Structural optimization and in vitro profiling of N-phenylbenzamide-based farnesoid X receptor antagonists.

Activation of the nuclear farnesoid X receptor (FXR) which acts as cellular bile acid sensor has been validated as therapeutic strategy to counter liver disorders such as non-alcoholic steatohepatitis by the clinical efficacy of obeticholic acid. FXR antagonism, in contrast, is less well studied and potent small molecule FXR antagonists are rare. Here we report the systematic optimization of a novel class of FXR antagonists towards low nanomolar potency. The most optimized compound antagonizes baseline and agonist induced FXR activity in a full length FXR reporter gene assay and represses intrinsic expression of FXR regulated genes in hepatoma cells. With this activity and a favorable toxicity-, stability- and selectivity-profile it appears suitable to further study FXR antagonism in vitro and in vivo.

Differential Therapeutic Effects of FXR Activation, sEH Inhibition, and Dual FXR/sEH Modulation in NASH in Diet-Induced Obese Mice.

Nonalcoholic fatty liver disease (NAFLD) is an epidemic chronic liver disease and may progress over nonalcoholic steatohepatitis (NASH) to liver cirrhosis and hepatocellular carcinoma. The multiple metabolic, environmental, and genetic factors that are involved in NAFLD/NASH pathogenesis and progression suggest a need for multimechanistic interventions. We have developed and preliminarily characterized a concept of dual farnesoid X receptor (FXR) and soluble epoxide hydrolase (sEH) modulation as a promising polypharmacological strategy to counteract NASH. Here we report the profiling of FXR activation, sEH inhibition, and simultaneous FXR/sEH modulation as an interventional treatment in pre-established NASH in mice with diet-induced obesity (DIO). We found that full FXR activation was required to obtain antisteatosis effects but also worsened ballooning degeneration and fibrosis. In contrast, sEH inhibition and dual FXR/sEH modulation, despite a lack of antisteatosis activity, had anti-inflammatory effects and efficiently counteracted hepatic fibrosis. These results demonstrate great therapeutic potential of sEH inhibition to counteract hepatic fibrosis and validate the designed polypharmacology concept of dual FXR/sEH modulation as a potentially superior avenue for the effective treatment of the multifactorial condition NASH.

Second-Generation Dual FXR/sEH Modulators with Optimized Pharmacokinetics.

Non-alcoholic steatohepatitis (NASH) presents as an epidemic chronic liver disease that is closely associated with metabolic disorders and involves hepatic steatosis, inflammation, and fibrosis as key factors. Despite the enormous global prevalence of NASH, effective pharmacological interventions are lacking. Based on the hypothesis that the multifactorial condition NASH may benefit from combined multiple modes of action for enhanced therapeutic efficacy, we have previously developed dual FXR activators/sEH inhibitors (FXRa/sEHi) and observed remarkable antifibrotic effects upon their use in rodent NASH models. However, these first-generation FXRa/sEHi were characterized by moderate metabolic stability and short in vivo half-life. Aiming to overcome these pharmacokinetic drawbacks, we have systematically studied the structure-activity and structure-stability relationships of the chemotype and obtained second-generation FXRa/sEHi with improved pharmacokinetic parameters. With high plasma exposure, a half-life greater than 5 h, and similar dual potency on the intended targets, 13 presents as a substantially optimized FXRa/sEHi for late-stage preclinical development.

A New FXR Ligand Chemotype with Agonist/Antagonist Switch.

Therapeutic modulation of the bile acid-sensing transcription factor farnesoid X receptor (FXR) is an appealing strategy to counteract hepatic and metabolic diseases. Despite the availability of several highly potent FXR agonists structural diversity of FXR modulators is limited, and new ligand scaffolds are needed. Here we report structure-activity relationship elucidation of a new FXR modulator chemotype whose activity can be tuned between agonism and antagonism by two minor structural modifications. Starting from a weak FXR/PPAR agonist, we have developed selective FXR activators and antagonists with nanomolar to low-micromolar potencies and binding affinities. The new FXR ligand chemotype modulates the FXR activity in the native cellular setting, is endowed with favorable metabolic stability, and lacks cytotoxicity. It valuably expands the collection of FXR modulators as a new scaffold for FXR-targeted drug discovery.

A triple farnesoid X receptor and peroxisome proliferator-activated receptor α/δ activator reverses hepatic fibrosis in diet-induced NASH in mice.

Non-alcoholic steatohepatitis (NASH) - a hepatic manifestation of the metabolic syndrome - is a multifactorial disease with alarming global prevalence. It involves steatosis, inflammation and fibrosis in the liver, thus demanding multiple modes of action for robust therapeutic efficacy. Aiming to fuse complementary validated anti-NASH strategies in a single molecule, we have designed and systematically optimized a scaffold for triple activation of farnesoid X receptor (FXR), peroxisome proliferator-activated receptor (PPAR) α and PPARδ. Pilot profiling of the resulting triple modulator demonstrated target engagement in native cellular settings and in mice, rendering it a suitable tool to probe the triple modulator concept in vivo. In DIO NASH in mice, the triple agonist counteracted hepatic inflammation and reversed hepatic fibrosis highlighting the potential of designed polypharmacology in NASH.

Dual Farnesoid X Receptor/Soluble Epoxide Hydrolase Modulators Derived from Zafirlukast.

The nuclear farnesoid X receptor (FXR) and the enzyme soluble epoxide hydrolase (sEH) are validated molecular targets to treat metabolic disorders such as non-alcoholic steatohepatitis (NASH). Their simultaneous modulation in vivo has demonstrated a triad of anti-NASH effects and thus may generate synergistic efficacy. Here we report dual FXR activators/sEH inhibitors derived from the anti-asthma drug Zafirlukast. Systematic structural optimization of the scaffold has produced favorable dual potency on FXR and sEH while depleting the original cysteinyl leukotriene receptor antagonism of the lead drug. The resulting polypharmacological activity profile holds promise in the treatment of liver-related metabolic diseases.

A dual farnesoid X receptor/soluble epoxide hydrolase modulator treats non-alcoholic steatohepatitis in mice.

Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are the most prevalent metabolic liver disorders and a serious global health burden. NAFLD/NASH pathogenesis and progression are highly multi-factorial and likely demand a combination of multiple mechanisms to provide a more effective treatment. We have developed a dual farnesoid X receptor agonist (FXRA)/soluble epoxide hydrolase inhibitor (sEHi) to simultaneously address two validated and complementary modes of action in NASH treatment. Here we report the in vivo profiling for this FXRA/sEHi in toxin- and diet-induced rodent NASH models. In streptozotocin-induced NASH as a proof-of-concept study, the experimental FXRA/sEHi drug robustly prevented hepatic steatosis and fibrosis, and improved lipid homeostasis as well as biochemical markers of liver health. In methionine-choline-deficient high-fat diet-induced NASH, FXRA/sEHi treatment reduced hepatic steatosis and fibrosis to levels similar to healthy animals and demonstrated anti-inflammatory activity confirming that dual FXRA/sEHi modulation produces a triad of complementary anti-NASH effects. Our results validate dual FXRA/sEHi modulation as an effective therapeutic strategy to treat NASH and advocates for a combinational drug therapeutic approach for multifactorial liver diseases.

Tuning Nuclear Receptor Selectivity of Wy14,643 towards Selective Retinoid X Receptor Modulation.

The fatty acid sensing nuclear receptor families retinoid X receptors (RXRs) and peroxisome proliferator-activated receptors (PPARs) hold therapeutic potential in neurodegeneration. Valuable pleiotropic activities of Wy14,643 in models of such conditions exceed its known PPAR agonistic profile. Here, we characterize the compound as an RXR agonist explaining the pleiotropic effects and report its systematic structure-activity relationship analysis with the discovery of specific molecular determinants driving activity on PPARs and RXRs. We have designed close analogues of the drug comprising selective and dual agonism on RXRs and PPARs that may serve as superior pharmacological tools to study the role and interplay of the nuclear receptors in various pathologies. A systematically optimized high potency RXR agonist revealed activity in vivo and active concentrations in brain. With its lack of RXR/liver X receptor-mediated side effects and superior profile compared to classical rexinoids, it establishes a new class of innovative RXR modulators to overcome key challenges in RXR targeting drug discovery.

Selective Optimization of Pranlukast to Farnesoid†X Receptor Modulators.

Selective optimization of side activities (SOSA) offers an alternative entry to early drug discovery and may provide rapid access to bioactive new chemical entities with desirable properties. SOSA aims to reverse a drug's side activities through structural modification and to design out the drug's original main action. We identified a moderate side activity for the cysteinyl leukotriene receptor 1 (CysLT1 R) antagonist pranlukast on the farnesoid X receptor (FXR). Systematic structural modification of the drug allowed remarkable optimization of its partial FXR agonism to sub-nanonmolar potency. The resulting FXR modulators lack any activity on CysLT1 R and are characterized by high selectivity, high metabolic stability, and low toxicity. With their favorable in vitro profile, these SOSA-derived FXR modulators constitute a new FXR ligand chemotype that appears suitable for further preclinical evaluation.

Structure-Based Approach toward Identification of Inhibitory Fragments for Eleven-Nineteen-Leukemia Protein (ENL).

Lysine acetylation is an epigenetic mark that is principally recognized by bromodomains, and recently structurally diverse YEATS domains also emerged as readers of lysine acetyl/acylations. Here we present a crystallography-based strategy and the discovery of fragments binding to the ENL YEATS domain, a potential drug target. Crystal structures combined with synthetic efforts led to the identification of a submicromolar binder, providing first starting points for the development of chemical probes for this reader domain family.

Allosteric modulation of the farnesoid X receptor by a small molecule.

The bile acid activated transcription factor farnesoid X receptor (FXR) regulates numerous metabolic processes and is a rising target for the treatment of hepatic and metabolic disorders. FXR agonists have revealed efficacy in treating non-alcoholic steatohepatitis (NASH), diabetes and dyslipidemia. Here we characterize imatinib as first-in-class allosteric FXR modulator and report the development of an optimized descendant that markedly promotes agonist induced FXR activation in a reporter gene assay and FXR target gene expression in HepG2 cells. Differential effects of imatinib on agonist-induced bile salt export protein and small heterodimer partner expression suggest that allosteric FXR modulation could open a new avenue to gene-selective FXR modulators.

Boosting Anti-Inflammatory Potency of Zafirlukast by Designed Polypharmacology.

Multitarget design offers access to bioactive small molecules with potentially superior efficacy and safety. Particularly multifactorial chronic inflammatory diseases demand multiple pharmacological interventions for stable treatment. By minor structural changes, we have developed a close analogue of the cysteinyl-leukotriene receptor antagonist zafirlukast that simultaneously inhibits soluble epoxide hydrolase and activates peroxisome proliferator-activated receptor γ. The triple modulator exhibits robust anti-inflammatory activity in vivo and highlights the therapeutic potential of designed multitarget agents.

Nonacidic Farnesoid X Receptor Modulators.

As a cellular bile acid sensor, farnesoid X receptor (FXR) participates in regulation of bile acid, lipid and glucose homeostasis, and liver protection. Clinical results have validated FXR as therapeutic target in hepatic and metabolic diseases. To date, potent FXR agonists share a negatively ionizable function that might compromise their pharmacokinetic distribution and behavior. Here we report the development and characterization of a high-affinity FXR modulator not comprising an acidic residue.

A Dual Modulator of Farnesoid X Receptor and Soluble Epoxide Hydrolase To Counter Nonalcoholic Steatohepatitis.

Nonalcoholic steatohepatitis arising from Western diet and lifestyle is characterized by accumulation of fat in liver causing inflammation and fibrosis. It evolves as serious health burden with alarming incidence, but there is no satisfying pharmacological therapy to date. Considering the disease's multifactorial nature, modulation of multiple targets might provide superior therapeutic efficacy. In particular, farnesoid X receptor (FXR) activation that revealed antisteatotic and antifibrotic effects in clinical trials combined with inhibition of soluble epoxide hydrolase (sEH) as anti-inflammatory strategy promises synergies. To exploit this dual concept, we developed agents exerting partial FXR agonism and sEH inhibitory activity. Merging known pharmacophores and systematic exploration of the structure-activity relationship on both targets produced dual modulators with low nanomolar potency. Extensive in vitro characterization confirmed high dual efficacy in cellular context combined with low toxicity, and pilot in vivo data revealed favorable pharmacokinetics as well as engagement on both targets in vivo.

NSAIDs Ibuprofen, Indometacin, and Diclofenac do not interact with Farnesoid X Receptor.

The nuclear farnesoid X receptor (FXR) is a ligand activated transcription factor and acts as cellular sensor for bile acids. In this role, FXR is a highly important liver protector and FXR inhibition by antagonists or knockout has shown several deleterious effects. A recent report characterized non-steroidal anti-rheumatic drugs (NSAIDs) such as ibuprofen or diclofenac as FXR antagonists and linked hepatotoxic effects of these drugs with antagonistic activity on FXR. Since this would guide a way to develop safer anti-inflammatory agents by sparing FXR, we intended to further characterize the reported antagonistic activity and intensively investigated ibuprofen, indometacin and diclofenac. However, we conclude that these agents do not interact with FXR and that the reported reduced FXR signaling induced by CDCA in presence of NSAIDs is merely a consequence than a cause of hepatotoxicity.