Publications by authors named "Ben Wen"

13 Publications

  • Page 1 of 1

Discovery of Orally Active Hydroxyethylamine Based SPPL2a Inhibitors.

ACS Med Chem Lett 2019 Jun 23;10(6):887-892. Epub 2019 May 23.

Global Discovery Chemistry, and Autoimmunity Transplantation Inflammation, Novartis Institutes for BioMedical Research, CH-4002 Basel, Switzerland.

SPPL2a (Signal Peptide Peptidase Like 2a) is an intramembrane aspartyl protease engaged in the function of B-cells and dendritic cells. Despite being an attractive target for modulation of the immune system, selective SPPL2a inhibitors are barely described in the literature. Recently, we have disclosed a selective, small molecular weight agent SPL-707 which confirmed that pharmacological inhibition of SPPL2a leads to the accumulation of its substrate CD74/p8 and as a consequence to a reduction in the number of B-cells as well as myeloid dendritic cells in mice. In this paper we describe the discovery of novel hydroxyethylamine based SPPL2a inhibitors. Starting from a rather lipophilic screening hit, several iterative optimization cycles allowed for its transformation into a highly potent and selective compound () which inhibited CD74/p8 fragment processing in mice at 10 mg/kg oral dose.
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http://dx.doi.org/10.1021/acsmedchemlett.9b00044DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6580379PMC
June 2019

Discovery of the First Potent, Selective, and Orally Bioavailable Signal Peptide Peptidase-Like 2a (SPPL2a) Inhibitor Displaying Pronounced Immunomodulatory Effects In Vivo.

J Med Chem 2018 02 23;61(3):865-880. Epub 2018 Jan 23.

The Genomics Institute of the Novartis Research Foundation , 10675 John Jay Hopkins Drive, San Diego, California 92121, United States.

Signal peptide peptidase-like 2a (SPPL2a) is an aspartic intramembrane protease which has recently been shown to play an important role in the development and function of antigen presenting cells such as B lymphocytes and dendritic cells. In this paper, we describe the discovery of the first selective and orally active SPPL2a inhibitor (S)-2-cyclopropyl-N1-((S)-5,11-dioxo-10,11-dihydro-1H,3H,5H-spiro[benzo[d]pyrazolo[1,2-a][1,2]diazepine-2,1'-cyclopropan]-10-yl)-N4-(5-fluoro-2-methylpyridin-3-yl)succinamide 40 (SPL-707). This compound shows adequate selectivity against the closely related enzymes γ-secretase and SPP and a good pharmacokinetic profile in mouse and rat. Compound 40 significantly inhibited processing of the SPPL2a substrate CD74/p8 fragment in rodents at doses ≤10 mg/kg b.i.d. po. Oral dosing of 40 for 11 days at ≥10 mg/kg b.i.d. recapitulated the phenotype seen in Sppl2a knockout (ko) and ENU mutant mice (reduced number of specific B cells and myeloid dendritic cells). Thus, we believe that SPPL2a represents an interesting and druggable pharmacological target, potentially providing a novel approach for the treatment of autoimmune diseases by targeting B cells and dendritic cells.
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http://dx.doi.org/10.1021/acs.jmedchem.7b01371DOI Listing
February 2018

Optimization of Platelet-Derived Growth Factor Receptor (PDGFR) Inhibitors for Duration of Action, as an Inhaled Therapy for Lung Remodeling in Pulmonary Arterial Hypertension.

J Med Chem 2016 09 19;59(17):7901-14. Epub 2016 Aug 19.

Genomics Institute of the Novartis Research Foundation , 10675 John Jay Hopkins Drive, San Diego, California 92121, United States.

A series of potent PDGFR inhibitors has been identified. The series was optimized for duration of action in the lung. A novel kinase occupancy assay was used to directly measure target occupancy after i.t. dosing. Compound 25 shows 24 h occupancy of the PDGFR kinase domain, after a single i.t. dose and has efficacy at 0.03 mg/kg, in the rat moncrotaline model of pulmonary arterial hypertension. Examination of PK/PD data from the optimization effort has revealed in vitro:in vivo correlations which link duration of action in vivo with low permeability and high basicity and demonstrate that nonspecific binding to lung tissue increases with lipophilicity.
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http://dx.doi.org/10.1021/acs.jmedchem.6b00703DOI Listing
September 2016

Proteasome inhibition for treatment of leishmaniasis, Chagas disease and sleeping sickness.

Nature 2016 09 8;537(7619):229-233. Epub 2016 Aug 8.

Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA.

Chagas disease, leishmaniasis and sleeping sickness affect 20 million people worldwide and lead to more than 50,000 deaths annually. The diseases are caused by infection with the kinetoplastid parasites Trypanosoma cruzi, Leishmania spp. and Trypanosoma brucei spp., respectively. These parasites have similar biology and genomic sequence, suggesting that all three diseases could be cured with drugs that modulate the activity of a conserved parasite target. However, no such molecular targets or broad spectrum drugs have been identified to date. Here we describe a selective inhibitor of the kinetoplastid proteasome (GNF6702) with unprecedented in vivo efficacy, which cleared parasites from mice in all three models of infection. GNF6702 inhibits the kinetoplastid proteasome through a non-competitive mechanism, does not inhibit the mammalian proteasome or growth of mammalian cells, and is well-tolerated in mice. Our data provide genetic and chemical validation of the parasite proteasome as a promising therapeutic target for treatment of kinetoplastid infections, and underscore the possibility of developing a single class of drugs for these neglected diseases.
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http://dx.doi.org/10.1038/nature19339DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5161665PMC
September 2016

Antitrypanosomal Treatment with Benznidazole Is Superior to Posaconazole Regimens in Mouse Models of Chagas Disease.

Antimicrob Agents Chemother 2015 Oct 3;59(10):6385-94. Epub 2015 Aug 3.

Department of Genetics and Neglected Diseases, Genomics Institute of the Novartis Research Foundation, San Diego, California, USA

Two CYP51 inhibitors, posaconazole and the ravuconazole prodrug E1224, were recently tested in clinical trials for efficacy in indeterminate Chagas disease. The results from these studies show that both drugs cleared parasites from the blood of infected patients at the end of the treatment but that parasitemia rebounded over the following months. In the current study, we sought to identify a dosing regimen of posaconazole that could permanently clear Trypanosoma cruzi from mice with experimental Chagas disease. Infected mice were treated with posaconazole or benznidazole, an established Chagas disease drug, and parasitological cure was defined as an absence of parasitemia recrudescence after immunosuppression. Twenty-day therapy with benznidazole (10 to 100 mg/kg of body weight/day) resulted in a dose-dependent increase in antiparasitic activity, and the 100-mg/kg regimen effected parasitological cure in all treated mice. In contrast, all mice remained infected after a 25-day treatment with posaconazole at all tested doses (10 to 100 mg/kg/day). Further extension of posaconazole therapy to 40 days resulted in only a marginal improvement of treatment outcome. We also observed similar differences in antiparasitic activity between benznidazole and posaconazole in acute T. cruzi heart infections. While benznidazole induced rapid, dose-dependent reductions in heart parasite burdens, the antiparasitic activity of posaconazole plateaued at low doses (3 to 10 mg/kg/day) despite increasing drug exposure in plasma. These observations are in good agreement with the outcomes of recent phase 2 trials with posaconazole and suggest that the efficacy models combined with the pharmacokinetic analysis employed here will be useful in predicting clinical outcomes of new drug candidates.
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http://dx.doi.org/10.1128/AAC.00689-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4576074PMC
October 2015

Inhibition of the Inositol Kinase Itpkb Augments Calcium Signaling in Lymphocytes and Reveals a Novel Strategy to Treat Autoimmune Disease.

PLoS One 2015 29;10(6):e0131071. Epub 2015 Jun 29.

The Genomics Institute of the Novartis Research Foundation (GNF), San Diego, California, United States of America.

Emerging approaches to treat immune disorders target positive regulatory kinases downstream of antigen receptors with small molecule inhibitors. Here we provide evidence for an alternative approach in which inhibition of the negative regulatory inositol kinase Itpkb in mature T lymphocytes results in enhanced intracellular calcium levels following antigen receptor activation leading to T cell death. Using Itpkb conditional knockout mice and LMW Itpkb inhibitors these studies reveal that Itpkb through its product IP4 inhibits the Orai1/Stim1 calcium channel on lymphocytes. Pharmacological inhibition or genetic deletion of Itpkb results in elevated intracellular Ca2+ and induction of FasL and Bim resulting in T cell apoptosis. Deletion of Itpkb or treatment with Itpkb inhibitors blocks T-cell dependent antibody responses in vivo and prevents T cell driven arthritis in rats. These data identify Itpkb as an essential mediator of T cell activation and suggest Itpkb inhibition as a novel approach to treat autoimmune disease.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0131071PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4488288PMC
April 2016

Oxysterols direct immune cell migration via EBI2.

Nature 2011 Jul 27;475(7357):524-7. Epub 2011 Jul 27.

Euroscreen S.A., 6041 Gosselies, Belgium.

Epstein-Barr virus-induced gene 2 (EBI2, also known as GPR183) is a G-protein-coupled receptor that is required for humoral immune responses; polymorphisms in the receptor have been associated with inflammatory autoimmune diseases. The natural ligand for EBI2 has been unknown. Here we describe the identification of 7α,25-dihydroxycholesterol (also called 7α,25-OHC or 5-cholesten-3β,7α,25-triol) as a potent and selective agonist of EBI2. Functional activation of human EBI2 by 7α,25-OHC and closely related oxysterols was verified by monitoring second messenger readouts and saturable, high-affinity radioligand binding. Furthermore, we find that 7α,25-OHC and closely related oxysterols act as chemoattractants for immune cells expressing EBI2 by directing cell migration in vitro and in vivo. A critical enzyme required for the generation of 7α,25-OHC is cholesterol 25-hydroxylase (CH25H). Similar to EBI2 receptor knockout mice, mice deficient in CH25H fail to position activated B cells within the spleen to the outer follicle and mount a reduced plasma cell response after an immune challenge. This demonstrates that CH25H generates EBI2 biological activity in vivo and indicates that the EBI2-oxysterol signalling pathway has an important role in the adaptive immune response.
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http://dx.doi.org/10.1038/nature10280DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4297623PMC
July 2011

Mechanistic studies of the immunochemical termination of self-tolerance with unnatural amino acids.

Proc Natl Acad Sci U S A 2009 Mar 25;106(11):4337-42. Epub 2009 Feb 25.

Department of Chemistry, The Scripps Research Institute, La Jolla, CA 92037, USA.

For more than 2 centuries active immunotherapy has been at the forefront of efforts to prevent infectious disease [Waldmann TA (2003) Nat Med 9:269-277]. However, the decreased ability of the immune system to mount a robust immune response to self-antigens has made it more difficult to generate therapeutic vaccines against cancer or chronic degenerative diseases. Recently, we showed that the site-specific incorporation of an immunogenic unnatural amino acid into an autologous protein offers a simple and effective approach to overcome self-tolerance. Here, we characterize the nature and durability of the polyclonal IgG antibody response and begin to establish the generality of p-nitrophenylalanine (pNO(2)Phe)-induced loss of self-tolerance. Mutation of several surface residues of murine tumor necrosis factor-alpha (mTNF-alpha) independently to pNO(2)Phe leads to a T cell-dependent polyclonal and sustainable anti-mTNF-alpha IgG autoantibody response that lasts for at least 40 weeks. The antibodies bind multiple epitopes on mTNF-alpha and protect mice from severe endotoxemia induced by lipopolysaccharide (LPS) challenge. Immunization of mice with a pNO(2)Phe(43) mutant of murine retinol-binding protein (RBP4) also elicited a high titer IgG antibody response, which was cross-reactive with wild-type mRBP4. These findings suggest that this may be a relatively general approach to generate effective immunotherapeutics against cancer-associated or other weakly immunogenic antigens.
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http://dx.doi.org/10.1073/pnas.0900507106DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2657443PMC
March 2009

Drak2 regulates the survival of activated T cells and is required for organ-specific autoimmune disease.

J Immunol 2008 Dec;181(11):7593-605

Department of Cellular and Molecular Medicine, Division of Biological Sciences, Molecular Biology Section, University of California, San Diego, La Jolla, CA 92093, USA.

Drak2 is a serine/threonine kinase expressed in T and B cells. The absence of Drak2 renders T cells hypersensitive to suboptimal stimulation, yet Drak2(-/-) mice are enigmatically resistant to experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis. We show in this study that Drak2(-/-) mice were also completely resistant to type 1 diabetes when bred to the NOD strain of mice that spontaneously develop autoimmune diabetes. However, there was not a generalized suppression of the immune system, because Drak2(-/-) mice remained susceptible to other models of autoimmunity. Adoptive transfer experiments revealed that resistance to disease was intrinsic to the T cells and was due to a loss of T cell survival under conditions of chronic autoimmune stimulation. Importantly, the absence of Drak2 did not alter the survival of naive T cells, memory T cells, or T cells responding to an acute viral infection. These experiments reveal a distinction between the immune response to persistent self-encoded molecules and transiently present infectious agents. We present a model whereby T cell survival depends on a balance of TCR and costimulatory signals to explain how the absence of Drak2 affects autoimmune disease without generalized suppression of the immune system.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2792703PMC
http://dx.doi.org/10.4049/jimmunol.181.11.7593DOI Listing
December 2008

Immunochemical termination of self-tolerance.

Proc Natl Acad Sci U S A 2008 Aug 6;105(32):11276-80. Epub 2008 Aug 6.

Department of Chemistry, Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.

The ability to selectively induce a strong immune response against self-proteins, or increase the immunogenicity of specific epitopes in foreign antigens, would have a significant impact on the production of vaccines for cancer, protein-misfolding diseases, and infectious diseases. Here, we show that site-specific incorporation of an immunogenic unnatural amino acid into a protein of interest produces high-titer antibodies that cross-react with WT protein. Specifically, mutation of a single tyrosine residue (Tyr(86)) of murine tumor necrosis factor-alpha (mTNF-alpha) to p-nitrophenylalanine (pNO(2)Phe) induced a high-titer antibody response in mice, whereas no significant antibody response was observed for a Tyr(86) --> Phe mutant. The antibodies generated against the pNO(2)Phe are highly cross-reactive with native mTNF-alpha and protect mice against lipopolysaccharide (LPS)-induced death. This approach may provide a general method for inducing an antibody response to specific epitopes of self- and foreign antigens that lead to a neutralizing immune response.
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http://dx.doi.org/10.1073/pnas.0804157105DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2516224PMC
August 2008

DRAK2, a lymphoid-enriched DAP kinase, regulates the TCR activation threshold during thymocyte selection.

Int Immunol 2005 Nov 19;17(11):1379-90. Epub 2005 Sep 19.

Department of Molecular Biology and Biochemistry, Center for Immunology, University of California-Irvine, Irvine, CA 92697-3900, USA.

DAP kinases are a family of serine/threonine kinases known to regulate intrinsic apoptotic processes. DAP-related apoptotic kinase-2 (DRAK2) is highly expressed in lymphoid organs, with differential expression during thymocyte development. Low levels of transcript were observed in CD4/CD8 double-positive (DP) and double-negative populations, whereas single-positive thymocytes possessed elevated levels. Ex vivo stimulation of DP thymocytes with phorbol myristate acetate or antibodies that activate the TCR complex led to the accumulation of DRAK2 in a protein kinase C- and MAP Kinase-dependent fashion. Although DAP kinase family members are thought to potentiate apoptosis, ectopic expression of DRAK2 using retroviral transduction of primary T cells and NIH3T3 fibroblasts failed to decrease rates of survival, suggesting that DRAK2 expression is not sufficient to promote apoptosis. Rather, our results demonstrate that DRAK2 is a primary response gene activated by TCR stimulation in DP thymocytes. Further, we observed that DRAK2 controlled the threshold for calcium signaling in the thymus since positively selected Drak2-deficient thymocytes displayed a reduced requirement for TCR cross-linking. These findings are consistent with a role for DRAK2 in thymocyte selection and lymphoid maturation, and demonstrate that DRAK2 transduces non-apoptotic signals during thymocyte differentiation.
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http://dx.doi.org/10.1093/intimm/dxh315DOI Listing
November 2005

A deficiency in Drak2 results in a T cell hypersensitivity and an unexpected resistance to autoimmunity.

Immunity 2004 Dec;21(6):781-91

Division of Biological Sciences, Department of Cellular and Molecular Medicine, Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093 USA.

DRAK2 is a member of the death-associated protein (DAP)-like family of serine/threonine kinases. Members of this family induce apoptosis in various cell types. DRAK2, in particular, is specifically expressed in T cells and B cells, and it is differentially regulated during T cell development. To determine whether DRAK2 regulates lymphocyte apoptosis, we produced Drak2(-/-) mice. Contrary to our expectations, Drak2(-/-) T cells did not demonstrate any defects in apoptosis or negative selection; however, T cells from Drak2(-/-) mice exhibited enhanced sensitivity to T cell receptor-mediated stimulation with a reduced requirement for costimulation. These results provide evidence that DRAK2 raises the threshold for T cell activation by negatively regulating signals through the TCR. In contrast to other models of T cell hypersensitivity, Drak2(-/-) mice were remarkably resistant to experimental autoimmune encephalomyelitis (EAE). These results expose a new pathway regulating T cell activation and highlight the intricacies of induced autoimmune disease.
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http://dx.doi.org/10.1016/j.immuni.2004.10.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2792702PMC
December 2004

Inositol (1,4,5) trisphosphate 3 kinase B controls positive selection of T cells and modulates Erk activity.

Proc Natl Acad Sci U S A 2004 Apr 2;101(15):5604-9. Epub 2004 Apr 2.

Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, CA 92121, USA.

The mechanisms governing positive selection of T cells in the thymus are still incompletely understood. Here, we describe a N-ethyl-N-nitrosourea induced recessive mouse mutant, Ms. T-less, which lacks T cells in the peripheral blood because of a complete block of thymocyte development at the CD4(+)CD8(+) stage. Single nucleotide polymorphism mapping and candidate gene sequencing revealed a nonsense mutation in the inositol (1,4,5) trisphosphate 3 kinase B (Itpkb) gene in Ms. T-less mice. Accordingly, Ms. T-less thymocytes do not show detectable expression of Itpkb protein and have drastically reduced basal inositol (1,4,5) trisphosphate kinase activity. Itpkb converts inositol (1,4,5) trisphosphate to inositol (1,3,4,5) tetrakisphosphate, soluble second messengers that have been implicated in Ca(2+) signaling. Surprisingly, Ca(2+) responses show no significant differences between wild type (WT) and mutant thymocytes. However, extracellular signal-regulated kinase (Erk) activation in response to suboptimal antigen receptor stimulation is attenuated in Ms. T-less thymocytes, suggesting a role for Itpkb in linking T cell receptor signaling to efficient and sustained Erk activation.
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http://dx.doi.org/10.1073/pnas.0306907101DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC397439PMC
April 2004