Inactivation of ANGPTL3 reduces hepatic VLDL-triglyceride secretion.

Humans and mice lacking angiopoietin-like protein 3 (ANGPTL3) have pan-hypolipidemia. ANGPTL3 inhibits two intravascular lipases, LPL and endothelial lipase, and the low plasma TG and HDL-cholesterol levels in ANGPTL3 deficiency reflect increased activity of these enzymes. The mechanism responsible for the low LDL-cholesterol levels associated with ANGPTL3 deficiency is not known. Here we used an anti-ANGPTL3 monoclonal antibody (REGN1500) to inactivate ANGPTL3 in mice with genetic deficiencies in key proteins involved in clearance of ApoB-containing lipoproteins. REGN1500 treatment consistently reduced plasma cholesterol levels in mice in which Apoe, Ldlr, Lrp1, and Sdc1 were inactivated singly or in combination, but did not alter clearance of rabbit (125)I-βVLDL or mouse (125)I-LDL. Despite a 61% reduction in VLDL-TG production, VLDL-ApoB-100 production was unchanged in REGN1500-treated animals. Hepatic TG content, fatty acid synthesis, and fatty acid oxidation were similar in REGN1500 and control antibody-treated animals. Taken together, our findings indicate that inactivation of ANGPTL3 does not affect the number of ApoB-containing lipoproteins secreted by the liver but alters the particles that are made such that they are cleared more rapidly from the circulation via a noncanonical pathway(s). The increased clearance of lipolytic remnants results in decreased production of LDL in ANGPTL3-deficient animals.
Copyright © 2015 by the American Society for Biochemistry and Molecular Biology, Inc.

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Budget Impact of Enzalutamide for Chemotherapy-Naïve Metastatic Castration-Resistant Prostate Cancer.

Prostate cancer is expected to account for approximately one quarter of all new diagnoses of cancer in American men in 2015. The cost of prostate cancer care is expected to reach $15.1 billion by the year 2020, up from $11.9 billion in 2010. Given the high burden of prostate cancer, health care payers are interested in quantifying the potential budget impact of new therapies.
To estimate the budget impact of enzalutamide for the treatment of chemotherapy-naïve metastatic castration-resistant prostate cancer (mCRPC) from a U.S. payer perspective.
A model was developed to assess the budget impact of enzalutamide for treatment of chemotherapy-naïve mCRPC patients in a hypothetical 1-million-member U.S. health plan over a 1-year time horizon. Comparators included abiraterone acetate, sipuleucel-T, radium Ra 223 dichloride, and docetaxel. Epidemiologic data, including National Cancer Institute Surveillance, Epidemiology, and End Results (SEER) incidence rates, were used to estimate the number of chemotherapy-naïve mCRPC patients. Dosing, administration, duration of therapy, and adverse event rates were based on package inserts and pivotal studies. Drug costs were obtained from RED BOOK and Centers for Medicare & Medicaid Services (CMS) average sales price pricing files, costs of administration and monitoring from the CMS physician fee schedule, and adverse events from the Agency for Healthcare Research and Quality Healthcare Cost and Utilization Project and published literature. Market shares were estimated for each comparator before and after adoption of enzalutamide. The incremental aggregate budget impact, per patient per year (PPPY), per patient per month (PPPM), and per member per month (PMPM), was calculated. One-way sensitivity analyses were performed.
In a population of 115 chemotherapy-naïve mCRPC patients, adopting enzalutamide had an annual incremental budget impact of $510,641 ($4,426 PPPY, $369 PPPM, and $0.04 PMPM). Results were most sensitive to enzalutamide drug cost, size of the chemotherapy-naïve mCRPC patient population, and enzalutamide adoption rate.
Results indicate a modest 1-year budget impact of adopting enzalutamide for chemotherapy-naïve mCRPC patients, partly because of the cost offset of a moderate incidence of adverse events and lack of additional required monitoring.
The study and its report were funded by Astellas Pharma Global Development and Medivation, which had a role in study design, data acquisition and interpretation, and manuscript development. Xcenda is a consulting company that received fees from Astellas Pharma Global Development and Medivation to support this research, including model and manuscript development. Bui, Flanders, Posta, and Tang are current employees of Astellas. Francis and Balk are current employees and stockholders of Medivation. Oestreicher is a former employee of Medivation. O’Day and Popelar are current employees of Xcenda. All authors contributed to the study concept and design, analysis and interpretation of data, and drafting and critical revision of the manuscript for important intellectual content. Bui and O’Day were responsible for acquisition of data. Bui obtained funding, and administrative, technical, or logistic support was provided by Bui and Popelar.

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Negative influence of programmed death-1-ligands on the survival of esophageal cancer patients treated with chemotherapy.

The programmed death-1/programmed death-1ligands (PD-1/PD-Ls) pathway plays an important role in immunological tumor evasion. However, clinical significance of the PD-Ls (L1 and L2) expression in esophageal cancer treated with chemotherapy has not been fully investigated. We examined the expression of PD-Ls of the primary tumors obtained from 180 esophageal cancer patients who underwent radical resection with or without neoadjuvant chemotherapy (NAC) using immunohistochemical staining. The relationship between the expression patterns and clinico-pathological characteristics were examined. The 53 patients (29.4%) and 88 patients (48.3%) were classified into positive for PD-L1 and PD-L2 expression, respectively. In all the patients examined in this study, overall survival rates of the patients with tumors positive for PD-L1 or PD-L2 were significantly worse than those with tumors negative for PD-L1 or PD-L2 (p=0.0010 and p=0.0237, respectively). However, subgroup analysis showed that these tendencies are only found in the patients treated with NAC, but not in the ones without NAC. The patients with positive PD-L1 expression had significantly higher rate of NAC history (p=0.0139), but those with positive PD-L2 expression did not (p=0.6127). There is no significant relationship between PD-L1 expression and response to chemotherapy (p=0.3118), but the patient with positive PD-L2 expression had significantly inferior responses to chemotherapy (p=0.0034). The PD-1/PD-Ls pathway might be an immunological mechanism associated with the long-term effectiveness of the chemotherapy in esophageal cancer patients. Further investigations on the roles of PD-1 pathway in chemotherapy would lead to the development of better treatments for this disease. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.

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Anti-CD25 monoclonal antibody Fc variants differentially impact Treg cells and immune homeostasis(1).

IL-2 is a critical regulator of immune homeostasis through its non-redundant role in regulatory T (Treg) cell biology. There is a major interest in therapeutic modulation of the IL-2 pathway to promote immune activation in the context of tumor immunotherapy or enhance immune suppression in the context of transplantation, autoimmunity and inflammatory diseases. Antibody mediated targeting of the high-affinity IL-2 receptor α chain (IL-2Rα or CD25) offers a direct mechanism to target IL-2 biology and is being actively explored in the clinic. In mouse models, the rat anti-mouse CD25 clone PC61 has been used extensively to investigate the biology of IL-2 and Treg cells; however, there has been controversy and conflicting data on the exact in vivo mechanistic function of PC61. Engineering antibodies to alter Fc/Fc receptor interactions can significantly alter their in vivo function. In this study, we re-engineered the heavy chain constant region of an anti-CD25 monoclonal antibody to generate variants with highly divergent Fc effector function. Using these anti-CD25 Fc variants in multiple mouse models, we investigated the in vivo impact of CD25 blockade versus depletion of CD25(+) Treg cells on immune homeostasis. We report that immune homeostasis can be maintained during CD25 blockade but aberrant T cell activation prevails when CD25(+) Treg cells are actively depleted. These results clarify the impact of PC61 on Treg cell biology and reveal an important distinction between CD25 blockade and depletion of CD25(+) Treg cells. These findings should inform therapeutic manipulation of the IL-2 pathway by targeting the high-affinity IL-2R. This article is protected by copyright. All rights reserved.
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Iron Overload in Hereditary Tyrosinemia Type 1 Induces Liver Injury through the Sp1/Tfr2/Hepcidin Axis.

Iron is an essential metal for fundamental metabolic processes, but little is known regarding the involvement of iron in other nutritional disorders. In the present study, we investigated disordered iron metabolism in a murine model of hereditary tyrosinemia type I (HT1), a disease of the tyrosine degradation pathway.
We analysed the status of iron accumulation following NTBC withdrawal from fah-/- mice, a murine model for HT1. Liver histology and serum parameters were used to assess the extent of liver injury and iron deposition. To determine the physiological significance of iron accumulation, mice were subjected to a low-iron food intake to reduce the iron accumulation. Mechanistic studies were performed on tissues and cells using immunoblotting, qRT-PCR, adenovirus transfection and other assays.
Severe iron overload was observed in the murine model of HT1 with dramatically elevated hepatic and serum iron levels. Mechanistic studies revealed that downregulation and dysfunction of Tfr2 decreased hepcidin, leading to iron overload. The fah-/- hepatocytes lost the ability of transferrin-sensitive induction of hepcidin. Forced expression of Tfr2 in the murine liver reduced the iron accumulation. Moreover, transcription factor Sp1 was downregulated and identified as a new regulator of Tfr2 here. Additionally, low-iron food intake effectively reduced the iron deposits, protected the liver and prolonged the survival in these mice.
Iron was severely overloaded in the HT1 mice via the Sp1/Tfr2/Hepcidin axis. The iron overload induced liver injury in the HT1 mice, and reduction of the iron accumulation ameliorated liver injury.
Primary and secondary iron overload is an abnormal status affecting millions of people worldwide. Here, we reported severe iron overload in a murine model of HT1, a disease of the tyrosine degradation pathway, and elucidated the mechanistic basis and the physiological significance of iron overload in HT1. These studies are of general interest not only with respect to secondary iron-induced liver injury in HT1 but also are important to elucidate the crosstalk between the two metabolic pathways.
Copyright © 2016. Published by Elsevier B.V.

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