Investigational farnesoid X receptor agonists for the treatment of primary biliary cholangitis

INTRODUCTION

Up to 40% of Primary biliary cholangitis (PBC) patients have a suboptimal response to Ursodeoxycholic acid (UDCA). Close to half of such patients show a remarkable improvement when additionally treated with Obeticholic acid (OCA) but have a dose-dependent increase of pruritus. This relative success of OCA, a first-in-class Farnesoid receptor (FXR) agonist, has positioned FXR as an attractive target for drug development. Novel candidates have since emerged, providing hope for this subgroup of patients who lack effective and safe treatments.

AREAS COVERED

We discussed the role of bile acids in PBC pathogenesis and how the FXR agonists provide therapeutic value by affecting bile acid synthesis and transport. Novel FXR agonists undergoing pre-clinical and clinical trials for PBC were enlisted via literature search by including the terms 'FXR agonists,' 'FXR PBC,' 'PBC clinical trials' on PubMed, MEDLINE via Ovid, and Clinicaltrials.gov.

EXPERT OPINION

Novel FXR agonists currently under investigation for PBC improve the disease surrogate markers in early trials. However, as with OCA, pruritus remains a concern with the newer drugs despite targeted chemical modifications to increase FXR specificity. Directing future resources toward studying the molecular mechanisms behind pruritus may lead to better drug design and efficacious yet safer drugs.

Herb-drug interactions of silybinin and cilofexor in beagle dogs based on pharmacokinetics by UPLC-MS/MS

Objective: A remarkably sensitive, accurate, and efficient ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) approach was developed as a facile and expeditious method for measuring cilofexor concentration in beagle dogs, the herb-drug interactions between silybinin and cilofexor was explored based on pharmacokinetics. Methods: The plasma sample protein of the beagles were rapidly sedimented with acetonitrile, and cilofexor and tropifexor (internal standard, ISTD) were separated by gradient elution using a 0.1% formic acid aqueous solution and acetonitrile as the mobile phase. The concentrations were detected using positive ion multiple reaction monitoring (MRM) mode. Mass transfer pairs were m/z 587.91→267.91 for cilofexor and m/z 604.08→228.03 for ISTD, respectively. A two-period self-controlled experimental design was adopted for the HDIs experiment. In the first period (Group A), six beagle dogs were orally administered cilofexor at a dose of 1 mg/kg. In the second period (Group B), silybinin (3 mg/kg) was orally administered to the six beagle dogs twice a day for seven consecutive days, after which cilofexor was orally administered. The cilofexor concentration in beagle dogs was determined, and HDIs were evaluated based on their pharmacokinetics. Results: The accuracy and precision of cilofexor were both less than 15%, and the recoveries, matrix effects, and stability met the relevant requirements. The Cmax of cilofexor in group B was 49.62% higher than that in group A, whereas the AUC(0-t) and AUC(0-∞) of cilofexor in group B were 47.85% and 48.52% higher, respectively, than those in group A. Meanwhile, the t1/2 extended from 7.84 h to 9.45 h, CL and Vz decreased in Group B. Conclusion: A novel UPLC-MS/MS approach was successfully applied for the measurement of cilofexor in beagle dog plasma. Silybinin can alter the pharmacokinetics of cilofexor in beagle dogs, thereby increasing plasma exposure to cilofexor.

Effect of Hepatic Impairment on the Pharmacokinetics and Pharmacodynamics of Cilofexor, a Selective Nonsteroidal Farnesoid X Receptor Agonist

Cilofexor is a nonsteroidal farnesoid X receptor agonist in clinical development for treatment of nonalcoholic steatohepatitis. This work characterized the pharmacokinetics, pharmacodynamics, safety, and tolerability of cilofexor in participants with normal hepatic function or hepatic impairment (HI). Participants with stable mild, moderate, or severe HI (Child-Pugh [CP] A, B, or C, respectively, [n = 10/group]) and healthy matched controls with normal hepatic function received a single oral dose of cilofexor (30 mg for CP-A or B; 10 mg for CP-C) with a standardized meal. Overall, 56 participants received cilofexor and completed the study. Cilofexor area under the plasma concentration-time curve was 76%, 2.5-fold, and 6.3-fold higher in participants with mild, moderate, or severe HI, respectively, relative to the area under the plasma concentration-time curve in matched participants with normal hepatic function. Cilofexor unbound fraction was 38%, 2-fold, and 3.16-fold higher in participants with mild, moderate, and severe HI, respectively, relative to participants with normal hepatic function. Moderate correlations were identified between cilofexor exposure and CP score or laboratory tests components of CP score. Serum 7α-hydroxy-4-cholesten-3-one and plasma fibroblast growth factor 19 were similar in participants with mild, moderate, or severe HI and participants with normal hepatic function. Cilofexor was generally well tolerated; all cilofexor-related adverse events were mild in severity. Cilofexor can be administered to patients with mild HI without dose adjustment. Caution and dose modification are warranted when administering cilofexor to patients with moderate or severe HI.

Effect of Renal Impairment on the Pharmacokinetics of Firsocostat, an Acetyl-Coenzyme A Carboxylase Inhibitor, and Cilofexor, a Selective Nonsteroidal Farnesoid X Receptor Agonist

Firsocostat, a liver-targeted acetyl-coenzyme A carboxylase inhibitor, and cilofexor, a nonsteroidal farnesoid X receptor agonist, are being developed in combination for treatment of nonalcoholic steatohepatitis. This phase 1 study evaluated firsocostat and cilofexor pharmacokinetics and tolerability in participants with severe renal impairment (SRI) and healthy matched controls (HMCs). Ten participants with SRI (estimated glomerular filtration rate by Modification of Diet in Renal Disease <30 mL/min/1.73 m² ), and 10 HMCs received single oral doses of firsocostat (20 mg) on day 1 and cilofexor (100 mg) on day 7 in a fasted state. Plasma concentrations of firsocostat (and nonactive metabolite GS-834773) and cilofexor (and nonactive metabolites GS-716070 and GS-1056756) were collected over 96 hours and quantified; plasma exposures (area under the concentration-time curve [AUC] and peak concentration [C_max ]) and plasma protein binding were characterized. Firsocostat AUC was ≈40% higher in SRI versus HMC, while C_max was 8% lower. Observed exposures of the firsocostat metabolite were ≈4.6-fold higher in SRI participants versus HMC. Exposures (AUC and C_max ) of cilofexor and metabolites and percentages of protein binding of all analytes were similar between SRI and HMC groups. Treatment-emergent adverse events were generally mild and not considered related to study drug. A <50% increase in firsocostat exposure was observed among SRI participants but was deemed not clinically relevant. There was no apparent effect of SRI on cilofexor exposure. Based on this trial, firsocostat and cilofexor dosing are not expected to require modification in patients who are renally impaired.

Safety and efficacy of combination therapy with semaglutide, cilofexor and firsocostat in patients with non-alcoholic steatohepatitis: A randomised, open-label phase II trial

BACKGROUND & AIMS

Non-alcoholic steatohepatitis (NASH) is associated with increased risk of liver-related and cardiovascular morbidity and mortality. Given the complex pathophysiology of NASH, combining therapies with complementary mechanisms may be beneficial. This trial evaluated the safety and efficacy of semaglutide, a glucagon-like peptide-1 receptor agonist, alone and in combination with the farnesoid X receptor agonist cilofexor and/or the acetyl-coenzyme A carboxylase inhibitor firsocostat in patients with NASH.

METHODS

This was a phase II, open-label, proof-of-concept trial in which patients with NASH (F2-F3 on biopsy, or MRI-proton density fat fraction [MRI-PDFF] ≥10% and liver stiffness by transient elastography ≥7 kPa) were randomised to 24 weeks' treatment with semaglutide 2.4 mg once weekly as monotherapy or combined with once-daily cilofexor (30 or 100 mg) and/or once-daily firsocostat 20 mg. The primary endpoint was safety. All efficacy endpoints were exploratory.

RESULTS

A total of 108 patients were randomised to semaglutide (n = 21), semaglutide plus cilofexor 30 mg (n = 22), semaglutide plus cilofexor 100 mg (n = 22), semaglutide plus firsocostat (n = 22) or semaglutide, cilofexor 30 mg and firsocostat (n = 21). Treatments were well tolerated - the incidence of adverse events was similar across groups (73-90%) and most events were gastrointestinal in nature. Despite similar weight loss (7-10%), compared with semaglutide monotherapy, combinations resulted in greater improvements in liver steatosis measured by MRI-PDFF (least-squares mean of absolute changes: -9.8 to -11.0% vs. -8.0%), liver biochemistry, and non-invasive tests of fibrosis.

CONCLUSIONS

In patients with mild-to-moderate fibrosis due to NASH, semaglutide with firsocostat and/or cilofexor was generally well tolerated. In exploratory efficacy analyses, treatment resulted in additional improvements in liver steatosis and biochemistry vs. semaglutide alone. Given this was a small-scale open-label trial, double-blind placebo-controlled trials with adequate patient numbers are warranted to assess the efficacy and safety of these combinations in NASH.

CLINICAL TRIAL REGISTRATION NUMBER

NCT03987074.

LAY SUMMARY

Non-alcoholic fatty liver disease and its more severe form, non-alcoholic steatohepatitis (NASH), are serious liver conditions that worsen over time if untreated. The reasons people develop NASH are complex and combining therapies that target different aspects of the disease may be more helpful than using single treatments. This trial showed that the use of 3 different types of drugs, namely semaglutide, cilofexor and firsocostat, in combination was safe and may offer additional benefits over treatment with semaglutide alone.

The identification of farnesoid X receptor modulators as treatment options for nonalcoholic fatty liver disease

INTRODUCTION

The farnesoid-x-receptor (FXR) is a ubiquitously expressed nuclear receptor selectively activated by primary bile acids.

AREA COVERED

FXR is a validated pharmacological target. Herein, the authors review preclinical and clinical data supporting the development of FXR agonists in the treatment of nonalcoholic fatty liver disease.

EXPERT OPINION

Development of systemic FXR agonists to treat the metabolic liver disease has been proven challenging because the side effects associated with these agents including increased levels of cholesterol and LDL-c and reduced HDL-c raising concerns over their long-term cardiovascular safety. Additionally, pruritus has emerged as a common, although poorly explained, dose-related side effect with all FXR ligands, but is especially common with OCA. FXR agonists that are currently undergoing phase 2/3 trials are cilofexor, tropifexor, nidufexor and MET409. Some of these agents are currently being developed as combination therapies with other agents including cenicriviroc, a CCR2/CCR5 inhibitor, or firsocostat an acetyl CoA carboxylase inhibitor. Additional investigations are needed to evaluate the beneficial effects of combination of these agents with statins. It is expected that in the coming years, FXR agonists will be developed as a combination therapy to minimize side effects and increase likelihood of success by targeting different metabolic pathways.

The Non-Steroidal FXR Agonist Cilofexor Improves Portal Hypertension and Reduces Hepatic Fibrosis in a Rat NASH Model

Background: The farnesoid X receptor (FXR) influences hepatic metabolism, inflammation and liver fibrosis as key components of non-alcoholic steatohepatitis (NASH). We studied the effects of the non-steroidal FXR agonist cilofexor (formerly GS-9674) on portal pressure and fibrosis in experimental NASH. Methods: NASH was induced in Wistar rats using a choline-deficient high-fat diet plus intraperitoneal sodium nitrite injections. First, a dose-finding study was performed with 10 mg/kg and 30 mg/kg of cilofexor, focusing on histological readouts. Liver fibrosis was assessed by Picro-Sirius-Red, desmin staining and hepatic hydroxyproline content. Gene expression was determined by RT-PCR. In a subsequent hemodynamic study, rats received 30 mg/kg cilofexor with or without propranolol (25 mg/kg). Portal pressure, systemic hemodynamics and splanchnic blood flow were measured. Results: Cilofexor dose-dependently induced FXR target genes shp, cyp7a1 and fgf15 in hepatic and ileal tissues, paralleled by a dose-dependent reduction in liver fibrosis area (Picro-Sirius-Red) of −41% (10 mg/kg) and −69% (30 mg/kg), respectively. The 30 mg/kg cilofexor dose significantly reduced hepatic hydroxyproline content (−41%), expression of col1a1 (−37%) and pdgfr-β (−36%), as well as desmin area (−42%) in NASH rats. Importantly, cilofexor decreased portal pressure (11.9 ± 2.1 vs. 8.9 ± 2.2 mmHg; p = 0.020) without affecting splanchnic blood-flow or systemic hemodynamics. The addition of propranolol to cilofexor additionally reduced splanchnic inflow (−28%) but also mean arterial pressure (−25%) and heart rate (−37%). Conclusion: The non-steroidal FXR agonist cilofexor decreased portal hypertension and reduced liver fibrosis in NASH rats. While cilofexor seems to primarily decrease sinusoidal resistance in cirrhotic portal hypertension, the combination with propranolol additionally reduced mesenteric hyperperfusion.