISA was performed to measure the levels of interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α , and TRP/KYN metabolic pathway-related factors [TRP, KYN, kynurenine acid (KYNA), quinolinic acid (QUIN)]. Results(i) In vivo experimental<italic/> results showed that ZGJTJYF-M and ZGJTJYF-L significantly improved the elevated blood glucose state of DD rats (P < 0.01 and P < 0.05, respectively); ZGJTJYF-H, ZGJTJYF-M, and ZGJTJYF-L increased their autonomous activity, learning, and memory ability (P < 0.01, P < 0.01, and P < 0.05, respectively). Moreover, the levels of 5-HT and TRP were significantly increased (P < 0.01), and the levels of KYN and IDO were significantly decreased in the hippocampus (P < 0.01) of rats after ZGJTJYF-M treatment. The protein expression levels of SYN and PSD-95 were significantly upregulated in hippocampal neurons (P < 0.01), while the abnormal activation of NR2A and NR2B was markedly inhibited in hippocampus (P < 0.05) of rats after ZGJTJYF-M treatment. (ii) In vitro experimental results showed that ZGJTJYF-containing serum significantly increased the protein expression levels of SYN and PSD-95 in hippocampal neurons (P < 0.01), decreased the levels of IL-1β (P < 0.01), IL-6 (P < 0.05), TNF-α (P < 0.01), IDO (P < 0.05), KYN (P < 0.05), and QUIN (P < 0.01), and increased the levels of TRP and KYNA (P < 0.01) in the simulated DD state. ZGJTJYF also had an significantly inhibitory effect on the abnormal activation of NR2A and NR2B in neurons (P < 0.05) in a stimulated DD state. ConclusionZGJTJYF can effectively improve 5-HT deficiency in the hippocampus of rats by inhibiting IDO expression and regulating the TRP/KYN metabolic pathway, and it has a favorable protective effect on hippocampal neuron injury caused by DD. Therefore, ZGJTJYF is an effective potential therapeutic drug for the prevention and treatment of DD.

Preliminary results of a phase II study of retifanlimab (PD-1 inhibitor) plus or minus epacadostat (IDO1 inhibitor) in combination with bevacizumab and hypofractionated radiotherapy for recurrent glioblastoma: NCT03532295.

2058 Background: Immunotherapies targeting the programmed cell death-1 (PD-1) pathway in recurrent glioblastoma (rGBM) have failed. We hypothesize that combining therapies targeting multiple immunosuppressive pathways with cytotoxic and antiangiogenic therapies will improve survival. Here, we evaluate the safety and efficacy of an anti-PD-1 monoclonal antibody (retifanlimab), hypofractionated radiotherapy (HFRT), and bevacizumab, with or without an oral IDO1 inhibitor (epacadostat), in patients with rGBM in a nonrandomized, noncomparative sequential two-arm Phase II study. Methods: This is an open-label Phase II study of 2 sequential cohorts (Table). Cohort A first examines retifanlimab + bevacizumab + HFRT in patients with IDH1/2-WT rGBM. After a toxicity monitoring period, Cohort B, which adds epacadostat, starts enrolling. Key inclusion criteria includes dexamethasone ≤ 4 mg/day at registration and candidacy for reirradiation. Previous bevacizumab use for radiation necrosis is permitted. The primary endpoint is OS probability at 9 months (OS-9). Secondary endpoints include PFS, OS, and toxicity. Exploratory endpoints include immunological phenotyping of blood and tissue. An increase of OS-9 from 38% (bevacizumab alone) to 60% is considered clinically relevant. Results: From 6/2020 to 12/2021, we have completed accrual for cohort A and the interim analysis results are presented here: 25 patients with rGBM enrolled, with 23 evaluable. Median age is 64.3 years (42.1-81.8), 30.4% female, 30.4% MGMT promotor methylated, median KPS 90 (range 70-100), baseline dexamethasone 0 mg (range 0-4) with 52.2% of patients on dexamethasone during the first 3 cycles, median baseline ALC 1,000 cells/µl (range 300-3,700). Patients received a median of 6 cycles to date (range 2-20). Median follow-up is 11.97 months per the reverse Kaplan-Meier method. Interim analysis shows a median PFS of 9.9 months (95%CI: 5.5 to not reached (NR)) and median OS of 12.2 months (95%CI 7.3-NR). Notably, Cohort A met the primary endpoint with an OS-9 of 71.4% (95%CI: 46.7% -86.1%). No dose limiting toxicities have been yet observed. Two treatment-related grade 3 toxicities have occurred (myositis, hypertension). Cohort B enrollment is ongoing, and correlative studies pending. Conclusions: Interim analysis suggests retifanlimab combined with HFRT and bevacizumab in patients with rGBM is well-tolerated and had encouraging OS and PFS at the time of data cutoff. Cohort B, which adds epacadostat, is currently enrolling. Clinical trial information: NCT03532295. [Table: see text]

A phase II trial of IDO-inhibitor, BMS-986205 (IDO), and PD-1 inhibitor, nivolumab (NIVO), in recurrent or persistent endometrial cancer (EC; CA017-056).

5589 Background: Indoleamine 2,3-dioxygenase 1 (IDO1) allows tumor escape through kynurenine production, which induces regulatory T cells and suppresses effector T-cell proliferation. NIVO, an anti-PD-1 inhibitor can upregulate IDO1, supporting the rationale for combining NIVO with IDO. We report results of NIVO as monotherapy and in combination with IDO inhibitor BMS-986205 in the treatment of pts with recurrent EC. Methods: In this single-institution, randomized phase 2 study, eligible pts must have received 1-4 prior lines of chemotherapy and have measurable disease by RECIST v 1.1. All EC histologies, including carcinosarcoma, were allowed. Pts with microsatellite insufficient (MSI-H) or mismatch repair (MMR)-deficient tumors were excluded. Pts were randomized to NIVO 480mg IV every 4 weeks (wks) with or without IDO 100mg orally daily. Primary endpoints were Overall Response Rate [ORR = Complete Response (CR) + Partial Response (PR)] by RECIST v 1.1. Secondary objectives were duration of response (DOR), median progression free survival (mPFS), PFS rate at 24 wks (PFS24wks) and safety. Overall survival (OS) was also evaluated. Results: Between 10/2019 and 11/2021, pts were randomized to receive either NIVO (n = 12) or NIVO + IDO (n = 12). Median age was 67 years (range 48-82) and median number of prior lines of therapy was 2 (range 1-3). Histologies included serous (n = 5, 21%), endometrioid (n = 10, 42%), clear cell (n = 1, 4.2%), carcinosarcoma (n = 6, 25%), undifferentiated (n = 1, 4.2%), and mucinous (n = 1, 4.2%). In the NIVO + IDO arm, 1 pt achieved partial response (8.3%, CI: 0.9-100%) with DOR of 17.6 months. In the NIVO arm, no responses were observed. Efficacy outcomes are summarized in the table. Treatment-related adverse events (TRAEs) grade ≥ 3 in the NIVO arm included acute kidney injury (n = 1, 8.3%), hypokalemia (n = 1, 8.3%), and thromboembolic event (n = 1, 8.3%). In the NIVO + IDO arm, TRAEs grade ≥ 3 included fatigue (n = 1, 8.3%), and elevated liver function (n = 1, 8.3%). No TRAEs led to study-drug interruption or dose reductions. Conclusions: NIVO monotherapy and in combination with IDO showed acceptable safety in pts with recurrent EC. NIVO in combination with IDO showed ORR of 8.3%. No responses were observed with NIVO monotherapy. The trial closed to accrual due to lack of observed clinical efficacy. Clinical trial information: NCT04106414. [Table: see text]

Phase I study of epacadostat in combination with sirolimus in advanced malignancy.

2575 Background: Epacadostat (E) is an inhibitor of Indoleamine 2,3 dioxygenase-1 (IDO1) which is a rate-limiting enzyme in the catabolism of tryptophan to kynurenine. The inhibition of IDO1 leads to increase tryptophan and reversal of immunosuppression by increasing the proliferation of T cells, suppression of regulatory T cells (Tregs) and activation of mTOR which suppresses autophagy. Sirolimus (S) can reverse the mTOR activation induced by E, suppress the expression of PD-L1 and function of Tregs. We initiated a phase I trial to test the safety and tolerability of SE combination in patients with advanced solid tumors, with plans for an expansion phase II study in patients with advanced recurrent lung cancer once maximum tolerated dose (MTD) was defined. Methods: The phase I trial portion of the study used a modified 3+3 design in which the dose transition rule was similar to standard 3+3 design with the modification based on sirolimus PK data. S had a lead-in of 3mg/day(d) at day -7 followed by 1mg/d with E added on day 1 of Cycle 1 starting at 300mg bid in a 28d cycle at dose level 1; then S is escalated to 6mg/d followed by 2mg/d maintenance with E at 300mg bid at level 2. An additional level 3 was added with S at 6mg/d followed by 2mg/day with E at 400 bid based on results of E at 400-600 mg bid in combination with a checkpoint inhibitor with improved control of peripheral kynurenine and intra-tumoral kynurenine reductions. Enrollment continued until Dose limiting toxicity (DLT) which was defined as grade 3 hematologic toxicities or grade 3 or 4 non-hematologic toxicities up to Cycle 2 day 1. MTD was defined as DLT not exceeding 33% of subjects. Results: The phase I study enrolled 15 patients, with 9 patients evaluable. The types of cancers were non-small cell lung ca (1), colorectal (5), esophagus (1), gallbladder (1) and sarcoma (1). DLT was not observed up to level 3. Adverse events attributed to SE were Grade 1 Diarrhea (2), stomach pain (1); elevated liver enzymes (ELE) (1), decreased white blood cell (1), anorexia (1), hypokalemia (1), dizziness (1), skin rash (1); Grade 2 ELE (1), Anemia (1), Vertigo (1), Constipation (1), Nausea (2); Grade 3: Diarrhea (1), serotonin syndrome (1), dyspnea (1). The best response observed was stable disease in 3 patients, 5 patients had disease progression and 1 patient was not assessable for response due treatment discontinuation related to side effect of serotonin syndrome. The Expansion Cohort (Part 2) did not proceed since the sponsor decided to discontinue further development of E. Conclusions: The combination of SE is feasible, tolerable with mostly grade 1 and 2 toxicities. There were few grades 3 toxicities. SE produced stable disease as best response in 33% of patients. Research using the combination of SE as an immunomodulatory therapy in patients with lung cancer resistant to checkpoint inhibitor is worth additional exploration. Clinical trial information: NCT03217669.

Inflammation and serotonin deficiency in major depressive disorder: molecular docking of antidepressant and anti-inflammatory drugs to tryptophan and indoleamine 2,3-dioxygenases.

The roles of the kynurenine pathway (KP) of tryptophan (Trp) degradation in serotonin deficiency in major depressive disorder (MDD) and the associated inflammatory state are considered in the present study. Using molecular docking in silico, we demonstrate binding of antidepressants to the crystal structure of tryptophan 2,3-dioxygenase (TDO) but not to indoleamine 2,3-dioxygenase (IDO). TDO is inhibited by a wide range of antidepressant drugs. The rapidly acting antidepressant ketamine does not dock to either enzyme but may act by inhibiting kynurenine monooxygenase thereby antagonising glutamatergic activation to normalise serotonin function. Antidepressants with anti-inflammatory properties are unlikely to act by direct inhibition of IDO but may inhibit IDO induction by lowering levels of proinflammatory cytokines in immune-activated patients. Of six anti-inflammatory drugs tested, only salicylate docks strongly to TDO and apart from celecoxib, the other five dock to IDO. TDO inhibition remains the major common property of antidepressants and TDO induction the most likely mechanism of defective serotonin synthesis in MDD. TDO inhibition and increased free Trp availability by salicylate may underpin the antidepressant effect of aspirin and distinguish it from other nonsteroidal anti-inflammatory drugs. The controversial findings with IDO in MDD patients with an inflammatory state can be explained by IDO induction being overridden by changes in subsequent KP enzymes influencing glutamatergic function. The pathophysiology of MDD may be underpinned by the interaction of serotonergic and glutamatergic activities.

Novel 1,2,3-Triazole Erlotinib Derivatives as Potent IDO1 Inhibitors: Design, Drug-Target Interactions Prediction, Synthesis, Biological Evaluation, Molecular Docking and ADME Properties Studies.

Indoleamine 2,3-dioxygenase 1 (IDO1) plays a predominant role in cancer immunotherapy which catalyzes the initial and rate limiting steps of the kynurenine pathway as a key enzyme. To explore novel IDO1 inhibitors, five derivatives of erlotinib-linked 1,2,3-triazole compounds were designed by using a structure-based drug design strategy. Drug-target interactions (DTI) were predicted by DeePurpose, an easy-to-use deep learning library that contains more than 50 algorithms. The DTI prediction results suggested that the designed molecules have potential inhibitory activities for IDO1. Chemical syntheses and bioassays showed that the compounds exhibited remarkable inhibitory activities against IDO1, among them, compound e was the most potent with an IC50 value of 0.32 ± 0.07 μM in the Hela cell assay. The docking model and ADME analysis exhibited that the effective interactions of these compounds with heme iron and better drug-likeness ensured the IDO1 inhibitory activities. The studies suggested that compound e was a novel and interesting IDO1 inhibitor for further development.

Mechanism Found for IDO1 Inhibitor Evasion

Researchers have pinpointed metabolic alterations that may allow tumors to evade the IDO1 inhibitor epacadostat. Tumor cells enlisted an alternative pathway to break down tryptophan, the target of IDO1, and increased the activity of pathways that generate NAD+. The metabolic changes also suppressed CD8+ T cells.

Anti-inflammatory effect of indoleamine 2,3-dioxygenase 1 inhibition for lipopolysaccharide induced epididymitis

ABSTRACT Introduction and Objective Even though antimicrobial therapy is received, some patients with epididymitis remaining inflammatory changes and led to refractory condition. Innovative therapy focused on the inflammatory changes is needed for epididymitis. Indoleamine 2,3-dioxygenase 1 (IDO1) catalyzes the first and rate-limiting step of tryptophan catabolism. IDO1 plays a key role in immune response and shows high expression in male genitalia. Furthermore, protective effect of IDO1 inhibition for various inflammatory disease was indicated in some reports. We hypothesize that IDO1 plays a central role for immunological reaction in epididymal inflammation. We investigated the relevance between IDO1 inhibition and epididymal inflammation. This study was approved by the safety committee for DNA experiments and the animal research committee of our facility (Approval No.14-35, 18-52). Materials and Methods Ten to twelve weeks old, C57BL/6 IDO1 knock out (IDO1 KO) mice were used through the research. Same conditional wild type (WT) mice were set as control. Lipopolysaccharide (LPS) 5μg/g(weight) was injected into epididymis from the vas deferens side. Epididymis was removed at a to 7 days after epididymitis modeling. Inflammatory changes in epididymis were investigated using histological, biochemical and immunohistochemical analysis. Series of these analysis were duplicated at least. Results Histological analysis using HE staining showed decreased effect of inflammation in IDO1 KO mice compared with WT mice. Proteomic analysis showed decreased effect of both inflammatory promoting cytokines (IL-1α, IL-6) and chemokines (CCL3, CXCL1) in IDO KO mice. On the other hand, increased effect of inflammatory inhibiting cytokines (IL-4, IL-10) were showed in IDO KO mice. Same results were obtained from immunohistochemical analysis using immunofluorescent staining. Conclusions IDO1 is involved in epididymal inflammation via cytokine and chemokine. IDO1 inhibition contribute to tissue protection for epididymitis. Therefore, IDO1 inhibition might be an innovative therapy for epididymitis. Disclosure Work supported by industry: no.

Anti-inflammatory mechanism of indoleamine 2,3-dioxygenase 1 inhibition for autoimmune induced chronic prostatitis

ABSTRACT Introduction and Objectives Evidence-based treatment for chronic prostatitis (CP) has not been established so far. Innovative therapy for CP is needed to establish evidence-based therapy. Indoleamine 2,3-dioxygenase1 (IDO1) catalyzes the first and rate-limiting step of tryptophan catabolism through the kynurenine pathway. IDO1 expression in prostate is higher than that of other organs. IDO1 is induced in various tissues during inflammatory disease. Furthermore, protective effect of IDO1 inhibition for inflammation was indicated in some reports. We hypothesize that IDO1 plays a central role for immunological reaction in CP. We investigated the relevance between IDO1 inhibition and CP using autoimmune induced CP model mice. This study was approved by the safety committee for DNA experiments and the animal research committee of our facility (Approval No.18-07 and 20-89). Materials and Methods Ten to twelve weeks old, IDO1 knock out (IDO1 KO) mice were used through the research. Same conditional wild type (WT) mice were set as control. Prostate gland extracted from Wister rat were used as prostate antigen (Pag) for mice. PAg 100µg / 100µl were injected into mice subcutaneously. After creating autoimmune induced CP model mice, inflammatory change in the prostate was investigated using histological, biochemical and immunohistochemical analysis. Results Histological analysis showed suppressive effect of inflammatory cells infiltration and interstitial fibrosis were observed in IDO1 KO CP model mice compared with that of WT CP model mice. Proteomic analysis showed decreased effect of lymphocyte and monocyte related cytokines (CCL2, CCL3) and fibrosis related cytokine (TIMP-1) in IDO1 KO CP model mice compared with that of WT CP model mice. Same results were obtained from immunohistochemical analysis using immunofluorescent stain. Conclusions IDO1 is involved in chronic inflammation via cytokines/chemokines in the prostate. IDO1 inhibition contribute to suppressive effect of chronic inflammation and fibrosis in the prostate. Therefore, IDO1 inhibition might be a novel target therapy for chronic prostatitis. Disclosure Work supported by industry: no.

Transient modification of macrophages for activation their pro‐inflammatory functions

Macrophages are innate immune cells that play an important role in both physiological and pathological conditions. According to the concept of binary polarization, there are two the most polar states of macrophages: pro‐inflammatory and anti‐inflammatory macrophages. We proposed that targeted programming of macrophages derived from the specific monocyte subpopulation is perspective strategy for activation their inflammation properties that could be used in therapy of cancer or endometriosis. This work is devoted to the study of the effect of Indoleamine 2,3‐dioxygenase 1 (IDO1) and its inhibitor BIN1 on the shift in the polarization of macrophages into a pro‐inflammatory phenotype. We used magnetic sorting, differentiation, and further pro‐inflammatory polarization of CD14+ monocytes from the blood of healthy donors. We obtained data on the transcriptome and proteome and carried out a bioinformatic analysis to identify the most significant differences between two groups of cells – naive and pro‐inflammatory macrophages. IDO1 has been identified as an enzyme with immunomodulatory functions and is also involved in the catabolism of the essential amino acid L‐tryptophan. This enzyme is expressed in macrophages and its expression is induced by pro‐inflammatory cytokines. It was shown that the BIN1 protein is an inhibitor of IDO1 and can inhibit the growth of cancer cells. It was shown that upon the polarization of macrophages towards the pro‐inflammatory phenotype by LPS addition, the expression of IDO1 increases, while the expression of BIN1 decreases (p &lt;0.05). To reveal the influence of the IDO1 and BIN1 genes on the shift of the polarization of macrophages towards the M1 phenotype, we decided to carry out knockdown by using siRNAs on the primary line of CD14+‐derived macrophages. The efficiency of transfection was assessed at different concentrations of siRNA ranged from 30 to 80%, but high concentrations of siRNA led to non‐specific activation of pro‐inflammatory phenotype. Expression analysis confirmed the silencing of the genes IDO1 and BIN1 using 5 nM siRNA. It was shown that knockdown of IDO1 and BIN1 leads to increased expression of pro‐inflammatory genes (CCR7 and TNFa) and decreased the level of anti‐inflammatory interleukin 10. Also, co‐cultivation CD14+ macrophages after knockdown of genes IDO1 and BIN1 didn’t influent on macrophage’s phagocytic functions. The proposed study has a scientific novelty since for the first time a transient modification of the primary line of macrophages from blood CD14 + was carried out and the influence of IDO1 and BIN1 on the activation of the pro‐ or anti‐inflammatory phenotype was shown. Directed programming of macrophages is a new and rapidly developing field.

Anti-inflammatory Response Induced by Exopolysaccharide of the Probiotic Bacillus subtilis

Abstract Probiotics can lessen the severity of intestinal inflammatory diseases, although the mechanisms by which this occur are poorly understood. We showed that exopolysaccharide (EPS) from the probiotic Bacillus subtilis induces anti-inflammatory macrophages and protects mice from enteric infection and sepsis. Here, we examined the molecular mechanisms by which EPS induces an anti-inflammatory response. In co-cultures of OVA-loaded bone marrow-derived dendritic cells (BMDC) and OT-II T cells, EPS inhibits T cell activation in a TLR4-dependent manner. We hypothesize that EPS engages TLR4 and activates the noncanonical NF-kB signaling pathway, which up-regulates the expression of indoleamine 2,3-dioxygenase (IDO). IDO degrades the essential amino acid tryptophan into kynurenine, which leads to suppression of T-cell activation and induction of tolerance. Western blot analysis of BMDCs treated with EPS showed nuclear translocation of the transcription factor RelB, which is central to the noncanonical pathway and upregulation of IDO. Inhibition of IDO using the inhibitor 1-methyl tryptophan, and ido1−/− BMDCs reverse the effect of EPS. We conclude that EPS inhibition of T cell activation and proliferation is mediated by IDO. We have identified a novel mechanism for immune protection by a probiotic molecule.

Expression, purification, and kinetic characterization of the human strep-IDO1.

BackgroundTryptophan catabolism leading to T cell suppression mediated by indoleamine 2,3-dioxygenase (IDO1) is an important mechanism of tumor immune escape, and IDO1 inhibitors have attracted increasing attention as anticancer therapeutics. However, the phase III clinical trial (ECHO-301/KEYNOTE-252) of epacadostat (INCB024360) had disappointing outcomes. This revealed that purification of IDO1 with high purity is one of the major constraints that limit the development of its inhibitors.MethodsPan-cancer analysis was used to elucidate the relationship between IDO1 function in tumor immunology. The recombinant pET28a-IDO1-strep plasmid and E. coli Rosetta (DE3) strain were used to express and strep-tactin beads to purify the strep-IDO1 protein. High performance liquid chromatography (HPLC) was used to detect enzymatic activity of IDO1. Ten female C57BL/6 mice was used to prepared polyclonal antibody. Enzyme linked immunosorbent assay (ELISA), Western blot, and immunofluorescence were used to measure polyclonal antibody.ResultsWe described an improved method for the purification of recombinant IDO1 protein based on the strep-tag using an E. coli expression system. We obtained large amount of IDO1 with enhanced purity by employing one-step purification through strep-tactin beads. The polyclonal antibody acquired immunized mice could specifically recognize both recombinant and endogenous IDO1.ConclusionsPurified human strep-IDO1 using the protocol described in our study could be used for further biochemical and structural analyses, which may facilitate functional research and further drug screening study on IDO1.

Watson-Crick Base Pairing-Inspired Laser/GSH Activatable miRNA-Coordination Polymer Nanoplexes for Combined Cancer Chemo-Immuno-Photothermal Therapy.

The tumor immunosuppressive microenvironment (TIM) greatly hindered the efficacy of cancer immunotherapy. Overexpressed indoleamine 2,3-dioxygenase-1 (IDO1) in tumor tissues plays a vital role in TIM generation, and downregulation of IDO1 expression may reverse TIM. Inspired by the Watson-Crick base-pairing rule, a versatile noncationic miRNA vector (miDAC@PDA) is developed for cancer immunotherapy. Doxorubicin (DOX), adenosine triphosphate (ATP), and copper ions (Cu2+) are coassembled into coordination polymer nanoparticles (DAC) and bind miRNA via the hydrogen bond interaction (miDAC) between adenine residues (ATP) and uracil residues (miRNA). Polydopamine (PDA) is deposited onto the surface of miDAC for photothermal therapy. miDAC@PDA can efficiently accumulate into tumor tissues for cellular uptake. Under laser irradiation and high intracellular GSH levels, the PDA shell of miDAC@PDA can dissociate from miDAC for miRNA release due to local hyperthermia. Cu2+-mediated GSH consumption and intracellular ATP release can amplify the DOX-based immunogenic cell death (ICD) cascade, together with miR-448-mediated IDO1 inhibition, and these versatile nanoplexes will not only restrain primary tumor growth but also display a remarkable abscopal effect on distant tumors. Collectively, our study provides a unique strategy for intracellular gene delivery and an inspirational approach for multimechanism cancer management.

Spiro-Oxindole Skeleton Compounds Are Efficient Inhibitors for Indoleamine 2,3-Dioxygenase 1: An Attractive Target for Tumor Immunotherapy.

Indoleamine 2,3-dioxygenase 1 (IDO1) is an attractive heme enzyme for its significant function in cancer immunotherapy. Potent IDO1 inhibitors have been discovered for decades, whereas no clinical drugs are used for cancer treatment up to now. With the goal of developing medically valuable IDO inhibitors, we performed a systematic study of SAR405838 analogs with a spiro-oxindole skeleton in this study. Based on the expression and purification of human IDO1, the inhibitory activity of spiro-oxindole skeleton compounds to IDO1 was evaluated by IC50 and Ki values. The results demonstrated that inhibitor 3 exhibited the highest IDO1 inhibitory activity with IC50 at 7.9 μM among all inhibitors, which is ~six-fold of the positive control (4−PI). Moreover, inhibitor 3 was found to have the most effective inhibition of IDO1 in MCF-7 cancer cells without toxic effects. Molecular docking analysis revealed that the hydrophobic interaction stabilized the binding of inhibitor 3 to the IDO1 active site and made an explanation for the uncompetitive mode of inhibitors. Therefore, this study provides valuable insights into the screen of more potent IDO1 inhibitors for cancer immunotherapy.