LEGACY: Phase 2a Trial to Evaluate the Safety, Pharmacokinetics, and Pharmacodynamic Effects of the Anti-EL (Endothelial Lipase) Antibody MEDI5884 in Patients With Stable Coronary Artery Disease.

OBJECTIVE: Functional HDL (high-density lipoprotein) particles that facilitate cholesterol efflux may be cardioprotective. EL (endothelial lipase) hydrolyzes phospholipids promoting catabolism of HDL and subsequent renal excretion. MEDI5884 is a selective, humanized, monoclonal, EL-neutralizing antibody. We sought to determine the safety, pharmacokinetics, and pharmacodynamic effects of multiple doses of MEDI5884 in patients with stable coronary artery disease. Approach and Results: LEGACY was a phase 2a, double-blind, placebo-controlled, parallel-design trial that randomized 132 patients with stable coronary artery disease receiving high-intensity statin therapy to 3 monthly doses of 1 of 5 dose levels of MEDI5884 (50, 100, 200, 350, or 500 mg SC) or matching placebo. The primary end point was the safety and tolerability of MEDI5884 through the end of the study (day 151). Additional end points included change in HDL cholesterol and cholesterol efflux from baseline to day 91, hepatic uptake of cholesterol at day 91, changes in various other lipid parameters. The incidence of adverse events was similar between the placebo and MEDI5884 groups. In a dose-dependent manner, MEDI5884 increased HDL cholesterol up to 51.4% (P<0.0001) and global cholesterol efflux up to 26.2% ([95% CI, 14.3-38.0] P<0.0001). MEDI5884 increased HDL particle number up to 14.4%. At the highest dose tested, an increase in LDL (low-density lipoprotein) cholesterol up to 28.7% (P<0.0001) and apoB (apolipoprotein B) up to 13.1% (P=0.04) was observed with MEDI5884. However, at the potential target doses for future studies, there was no meaningful increase in LDL cholesterol or apoB. CONCLUSIONS: Inhibition of EL by MEDI5884 increases the quantity and quality of functional HDL in patients with stable coronary artery disease on high-intensity statin therapy without an adverse safety signal at the likely dose to be used. These data support further clinical investigation. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03351738.

Blocking endothelial lipase with monoclonal antibody MEDI5884 durably increases high density lipoprotein in nonhuman primates and in a phase 1 trial.

Cardiovascular disease (CVD) is the leading global cause of death, and treatments that further reduce CV risk remain an unmet medical need. Epidemiological studies have consistently identified low high-density lipoprotein cholesterol (HDL-C) as an independent risk factor for CVD, making HDL elevation a potential clinical target for improved CVD resolution. Endothelial lipase (EL) is a circulating enzyme that regulates HDL turnover by hydrolyzing HDL phospholipids and driving HDL particle clearance. Using MEDI5884, a first-in-class, EL-neutralizing, monoclonal antibody, we tested the hypothesis that pharmacological inhibition of EL would increase HDL-C by enhancing HDL stability. In nonhuman primates, MEDI5884 treatment resulted in lasting, dose-dependent elevations in HDL-C and circulating phospholipids, confirming the mechanism of EL action. We then showed that a favorable lipoprotein profile of elevated HDL-C and reduced low-density lipoprotein cholesterol (LDL-C) could be achieved by combining MEDI5884 with a PCSK9 inhibitor. Last, when tested in healthy human volunteers, MEDI5884 not only raised HDL-C but also increased HDL particle numbers and average HDL size while enhancing HDL functionality, reinforcing EL neutralization as a viable clinical approach aimed at reducing CV risk.

Mode of action framework analysis for receptor-mediated toxicity: The peroxisome proliferator-activated receptor alpha (PPARα) as a case study.

Several therapeutic agents and industrial chemicals induce liver tumors in rodents through the activation of the peroxisome proliferator-activated receptor alpha (PPARα). The cellular and molecular events by which PPARα activators induce rodent hepatocarcinogenesis has been extensively studied and elucidated. This review summarizes the weight of evidence relevant to the hypothesized mode of action (MOA) for PPARα activator-induced rodent hepatocarcinogenesis and identifies gaps in our knowledge of this MOA. Chemical-specific and mechanistic data support concordance of temporal and dose-response relationships for the key events associated with many PPARα activators including a phthalate ester plasticizer di(2-ethylhexyl) phthalate (DEHP) and the drug gemfibrozil. While biologically plausible in humans, the hypothesized key events in the rodent MOA, for PPARα activators, are unlikely to induce liver tumors in humans because of toxicodynamic and biological differences in responses. This conclusion is based on minimal or no effects observed on growth pathways, hepatocellular proliferation and liver tumors in humans and/or species (including hamsters, guinea pigs and cynomolgous monkeys) that are more appropriate human surrogates than mice and rats at overlapping dose levels. Overall, the panel concluded that significant quantitative differences in PPARα activator-induced effects related to liver cancer formation exist between rodents and humans. On the basis of these quantitative differences, most of the workgroup felt that the rodent MOA is "not relevant to humans" with the remaining members concluding that the MOA is "unlikely to be relevant to humans". The two groups differed in their level of confidence based on perceived limitations of the quantitative and mechanistic knowledge of the species differences, which for some panel members strongly supports but cannot preclude the absence of effects under unlikely exposure scenarios.

Camptothecin induces the ubiquitin-like protein, ISG15, and enhances ISG15 conjugation in response to interferon.

Interferon (IFN)-stimulated gene (15 kDa) (ISG15) is a ubiquitin-like protein that forms covalent conjugates with cellular proteins. ISG15 is induced by IFN, microbial challenge, and p53, suggesting that it represents a genetic response that is shared among diverse stress stimuli. To investigate the regulation of this posttranslational modification pathway by a genotoxic chemotherapeutic agent, we examined ISG15 induction and conjugation in cells treated with the topoisomerase I (topoI) poison, camptothecin (CPT). CPT induced ISG15mRNA, and induction required protein synthesis and a functional p53 protein. However, IFN and the Jak-Stat components of the IFN signaling pathway were dispensable for CPT induction of ISG15. CPT induced free ISG15 and conjugates in a dose-dependent and time-dependent manner. A single 55-kDa protein was the prominent CPT-induced ISG15 conjugate and localized to the nuclear compartment. CPT-induced ISG15 conjugates were distinct from those induced by IFN; however, CPT treatment dramatically enhanced ISG15 conjugation in response to IFN. These findings provide the first evidence of a stimulus-specific induction of discrete ISG15 conjugate species and demonstrate that treatment with a combination of cancer therapeutic agents can cooperate to enhance ISG15 conjugation. Identification of the specific ISG15 conjugates induced by chemotherapeutic agents may reveal novel molecular targets.

Expression of Smad4 in the FaDu cell line partially restores TGF-beta growth inhibition but is not sufficient to regulate fibronectin expression or suppress tumorigenicity.

Mutations of the Smad4 gene, a member of a group of TGF-beta signal transduction components, occur in several types of cancer suggesting that its inactivation significantly affects TGF-beta responsiveness in these tumors. To further investigate the role of Smad4 with respect to TGF-beta signaling and carcinogenesis, we re-expressed the Smad4 gene in the Smad4-deficient cancer cell line FaDu by microcell-mediated chromosome transfer (MMCT) and retroviral infection to closely approximate physiological protein levels. The Smad4-expressing FaDu clones were then evaluated for TGF-beta responsiveness to assess the role of Smad4 in TGF-beta-induced growth inhibition and target gene regulation. We found that the re-expression of the Smad4 gene by either method partially restored TGF-beta responsiveness in FaDu cells with respect to both growth inhibition and expression of p21WAF1/CIP1 and p15INK4B. However, only the microcell hybrids showed growth retardation in organotypic raft culture and an enhanced ability to upregulate fibronectin. In contrast, the re-expression of Smad4 by either method failed to suppress tumorigenicity. These results suggest that in addition to a homozygous deletion of Smad4, FaDu cells contain additional defects within the TGF-beta signaling pathway, thereby limiting the extent of TGF-beta responsiveness upon Smad4 re-expression and perhaps accounting for the inability to induce p15INK4B to a high level. They also demonstrate the advantages of providing a physiological extracellular environment, when assessing TGFbeta responsiveness.