Drug Repurposing: The Anthelmintics Niclosamide and Nitazoxanide Are Potent TMEM16A Antagonists That Fully Bronchodilate Airways.

There is an unmet need in severe asthma where approximately 40% of patients exhibit poor ß-agonist responsiveness, suffer daily symptoms and show frequent exacerbations. Antagonists of the Ca2+-activated Cl- channel, TMEM16A, offers a new mechanism to bronchodilate airways and block the multiple contractiles operating in severe disease. To identify TMEM16A antagonists we screened a library of ∼580,000 compounds. The anthelmintics niclosamide, nitazoxanide, and related compounds were identified as potent TMEM16A antagonists that blocked airway smooth muscle depolarization and contraction. To evaluate whether TMEM16A antagonists resist use- and inflammatory-desensitization pathways limiting ß-agonist action, we tested their efficacy under harsh conditions using maximally contracted airways or airways pretreated with a cytokine cocktail. Stunningly, TMEM16A antagonists fully bronchodilated airways, while the ß-agonist isoproterenol showed only partial effects. Thus, antagonists of TMEM16A and repositioning of niclosamide and nitazoxanide represent an important additional treatment for patients with severe asthma and COPD that is poorly controlled with existing therapies. It is of note that drug repurposing has also attracted wide interest in niclosamide and nitazoxanide as a new treatment for cancer and infectious disease. For the first time we identify TMEM16A as a molecular target for these drugs and thus provide fresh insights into their mechanism for the treatment of these disorders in addition to respiratory disease.

Development of an ICOSL and BAFF bispecific inhibitor AMG 570 for systemic lupus erythematosus treatment.

OBJECTIVES: Systemic lupus erythematous (SLE) is a heterogeneous disease lacking highly effective treatment options. Here we tested if targeting both BAFF and ICOSL has superior efficacy than single target inhibition in the mouse arthritis and lupus models. We also generated AMG 570, an ICOSL and BAFF bispecific inhibitory molecule, for potential treatment of autoimmune diseases such as SLE. METHODS: Murine BAFF/ICOSL bispecific, combination of BAFF and ICOSL inhibitors or single inhibitor was evaluated in the sheep red blood cell (SRBC) challenge model, mouse collagen induced arthritis (CIA) model, or NZB/NZW lupus models. AMG 570 was tested for human and cyno BAFF and ICOSL binding affinities by Kinexa A. AMG 570 dual target blocking activities was evaluated in human and cyno BAFF and ICOSL mediated B cell and T cell assay, respectively. Pharmacodynamics effect of AMG 570 was evaluated in cynomolgus monkey. RESULTS: Treatment with murine ICOSL/BAFF bispecific or combination therapy was more efficacious than single ICOSL or BAFF inhibitor in mouse NZB/NZW lupus model. Dual ICOSL and BAFF inhibition was also more effective in the mouse collagen induced arthritis (CIA) model. AMG 570 was developed as the clinical bispecific lead. AMG 570 inhibits human and cynomolgus monkey ICOSL and BAFF. B cell reduction was observed after AMG 570 treatment in cynomolgus monkeys, consistent with the pharmacological effect of BAFF inhibition. CONCLUSIONS: By targeting both ICOSL and BAFF, AMG 570 has the potential to achieve superior efficacy in treatment of autoimmune diseases such as SLE and rheumatoid arthritis.

Discovery and in vivo evaluation of dual PI3Kß/δ inhibitors.

Structure-based rational design led to the synthesis of a novel series of potent PI3K inhibitors. The optimized pyrrolopyridine analogue 63 was a potent and selective PI3Kß/δ dual inhibitor that displayed suitable physicochemical properties and pharmacokinetic profile for animal studies. Analogue 63 was found to be efficacious in animal models of inflammation including a keyhole limpet hemocyanin (KLH) study and a collagen-induced arthritis (CIA) disease model of rheumatoid arthritis. These studies highlight the potential therapeutic value of inhibiting both the PI3Kß and δ isoforms in the treatment of a number of inflammatory diseases.

Murine collagen antibody induced arthritis (CAIA) and primary mouse hepatocyte culture as models to study cytochrome P450 suppression.

Changes in cytochrome P450 expression incurred by inflammatory disease were studied in a murine collagen antibody induced arthritis (CAIA) model and compared to bacterial lipopolysaccharide-treated mice and to cytochrome P450 changes in primary mouse hepatocytes following combination treatments with cytokines IL-1ß, IL-6, or TNFα. CAIA in female mice increased serum IL-1ß, IL-6 and hepatic serum amyloid A (SAA) mRNA and significantly altered cytochrome P450 mRNA and activity levels. Most cytochrome P450 isoforms were down-regulated, although some, such as Cyp3a13, were up-regulated. Cytokine effects on cytochrome P450 levels in mouse hepatocytes were compared at in vitro cytokine concentrations similar to those measured in CAIA mouse serum in vivo. In vivo and in vitro cytochrome P450 suppression by cytokines was congruent for some cytochrome P450 isoforms (Cyp1a2, Cyp2c29, and Cyp3a11) but not for others (cytochrome P450 oxidoreductase (POR) and Cyp2e1). In mouse hepatocytes, IL-6 and IL-1ß in combination in vitro caused a synergistic increase in SAA mRNA expression, but not in cytochrome P450 suppression. IL-1ß and IL-6 were equipotent in the suppression of cytochrome P450 gene expression, while TNFα caused mild suppression only at the highest concentrations used. TNFα in combination with IL-1ß, IL-6, or both had a protective effect against IL-1ß and IL-6-mediated cytochrome P450 suppression. When IL-1ß or IL-6 was combined with low concentrations of TNFα, several P450 isoforms were induced rather than suppressed. These data highlight the complexities of performing in vitro-in vivo comparisons using disease models for cytochrome P450 regulation by cytokines.

A novel modality of BAFF-specific inhibitor AMG623 peptibody reduces B-cell number and improves outcomes in murine models of autoimmune disease.

OBJECTIVES: AMG623, also known as A-623, is an antagonist of B-cell activating factor (BAFF). The present study was to evaluate the effects of AMG623 on murine models of autoimmune diseases. METHODS: AMG623 was generated through phage library. Inhibitory activities of AMG623 against human and murine BAFF were measured by biacore binding and BAFF-mediated B-cell proliferation assay. Pharmacological effects of AMG623 were studied in BALB/c mice, collagen-induced arthritis model (CIA) and in the NZBxNZW F1 lupus model. RESULTS: AMG623 binds to both soluble and cell surface BAFF. AMG623 blocks both human murine BAFF binding to the receptors. Treatment of AMG623 resulted in B-cell number reduction, and improvement of arthritis and lupus development in mice. CONCLUSIONS: AMG623 is a novel modality of BAFF antagonist. AMG623 is a potential therapeutic agent for the treatment of SLE, rheumatoid arthritis, and other B-cell-mediated autoimmune diseases.

Part 2: Structure-activity relationship (SAR) investigations of fused pyrazoles as potent, selective and orally available inhibitors of p38alpha mitogen-activated protein kinase.

A novel class of pyrazolopyridazine p38alpha mitogen-activated protein kinase (MAPK) inhibitors is disclosed. A structure activity relationship (SAR) investigation was conducted driven by the ability of these compounds to inhibit the p38alpha enzyme, the secretion of TNFalpha in a LPS-challenged THP1 cell line and TNFalpha-induced production of IL-8 in the presence of 50% human whole blood (hWB). This study resulted in the discovery of several inhibitors with IC(50) values in the single-digit nanomolar range in hWB. Further investigation of the pharmacokinetic profiles of these lead compounds led to the identification of three potent and orally bioavailable p38alpha inhibitors 2h, 2m, and 13h. Inhibitor 2m was found to be highly selective for p38alpha/beta over a panel of 402 other kinases in Ambit screening, and was highly efficacious in vivo in the inhibition of TNFalpha production in LPS-stimulated Lewis rats with an ED(50) of ca. 0.08mg/kg.

Part 1: Structure-Activity Relationship (SAR) investigations of fused pyrazoles as potent, selective and orally available inhibitors of p38alpha mitogen-activated protein kinase.

A novel class of fused pyrazole-derived inhibitors of p38alpha mitogen-activated protein kinase (MAPK) is disclosed. These inhibitors were evaluated for their ability to inhibit the p38alpha enzyme, the secretion of TNFalpha in a LPS-challenged THP1 cell line and TNFalpha-induced production of IL-8 in 50% human whole blood. This series was optimized through a SAR investigation to provide inhibitors with IC(50) values in the low single-digit nanomolar range in whole blood. Further investigation of their pharmacokinetic profiles led to the identification of two potent and orally bioavailable p38 inhibitors 10 m and 10 q. Inhibitor 10 m was found to be efficacious in vivo in the inhibition of TNFalpha production in LPS-stimulated Lewis rats with an ED(50) of 0.1mg/kg while 10 q was found to have an ED(50) of 0.05-0.07 mg/kg.