New Therapeutic Uses for Existing Drugs.

Eighty percent of drugs that enter human clinical testing are never approved for use. This means that for every five drugs that make it into the clinic, there are four that failed to show effectiveness for treating the disease or condition the drug was designed to treat.This high failure rate means there are many existing, partially developed therapeutic candidates with known pharmacology, formulation, and potential toxicity. Finding new uses for existing experimental drugs or biologics "repositioning" builds upon previous research and development efforts, so new candidate therapies can be advanced to clinical trials for a new use more quickly than starting from scratch.Federal funding initiatives in the U.S. and UK started to support pre-clinical /or early stage trials for repositioning existing experimental drugs or biologics (therapies). This chapter covers some of the process issues that have been solved and the remaining challenges that are still in need of solutions. The chapter is primarily written from a U.S. federal funding perspective. The general concepts could be applied more globally to benefit rare and neglected disease populations. The drug development and process bottlenecks are the same for both rare and common disease.

Biologically active fibronectin fragments stimulate release of MCP-1 and catabolic cytokines from murine retinal pigment epithelium.

PURPOSE: High-temperature requirement serine protease (HTRA1) was identified as a candidate age-related macular degeneration gene in multiple genetic studies in humans. To date, no functional studies have shown a mechanism for HTRA1 to instigate ocular tissue abnormalities. In the present study, the authors focused on a substrate of HTRA1, fibronectin, because fibronectin fragments (Fnfs) stimulate biochemical events in other age-related degenerative diseases that are analogous to changes associated with age-related macular degeneration (AMD). The purpose of the study was to determine whether Fnfs stimulate the release of proinflammatory and catabolic cytokines from murine retinal pigment epithelium (RPE). METHODS: Fibronectin was purified from murine serum by gelatin cross-linked agarose chromatography and subsequently was enzymatically digested with alpha-chymotrypsin. The bioactivity of Fnfs was verified by measuring levels of IL-6 and TNF-alpha in Fnf-exposed murine splenocytes. To analyze the effect of Fnfs on RPE, cytokine and chemokine levels in RPE culture supernatants were assayed by ELISA. RESULTS: IL-6 and TNF-alpha proinflammatory cytokines were released from primary murine splenocytes in proportion to the dose and length of Fnf treatment, indicating that alpha-chymotryptic digests of fibronectin are biologically active. Fnf treatment of murine RPE cells stimulated the release of microgram and nanogram levels of IL-6, MMP-3, MMP-9, and MCP-1, whereas only picogram levels were detected in untreated cells. CONCLUSIONS: Fnfs stimulate the release of proinflammatory cytokines, matrix metalloproteinases, and monocyte chemoattractant protein from murine RPE cells. This observation indicated that Fnfs could contribute to ocular abnormalities by promoting inflammation, catabolism, and monocyte chemoattraction.

LX211 (voclosporin) suppresses experimental uveitis and inhibits human T cells.

PURPOSE: To test the therapeutic effectiveness of voclosporin against experimental autoimmune uveoretinitis (EAU) in rats and to evaluate its effect on human T cells. METHODS: EAU was induced by immunization with a uveitogenic protein. Voclosporin administration, by subcutaneous injection, began on day (d) 0 or d7 after immunization. Treatment effectiveness was evaluated in vivo using clinical EAU scoring (d7-d13) and histopathologic evaluation of enucleated eyes after experimental termination. Rodent lymphocytes were harvested from lymph nodes on d14 for antigen-specific proliferation assays. The effect of voclosporin on human T-cell proliferation and cytokine secretion was examined in vitro. RESULTS: Voclosporin prevented EAU development in rats receiving medium and high preventive doses, whereas high-dose voclosporin administration effectively treated EAU. Lymphocytes from animals treated with voclosporin had decreased antigen-specific proliferation in vitro compared with lymphocytes from untreated animals. No evidence of abnormal ocular histopathology was found in the eyes from animals that received high doses of therapeutic voclosporin. Using human T cells, voclosporin inhibited human T-cell proliferation up to 100-fold. Furthermore, voclosporin treatment of human T cells significantly reduced pan T-cell effector responses. CONCLUSIONS: Voclosporin effectively suppressed uveoretinitis in an animal model that imitates the human inflammatory ocular disease by inhibiting lymphocyte proliferation. In addition, voclosporin effectively inhibited human T-cell proliferation and function in vitro. The authors report the first evidence supporting the application of voclosporin to treat intraocular inflammation.

Oligoadenylate synthetase/protein kinase R pathways and alphabeta TCR+ T cells are required for adenovirus vector: IFN-gamma inhibition of herpes simplex virus-1 in cornea.

An adenoviral (Ad) vector containing the murine IFN-gamma transgene (Ad:IFN-gamma) was evaluated for its capacity to inhibit HSV-1. To measure effectiveness, viral titers were analyzed in cornea and trigeminal ganglia (TG) during acute ocular HSV-1 infection. Ad:IFN-gamma potently suppressed HSV-1 replication in a dose-dependent fashion, requiring IFN-gamma receptor. Moreover, Ad:IFN-gamma was effective when delivered -72 and -24 h before infection as well as 24 h postinfection. Associated with antiviral opposition, TG from Ad:IFN-gamma-transduced mice harbored fewer T cells. Also related to T cell involvement, Ad:IFN-gamma was effective but attenuated in TG from alphabeta TCR-deficient mice. In corneas, alphabeta TCR(+) T cells were obligatory for protection against viral multiplication. Type I IFN involvement amid antiviral efficacy of Ad:IFN-gamma was further investigated because types I and II IFN pathways have synergistic anti-HSV-1 activity. Ad:IFN-gamma inhibited viral reproduction in corneas and TG from alphabeta IFNR-deficient (CD118(-/-)) mice, although viral titers were 2- to 3-fold higher in cornea and TG compared with wild-type mice. The absence of IFN-stimulated antiviral proteins, 2'-5' oligoadenylate synthetase/RNase L, and dsRNA-dependent protein kinase R completely eliminated the antiviral effectiveness of Ad:IFN-gamma. Collectively, the results demonstrate the following: 1) nonexistence of type I IFN receptor does not abolish defense of Ad:IFN-gamma against HSV-1; 2) antiviral pathways oligoadenylate synthetase-RNase L and protein kinase R are mandatory; and 3) alphabeta TCR(+) T cells are compulsory for Ad:IFN-gamma effectiveness against HSV-1 in cornea but not in TG.

Direct application of plasmid DNA containing type I interferon transgenes to vaginal mucosa inhibits HSV-2 mediated mortality.

The application of naked DNA containing type I interferon (IFN) transgenes is a promising potential therapeutic approach for controlling chronic viral infections. Herein, we detail the application of this approach that has been extensively used to restrain ocular HSV-1 infection, for antagonizing vaginal HSV-2 infection. We show that application of IFN-alpha1, -alpha5, and -beta transgenes to vaginal mouse lumen 24 hours prior to HSV-2 infection reduces HSV-2 mediated mortality by 2.5 to 3-fold. However, other type I IFN transgenes (IFN- alpha4, -alpha5, -alpha6, and -alpha9) are non effectual against HSV-2. We further show that the efficacy of IFN-alpha1 transgene treatment is independent of CD4+ T lymphocytes. However, in mice depleted of CD8+ T lymphocytes, the ability of IFN-alpha1 transgene treatment to antagonize HSV-2 was lost.

Intact TRL 9 and type I interferon signaling pathways are required to augment HSV-1 induced corneal CXCL9 and CXCL10.

Herpes simplex virus type 1 ocular infection elicits a potent inflammatory response including the production of the chemokines, CXCL9 and CXCL10, in mice. Since HSV-1 nucleic acid is recognized by pattern receptors including Toll-like receptor (TLR) 9, we tested the hypothesis that TLR9 is necessary for the early augmentation of CXCL10 following HSV-1 infection. Similar to wild type controls, TLR9 deficient mice constitutively expressed CXCL10 in the cornea. Following infection or stimulation with the deoxycytidylate-phosphate-deoxyguanylate (CpG) motif, CXCL10 levels were significantly elevated in the cornea of wild type but not TLR9 or type I interferon receptor deficient mice. The reduced CXCL10 response in the cornea of TLR deficient mice was correlative with an increase in virus shedding and a reduction in neutrophil infiltration. This is the first report that shows enhanced CXCL10 expression following neurotropic viral replication requires both intact TLR 9 and type I interferon signaling pathways.

OAS and PKR are not required for the antiviral effect of Ad:IFN-gamma against acute HSV-1 in primary trigeminal ganglia cultures.

Three interferon-gamma (IFN-gamma)-induced antiviral pathways have been reported. Involved antiviral proteins include: Mx, RNase L/2',5'-OAS, and protein kinase R (PKR). Involvement of OAS and PKR in IFN-gamma-induced anti-herpes simplex virus-1 (HSV-1) pathways has not been reported previously, but IFN-gamma induces OAS and PKR when other viruses invade the nervous system. The aim of the current study was to determine if the absence of intact OAS and PKR antiviral pathways affects the antiviral activity of IFN-gamma during acute HSV-1 infection within the trigeminal ganglia (TG). To investigate this, primary TG cultures were established using TGs removed from C57BL/6 (wild-type), RNase L knockout, and RNase L/PKR double knockout mice. Each dissociated TG was transduced with an adenoviral vector containing an IFN-gamma transgene or vector alone. Viral titers after HSV-1 infection of primary TG cell cultures were determined. Significant differences in viral titer for Ad:Null-transduced vs. Ad:IFN-gamma-tranduced TG were found in each genotype. However, the effectiveness of Ad:IFN-gamma was not reduced in the absence of both OAS and PKR pathways or OAS alone. Recombinant IFN-gamma also exhibited anti-HSV-1 activity. The effectiveness of the IFN-gamma transgene was lost in primary TG cells from IFN-gamma receptor knockout mice. The data suggest that novel anti-HSV-1 mechanisms are induced by IFN-gamma.

Critical role for the oligoadenylate synthetase/RNase L pathway in response to IFN-beta during acute ocular herpes simplex virus type 1 infection.

We previously demonstrated that IFN-beta transgene treatment protects mouse trigeminal ganglia (TG) cells from acute HSV-1 infection in vitro. However, IFN-alpha6 transgene treatment does not provide protection against acute HSV-1 infection in vitro, even though equivalent levels of IFN are expressed with both transgene treatments. In the present study we show that IFN-beta transgene treatment before acute ocular HSV-1 infection protects mice from HSV-1-mediated mortality, whereas IFN-alpha6 transgene treatment does not reduce mortality. Treatment with the IFN-beta and IFN-alpha6 transgenes was associated with increased expression of oligoadenylate synthetase (OAS)1a mRNA in the eye. However, protein kinase R mRNA was not up-regulated in the eye. In TG, only IFN-beta transgene treatment reduced infectious virus levels. Furthermore, in the absence of a functional OAS pathway, corneal HSV-1 Ag expression was more widespread, and the ability of IFN-beta transgene treatment to reduce infectious HSV-1 in eyes and TG was lost. Along with selective up-regulation of OAS1a mRNA expression in TG from IFN-beta transgene-treated mice, we found increased levels of phospho-STAT1. Likewise, p38 MAPK phosphorylation was increased in TG from IFN-beta transgene-treated mice, compared with both IFN-alpha6 and vector-treated mice. We also observed a time-dependent increase in JNK phosphorylation in TG from IFN-beta transgene-treated vs IFN-alpha6 and vector-treated mice. Our results demonstrate that IFN-beta is a potent antiviral cytokine that exerts protection against ocular HSV-1 infection via selective up-regulation of OAS1a mRNA in TG and by altering the phosphorylation of proteins in antiviral signaling cascades.