Design and synthesis of potent and orally active GPR4 antagonists with modulatory effects on nociception, inflammation, and angiogenesis.

GPR4, a G-protein coupled receptor, functions as a proton sensor being activated by extracellular acidic pH and has been implicated in playing a key role in acidosis associated with a variety of inflammatory conditions. An orally active GPR4 antagonist 39c was developed, starting from a high throughput screening hit 1. The compound shows potent cellular activity and is efficacious in animal models of angiogenesis, inflammation and pain.

First-in-Human Study of the Safety, Pharmacokinetics, and Pharmacodynamics of MHV370, a Dual Inhibitor of Toll-Like Receptors 7 and 8, in Healthy Adults.

BACKGROUND AND OBJECTIVE: MHV370, a dual antagonist of human Toll-like receptors (TLR) 7 and 8, suppresses cytokines and interferon-stimulated genes in vitro and in vivo, and  has demonstrated efficacy in murine models of lupus. This first-in-human study aimed to evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of single and multiple doses of MHV370 in healthy adults, as well as the effects of food consumption on a single dose of MHV370. METHODS: This was a phase 1, randomised, placebo-controlled study conducted in three parts. In part A, participants received (3:1) a single ascending dose (SAD) of 1, 3, 10, 20, 40, 80, 160, 320, 640 and 1000 mg MHV370 or placebo. In part B, participants received (3:1) multiple ascending doses (MAD) of 25, 50, 100, 200 and 400 mg MHV370 twice daily (b.i.d) or placebo for 14 days. In part C, participants received an open-label single dose of 200 mg MHV370 under fasted or fed conditions. Safety, pharmacokinetic and pharmacodynamic parameters were evaluated. RESULTS: MHV370 was well tolerated, and no safety signal was observed in the study. No dose-limiting adverse events occurred across the dose range evaluated. Plasma concentrations of MHV370 increased with dose (mean [SD] maximum plasma concentrations ranged from 0.97 [0.48] to 1670 [861.0] ng/mL for SAD of 3-1000 mg, 29.5 [7.98] to 759 [325.0] ng/mL for MAD of 25-400 mg b.i.d. on day 1). The intake of food did not have a relevant impact on the pharmacokinetics of MHV370. Pharmacodynamic data indicated time- and dose-dependent inhibition of TLR7-mediated CD69 expression on B cells (100% inhibition at 24 h post-dose starting from SAD 160 mg and MAD 50 mg b.i.d.) and TLR8-mediated TNF release after ex vivo stimulation (>90% inhibition at 24 h post-dose starting from SAD 320 mg and MAD 100 mg b.i.d.). CONCLUSION: The safety, pharmacokinetic and pharmacodynamic data support the further development of MHV370 in systemic autoimmune diseases driven by the overactivation of TLR7 and TLR8.

Discovery of the TLR7/8 Antagonist MHV370 for Treatment of Systemic Autoimmune Diseases.

Toll-like receptor (TLR) 7 and TLR8 are endosomal sensors of the innate immune system that are activated by GU-rich single stranded RNA (ssRNA). Multiple genetic and functional lines of evidence link chronic activation of TLR7/8 to the pathogenesis of systemic autoimmune diseases (sAID) such as Sjögren's syndrome (SjS) and systemic lupus erythematosus (SLE). This makes targeting TLR7/8-induced inflammation with small-molecule inhibitors an attractive approach for the treatment of patients suffering from systemic autoimmune diseases. Here, we describe how structure-based optimization of compound 2 resulted in the discovery of 34 (MHV370, (S)-N-(4-((5-(1,6-dimethyl-1H-pyrazolo[3,4-b]pyridin-4-yl)-3-methyl-4,5,6,7-tetrahydro-1H-pyrazolo[4,3-c]pyridin-1-yl)methyl)bicyclo[2.2.2]octan-1-yl)morpholine-3-carboxamide). Its in vivo activity allows for further profiling toward clinical trials in patients with autoimmune disorders, and a Phase 2 proof of concept study of MHV370 has been initiated, testing its safety and efficacy in patients with Sjögren's syndrome and mixed connective tissue disease.

Preclinical characterization of the Toll-like receptor 7/8 antagonist MHV370 for lupus therapy.

Genetic and in vivo evidence suggests that aberrant recognition of RNA-containing autoantigens by Toll-like receptors (TLRs) 7 and 8 drives autoimmune diseases. Here we report on the preclinical characterization of MHV370, a selective oral TLR7/8 inhibitor. In vitro, MHV370 inhibits TLR7/8-dependent production of cytokines in human and mouse cells, notably interferon-α, a clinically validated driver of autoimmune diseases. Moreover, MHV370 abrogates B cell, plasmacytoid dendritic cell, monocyte, and neutrophil responses downstream of TLR7/8. In vivo, prophylactic or therapeutic administration of MHV370 blocks secretion of TLR7 responses, including cytokine secretion, B cell activation, and gene expression of, e.g., interferon-stimulated genes. In the NZB/W F1 mouse model of lupus, MHV370 halts disease. Unlike hydroxychloroquine, MHV370 potently blocks interferon responses triggered by specific immune complexes from systemic lupus erythematosus patient sera, suggesting differentiation from clinical standard of care. These data support advancement of MHV370 to an ongoing phase 2 clinical trial.

Structure-Based Optimization of a Fragment-like TLR8 Binding Screening Hit to an In Vivo Efficacious TLR7/8 Antagonist.

Inappropriate activation of TLR7 and TLR8 is linked to several autoimmune diseases, such as lupus erythematosus. Here we report on the efficient structure-based optimization of the inhibition of TLR8, starting from a co-crystal structure of a small screening hit. Further optimization of the physicochemical properties for cellular potency and expansion of the structure-activity relationship for dual potency finally resulted in a highly potent TLR7/8 antagonist with demonstrated in vivo efficacy after oral dosing.

Novel 3-aminopyrazole inhibitors of MK-2 discovered by scaffold hopping strategy.

New, selective 3-aminopyrazole based MK2-inhibitors were discovered by scaffold hopping strategy. The new derivatives proved to inhibit intracellular phosphorylation of hsp27 as well as LPS-induced TNFalpha release in cells. In addition, selected derivative 14e also inhibited LPS-induced TNFalpha release in vivo.

In vivo and in vitro SAR of tetracyclic MAPKAP-K2 (MK2) inhibitors. Part I.

Pyrrolo[2,3-f]isoquinoline based amino acids, tetracyclic lactams and cyclic ketone analogues are described as novel MK2 inhibitors with IC(50) as low as 5nM and good selectivity profiles against a number of related kinases including ERK, p38alpha and JNKs. TNFalpha release was suppressed from human peripheral blood mononuclear cells (hPBMCs), and a representative compound inhibited LPS induced TNFalpha release in mice illustrating the potential of this series to provide orally active MK2 inhibitors.

In vivo and in vitro SAR of tetracyclic MAPKAP-K2 (MK2) inhibitors. Part II.

Spirocyclopropane- and spiroazetidine-substituted tetracycles 13D-E and 16A are described as orally active MK2 inhibitors. The spiroazetidine derivatives are potent MK2 inhibitors with IC(50)<3 nM and inhibit the release of TNFalpha (IC(50)<0.3 microM) from hPBMCs and hsp27 phosphorylation in anisomycin stimulated THP-1 cells. The spirocyclopropane analogues are less potent against MK2 (IC(50)=0.05-0.23 microM), less potent in cells (IC(50)<1.1 microM), but show good oral absorption. Compound 13E (100mg/kg po; bid) showed oral activity in rAIA and mCIA, with significant reduction of swelling and histological score.

Target-Based Identification and Optimization of 5-Indazol-5-yl Pyridones as Toll-like Receptor 7 and 8 Antagonists Using a Biochemical TLR8 Antagonist Competition Assay.

Inappropriate activation of endosomal TLR7 and TLR8 occurs in several autoimmune diseases, in particular systemic lupus erythematosus (SLE). Herein, the development of a TLR8 antagonist competition assay and its application for hit generation of dual TLR7/8 antagonists are reported. The structure-guided optimization of the pyridone hit 3 using this biochemical assay in combination with cellular and TLR8 cocrystal structural data resulted in the identification of a highly potent and selective TLR7/8 antagonist (27) with in vivo efficacy. The two key steps for optimization were (i) a core morph guided by a TLR7 sequence alignment to achieve a dual TLR7/8 antagonism profile and (ii) introduction of a fluorine in the piperidine ring to reduce its basicity, resulting in attractive oral pharmacokinetic (PK) properties and improved TLR8 binding affinity.

Discovery of 4-((2S,4S)-4-Ethoxy-1-((5-methoxy-7-methyl-1H-indol-4-yl)methyl)piperidin-2-yl)benzoic Acid (LNP023), a Factor B Inhibitor Specifically Designed To Be Applicable to Treating a Diverse Array of Complement Mediated Diseases.

The alternative pathway (AP) of the complement system is a key contributor to the pathogenesis of several human diseases including age-related macular degeneration, paroxysmal nocturnal hemoglobinuria (PNH), atypical hemolytic uremic syndrome (aHUS), and various glomerular diseases. The serine protease factor B (FB) is a key node in the AP and is integral to the formation of C3 and C5 convertase. Despite the prominent role of FB in the AP, selective orally bioavailable inhibitors, beyond our own efforts, have not been reported previously. Herein we describe in more detail our efforts to identify FB inhibitors by high-throughput screening (HTS) and leveraging insights from several X-ray cocrystal structures during optimization efforts. This work culminated in the discovery of LNP023 (41), which is currently being evaluated clinically in several diverse AP mediated indications.

Pyrrolo-pyrimidones: a novel class of MK2 inhibitors with potent cellular activity.

Pyrrolo-pyrimidones of the general structure 1 were synthesized and evaluated for their potential as MK2 inhibitors. Potent derivatives were discovered which inhibit MK2 in the nanomolar range and show potent inhibition of cytokine release from LPS-stimulated monocytes. These derivatives were shown to inhibit phosphorylation of hsp27, a downstream target of MK2 and are modestly selective in a panel of 28 kinases.

Modulating ADME Properties by Fluorination: MK2 Inhibitors with Improved Oral Exposure.

MAP-activated protein kinase 2 (MK2) plays an important role in the regulation of innate immune response as well as in cell survival upon DNA damage. Despite its potential for the treatment of inflammation and cancer, to date no MK2 low molecular weight inhibitors have reached the clinic, mainly due to inadequate absorption, distribution, metabolism, and excretion (ADME) properties. We describe here an approach based on specifically placed fluorine within a recently described pyrrole-based MK2 inhibitor scaffold for manipulation of its physicochemical and ADME properties. While preserving target potency, the novel fluoro-derivatives showed greatly improved permeability as well as enhanced solubility and reduced in vivo clearance leading to significantly increased oral exposure.

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

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.

Development of Selective, Orally Active GPR4 Antagonists with Modulatory Effects on Nociception, Inflammation, and Angiogenesis.

A novel, selective, and efficacious GPR4 antagonist 13 was developed starting from lead compound 1a. While compound 1a showed promising efficacy in several disease models, its binding to a H3 receptor as well as a hERG channel prevented it from further development. Therefore, a new round of optimization addressing the key liabilities was performed and led to discovery of compound 13 with an improved profile. Compound 13 showed significant efficacy in the rat antigen induced arthritis as well as in the hyperalgesia and angiogenesis model at a well-tolerated dose of 30 mg/kg.

Discovery and Pharmacological Characterization of Novel Quinazoline-Based PI3K Delta-Selective Inhibitors.

Inhibition of the lipid kinase PI3Kδ is a promising principle to treat B and T cell driven inflammatory diseases. Using a scaffold deconstruction-reconstruction strategy, we identified 4-aryl quinazolines that were optimized into potent PI3Kδ isoform selective analogues with good pharmacokinetic properties. With compound 11, we illustrate that biochemical PI3Kδ inhibition translates into modulation of isoform-dependent immune cell function (human, rat, and mouse). After oral administration of compound 11 to rats, proximal PD markers are inhibited, and dose-dependent efficacy in a mechanistic plaque forming cell assay could be demonstrated.

Beta-aryl-succinic acid hydroxamates as dual inhibitors of matrix metalloproteinases and tumor necrosis factor alpha converting enzyme.

Novel hydroxamate inhibitors of tumor necrosis factor converting enzyme (TACE) and matrix metalloproteases (MMPs) have been synthesized via the Claisen-Ireland rearrangement. Aryl residues have been introduced to fill the enzyme's P1' specificity pocket. The best compound inhibits MMPs and TACE with nanomolar potency and inhibits the release of TNFalpha from cells with an IC50 of 48 nM. Oral administration to rats inhibits the LPS-induced plasma TNFalpha levels with an ED50 of 1 mg/kg.

Evaluation of protease-activated receptor 2 in murine models of arthritis.

OBJECTIVE: Protease-activated receptor 2 (PAR-2) activation has been linked to pro- and antiinflammatory cellular responses. We undertook this study to explore the importance of PAR-2 activation in 4 murine models of arthritis and to analyze the expression of PAR-2 in human arthritic synovium. METHODS: Zymosan-induced arthritis (ZIA), K/BxN serum-induced arthritis, and Freund's complete adjuvant (CFA)-induced arthritis were generated in naive PAR-2(-/-) mice and PAR-2(+/+) littermates. Antigen-induced arthritis (AIA) was generated in immunized mice using methylated bovine serum albumin (mBSA). The severity of arthritis was assessed by clinical scoring, technetium uptake measurement, and histologic analysis. Immune responses to mBSA were also evaluated from AIA. The expression of PAR-2 in synovial tissues from rheumatoid arthritis (RA) and osteoarthritis (OA) patients was compared. RESULTS: In AIA, arthritis was significantly decreased in PAR-2-deficient mice and was associated with decreased levels of anti-mBSA IgG antibodies and lymph node cell proliferation. No difference in arthritis severity was seen in mice with ZIA, K/BxN serum-induced arthritis, and CFA-induced arthritis. Synovial biopsy specimens from RA patients demonstrated significantly increased expression of PAR-2 compared with those from OA patients. CONCLUSION: PAR-2 deficiency was found to modulate articular inflammation in murine models of arthritis that require prior immunization and was associated with reduced levels of anti-mBSA IgG and lymph node cell proliferation in AIA. Expression of PAR-2 in RA synovium was significantly higher than that in OA synovium, and this suggests that PAR-2 is implicated in the pathogenesis of immune-mediated forms of arthritis.

The role of interstitial macrophages in nephropathy of type 2 diabetic db/db mice.

Diabetic nephropathy is associated with interstitial macrophage infiltrates, but their contribution to disease progression is unclear. We addressed this question by blockade of chemokine receptor (CCR)1 because CCR1 mediates the macrophage recruitment to the renal interstitium. In fact, when CCR1 was blocked with BL5923, a novel orally available CCR1 antagonist, the interstitial recruitment of ex vivo labeled macrophages was markedly decreased in uninephrectomized male db/db mice with advanced diabetic nephropathy. Likewise, BL5923 (60 mg/kg, twice a day) orally administered from months 5 to 6 of life reduced the numbers of interstitial macrophages in uninephrectomized db/db mice. This was associated with reduced numbers of Ki-67 proliferating tubular epithelial and interstitial cells, tubular atrophy, and interstitial fibrosis in uninephrectomized db/db mice. Glomerular pathology and proteinuria were not affected by the CCR1 antagonist. BL5923 reduced renal mRNA expression of Ccl2, Ccr1, Ccr2, Ccr5, transforming growth factor-beta1, and collagen I-alpha1 when compared with untreated uninephrectomized male db/db mice of the same age. Thus, we identified a previously unrecognized role for interstitial macrophages for tubulointerstitial injury, loss of peritubular microvasculature, interstitial inflammation, and fibrosis in type 2 diabetic db/db mice. These data identify oral treatment with the CCR1 antagonist BL5923 as a potential therapy for late-stage diabetic nephropathy.

A cassette-dosing approach for improvement of oral bioavailability of dual TACE/MMP inhibitors.

The structural features contributing to the different pharmacokinetic properties of the TACE/MMP inhibitors TNF484 and Trocade were analyzed using an in vivo cassette-dosing approach in rats. This enabled us to identify a new lead compound with excellent pharmacokinetic properties, but weaker activity on the biological targets. Directed structural modifications maintained oral bioavailability and restored biological activity, leading to a novel compound almost equipotent to TNF484 in vivo, but with a more than tenfold higher oral bioavailability.

Pyrazoloheteroaryls: novel p38alpha MAP kinase inhibiting scaffolds with oral activity.

A test library with three novel p38alpha inhibitory scaffolds and a narrow set of substituents was prepared. Appropriate combination of substituent and scaffold generated potent p38alpha inhibitors, for example, pyrazolo[3,4-b]pyridine 9, pyrazolo[3,4-d]pyrimidine 18a and pyrazolo[3,4-b]pyrazine 23b with potent in vivo activity upon oral administration in animal models of rheumatoid arthritis.