Biological basis and proposed mechanism of action of CSL112 (Apolipoprotein A-I [Human]) for prevention of major adverse cardiovascular events in patients with myocardial infarction

Despite current standard of care treatment, the period shortly after acute myocardial infarction (AMI) is associated with high residual CV risk, with high rates of recurrent AMI and CV death in the first 90 days following the index event. This represents an area of high unmet need which may be potentially addressed by novel therapeutic agents that optimize high-density lipoprotein cholesterol (HDL-C) function rather than increase HDL-C concentrations. Apolipoprotein A-I (apoA-I) is the major constituent of HDL and a key mediator of cholesterol efflux from macrophages within atherosclerotic plaque, a property especially relevant during the high risk period immediately following an AMI when cholesterol efflux capacity is found to be reduced. CSL112 is a novel formulation of human plasma-derived apolipoprotein A-I (apoA-I), currently being evaluated in a phase 3 clinical trial (AEGIS-II) for the reduction of major adverse CV events (MACE) in the 90 day high risk period post AMI. In this review, we provide an overview of the biological properties of CSL112 that contribute to its proposed mechanism of action for potential therapeutic benefit. These properties include rapid and robust promotion of cholesterol efflux from cells abundant in atherosclerotic plaque, in addition to anti-inflammatory effects, which together, may have a stabilizing effect on atherosclerotic plaque. We provide a detailed overview of these mechanisms, in addition to information on the composition of CSL112 and how it is manufactured.

CSL112 (Apolipoprotein A-I [Human]) Strongly Enhances Plasma Apoa-I and Cholesterol Efflux Capacity in Post-Acute Myocardial Infarction Patients: A PK/PD Substudy of the AEGIS-I Trial

Introduction:

Cholesterol efflux capacity (CEC) is impaired following acute myocardial infarction (AMI). CSL112 is an intravenous preparation of human plasma-derived apoA-I formulated with phosphatidylcholine (PC). CSL112 is intended to improve CEC and thereby prevent early recurrent cardiovascular events following AMI. AEGIS-I (ApoA-I Event Reducing in Ischemic Syndromes I) was a multicenter, randomized, double-blind, placebo-controlled, dose-ranging phase 2b study, designed to evaluate the hepatic and renal safety of CSL112. Here, we report an analysis of a pharmacokinetic (PK) and pharmacodynamic (PD) substudy of AEGIS-I.

Methods:

AMI patients were stratified by renal function and randomized 3:3:2 to 4, weekly, 2-hour infusions of low- and high-dose (2 g and 6 g) CSL112, or placebo. PK/PD assessments included plasma concentrations of apoA-I and PC, and measures of total and ABCA1-dependent CEC, as well as lipids/lipoproteins including high density lipoprotein cholesterol (HDL-C), non-HDL-C, low density lipoprotein cholesterol (LDL-C), ApoB, and triglycerides. Inflammatory and cardio-metabolic biomarkers were also evaluated.

Results:

The substudy included 63 subjects from AEGIS-I. CSL112 infusions resulted in rapid, dose-dependent increases in baseline corrected apoA-I and PC, which peaked at the end of the infusion (Tmax ≈ 2 hours). Similarly, there was a dose-dependent elevation in both total CEC and ABCA1-mediated CEC. Mild renal impairment did not affect the PK or PD of CSL112. CSL112 administration was also associated with an increase in plasma levels of HDL-C but not non-HDL-C, LDL-C, apoB, or triglycerides. No dose-effects on inflammatory or cardio-metabolic biomarkers were observed.

Conclusion:

Among patients with AMI, impaired CEC was rapidly elevated by CSL112 infusions in a dose-dependent fashion, along with an increase in apoA-I plasma concentrations. Findings from the current sub-study of the AEGIS-I support a potential atheroprotective benefit of CSL112 for AMI patients.

Cholesterol Efflux Capacity and Its Association With Adverse Cardiovascular Events: A Systematic Review and Meta-Analysis

Background: Serum high-density lipoprotein cholesterol (HDL-C) levels are inversely associated with cardiovascular disease events. Yet, emerging evidence suggests that it is the functional properties of HDL, in particular, reverse cholesterol transport, which is a key protective mechanism mediating cholesterol removal from macrophage cells and reducing plaque lipid content. Cholesterol efflux capacity (CEC) measures the capacity of HDL to perform this function. A systematic review and meta-analysis were conducted to explore the association of CEC and adverse cardiovascular events.

Methods: A comprehensive literature review of Embase, PubMed, and Web of Science Core Collection from inception to September 2019 was performed for all studies that examined the association between CEC and cardiovascular outcomes. The primary outcome was adverse cardiovascular events, which were inclusive of atherosclerotic cardiovascular disease (ASCVD) or mortality.

Results: A total of 20 trials were included. Compared with low CEC levels, high CEC levels were associated with a 37% lower risk of adverse cardiovascular events (crude RR = 0.63; 95% CI, 0.52–0.76; P < 0.00001). Every SD increase of CEC was associated with a 20% lower risk of adverse cardiovascular events (HR = 0.80; 95% CI, 0.66–0.97; P = 0.02). The association remained significant after adjusting for cardiovascular risk factors, medications, and HDL-C levels (HR = 0.76; 95% CI, 0.63–0.91; P = 0.004). A significant CEC-endpoint relationship was observed (P = 0.024) such that for every 0.1 unit increase in CEC, there was a 5% reduced risk for adverse cardiovascular events (RR = 0.95; 95% CI, 0.91–0.99).

Conclusions: Higher CEC is associated with lower adverse cardiovascular outcomes. These findings warrant further research on whether CEC is merely a biomarker or a mechanism that could be targeted as a pharmacologic intervention for improving clinical outcomes.

PROSPERO Registration Number: CRD42020146681; https://www.crd.york.ac.uk/prospero/.

Effect of azithromycin and hydroxychloroquine in patients hospitalized with COVID-19: Network meta-analysis of randomized controlled trials

Chloroquine or its derivative hydroxychloroquine (HCQ) combined with or without azithromycin (AZ) have been widely investigated in observational studies as a treatment option for coronavirus 2019 (COVID‐19) infection. The network meta‐analysis aims to summarize evidence from randomized controlled trials (RCTs) to determine if AZ or HCQ is associated with improved clinical outcomes. PubMed and Embase were searched from inception to March 7, 2021. We included published RCTs that investigated the efficacy of AZ, HCQ, or its combination among hospitalized patients with COVID‐19 infection. The outcomes of interest were all‐cause mortality and the use of mechanical ventilation. The pooled odds ratio was calculated using a random‐effect model. A total of 10 RCTs were analyzed. Participant's mean age ranged from 40.4 to 66.5 years. There was no significant effect on mortality associated with AZ plus HCQ (odds ratio [OR] = 0.562 [95% confidence interval {CI}: 0.168–1.887]), AZ alone (OR = 0.965 [95% CI: 0.865–1.077]), or HCQ alone (OR = 1.122 [95% CI: 0.995–1.266]; p = 0.06). Similarly, based on pooled effect sizes derived from direct and indirect evidence, none of the treatments had a significant benefit in decreasing the use of mechanical ventilation. No heterogeneity was identified (Cochran's Q = 1.68; p = 0.95; τ² = 0; I² = 0% [95% CI: 0%–0%]). Evidence from RCTs suggests that AZ with or without HCQ was not associated with a significant effect on the mortality or mechanical ventilation rates in hospitalized patients with COVID‐19. More research is needed to explore therapeutics agents that can effectively reduce the mortality or severity of COVID‐19.

Association of Anemia with Venous Thromboembolism in Acutely Ill Hospitalized Patients: An APEX Trial Substudy

BACKGROUND

Anemia is a common finding and independent predictor for adverse outcomes in hospitalized patients with medical illness. It remains unclear whether anemia is a risk factor for venous thromboembolism and whether the presence of anemia can refine risk assessment for prediction of venous thromboembolism, thereby adding incremental utility to a validated model.

METHODS

In the Acute Medically Ill Venous Thromboembolism Prevention with Extended Duration Betrixaban trial (APEX), 7513 hospitalized medical patients were randomized to receive either betrixaban or standard-of-care enoxaparin for thromboprophylaxis. Baseline hemoglobin concentrations were obtained in 6861 patients, with a follow-up of 77 days. Symptomatic venous thromboembolism events, including symptomatic deep vein thrombosis, pulmonary embolism, and venous thromboembolism-related mortality, were compared between low-hemoglobin and normal-hemoglobin groups (normal range: 12.5-17.0 g/dL for males and 11.0-15.5 g/dL for females). The relationship between anemia and venous thromboembolism events was assessed by fitting a univariable and multivariable logistic regression model composed of thromboprophylaxis and risk factors. Venous thromboembolism risk refinement by hemoglobin measurement was evaluated in the International Medical Prevention Registry on Venous Thromboembolism (IMPROVE) risk assessment model.

RESULTS

Low hemoglobin at baseline was associated with a greater risk of symptomatic venous thromboembolism (relative risk [RR] 1.94 [95% confidence interval, 1.27-2.98]; P = .002), symptomatic deep vein thrombosis (RR 2.29 [1.12-4.68]; P = .019), and nonfatal pulmonary embolism (RR 2.63 [1.22-5.65]; P = .010) but not venous thromboembolism-related mortality (RR 1.47 [0.71-3.04]; P = .30). After adjusting for thromboprophylaxis, history of previous venous thromboembolism, intensive or coronary unit admission, and D-dimer, low hemoglobin (as a categorical or continuous variable) remained associated with an increased likelihood of venous thromboembolism (adjusted odds ratio 1.71 [95% confidence interval, 1.09-2.69]; P = .020). Low hemoglobin also improved risk discrimination and reclassification after inclusion in the IMPROVE model.

CONCLUSIONS

Anemia was independently associated with a greater risk of symptomatic venous thromboembolism among acutely ill medical patients despite the provision of thromboprophylaxis. Hemoglobin measurement also improved risk stratification by the IMPROVE venous thromboembolism risk score.