Epacadostat Research Articles

Chemo-immunotherapy by nanoliposomal epacadostat and docetaxel combination to IDO1 inhibition and tumor microenvironment suppression

The over-activation of tryptophan (Trp) metabolism to kynurenine (Kyn) catalyzed by Indoleamine 2,3-dioxygenase-1 (IDO1) enzyme, is one of the main metabolic pathways involved in tumor microenvironment (TME) immune escape and cancer treatment failure. The most efficient of IDO1 inhibitors is Epacadostat (EPA). Since monotherapy with single-agent IDO1 inhibitor regimen has led to an insufficient anti-tumor activity, we examined the efficacy of simultaneous treatment by Liposomal epacadostat (Lip-EPA) as a potent IDO inhibitor, in combination with docetaxel (DTX) as a complement immunogenic cell death (ICD) agent against B16F10 model. First, the in vitro combination index (CI) of epacadostat (EPA) and DTX was investigated by using the unified theory. Then, the in vivo efficacy of the combination therapy was assessed. Results indicated the synergestic cytotoxic effect of the combination on B16F10 compared to normal fibroblast cells (NIH). The immune profiling demonstrated a significant increase in the percentage of infiltrated T lymphocytes and IFN-γ release, a significant decrease in the percentage of regulatory T cells (Treg) population and the subsequent low levels of IL-10 generation in mice treated with Lip-EPA + DTX. Further, a significant tumor growth delay (TGD = 69.15 %) and an increased life span (ILS > 47.83 %) was observed with the combination strategy. Histopathology analysis revealed a remarkable increase in the Trp concentration following combination treatment, while Kyn levels significantly decreased. Results showed that the nano-liposomal form of IDO1 inhibitor in combination with chemotherapy could significantly improve the imunity response and dominate the tumor immuno-suppressive micro-environment, which merits further investigations.

Design of a targeted dual drug delivery system for boosting the efficacy of photoimmunotherapy against melanoma proliferation and metastasis

IntroductionThe combination of a photosensitizer and indoleamine-2,3 dioxygenase (IDO) inhibitor provides a promising photoimmunotherapy (PIT) strategy for melanoma treatment. A dual drug delivery system offers a potential approach for optimizing the inhibitory effects of PIT on melanoma proliferation and metastasis. ObjectiveTo develop a dual drug delivery system based on PIT and to study its efficacy in inhibiting melanoma proliferation and metastasis. MethodsWe constructed a multifunctional nano-porphyrin material (P18-APBA-HA) using the photosensitizer-purpurin 18 (P18), hyaluronic acid (HA), and 4-(aminomethyl) phenylboronic acid (APBA). The resulting P18-APBA-HA was inserted into a phospholipid membrane and the IDO inhibitor epacadostat (EPA) was loaded into the internal phase to prepare a dual drug delivery system (Lip\\EPA\\P18-APBA-HA). Moreover, we also investigated its physicochemical properties, targeting, anti-tumor immunity, and anti-tumor proliferation and metastasis effects. ResultsThe designed system utilized the pH sensitivity of borate ester to realize an enhanced-targeting strategy to facilitate the drug distribution in tumor lesions and efficient receptor-mediated cellular endocytosis. The intracellular release of EPA from Lip\\EPA\\P18-APBA-HA was triggered by thermal radiation, thereby inhibiting IDO activity in the tumor microenvironment, and promoting activation of the immune response. Intravenous administration of Lip\\EPA\\P18-APBA-HA effectively induced anti-tumor immunity by promoting dendritic cell maturation, cytotoxic T cell activation, and regulatory T cell suppression, and regulating cytokine secretion, to inhibit the proliferation of melanoma and lung metastasis. ConclusionThe proposed nano-drug delivery system holds promise as offers a promising strategy to enhance the inhibitory effects of the combination of EPA and P18 on melanoma proliferation and metastasis.

A peripheral blood mononuclear cell-based in vitro model: A tool to explore indoleamine 2, 3-dioxygenase-1 (IDO1)

BackgroundProinflammatory cytokines powerfully induce the rate-limiting enzyme indoleamine 2, 3-dioxygenase-1 (IDO-1) in dendritic cells (DCs) and monocytes, it converts tryptophan (Trp) into L-kynurenine (KYN), along the kynurenine pathway (KP). This mechanism represents a crucial innate immunity regulator that can modulate T cells. This work explores the role of IDO1 in lymphocyte proliferation within a specific pro-inflammatory milieu. MethodsPeripheral blood mononuclera cells (PBMCs) were isolated from buffy coats taken from healthy blood donors and exposed to a pro-inflammatory milieu triggered by a double-hit stimulus: lipopolysaccharide (LPS) plus anti-CD3/CD28. The IDO1 mRNA levels in the PBMCs were measured by RT-PCR; the IDO1 activity was analyzed using the KYN/Trp ratio, measured by HPLC-EC; and lymphocyte proliferation was measured by flow cytometry. Trp and epacadostat (EP) were used as an IDO1 substrate and inhibitor, respectively. KYN, which is known to modulate Teffs, was tested as a positive control in lymphocyte proliferation. ResultsIDO1 expression and activity in PBMCs increased in an in vitro pro-inflammatory milieu. The lymphoid stimulus increased IDO1 expression and activity, which supports the interaction between the activated lymphocytes and the circulating myeloid IDO1-expressing cells. The addition of Trp decreased lymphocyte proliferation but EP, which abrogated the IDO1 function, had no impact on proliferation. Additionally, incubation with KYN seemed to decrease the lymphocyte proliferation. ConclusionIDO1 inhibition did not change T lymphocyte proliferation. We present herein an in vitro experimental model suitable to measure IDO1 expression and activity in circulating myeloid cells.

Sphingomyelin-derived nanovesicles for the delivery of the IDO1 inhibitor epacadostat enhance metastatic and post-surgical melanoma immunotherapy

Epacadostat (EPA), the most advanced IDO1 inhibitor, in combination with PD-1 checkpoint inhibitor, has failed in a recent Phase III clinical trial for treating metastatic melanoma. Here we report an EPA nanovesicle therapeutic platform (Epacasome) based on chemically attaching EPA to sphingomyelin via an oxime-ester bond highly responsive to hydrolase cleavage. Via clathrin-mediated endocytosis, Epacasome displays higher cellular uptake and enhances IDO1 inhibition and T cell proliferation compared to free EPA. Epacasome shows improved pharmacokinetics and tumour accumulation with efficient intratumoural drug release and deep tumour penetration. Additionally, it outperforms free EPA for anticancer efficacy, potentiating PD-1 blockade with boosted cytotoxic T lymphocytes (CTLs) and reduced regulatory T cells and myeloid-derived suppressor cells responses in a B16-F10 melanoma model in female mice. By co-encapsulating immunogenic dacarbazine, Epacasome further enhances anti-tumor effects and immune responses through the upregulation of NKG2D-mediated CTLs and natural killer cells responses particularly when combined with the PD-1 inhibitor in the late-stage metastatic B16-F10-Luc2 model in female mice. Furthermore, this combination prevents tumour recurrence and prolongs mouse survival in a clinically relevant, post-surgical melanoma model in female mice. Epacasome demonstrates potential to synergize with PD-1 blockade for improved response to melanoma immunotherapy.

Development of a novel formulation method to prepare liposomal Epacadostat

BackgroundOne of the important metabolic pathways in cancer progression is tryptophan catabolism by the indoleamin-2,3-dioxygenase (IDO) enzyme, which suppresses the immune system and induces tolerance. Inhibition of IDO1 is an important therapeutic goal for immunotherapy in many cancers such as metastatic melanoma. Epacadostat (EPA) is a very strong inhibitor of IDO1, and its clinical studies are being performed in a higher clinical phase than other inhibitors. In this study, we have developed a new liposomal EPA formulation to reduce the dose, side effects, and treatment costs. MethodsLiposomes containing EPA were formulated using a novel remote loading method. Their morphology, particle size, surface charge, total phospholipid content, and drug loading were evaluated. Validation method studies to assay of EPA were carried out according to ICHQ2B guidelines. For in-vivo study, B16F10 melanoma bearing C57BL/6 mice were treated with the free or liposomal forms of EPA, and then monitored for tumor size and survival rate. ResultsA validated method for EPA determination in liposomal form using UV-visible spectrophotometry was developed which was a precise, accurate and robust method. The particle size, zeta potential, and encapsulation efficacy of liposomes was 128.1 ± 1.1 nm, -16.5 ± 1 mV, and 64.9 ± 3.5, respectively. The half maximal inhibitory concentration (IC50) of liposomal EPA was 64 ng/ml that was lower than free EPA (128 ng/ml). In-vivo results also showed that tumor growth was slower in mice receiving liposomal EPA than in the group receiving free EPA. ConclusionA new method was developed to load EPA into liposomes. Moreover, the use of the nanoliposomal EPA showed more efficacy than EPA in inhibiting the tumor growth in melanoma model. Therefore, it might be used in further clinical studies as a good candidate for immunotherapy alone or in combination with other treatments.

Protective Effects of Necrostatin-1 in Acute Pancreatitis: Partial Involvement of Receptor Interacting Protein Kinase 1.

Acute pancreatitis (AP) is a severe and potentially fatal disease caused predominantly by alcohol excess and gallstones, which lacks a specific therapy. The role of Receptor-Interacting Protein Kinase 1 (RIPK1), a key component of programmed necrosis (Necroptosis), is unclear in AP. We assessed the effects of RIPK1 inhibitor Necrostatin-1 (Nec-1) and RIPK1 modification (RIPK1K45A: kinase dead) in bile acid (TLCS-AP), alcoholic (FAEE-AP) and caerulein hyperstimulation (CER-AP) mouse models. Involvement of collateral Nec-1 target indoleamine 2,3-dioxygenase (IDO) was probed with the inhibitor Epacadostat (EPA). Effects of Nec-1 and RIPK1K45A were also compared on pancreatic acinar cell (PAC) fate in vitro and underlying mechanisms explored. Nec-1 markedly ameliorated histological and biochemical changes in all models. However, these were only partially reduced or unchanged in RIPK1K45A mice. Inhibition of IDO with EPA was protective in TLCS-AP. Both Nec-1 and RIPK1K45A modification inhibited TLCS- and FAEE-induced PAC necrosis in vitro. Nec-1 did not affect TLCS-induced Ca2+ entry in PACs, however, it inhibited an associated ROS elevation. The results demonstrate protective actions of Nec-1 in multiple models. However, RIPK1-dependent necroptosis only partially contributed to beneficial effects, and actions on targets such as IDO are likely to be important.

Co-delivery of doxorubicin and epacadostat via heparin coated pH-sensitive liposomes to suppress the lung metastasis of melanoma.

High metastasis is responsible for the failure in the treatment of melanoma. Chemoimmunotherapy has shown conspicuous inhibition effects not only on the growth of tumor in situ, but also on the metastasis to distant organs. Given that the indoleamine-2,3 dioxygenase (IDO) overexpressed in the microenvironment of tumor leads to the immune escape, the combination of chemotherapeutic drug and IDO inhibitor might be a promising chemoimmunotherapy. Besides, the hematogenous metastasis mediated by platelets was supposed to be blocked by the heparin (HP). Therefore, a drug delivery system with all these elements involved might be a potential treatment for melanoma. Here, we developed a pH-sensitive liposomal dual-delivery system for doxorubicin (DOX) and epacadostat (EPA) with HP coated (HP/LDE). It was confirmed to enhance cytotoxicity and apoptosis, reverse the platelets-activated epithelial mesenchymal transformation (EMT) and prevent the invasion and migration in vitro. After systemic administration, HP/LDE provided the optimum anti-metastasis effect on the melanoma. The results of evaluation on DC maturation, CD8+ cytotoxic T lymphocytes (CTLs) activation and T cell mediated cytotoxicity were consistent in vitro and in vivo. Taken together, our study established a functional liposomal dual-delivery system with ideal anti-metastasis efficacy on melanoma.

X-ray crystallography of Epacadostat in adduct with Carbonic Anhydrase IX.

Epacadostat (EPA), a new and promising anti-cancer small molecule is firmly established as selective inhibitor of the enzyme indoleamine 2,3-dioxygenase 1 (IDO1). The X-Ray structure of the human CA IX mimic in complex with EPA is investigated here for the first time and compared to previously reported EPA-CA II adduct. The structural information obtained are all in agreement with the in vitro kinetic data which accounted for a selective inhibition of the CA IX over the CA II isoform.

Effects of Epacadostat on Brain Extracellular Fluid Concentrations of Serotonin-an Intracerebral Microdialysis Study in Sprague-Dawley Rats.

Epacadostat (EPAC) is an indoleamine 2,3-dioxygenase 1 (IDO1) inhibitor that has been examined in multiple clinical trials. The substrate for IDO1 is tryptophan and there is a theoretical concern that inhibition of IDO1 may increase the concentrations of tryptophan and subsequently serotonin, potentially leading to serotonin syndrome (SS). The objective of this study was to evaluate the effect of EPAC, either alone or with linezolid, a monoamine oxidase inhibitor (MAOI), on brain extracellular fluid (ECF) concentrations of serotonin in rats, using microdialysis. While fluoxetine, a selective serotonin reuptake inhibitor, increased the serotonin ECF concentration by 2-fold, the combination of fluoxetine with linezolid (a positive control used in the study) resulted in a 9-fold increase. Neither EPAC monotherapy nor combination with linezolid had any effect on serotonin concentration. In addition, EPAC was shown to have poor penetration across the rat blood-brain barrier. Across multiple phase I/II clinical studies with EPAC, four SS-like episodes were observed out of 2490 subjects, but none of the incidences were confirmed as a true case of SS. These data suggest that EPAC is unlikely to cause SS following either monotherapy or in combination with MAOIs. Thus, the exclusion of MAOI from clinical studies with EPAC has been lifted.

Target exposure and pharmacodynamics study of the indoleamine 2,3-dioxygenase-1 (IDO-1) inhibitor epacadostat in the CT26 mouse tumor model

Indoleamine-2,3-dioxygénase (IDO1) is an enzyme which converts tryptophan (Trp) into kynurenine (Kyn). Having a critical role in tumor immune escape by decreasing Trp and increasing Kyn levels in the microenvironment, IDO1 was one of the first targets for small molecules drug discovery in the field of immuno-oncology. A potent and selective IDO1 inhibitor such as Epacadostat (EPA) was shown to enhance the antitumor activity by restoring the immune system fitness. As exposure at the site of action and to its specific target are identified as the most important factors for success in drug discovery, the objective of this study was to explore the target exposure and intra-tumor pharmacodynamics effects of EPA drug on the tumor metabolism. To do so, we used both Quantitative Mass Spectrometry Imaging (QMSI) and liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) technologies in order to monitor drug and metabolites distribution and their endogenous quantity in the CT26 mouse tumor model. Target exposure analysis showed that almost 61% of EPA signal (26 μg/g) was concentrated within 38% of the entire tumor surface. Semi quantitative analysis of this region confirmed a positive correlation between IDO1 expression and EPA concentration. In parallel, pharmacodynamics analysis highlighted a response efficacy through Kyn/Trp ratio calculation that was shown decreasing after EPA treatment as noticed in treated CT26 tumors (−82%), plasma (−63%) and blood (−62%) compared to control samples. Finally, 15% and 85% of Kyn signal was found in regions with high and low EPA, respectively. In this study, using QMSI, we went further than only quantifying the metabolites and the drug, by estimating the pharmacological effect efficacy of the drug through a target exposure study handled in different regions of the tumor either expressing IDO1 or Kyn.

Polypharmacology of epacadostat: a potent and selective inhibitor of the tumor associated carbonic anhydrases IX and XII.

Epacadostat (EPA), a selective indoleamine-2,3-dioxygenase 1 (IDO1) inhibitor, has been investigated in vitro as a human (h) Carbonic Anhydrase Inhibitor (CAI). The kinetic data clearly show, for the first time, EPA to be a highly effective and selective inhibitor for the tumor-associated isoforms hCA IX/XII. We report the high resolution X-ray crystal structure of the EPA-hCA II adduct, and assessed its binding mode to CA IX/XII by means of computational techniques. EPA may exert antitumor effects also due to the potent inhibition of the tumor-associated CAs.

Pharmacokinetics of S-EPA, and its inhibition on indoleamine 2,3-dioxgenase: a case of sulfur-substitution affecting distributions in blood cells

1. S-EPA is a sulfur-substitution analog of epacadostat (EPA), an effective small molecule indoleamine 2,3-dioxgenase1 (IDO) inhibitor. By in vitro and in vivo experiments, pharmacokinetic differences of two closely related analogs, S-EPA and EPA was investigated in this study.2. Liver microsomes clearance experiments showed S-EPA had comparable metabolic stability with EPA in rat and human liver microsomes. The whole blood distribution experiments showed the distribution ratio of S-EPA in blood cells to plasma in mice, rats, dogs and monkey was 1.2, 4.8, 2.2 and 40.6, respectively. While the distribution ratio of EPA ranged from 0.94 to 1.30 in mice, rats, dogs and was 3.1 in monkeys.3. The pharmacokinetic study in rats showed the exposure (AUClast) of S-EPA in plasma and blood cells was 1.7-fold and 3.9-fold higher than that of EPA, respectively. Moreover, the exposure ratio of S-EPA in blood cells to plasma was 3.7, while the ratio of EPA was 1.6.4. In CT26 tumor bearing mice, the IDO inhibition of S-EPA and EPA on plasma or tumor kynurenine was generally consistent. And the inhibition ratio could reach at more than 50% at 3 h after single dose, at least lasting up to 8 h.

Abstract 3512: Impact of IDO inhibitor on tryptophan and kynurenine pathway reflected in the tumor microenvironment and highlighted using quantitative mass spectrometry imaging

Abstract Introduction: Indoleamine-2,3-dioxygenase (IDO1) is an enzyme which converts tryptophan (Trp) into kynurenine (Kyn) in many cell types. IDO1 has a critical role in immunosuppressive mechanisms that permit tumor cells to escape the immune system when Trp and Kyn level decrease and increase in the microenvironment, respectively. Therefore, IDO1 has been one of the first targets that have really been purposed for immuno-oncology (I-O) applications and immunotherapies development. A potent and selective IDO1 inhibitor such as Epacadostat (EPA) can significantly enhance the antitumor activity by restoring the body's natural ability to recognize and to fight cancer. In this study, using quantitative mass spectrometry imaging (QMSI, we went further than only quantifying the metabolites and the drug. Both target exposure and engagement studies were handled in CT26 mouse tumor model, plasma and whole blood. Methods: Undifferentiated colon carcinoma CT26 cell line was implanted into mice. Tumors, plasma and blood were sampled from two groups: one treated group (3 mice, 100mg/Kg of EPA 2 hours before sampling), and one control group of 2 mice. All samples were stored at -80°C until use. 1,5-diaminonaphthalene (1,5-DAN) matrix mixed to internal standards was sprayed onto tumor tissue sections of 10 µm thickness using the automatic TM Sprayer (HTX Technologies, LLC) prior analysis. Data acquisition was performed using 7T MALDI-FTICR (SolariX XR, Bruker Daltonics) at 120 µm spatial resolution in full scan negative mode. Acquired data were treated with MultimagingTM software (ImaBiotech). Histological staining was applied afterwards. Quantitative results of Trp, Kyn and EPA in whole tumors, plasma and blood were then confirmed by LC-MS/MS analysis. Results: Using both QMSI and LC-MS/MS technologies, quantification was realized for the two endogenous metabolites and the drug. Thus, using a potent and selective IDO1 inhibitor, EPA, CT26 model validation was possible. As expected, a decrease of Kyn/Trp ratio was noticed in treated CT26 tumors (-24%), plasma (-57%) and blood (-45%) compared to control samples. By inhibiting IDO1 and decreasing Kyn in tumor cells, EPA increases and restores the proliferation, activation and regulation of various immune cells. This promoted infiltration of active immune cells into the tumor microenvironment is an important feature of many immunotherapies. It is marked by glycolysis signatures and adenosine-inosine metabolism. Citation Format: Lauranne Poncelet, Rima Ait-Belkacem, Bruno Gomes, Stefan Linehan, Gregory Hamm, Jonathan Stauber. Impact of IDO inhibitor on tryptophan and kynurenine pathway reflected in the tumor microenvironment and highlighted using quantitative mass spectrometry imaging [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3512.

In Vitro Interactions of Epacadostat and its Major Metabolites with Human Efflux and Uptake Transporters: Implications for Pharmacokinetics and Drug Interactions.

Epacadostat (EPAC) is a first-in-class, orally active inhibitor of the enzyme indoleamine 2,3-dioxygenase 1 and has demonstrated promising clinical activity. In humans, three major plasma metabolites have been identified: M9 (a glucuronide-conjugate), M11 (a gut microbiota metabolite), and M12 (a secondary metabolite formed from M11). It is proposed, based on the human pharmacokinetics of EPAC, that the biliary excretion of M9, the most abundant metabolite, leads to the enterohepatic circulation of EPAC. Using various in vitro systems, we evaluated in the present study the vitro interactions of EPAC and its major metabolites with major drug transporters involved in drug absorption and disposition. EPAC is a substrate for efflux transporters P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP), but it is not a substrate for hepatic uptake transporters [organic anion transporting polypeptides OATP1B1 and OATP1B3]. The low permeability of M9 suggests an essential role for transporters in its disposition. M9 is likely excreted from hepatocytes into bile via multidrug resistance-associated protein 2 (MRP2) and BCRP, excreted into blood via MRP3, and transported from blood back into hepatocytes via OATP1B1 and OATP1B3. M11 and M12 are not substrates for P-gp, OATP1B1 or OATP1B3, and M11, but not M12, is a substrate for BCRP. With respect to inhibition of drug transporters, the potential of EPAC, M9, M11, and M12 to cause clinical drug-drug interactions via inhibition of P-gp, BCRP, OATP1B1, OATP1B3, OAT1, OAT3, or organic cation transporter 2 was estimated to be low. The current investigation underlines the importance of metabolite-transporter interactions in the disposition of clinically relevant metabolites, which may have implications for the pharmacokinetics and drug interactions of parent drugs.