Brain Shuttle Neprilysin reduces central Amyloid-ß levels.

Reducing Amyloid ß (Aß) in the brain is of fundamental importance for advancing the therapeutics for Alzheimer`s disease. The endogenous metallopeptidase neprilysin (NEP) has been identified as one of the key Aß-degrading enzymes. Delivery of NEP to the brain by utilizing the Brain Shuttle (BS) transport system offers a promising approach for clearing central Aß. We fused the extracellular catalytic domain of NEP to an active or inactive BS module. The two BS-NEP constructs were used to investigate the pharmacokinetic/pharmacodynamics relationships in the blood and the cerebrospinal fluid (CSF) in dose-response and multiple dosing. As previously shown, NEP was highly effective at degrading Aß in blood but not in the CSF compartment after systemic administration. In contrast, the NEP with an active BS module led to a significant CSF exposure of BS-NEP, followed by substantial Aß reduction in CSF and brain parenchyma. Our data show that a BS module against the transferrin receptor facilitates the transport of an Aß degrading enzyme across the blood-brain barriers to efficiently reduce Aß levels in both CSF and brain.

Radiometal-Dependent Biological Profile of the Radiolabeled Gastrin-Releasing Peptide Receptor Antagonist SB3 in Cancer Theranostics: Metabolic and Biodistribution Patterns Defined by Neprilysin.

Recent advances in oncology involve the use of diagnostic/therapeutic radionuclide-carrier pairs that target cancer cells, offering exciting opportunities for personalized patient treatment. Theranostic gastrin-releasing peptide receptor (GRPR)-directed radiopeptides have been proposed for the management of GRPR-expressing prostate and breast cancers. We have recently introduced the PET tracer 68Ga-SB3 (SB3, DOTA- p-aminomethylaniline-diglycolic acid-DPhe-Gln-Trp-Ala-Val-Gly-His-Leu-NHEt), a receptor-radioantagonist that enables the visualization of GRPR-positive lesions in humans. Aiming to fully assess the theranostic potential of SB3, we herein report on the impact of switching 68Ga to 111In/177Lu-label on the biological properties of resulting radiopeptides. Notably, the bioavailability of 111In/177Lu-SB3 in mice drastically deteriorated compared with metabolically robust 68Ga-SB3, and as a result led to poorer 111In/177Lu-SB3 uptake in GRPR-positive PC-3 xenografts. The peptide cleavage sites were identified by chromatographic comparison of blood samples from mice intravenously receiving 111In/177Lu-SB3 with each of newly synthesized 111In/177Lu-SB3-fragments. Coinjection of the radioconjugates with the neprilysin (NEP)-inhibitor phosphoramidon led to full stabilization of 111In/177Lu-SB3 in peripheral mouse blood and resulted in markedly enhanced radiolabel uptake in the PC-3 tumors. In conclusion, in situ NEP-inhibition led to indistinguishable 68Ga/111In/177Lu-SB3 profiles in mice emphasizing the theranostic prospects of SB3 for clinical use.

Pharmacokinetics After Single Ascending Dose, Food Effect, and Safety of Sacubitril/Valsartan (LCZ696), an Angiotensin Receptor and Neprilysin Inhibitor, in Healthy Japanese Subjects.

BACKGROUND AND OBJECTIVES: LCZ696 (sacubitril/valsartan) is a novel angiotensin receptor neprilysin inhibitor (ARNI) that has been developed for treatment of heart failure patients with reduced ejection fraction and approved in the US, Europe, and many other countries. METHODS: This randomized, placebo-controlled study was conducted in healthy Japanese male subjects (N = 50) to assess the pharmacokinetics and safety of single ascending oral doses (20-600 mg) of LCZ696. Food effect was also evaluated following administration of 200 mg dose. Plasma and urine samples from 40 subjects receiving LCZ696 were collected to assess pharmacokinetics of LCZ696 analytes (sacubitril, sacubitrilat, and valsartan). RESULTS: Following single oral dose administration of LCZ696, sacubitril and valsartan rapidly appeared in systemic circulation with a dose-linear increase in the exposure to the LCZ696 analytes. Of the administered dose, approximately 0.85 %, 54.0 %, and 8.19 % of sacubitril, sacubitrilat, and valsartan, respectively, were recovered in urine. Food reduced AUC of sacubitril, sacubitrilat, and valsartan by 21, 8, and 40 %, respectively, and C max by 72, 27, and 51 %, respectively. CONCLUSION: Single oral doses of up to 600 mg of LCZ696 were safe and generally well tolerated in healthy Japanese male subjects.

Convection-enhanced delivery of neprilysin: a novel amyloid-ß-degrading therapeutic strategy.

Enzymatic degradation contributes to the control of intracerebral amyloid-ß (Aß) peptide levels. Previous studies have demonstrated the therapeutic potential of viral vector-mediated neprilysin (NEP) gene therapy in mouse models of Alzheimer's disease (AD). However, clinical translation of NEP gene therapy is limited by ethical and practical considerations. In this study we have assessed the potential of convection-enhanced delivery (CED) as a means of elevating intracerebral NEP level and activity and degrading endogenous Aß. We analyzed the interstitial and perivascular distribution of NEP following CED into rat striatum. We measured NEP protein level, clearance, activity, and toxicity by ELISA for NEP and synaptophysin, NEP-specific activity assay, and immunohistochemistry for NEP, NeuN, glial fibrillary acidic protein and Iba1. We subsequently performed CED of NEP in normal aged rats and measured endogenous Aß by ELISA. CED resulted in widespread distribution of NEP, and a 20-fold elevation of NEP protein level with preservation of enzyme activity and without evidence of toxicity. CED in normal, aged rats resulted in a significant reduction in endogenous Aß(40) (p = 0.04), despite rapid NEP clearance from the brain (half-life ~3 h). CED of NEP has therapeutic potential as a dynamically controllable Aß(40)-degrading therapeutic strategy for AD. Further studies are required to determine the longer term effects on Aß (including Aß(42)) and on cognitive function.

[Dual inhibition of converting enzyme and neutral endopeptidase: a research new way in the field of hypertension]. / Inhibition conjointe de l'enzyme de conversion et de l'endopeptidase neutre: une nouvelle voie de recherche dans le domaine de l'hypertension.

Two metallopeptidases, angiotensin converting enzyme (ACE) and neutral endopeptidase (NEP) are involved respectively in the release of angiotensin II which is a vasoconstrictor, and in the metabolism of atrial natriuretic peptide which is diuretic and bradykinin which is a vasodilatator. The dual inhibition of these two peptidases represents a new way to regulate the blood pressure in various cardiovascular diseases. Taking into account the mechanism of action of metallopeptidases and the substrate specificity of ACE and NEP, dual inhibitors corresponding to the general formula HS-CH2-CH(R1)CONH-CH(R2)COOH and HS-CH(R1)CONH-CH(R2)CONH-CH(R3)COOH and having inhibitory potencies on each enzyme in the nanomolar range were designed. The most efficient inhibitors have been transformed into lipophilic prodrugs which were found to be active after oral administration. These compounds have been tested on an experimental model of hypertension in rats and, as expected, have been shown to be both diuretic (NEP inhibition) and hypotensive (ACE inhibition).