The Perspective of DMPK on Recombinant Adeno-Associated Virus-Based Gene Therapy: Past Learning, Current Support, and Future Contribution.

Given the recent success of gene therapy modalities and the growing number of cell and gene-based therapies in clinical development across many different therapeutic areas, it is evident that this evolving field holds great promise for the unmet medical needs of patients. The recent approvals of Luxturna® and Zolgensma® prove that recombinant adeno-associated virus (rAAV)-based gene therapy is a transformative modality that enables curative treatment for genetic disorders. Over the last decade, Takeda has accumulated significant experience with rAAV-based gene therapies, especially in the early stage of development. In this review, based on the learnings from Takeda and publicly available information, we aim to provide a guiding perspective on Drug Metabolism and Pharmacokinetics (DMPK) substantial role in advancing therapeutic gene therapy modalities from nonclinical research to clinical development, in particular the characterization of gene therapy product biodistribution, elimination (shedding), immunogenicity assessment, multiple platform bioanalytical assays, and first-in-human (FIH) dose projection strategies. Graphical abstract.

Structure-Based Discovery of Proline-Derived Arginase Inhibitors with Improved Oral Bioavailability for Immuno-Oncology.

Recent data suggest that the inhibition of arginase (ARG) has therapeutic potential for the treatment of a number of indications ranging from pulmonary and vascular disease to cancer. Thus, high demand exists for selective small molecule ARG inhibitors with favorable druglike properties and good oral bioavailability. In light of the significant challenges associated with the unique physicochemical properties of previously disclosed ARG inhibitors, we use structure-based drug design combined with a focused optimization strategy to discover a class of boronic acids featuring a privileged proline scaffold with superior potency and oral bioavailability. These compounds, exemplified by inhibitors 4a, 18, and 27, demonstrated a favorable overall profile, and 4a was well tolerated following multiple days of dosing at concentrations that exceed those required for serum arginase inhibition and concomitant arginine elevation in a syngeneic mouse carcinoma model.

CYP27A1-dependent anti-melanoma activity of limonoid natural products targets mitochondrial metabolism.

Three limonoid natural products with selective anti-proliferative activity against BRAF(V600E) and NRAS(Q61K)-mutation-dependent melanoma cell lines were identified. Differential transcriptome analysis revealed dependency of compound activity on expression of the mitochondrial cytochrome P450 oxidase CYP27A1, a transcriptional target of melanogenesis-associated transcription factor (MITF). We determined that CYP27A1 activity is necessary for the generation of a reactive metabolite that proceeds to inhibit cellular proliferation. A genome-wide small interfering RNA screen in combination with chemical proteomics experiments revealed gene-drug functional epistasis, suggesting that these compounds target mitochondrial biogenesis and inhibit tumor bioenergetics through a covalent mechanism. Our work suggests a strategy for melanoma-specific targeting by exploiting the expression of MITF target gene CYP27A1 and inhibiting mitochondrial oxidative phosphorylation in BRAF mutant melanomas.

Discovery and Optimization of Rationally Designed Bicyclic Inhibitors of Human Arginase to Enhance Cancer Immunotherapy.

The action of arginase, a metalloenzyme responsible for the hydrolysis of arginine to urea and ornithine, is hypothesized to suppress immune-cell activity within the tumor microenvironment, and thus its inhibition may constitute a means by which to potentiate the efficacy of immunotherapeutics such as anti-PD-1 checkpoint inhibitors. Taking inspiration from reported enzyme-inhibitor cocrystal structures, we designed and synthesized novel inhibitors of human arginase possessing a fused 5,5-bicyclic ring system. The prototypical member of this class, 3, when dosed orally, successfully demonstrated serum arginase inhibition and concomitant arginine elevation in a syngeneic mouse carcinoma model, despite modest oral bioavailability. Structure-based design strategies to improve the bioavailability of this class, including scaffold modification, fluorination, and installation of active-transport recognition motifs were explored.

Demonstration of Solar Cell on a Graphite Sheet with Carbon Diffusion Barrier Evaluation.

An amorphous Si (a-Si) solar cell with a back reflector composed of zinc oxide (ZnO) and silver (Ag) is potentially the most plausible and flexible solar cell if a graphite sheet is used as the substrate. Graphite supplies lightness, conductivity and flexibility to devices. When a graphite sheet is used as the substrate, carbon can diffuse into the Ag layer in the subsequent p-i-n process at 200-400 °C. To prevent this, we added an oxide layer as a carbon diffusion barrier between the carbon substrate and the back reflector. For the carbon diffusion barrier, silicon oxide (SiO2) or tin oxide (SnOx) was used. We evaluated the thermal stability of the back reflector of a carbon substrate using secondary-ion mass spectrometry (SIMS) to analyze the carbon diffusion barrier material. We confirmed the deposition characteristics, reflectance and prevention of carbon diffusion with and without the barrier. Finally, the structures were incorporated into the solar cell and their performances compared. The results showed that the back reflectors that were connected to a carbon diffusion barrier presented better performance, and the reflector with an SnOx layer presented the best performance.

Indolyl-Pyridinyl-Propenone-Induced Methuosis through the Inhibition of PIKFYVE.

Methuosis is a form of nonapoptotic cell death characterized by the accumulation of macropinosome-derived vacuoles. Herein, we identify PIKFYVE, a class III phosphoinositide (PI) kinase, as the protein target responsible for the methuosis-inducing activity of indolyl-pyridinyl-propenones (3-(5-methoxy-2-methyl-1H-indol-3-yl)-1-(4-pyridinyl)-2-propen-1-one). We further characterize the effects of chemical substitutions at the 2- and 5-indolyl positions on cytoplasmic vacuolization and PIKFYVE binding and inhibitory activity. Our study provides a better understanding of the mechanism of methuosis-inducing indolyl-pyridinyl-propenones.

InPZnS alloy quantum dots with tris(hexylthio)phosphine as a dual anionic precursor.

Recently, InP-based quantum dots (QDs) have received significant attention due to their usefulness in display applications, and the search for good optical properties has led to numerous reports on the testing of reaction variables. However, most researchers have precluded the most important anion precursors in their studies, instead of focusing only on tris(trimethylsilyl)phosphine(P(SiMe3)3, TMS3P) precursors. Due to its vulnerability to moisture, TMS3P is unstable and difficult to handle. In the current study, a new anionic precursor, tris(hexylthio)phosphine(THTP), is introduced for use with InP-based QDs. Owing to its activated phosphine and sulfur atoms, the THTP molecule is a dual anionic precursor for both InP and ZnS QDs. When THTP is reacted with indium and zinc precursors, InPZnS alloy QDs can be fabricated. To observe the synthesis mechanism and probe the intermediate, FAB-mass and 31P-NMR analyses were conducted, resulting in the identification of an intermediate of MW 504. Finally, the surface was coated with a ZnS shell to obtain the emission wavelength from 530 nm to 570 nm and a maximum quantum efficiency of 42% when a ZnI2 precursor was used.

Correction to Indolyl-Pyridinyl-Propenone-Induced Methuosis through the Inhibition of PIKFYVE.

[This corrects the article DOI: 10.1021/acsomega.8b00202.].

Negative regulation of NF-κB activity by brain-specific TRIpartite Motif protein 9.

The TRIpartite Motif (TRIM) family of RING-domain-containing proteins participate in a variety of cellular functions. The ß-transducin repeat-containing protein (ß-TrCP), a component of the Skp-Cullin-F-box-containing (SCF) E3 ubiquitin ligase complex, recognizes the NF-κB inhibitor IκBα and precursor p100 for proteasomal degradation and processing, respectively. ß-TrCP thus plays a critical role in both canonical and non-canonical NF-κB activation. Here we report that TRIM9 is a negative regulator of NF-κB activation. Interaction between the phosphorylated degron motif of TRIM9 and the WD40 repeat region of ß-TrCP prevented ß-TrCP from binding its substrates, stabilizing IκBα and p100 and thereby blocking NF-κB activation. Consequently, expression or depletion of the TRIM9 gene significantly affected NF-κB-induced inflammatory cytokine production. This study not only elucidates a mechanism for TRIM9-mediated regulation of the ß-TrCP SCF complex activity but also identifies TRIM9 as a brain-specific negative regulator of the NF-κB pro-inflammatory signalling pathway.

Genome-wide RNAi screen identifies broadly-acting host factors that inhibit arbovirus infection.

Vector-borne viruses are an important class of emerging and re-emerging pathogens; thus, an improved understanding of the cellular factors that modulate infection in their respective vertebrate and insect hosts may aid control efforts. In particular, cell-intrinsic antiviral pathways restrict vector-borne viruses including the type I interferon response in vertebrates and the RNA interference (RNAi) pathway in insects. However, it is likely that additional cell-intrinsic mechanisms exist to limit these viruses. Since insects rely on innate immune mechanisms to inhibit virus infections, we used Drosophila as a model insect to identify cellular factors that restrict West Nile virus (WNV), a flavivirus with a broad and expanding geographical host range. Our genome-wide RNAi screen identified 50 genes that inhibited WNV infection. Further screening revealed that 17 of these genes were antiviral against additional flaviviruses, and seven of these were antiviral against other vector-borne viruses, expanding our knowledge of invertebrate cell-intrinsic immunity. Investigation of two newly identified factors that restrict diverse viruses, dXPO1 and dRUVBL1, in the Tip60 complex, demonstrated they contributed to antiviral defense at the organismal level in adult flies, in mosquito cells, and in mammalian cells. These data suggest the existence of broadly acting and functionally conserved antiviral genes and pathways that restrict virus infections in evolutionarily divergent hosts.

A short hairpin RNA screen of interferon-stimulated genes identifies a novel negative regulator of the cellular antiviral response.

The type I interferon (IFN) signaling pathway restricts infection of many divergent families of RNA and DNA viruses by inducing hundreds of IFN-stimulated genes (ISGs), some of which have direct antiviral activity. We screened 813 short hairpin RNA (shRNA) constructs targeting 245 human ISGs using a flow cytometry approach to identify genes that modulated infection of West Nile virus (WNV) in IFN-ß-treated human cells. Thirty ISGs with inhibitory effects against WNV were identified, including several novel genes that had antiviral activity against related and unrelated positive-strand RNA viruses. We also defined one ISG, activating signal cointegrator complex 3 (ASCC3), which functioned as a negative regulator of the host defense response. Silencing of ASCC3 resulted in upregulation of multiple antiviral ISGs, which correlated with inhibition of infection of several positive-strand RNA viruses. Reciprocally, ectopic expression of human ASCC3 or mouse Ascc3 resulted in downregulation of ISGs and increased viral infection. Mechanism-of-action and RNA sequencing studies revealed that ASCC3 functions to modulate ISG expression in an IRF-3- and IRF-7-dependent manner. Compared to prior ectopic ISG expression studies, our shRNA screen identified novel ISGs that restrict infection of WNV and other viruses and defined a new counterregulatory ISG, ASCC3, which tempers cell-intrinsic immunity.

A role for Ifit2 in restricting West Nile virus infection in the brain.

Previous studies have demonstrated that type I interferon (IFN-I) restricts West Nile virus (WNV) replication and pathogenesis in peripheral and central nervous system (CNS) tissues. However, the in vivo role of specific antiviral genes that are induced by IFN-I against WNV infection remains less well characterized. Here, using Ifit2(-/-) mice, we defined the antiviral function of the interferon-stimulated gene (ISG) Ifit2 in limiting infection and disease in vivo by a virulent North American strain of WNV. Compared to congenic wild-type controls, Ifit2(-/-) mice showed enhanced WNV infection in a tissue-restricted manner, with preferential replication in the CNS of animals lacking Ifit2. Virological analysis of cultured macrophages, dendritic cells, fibroblasts, cerebellar granule cell neurons, and cortical neurons revealed cell type-specific antiviral functions of Ifit2 against WNV. In comparison, small effects of Ifit2 were observed on the induction or magnitude of innate or adaptive immune responses. Our results suggest that Ifit2 restricts WNV infection and pathogenesis in different tissues in a cell type-specific manner.

Differential innate immune response programs in neuronal subtypes determine susceptibility to infection in the brain by positive-stranded RNA viruses.

Although susceptibility of neurons in the brain to microbial infection is a major determinant of clinical outcome, little is known about the molecular factors governing this vulnerability. Here we show that two types of neurons from distinct brain regions showed differential permissivity to replication of several positive-stranded RNA viruses. Granule cell neurons of the cerebellum and cortical neurons from the cerebral cortex have unique innate immune programs that confer differential susceptibility to viral infection ex vivo and in vivo. By transducing cortical neurons with genes that were expressed more highly in granule cell neurons, we identified three interferon-stimulated genes (ISGs; Ifi27, Irg1 and Rsad2 (also known as Viperin)) that mediated the antiviral effects against different neurotropic viruses. Moreover, we found that the epigenetic state and microRNA (miRNA)-mediated regulation of ISGs correlates with enhanced antiviral response in granule cell neurons. Thus, neurons from evolutionarily distinct brain regions have unique innate immune signatures, which probably contribute to their relative permissiveness to infection.

Calculation of patient effective dose and scattered dose for dental mobile fluoroscopic equipment: application of the Monte Carlo simulation.

The objective of this study was to evaluate the patient effective dose and scattered dose from recently developed dental mobile equipment in Korea. The MCNPX 2.6 (Los Alamos National Laboratory, USA) was used in a Monte Carlo simulation to calculate both the effective and scattered doses. The MCNPX code was constructed identically as in the general use of equipment and the effective dose and scattered dose were calculated using the KTMAN-2 digital phantom. The effective dose was calculated as 906 µSv. The equivalent doses per organ were calculated via the MCNPX code, and were 32 174 and 19 µSv in the salivary gland and oesophagus, respectively. The scattered dose of 22.5-32.6 µSv of the tube side at 25 cm from the centre in anterior and posterior planes was measured as 1.4-3 times higher than the detector side of 10.5-16.0 µSv.

Immune responses to West Nile virus infection in the central nervous system.

West Nile virus (WNV) continues to cause outbreaks of severe neuroinvasive disease in humans and other vertebrate animals in the United States, Europe, and other regions of the world. This review discusses our understanding of the interactions between virus and host that occur in the central nervous system (CNS), the outcome of which can be protection, viral pathogenesis, or immunopathogenesis. We will focus on defining the current state of knowledge of WNV entry, tropism, and host immune response in the CNS, all of which affect the balance between injury and successful clearance.

Viral MHC class I inhibition evades CD8+ T-cell effector responses in vivo but not CD8+ T-cell priming.

Although viral MHC class I inhibition is considered a classic immune-evasion strategy, its in vivo role is largely unclear. Mutant cowpox virus lacking its MHC class I inhibitors is markedly attenuated during acute infection because of CD8(+) T-cell-dependent control, but it was not known how CD8(+) T-cell responses are affected. Interestingly, we found no major effect of MHC class I down-regulation on priming of functional cowpox virus-specific CD8(+) T cells. Instead, we demonstrate that, during acute infection in vivo, MHC class I down-regulation prevents primed virus-specific CD8(+) T cells from recognizing infected cells and exerting effector responses to control the infection.

2'-O methylation of the viral mRNA cap by West Nile virus evades ifit1-dependent and -independent mechanisms of host restriction in vivo.

Prior studies have shown that 2'-O methyltransferase activity of flaviviruses, coronaviruses, and poxviruses promotes viral evasion of Ifit1, an interferon-stimulated innate immune effector protein. Viruses lacking 2'-O methyltransferase activity exhibited attenuation in primary macrophages that was rescued in cells lacking Ifit1 gene expression. Here, we examined the role of Ifit1 in restricting pathogenesis in vivo of wild type WNV (WNV-WT) and a mutant in the NS5 gene (WNV-E218A) lacking 2'-O methylation of the 5' viral RNA cap. While deletion of Ifit1 had marginal effects on WNV-WT pathogenesis, WNV-E218A showed increased replication in peripheral tissues of Ifit1⁻/⁻ mice after subcutaneous infection, yet this failed to correlate with enhanced infection in the brain or lethality. In comparison, WNV-E218A was virulent after intracranial infection as judged by increased infection in different regions of the central nervous system (CNS) and a greater than 16,000-fold decrease in LD(50) values in Ifit1⁻/⁻ compared to wild type mice. Ex vivo infection experiments revealed cell-type specific differences in the ability of an Ifit1 deficiency to complement the replication defect of WNV-E218A. In particular, WNV-E218A infection was impaired in both wild type and Ifit1⁻/⁻ brain microvascular endothelial cells, which are believed to participate in blood-brain barrier (BBB) regulation of virus entry into the CNS. A deficiency of Ifit1 also was associated with increased neuronal death in vivo, which was both cell-intrinsic and mediated by immunopathogenic CD8⁺ T cells. Our results suggest that virulent strains of WNV have largely evaded the antiviral effects of Ifit1, and viral mutants lacking 2'-O methylation are controlled in vivo by Ifit1-dependent and -independent mechanisms in different cell types.

Inhibitor of κB kinase epsilon (IKK(epsilon)), STAT1, and IFIT2 proteins define novel innate immune effector pathway against West Nile virus infection.

West Nile virus is an emerging virus whose virulence is dependent upon viral evasion of IFN and innate immune defenses. The actions of IFN-stimulated genes (ISGs) impart control of virus infection, but the specific ISGs and regulatory pathways that restrict West Nile virus (WNV) are not defined. Here we show that inhibitor of κB kinase ε (IKKε) phosphorylation of STAT1 at serine 708 (Ser-708) drives IFIT2 expression to mediate anti-WNV effector function of IFN. WNV infection was enhanced in cells from IKKε(-/-) or IFIT2(-/-) mice. In IKKε(-/-) cells, the loss of IFN-induced IFIT2 expression was linked to lack of STAT1 phosphorylation on Ser-708 but not Tyr-701 nor Ser-727. STAT1 Ser-708 phosphorylation occurs independently of IRF-3 but requires signaling through the IFN-α/ß receptor as a late event in the IFN-induced innate immune response that coincides with IKKε-responsive ISGs expression. Biochemical analyses show that STAT1 tyrosine dephosphorylation and CRM1-mediated STAT1 nuclear-cytoplasmic shuttling are required for STAT1 Ser-708 phosphorylation. When compared with WT mice, WNV-infected IKKε(-/-) mice exhibit enhanced kinetics of virus dissemination and increased pathogenesis concomitant with loss of STAT1 Ser-708 phosphorylation and IFIT2 expression. Our results define an IFN-induced IKKε signaling pathway of specific STAT1 phosphorylation and IFIT2 expression that imparts innate antiviral immunity to restrict WNV infection and control viral pathogenesis.

Interferon regulatory factor-1 (IRF-1) shapes both innate and CD8(+) T cell immune responses against West Nile virus infection.

Interferon regulatory factor (IRF)-1 is an immunomodulatory transcription factor that functions downstream of pathogen recognition receptor signaling and has been implicated as a regulator of type I interferon (IFN)-αß expression and the immune response to virus infections. However, this role for IRF-1 remains controversial because altered type I IFN responses have not been systemically observed in IRF-1(-/-) mice. To evaluate the relationship of IRF-1 and immune regulation, we assessed West Nile virus (WNV) infectivity and the host response in IRF-1(-/-) cells and mice. IRF-1(-/-) mice were highly vulnerable to WNV infection with enhanced viral replication in peripheral tissues and rapid dissemination into the central nervous system. Ex vivo analysis revealed a cell-type specific antiviral role as IRF-1(-/-) macrophages supported enhanced WNV replication but infection was unaltered in IRF-1(-/-) fibroblasts. IRF-1 also had an independent and paradoxical effect on CD8(+) T cell expansion. Although markedly fewer CD8(+) T cells were observed in naïve animals as described previously, remarkably, IRF-1(-/-) mice rapidly expanded their pool of WNV-specific cytolytic CD8(+) T cells. Adoptive transfer and in vitro proliferation experiments established both cell-intrinsic and cell-extrinsic effects of IRF-1 on the expansion of CD8(+) T cells. Thus, IRF-1 restricts WNV infection by modulating the expression of innate antiviral effector molecules while shaping the antigen-specific CD8(+) T cell response.

A short N-terminal peptide motif on flavivirus nonstructural protein NS1 modulates cellular targeting and immune recognition.

Flavivirus NS1 is a versatile nonstructural glycoprotein, with intracellular NS1 functioning as an essential cofactor for viral replication and cell surface and secreted NS1 antagonizing complement activation. Even though NS1 has multiple functions that contribute to virulence, the genetic determinants that regulate the spatial distribution of NS1 in cells among different flaviviruses remain uncharacterized. Here, by creating a panel of West Nile virus-dengue virus (WNV-DENV) NS1 chimeras and site-specific mutants, we identified a novel, short peptide motif immediately C-terminal to the signal sequence cleavage position that regulates its transit time through the endoplasmic reticulum and differentially directs NS1 for secretion or plasma membrane expression. Exchange of two amino acids within this motif reciprocally changed the cellular targeting pattern of DENV or WNV NS1. For WNV, this substitution also modulated infectivity and antibody-induced phagocytosis of infected cells. Analysis of a mutant lacking all three conserved N-linked glycosylation sites revealed an independent requirement of N-linked glycans for secretion but not for plasma membrane expression of WNV NS1. Collectively, our experiments define the requirements for cellular targeting of NS1, with implications for the protective host responses, immune antagonism, and association with the host cell sorting machinery. These studies also suggest a link between the effects of NS1 on viral replication and the levels of secreted or cell surface NS1.