BET inhibition blocks inflammation-induced cardiac dysfunction and SARS-CoV-2 infection.

Cardiac injury and dysfunction occur in COVID-19 patients and increase the risk of mortality. Causes are ill defined but could be through direct cardiac infection and/or inflammation-induced dysfunction. To identify mechanisms and cardio-protective drugs, we use a state-of-the-art pipeline combining human cardiac organoids with phosphoproteomics and single nuclei RNA sequencing. We identify an inflammatory "cytokine-storm", a cocktail of interferon gamma, interleukin 1ß, and poly(I:C), induced diastolic dysfunction. Bromodomain-containing protein 4 is activated along with a viral response that is consistent in both human cardiac organoids (hCOs) and hearts of SARS-CoV-2-infected K18-hACE2 mice. Bromodomain and extraterminal family inhibitors (BETi) recover dysfunction in hCOs and completely prevent cardiac dysfunction and death in a mouse cytokine-storm model. Additionally, BETi decreases transcription of genes in the viral response, decreases ACE2 expression, and reduces SARS-CoV-2 infection of cardiomyocytes. Together, BETi, including the Food and Drug Administration (FDA) breakthrough designated drug, apabetalone, are promising candidates to prevent COVID-19 mediated cardiac damage.

Inhibitors of bromodomain and extra-terminal proteins for treating multiple human diseases.

Clinical development of bromodomain and extra-terminal (BET) protein inhibitors differs from the traditional course of drug development. These drugs are simultaneously being evaluated for treating a wide spectrum of human diseases due to their novel mechanism of action. BET proteins are epigenetic "readers," which play a primary role in transcription. Here, we briefly describe the BET family of proteins, of which BRD4 has been studied most extensively. We discuss BRD4 activity at latent enhancers as an example of BET protein function. We examine BRD4 redistribution and enhancer reprogramming in embryonic development, cancer, cardiovascular, autoimmune, and metabolic diseases, presenting hallmark studies that highlight BET proteins as attractive targets for therapeutic intervention. We review the currently available approaches to targeting BET proteins, methods of selectively targeting individual bromodomains, and review studies that compare the effects of selective BET inhibition to those of pan-BET inhibition. Lastly, we examine the current clinical landscape of BET inhibitor development.

Apabetalone and hospitalization for heart failure in patients following an acute coronary syndrome: a prespecified analysis of the BETonMACE study.

BACKGROUND: Patients with diabetes and acute coronary syndrome (ACS) are at high risk for subsequent heart failure. Apabetalone is a selective inhibitor of bromodomain and extra-terminal (BET) proteins, epigenetic regulators of gene expression. Preclinical data suggest that apabetalone exerts favorable effects on pathways related to myocardial structure and function and therefore could impact subsequent heart failure events. The effect of apabetalone on heart failure events after an ACS is not currently known. METHODS: The phase 3 BETonMACE trial was a double-blind, randomized comparison of apabetalone versus placebo on the incidence of major adverse cardiovascular events (MACE) in 2425 patients with a recent ACS and diabetes. This prespecified secondary analysis investigated the impact of apabetalone on hospitalization for congestive heart failure, not previously studied. RESULTS: Patients (age 62 years, 74.4% males, 90% high-intensity statin use, LDL-C 70.3 mg/dL, HDL-C 33.3 mg/dL and HbA1c 7.3%) were followed for an average 26 months. Apabetalone treated patients experienced the nominal finding of a lower rate of first hospitalization for heart failure (2.4% vs. 4.0%, HR 0.59 [95%CI 0.38-0.94], P = 0.03), total number of hospitalizations for heart failure (35 vs. 70, HR 0.47 [95%CI 0.27-0.83], P = 0.01) and the combination of cardiovascular death or hospitalization for heart failure (5.7% vs. 7.8%, HR 0.72 [95%CI 0.53-0.98], P = 0.04). CONCLUSION: Apabetalone treatment was associated with fewer hospitalizations for heart failure in patients with type 2 diabetes and recent ACS. Future studies are warranted to define the potential for BET inhibition with apabetalone to prevent heart failure in patients with diabetes and ACS.

Relation of insulin treatment for type 2 diabetes to the risk of major adverse cardiovascular events after acute coronary syndrome: an analysis of the BETonMACE randomized clinical trial.

BACKGROUND: In stable patients with type 2 diabetes (T2D), insulin treatment is associated with elevated risk for major adverse cardiovascular events (MACE). Patients with acute coronary syndrome (ACS) and T2D are at particularly high risk for recurrent MACE despite evidence-based therapies. It is uncertain to what extent this risk is further magnified in patients with recent ACS who are treated with insulin. We examined the relationship of insulin use to risk of MACE and modification of that risk by apabetalone, a bromodomain and extra-terminal (BET) protein inhibitor. METHODS: The analysis utilized data from the BETonMACE phase 3 trial that compared apabetalone to placebo in patients with T2D, low HDL cholesterol, andACS. The primary MACE outcome (cardiovascular death, myocardial infarction, or stroke) was examined according to insulin treatment and assigned study treatment. Multivariable Cox regression was used to determine whether insulin use was independently associated with the risk of MACE. RESULTS: Among 2418 patients followed for median 26.5 months, 829 (34.2%) were treated with insulin. Despite high utilization of evidence-based treatments including coronary revascularization, intensive statin treatment, and dual antiplatelet therapy, the 3-year incidence of MACE in the placebo group was elevated among insulin-treated patients (20.4%) compared to those not-treated with insulin (12.8%, P = 0.0001). Insulin treatment remained strongly associated with the risk of MACE (HR 2.10, 95% CI 1.42-3.10, P = 0.0002) after adjustment for demographic, clinical, and treatment variables. Apabetalone had a consistent, favorable effect on MACE in insulin-treated and not insulin-treated patients. CONCLUSION: Insulin-treated patients with T2D, low HDL cholesterol, and ACS are at high risk for recurrent MACE despite the use of evidence-based, contemporary therapies. A strong association of insulin treatment with risk of MACE persists after adjustment for other characteristics associated with MACE. There is unmet need for additional treatments to mitigate this risk. Trial registration ClinicalTrials.gov NCT02586155, registered October 26, 2015.

Pharmacologic epigenetic modulators of alkaline phosphatase in chronic kidney disease.

PURPOSE OF REVIEW: In chronic kidney disease (CKD), disturbance of several metabolic regulatory mechanisms cause premature ageing, accelerated cardiovascular disease (CVD), and mortality. Single-target interventions have repeatedly failed to improve the prognosis for CKD patients. Epigenetic interventions have the potential to modulate several pathogenetic processes simultaneously. Alkaline phosphatase (ALP) is a robust predictor of CVD and all-cause mortality and implicated in pathogenic processes associated with CVD in CKD. RECENT FINDINGS: In experimental studies, epigenetic modulation of ALP by microRNAs or bromodomain and extraterminal (BET) protein inhibition has shown promising results for the treatment of CVD and other chronic metabolic diseases. The BET inhibitor apabetalone is currently being evaluated for cardiovascular risk reduction in a phase III clinical study in high-risk CVD patients, including patients with CKD (ClinicalTrials.gov Identifier: NCT02586155). Phase II studies demonstrate an ALP-lowering potential of apabetalone, which was associated with improved cardiovascular and renal outcomes. SUMMARY: ALP is a predictor of CVD and mortality in CKD. Epigenetic modulation of ALP has the potential to affect several pathogenetic processes in CKD and thereby improve cardiovascular outcome.

Multicenter Preclinical Validation of BET Inhibition for the Treatment of Pulmonary Arterial Hypertension.

Rationale: Pulmonary arterial hypertension (PAH) is a degenerative arteriopathy that leads to right ventricular (RV) failure. BRD4 (bromodomain-containing protein 4), a member of the BET (bromodomain and extra-terminal motif) family, has been identified as a critical epigenetic driver for cardiovascular diseases.Objectives: To explore the therapeutic potential in PAH of RVX208, a clinically available BET inhibitor.Methods: Microvascular endothelial cells, smooth muscle cells isolated from distal pulmonary arteries of patients with PAH, rats with Sugen5416 + hypoxia- or monocrotaline + shunt-induced PAH, and rats with RV pressure overload induced by pulmonary artery banding were treated with RVX208 in three independent laboratories.Measurements and Main Results: BRD4 is upregulated in the remodeled pulmonary vasculature of patients with PAH, where it regulates FoxM1 and PLK1, proteins implicated in the DNA damage response. RVX208 normalized the hyperproliferative, apoptosis-resistant, and inflammatory phenotype of microvascular endothelial cells and smooth muscle cells isolated from patients with PAH. Oral treatment with RVX208 reversed vascular remodeling and improved pulmonary hemodynamics in two independent trials in Sugen5416 + hypoxia-PAH and in monocrotaline + shunt-PAH. RVX208 could be combined safely with contemporary PAH standard of care. RVX208 treatment also supported the pressure-loaded RV in pulmonary artery banding rats.Conclusions: RVX208, a clinically available BET inhibitor, modulates proproliferative, prosurvival, and proinflammatory pathways, potentially through interactions with FoxM1 and PLK1. This reversed the PAH phenotype in isolated PAH microvascular endothelial cells and smooth muscle cells in vitro, and in diverse PAH rat models. RVX208 also supported the pressure-loaded RV in vivo. Together, these data support the establishment of a clinical trial with RVX208 in patients with PAH.

Effect of Apabetalone Added to Standard Therapy on Major Adverse Cardiovascular Events in Patients With Recent Acute Coronary Syndrome and Type 2 Diabetes: A Randomized Clinical Trial.

Importance: Bromodomain and extraterminal proteins are epigenetic regulators of gene transcription. Apabetalone is a selective bromodomain and extraterminal protein inhibitor targeting bromodomain 2 and is hypothesized to have potentially favorable effects on pathways related to atherothrombosis. Pooled phase 2 data suggest favorable effects on clinical outcomes. Objective: To test whether apabetalone significantly reduces major adverse cardiovascular events. Design, Setting, and Participants: A randomized, double-blind, placebo-controlled trial, conducted at 190 sites in 13 countries. Patients with an acute coronary syndrome in the preceding 7 to 90 days, type 2 diabetes, and low high-density lipoprotein cholesterol levels were eligible for enrollment, which started November 11, 2015, and ended July 4, 2018, with end of follow-up on July 3, 2019. Interventions: Patients were randomized (1:1) to receive apabetalone, 100 mg orally twice daily (n = 1215), or matching placebo (n = 1210) in addition to standard care. Main Outcomes and Measures: The primary outcome was a composite of time to the first occurrence of cardiovascular death, nonfatal myocardial infarction, or stroke. Results: Among 2425 patients who were randomized (mean age, 62 years; 618 women [25.6%]), 2320 (95.7%) had full ascertainment of the primary outcome. During a median follow-up of 26.5 months, 274 primary end points occurred: 125 (10.3%) in apabetalone-treated patients and 149 (12.4%) in placebo-treated patients (hazard ratio, 0.82 [95% CI, 0.65-1.04]; P = .11). More patients allocated to apabetalone than placebo discontinued study drug (114 [9.4%] vs 69 [5.7%]) for reasons including elevations of liver enzyme levels (35 [2.9%] vs 11 [0.9%]). Conclusions and Relevance: Among patients with recent acute coronary syndrome, type 2 diabetes, and low high-density lipoprotein cholesterol levels, the selective bromodomain and extraterminal protein inhibitor apabetalone added to standard therapy did not significantly reduce the risk of major adverse cardiovascular events. Trial Registration: ClinicalTrials.gov Identifier: NCT02586155.

Effect of selective BET protein inhibitor apabetalone on cardiovascular outcomes in patients with acute coronary syndrome and diabetes: Rationale, design, and baseline characteristics of the BETonMACE trial.

After an acute coronary syndrome (ACS), patients with diabetes remain at high risk for additional cardiovascular events despite use of current therapies. Bromodomain and extra-terminal (BET) proteins are epigenetic modulators of inflammation, thrombogenesis, and lipoprotein metabolism implicated in atherothrombosis. The BETonMACE trial tests the hypothesis that treatment with apabetalone, a selective BET protein inhibitor, will improve cardiovascular outcomes in patients with diabetes after an ACS. DESIGN: Patients (n = 2425) with ACS in the preceding 7 to 90 days, with type 2 diabetes and low HDL cholesterol (≤40 mg/dl for men, ≤45 mg/dl for women), receiving intensive or maximum-tolerated therapy with atorvastatin or rosuvastatin, were assigned in double-blind fashion to receive apabetalone 100 mg orally twice daily or matching placebo. Baseline characteristics include female sex (25%), myocardial infarction as index ACS event (74%), coronary revascularization for index ACS (80%), treatment with dual anti-platelet therapy (87%) and renin-angiotensin system inhibitors (91%), median LDL cholesterol 65 mg per deciliter, and median HbA1c 7.3%. The primary efficacy measure is time to first occurrence of cardiovascular death, non-fatal myocardial infarction, or stroke. Assumptions include a primary event rate of 7% per annum in the placebo group and median follow-up of 1.5 years. Patients will be followed until at least 250 primary endpoint events have occurred, providing 80% power to detect a 30% reduction in the primary endpoint with apabetalone. SUMMARY: BETonMACE will determine whether the addition of the selective BET protein inhibitor apabetalone to contemporary standard of care for ACS reduces cardiovascular morbidity and mortality in patients with type 2 diabetes. Results are expected in 2019.

Apabetalone Mediated Epigenetic Modulation is Associated with Favorable Kidney Function and Alkaline Phosphatase Profile in Patients with Chronic Kidney Disease.

BACKGROUND/AIMS: The association between serum alkaline phosphatase (ALP) with adverse cardiovascular outcomes, in Chronic Kidney Disease (CKD) patients has previously been reported and may be a result of increased vascular calcification and inflammation. Here we report, for the first time, the effects of pharmacologic epigenetic modulation on levels of ALP and kidney function via a novel oral small molecule BET inhibitor, apabetalone, in CKD patients. METHODS: A post-hoc analysis evaluated patients with estimated glomerular filtration rate (eGFR) <60 mL/min/1.73m2, who participated in the apabetalone phase 2 randomized controlled trials (SUSTAIN and ASSURE). 48 CKD subjects with a history of cardiovascular disease (CVD) were treated with 100mg twice-daily of 24 and 26 weeks of apabetalone or placebo. ALP and eGFR were measured prior to randomization and at final visits. RESULTS: Patients who received apabetalone (n=35) versus placebo (n=13) over 6 months showed significantly (p=0.02) lowered serum ALP -14.0% (p<0.0001 versus baseline) versus -6.3% (p=0.9 versus baseline). The eGFR in the apabetalone group increased by 3.4% (1.7 mL/min/1.73 m2) (p=0.04 versus baseline) and decreased by 5.8% (2.9 mL/min/1.73 m2) (p=0.6 versus baseline) in the placebo group. Apabetalone was well tolerated. CONCLUSION: A post-hoc analysis of CKD subjects from the SUSTAIN and ASSURE randomized controlled trials demonstrated favorable effects of apabetalone on ALP and eGFR, and generated the hypothesis that epigenetic modulation by BET inhibition may potentially offer a novel therapeutic strategy to treat CVD and progressive kidney function loss in CKD patients. This is being examined in the phase III trial BETonMACE.

RVX-297, a BET Bromodomain Inhibitor, Has Therapeutic Effects in Preclinical Models of Acute Inflammation and Autoimmune Disease.

Bromodomain (BD) and extra-terminal domain containing proteins (BET) are chromatin adapters that bind acetylated histone marks via two tandem BDs, BD1 and BD2, to regulate gene transcription. BET proteins are involved in transcriptional reprogramming in response to inflammatory stimuli. BET BD inhibitors (BETis) that are nonselective for BD1 or BD2 have recognized anti-inflammatory properties in vitro and counter pathology in models of inflammation or autoimmune disease. Although both BD1 and BD2 bind acetylated histone residues, they may independently regulate the expression of BET-sensitive genes. Here we characterized the ability of RVX-297, a novel orally active BETi with selectivity for BD2, to modulate inflammatory processes in vitro, in vivo, and ex vivo. RVX-297 suppressed inflammatory gene expression in multiple immune cell types in culture. Mechanistically, RVX-297 displaced BET proteins from the promoters of sensitive genes and disrupted recruitment of active RNA polymerase II, a property shared with pan-BETis that nonselectively bind BET BDs. In the lipopolysaccharide model of inflammation, RVX-297 reduced proinflammatory mediators assessed in splenic gene expression and serum proteins. RVX-297 also countered pathology in three rodent models of polyarthritis: rat and mouse collagen-induced arthritis, and mouse collagen antibody-induced arthritis. Further, RVX-297 prevented murine experimental autoimmune encephalomyelitis (a model of human multiple sclerosis) disease development when administered prophylactically and reduced hallmarks of pathology when administered therapeutically. We show for the first time that a BD2-selective BETi maintains anti-inflammatory properties and is effective in preclinical models of acute inflammation and autoimmunity.

Apabetalone, a Clinical-Stage, Selective BET Inhibitor, Opposes DUX4 Target Gene Expression in Primary Human FSHD Muscle Cells.

Facioscapulohumeral dystrophy (FSHD) is a muscle disease caused by inappropriate expression of the double homeobox 4 (DUX4) gene in skeletal muscle, and its downstream activation of pro-apoptotic transcriptional programs. Inhibitors of DUX4 expression have the potential to treat FSHD. Apabetalone is a clinical-stage bromodomain and extra-terminal (BET) inhibitor, selective for the second bromodomain on BET proteins. Using primary human skeletal muscle cells from FSHD type 1 patients, we evaluated apabetalone for its ability to counter DUX4's deleterious effects and compared it with the pan-BET inhibitor JQ1, and the p38 MAPK inhibitor-and DUX4 transcriptional repressor-losmapimod. We applied RNA-sequencing and bioinformatic analysis to detect treatment-associated impacts on the transcriptome of these cells. Apabetalone inhibited the expression of DUX4 downstream markers, reversing hallmarks of FSHD gene expression in differentiated muscle cells. JQ1, but not apabetalone, was found to induce apoptosis. While both BET inhibitors modestly impacted differentiation marker expression, they did not affect myotube fusion. Losmapimod also reduced expression of DUX4 target genes but differed in its impact on FSHD-associated pathways. These findings demonstrate that apabetalone inhibits DUX4 target gene expression and reverses transcriptional programs that contribute to FSHD pathology, making this drug a promising candidate therapeutic for FSHD.

Epigenetic BET reader inhibitor apabetalone (RVX-208) counters proinflammatory aortic gene expression in a diet induced obesity mouse model and in human endothelial cells.

BACKGROUND AND AIMS: Obese patients are at risk for type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). A lipid-rich diet promotes arterial changes by inducing hypertension, oxidative stress, and inflammation. Bromodomain and extraterminal (BET) proteins contribute to endothelial and immune cell activation in vitro and in atherosclerosis mouse models. We aim to determine if BET inhibition can reduce lipid-rich diet-induced vascular inflammation in mice. METHODS: Body weight, serum glucose and lipid levels were measured in mice fed a high-fat diet (HFD) or low-fat diet (LFD) for 6 weeks and at study termination. BET inhibitors apabetalone and JQ1 were co-administered with the HFD for additional 16 weeks. Aortic gene expression was analyzed post necropsy by PCR, Nanostring nCounter® Inflammation Panel and bioinformatics pathway analysis. Transcription changes and BRD4 chromatin occupancy were analyzed in primary human endothelial cells in response to TNFα and apabetalone. RESULTS: HFD induced weight gain, visceral obesity, high fasting blood glucose, glucose intolerance and insulin resistance compared to LFD controls. HFD upregulated the aortic expression of 47 genes involved in inflammation, innate immunity, cytoskeleton and complement pathways. Apabetalone and JQ1 treatment reduced HFD-induced aortic expression of proinflammatory genes. Congruently, bioinformatics predicted enhanced signaling by TNFα in the HFD versus LFD aorta, which was countered by BETi treatment. TNFα-stimulated human endothelial cells had increased expression of HFD-sensitive genes and higher BRD4 chromatin occupancy, which was countered by apabetalone treatment. CONCLUSIONS: HFD induces vascular inflammation in mice through TNFα signaling. Apabetalone treatment reduces this proinflammatory phenotype, providing mechanistic insight into how BET inhibitors may reduce CVD risk in obese patients.

Apabetalone Downregulates Fibrotic, Inflammatory and Calcific Processes in Renal Mesangial Cells and Patients with Renal Impairment.

Epigenetic mechanisms are implicated in transcriptional programs driving chronic kidney disease (CKD). Apabetalone is an orally available inhibitor of bromodomain and extraterminal (BET) proteins, which are epigenetic readers that modulate gene expression. In the phase 3 BETonMACE trial, apabetalone reduced risk of major adverse cardiac events (MACE) by 50% in the CKD subpopulation, indicating favorable effects along the kidney-heart axis. Activation of human renal mesangial cells (HRMCs) to a contractile phenotype that overproduces extracellular matrix (ECM) and inflammatory cytokines, and promotes calcification, frequently accompanies CKD to drive pathology. Here, we show apabetalone downregulated HRMC activation with TGF-ß1 stimulation by suppressing TGF-ß1-induced α-smooth muscle actin (α-SMA) expression, α-SMA assembly into stress fibers, enhanced contraction, collagen overproduction, and expression of key drivers of fibrosis, inflammation, or calcification including thrombospondin, fibronectin, periostin, SPARC, interleukin 6, and alkaline phosphatase. Lipopolysaccharide-stimulated expression of inflammatory genes IL6, IL1B, and PTGS2 was also suppressed. Transcriptomics confirmed apabetalone affected gene sets of ECM remodeling and integrins. Clinical translation of in vitro results was indicated in CKD patients where a single dose of apabetalone reduced plasma levels of key pro-fibrotic and inflammatory markers, and indicated inhibition of TGF-ß1 signaling. While plasma proteins cannot be traced to the kidney alone, anti-fibrotic and anti-inflammatory effects of apabetalone identified in this study are consistent with the observed decrease in cardiovascular risk in CKD patients.

Dual mechanism: Epigenetic inhibitor apabetalone reduces SARS-CoV-2 Delta and Omicron variant spike binding and attenuates SARS-CoV-2 RNA induced inflammation.

The SARS-CoV-2 virus initiates infection via interactions between the viral spike protein and the ACE2 receptors on host cells. Variants of concern have mutations in the spike protein that enhance ACE2 binding affinity, leading to increased virulence and transmission. Viral RNAs released after entry into host cells trigger interferon-I (IFN-I) mediated inflammatory responses for viral clearance and resolution of infection. However, overreactive host IFN-I responses and pro-inflammatory signals drive COVID-19 pathophysiology and disease severity during acute infection. These immune abnormalities also lead to the development of post-COVID syndrome if persistent. Novel therapeutics are urgently required to reduce short- and long-term pathologic consequences associated with SARS-CoV-2 infection. Apabetalone, an inhibitor of epigenetic regulators of the BET protein family, is a candidate for COVID-19 treatment via a dual mechanism of action. In vitro, apabetalone downregulates ACE2 gene expression to limit SARS-CoV-2 entry and propagation. In pre-clinical models and patients treated for cardiovascular disease, apabetalone inhibits expression of inflammatory mediators involved in the pathologic cytokine storm (CS) stimulated by various cytokines. Here we show apabetalone treatment of human lung epithelial cells reduces binding of viral spike protein regardless of mutations found in the highly contagious Delta variant and heavily mutated Omicron. Additionally, we demonstrate that apabetalone counters expression of pro-inflammatory factors with roles in CS and IFN-I signaling in lung cells stimulated with SARS-CoV-2 RNA. Our results support clinical evaluation of apabetalone to treat COVID-19 and post-COVID syndrome regardless of the SARS-CoV-2 variant.

The BET inhibitor apabetalone decreases neuroendothelial proinflammatory activation in vitro and in a mouse model of systemic inflammation.

Brain vascular inflammation is characterized by endothelial activation and immune cell recruitment to the blood vessel wall, potentially causing a breach in the blood - brain barrier, brain parenchyma inflammation, and a decline of cognitive function. The clinical-stage small molecule, apabetalone, reduces circulating vascular endothelial inflammation markers and improves cognitive scores in elderly patients by targeting epigenetic regulators of gene transcription, bromodomain and extraterminal proteins. However, the effect of apabetalone on cytokine-activated brain vascular endothelial cells (BMVECs) is unknown. Here, we show that apabetalone treatment of BMVECs reduces hallmarks of in vitro endothelial activation, including monocyte chemoattractant protein-1 (MCP-1) and RANTES chemokine secretion, cell surface expression of endothelial cell adhesion molecule VCAM-1, as well as endothelial capture of THP-1 monocytes in static and shear stress conditions. Apabetalone pretreatment of THP-1 downregulates cell surface expression of chemokine receptors CCR1, CCR2, and CCR5, and of the VCAM-1 cognate receptor, integrin α4. Consequently, apabetalone reduces THP-1 chemoattraction towards soluble CCR ligands MCP-1 and RANTES, and THP-1 adhesion to activated BMVECs. In a mouse model of brain inflammation, apabetalone counters lipopolysaccharide-induced transcription of endothelial and myeloid cell markers, consistent with decreased neuroendothelial inflammation. In conclusion, apabetalone decreases proinflammatory activation of brain endothelial cells and monocytes in vitro and in the mouse brain during systemic inflammation.

Breaking boundaries: Pan BETi disrupt 3D chromatin structure, BD2-selective BETi are strictly epigenetic transcriptional regulators.

BACKGROUND: Bromodomain and extraterminal proteins (BETs) are more than just epigenetic regulators of transcription. Here we highlight a new role for the BET protein BRD4 in the maintenance of higher order chromatin structure at Topologically Associating Domain Boundaries (TADBs). BD2-selective and pan (non-selective) BET inhibitors (BETi) differentially support chromatin structure, selectively affecting transcription and cell viability. METHODS: Using RNA-seq and BRD4 ChIP-seq, the differential effect of BETi treatment on the transcriptome and BRD4 chromatin occupancy of human aortic endothelial cells from diabetic patients (dHAECs) stimulated with TNFα was evaluated. Chromatin decondensation and DNA fragmentation was assessed by immunofluorescence imaging and quantification. Key dHAEC findings were verified in proliferating monocyte-like THP-1 cells using real time-PCR, BRD4 co-immunoprecipitation studies, western blots, proliferation and apoptosis assays. FINDINGS: We discovered that 1) BRD4 co-localizes with Ying-Yang 1 (YY1) at TADBs, critical chromatin structure complexes proximal to many DNA repair genes. 2) BD2-selective BETi enrich BRD4/YY1 associations, while pan-BETi do not. 3) Failure to support chromatin structures through BRD4/YY1 enrichment inhibits DNA repair gene transcription, which induces DNA damage responses, and causes widespread chromatin decondensation, DNA fragmentation, and apoptosis. 4) BD2-selective BETi maintain high order chromatin structure and cell viability, while reducing deleterious pro-inflammatory transcription. INTERPRETATION: BRD4 plays a previously unrecognized role at TADBs. BETi differentially impact TADB stability. Our results provide translational insight for the development of BETi as therapeutics for a range of diseases including CVD, chronic kidney disease, cancer, and COVID-19.

Inhibition of epigenetic reader proteins by apabetalone counters inflammation in activated innate immune cells from Fabry disease patients receiving enzyme replacement therapy.

Fabry disease (FD) is a rare X-linked disorder of lipid metabolism, characterized by the accumulation of globotriaosylceramide (Gb3) due to defective the lysosomal enzyme, α-galactosidase. Gb3 deposits activate immune-mediated systemic inflammation, ultimately leading to life-threatening consequences in multiple organs such as the heart and kidneys. Enzyme replacement therapy (ERT), the standard of care, is less effective with advanced tissue injury and inflammation in patients with FD. Here, we showed that MCP-1 and TNF-α cytokine levels were almost doubled in plasma from ERT-treated FD patients. Chemokine receptor CCR2 surface expression was increased by twofold on monocytes from patients with low eGFR. We also observed an increase in IL12B transcripts in unstimulated peripheral blood mononuclear cells (PBMCs) over a 2-year period of continuous ERT. Apabetalone is a clinical-stage oral bromodomain and extra terminal protein inhibitor (BETi), which has beneficial effects on cardiovascular and kidney disease related pathways including inflammation. Here, we demonstrate that apabetalone, a BD2-selective BETi, dose dependently reduced the production of MCP-1 and IL-12 in stimulated PBMCs through transcriptional regulation of their encoding genes. Reactive oxygen species production was diminished by up to 80% in stimulated neutrophils following apabetalone treatment, corresponding with inhibition of NOX2 transcription. This study elucidates that inhibition of BET proteins by BD2-selective apabetalone alleviates inflammatory processes and oxidative stress in innate immune cells in general and in FD. These results suggest potential benefit of BD2-selective apabetalone in controlling inflammation and oxidative stress in FD, which will be further investigated in clinical trials.

Reduction in the risk of major adverse cardiovascular events with the BET protein inhibitor apabetalone in patients with recent acute coronary syndrome, type 2 diabetes, and moderate to high likelihood of non-alcoholic fatty liver disease.

Background: Nonalcoholic fatty liver disease (NAFLD) is common among patients with type 2 diabetes mellitus (T2DM) and is associated with increased risk for coronary atherosclerosis and acute cardiovascular (CV) events. We employed the validated, non-invasive Angulo NAFLD fibrosis score (FS) in an intervention study in patients with T2DM and recent acute coronary syndrome (ACS) to determine the association of FS with CV risk and treatment response to apabetalone. Apabetalone is a novel selective inhibitor of the second bromodomain of bromodomain and extra-terminal (BET) proteins, epigenetic regulators of gene expression. Methods: The Phase 3 BETonMACE trial compared apabetalone with placebo in 2,425 patients with T2DM and recent ACS. In this post hoc analysis, we evaluated the impact of apabetalone therapy on CV risk, defined as a composite of major adverse cardiovascular events (MACE: CV death, non-fatal myocardial infarction [MI], or stroke) and hospitalization for heart failure (HHF) in two patient categories of FS that reflect the likelihood of underlying NAFLD. Patients were initially classified into three mutually exclusive categories according to a baseline Angulo FS <-1.455 (F0-F2), -1.455 to 0.675 (indeterminant), and >0.675 (F3-F4), where F0 through F4 connote fibrosis severity none, mild, moderate, severe, and cirrhosis, respectively. The composite of ischemic MACE and HHF in the placebo group was higher in indeterminant and F3-F4 categories compared to the F0-F2 category (17.2% vs 15.0% vs 9.7%). Therefore, for the present analysis, the former two categories were combined into an elevated NAFLD CVD risk group (FS+) that was compared with the F0-F2 group (lower NAFLD risk, FS0-2). Results: In 73.7% of patients, FS was elevated and consistent with a moderate-to-high likelihood of advanced liver fibrosis (FS+); 26.3% of patients had a lower FS (FS0-2). In the placebo group, FS+ patients had a higher incidence of ischemic MACE and HHF (15.4%) than FS0-2 patients (9.7%). In FS+ patients, addition of apabetalone to standard of care treatment lowered the rate of ischemic MACE compared with placebo (HR = 0.79; 95% CI 0.60-1.05; p=0.10), HHF (HR = 0.53; 95% CI 0.33-0.86; p=0.01), and the composite of ischemic MACE and HHF (HR = 0.76; 95% CI 0.59-0.98; p=0.03). In contrast, there was no apparent benefit of apabetalone in FS0-2 patients (HR 1.24; 95% CI 0.75-2.07; p=0.40; HR 1.12; 95% CI 0.30-4.14; p=0.87; and HR 1.13; 95% CI 0.69-1.86; p=0.62, respectively). Over a median duration of 26.5 months, FS increased from baseline in both treatment groups, but the increase was smaller in patients assigned to apabetalone than to placebo (p=0.04). Conclusions: Amongst patients with T2DM, recent ACS, and a moderate-to-high likelihood of advanced liver fibrosis, apabetalone was associated with a significantly lower rate of ischemic MACE and HHF and attenuated the increase in hepatic FS over time.