Direct Renin Inhibitors as A New Therapy for Hypertension

Perspective Articel - No abstract require

Trans-(3S,4S)-Disubstituted Pyrrolidines as Inhibitors of the Human Aspartyl Protease Renin. Part I: Prime Site exploration using an amino linker

Recently, we reported on the discovery of (3S,4S)-disubstituted pyrrolidines (e.g. 2) as inhibitors of the human aspartyl protease renin. In our effort to further expand the scope of this novel class of direct renin inhibitors, a new sub-series was designed in which the prime site substituents are linked to the pyrrolidine core by a (3S)-amino functional group. In particular, analogs bearing the corresponding sulfonamide spacer (50, 51 and 54a) demonstrated a pronounced increase in in vitro potency compared to compound 2

Structure-based library design and fragment-based screening for the identification of novel Factor D inhibitors

Chronic dysregulation of alternative complement pathway activation has been associated with diverse clinical disorders including age-related macular degeneration and paroxysmal nocturnal hemoglobinurea. Factor D is a trypsin-like serine protease with a narrow specificity for arginine in the P1 position, which catalyses the first enzymatic reaction of the amplification loop of the alternative pathway. In this paper, we describe two hit finding approaches leading to the discovery of new chemical matter for this pivotal protease of the complement system: in silico active site mapping for hot spots identification to guide rational structure-based design and NMR screening of focussed and diverse fragment libraries. The wealth of information gathered by these complementary approaches enabled the identification of ligands binding to different sub-pockets of the latent Factor D conformation and was instrumental for understanding the binding requirements for the generation of the first known potent non-covalent reversible Factor D inhibitors

Discovery and design of first benzylamine-based ligands binding to an unlocked conformation of the Complement Factor D

Complement Factor D, a serine protease of the S1 family and key component of the alternative pathway amplification loop, represents a promising target for the treatment of several prevalent and rare diseases linked to the innate immune system. Previously reported FD inhibitors have been shown to bind to the FD active site in its self-inhibited conformation characterized by the presence of a salt bridge at the bottom of the S1 pocket between Asp189 and Arg218. We report herein a new set of small-molecule FD ligands that harbor a basic S1 binding moiety directly binding to the carboxylate of Asp189, thereby displacing the Asp189-Arg218 ionic interaction and significantly changing the conformation of the self-inhibitory loop

Crystal structure of human BACE2 in complex with a hydroxyethylamine transition-state inhibitor.

BACE2 is a membrane-bound aspartic protease of the A1 family with a high level of sequence homology to BACE1. While BACE1 is involved in the generation of amyloid plaques in Alzheimer's disease by cleaving Abeta-peptides from the amyloid precursor protein, the physiological function of BACE2 is not well understood. BACE2 appears to be associated with the early onset of dementia in patients with Down's syndrome, and it has been shown to be highly expressed in breast cancers. Further, it may participate in the function of normal and abnormal processes of human muscle biology. Similar to other aspartic proteases, BACE2 is expressed as an inactive zymogen requiring the cleavage of its pro-sequence during the maturation process. We have produced mature BACE2 by expression of pro-BACE2 in Escherichia coli as inclusion bodies, followed by refolding and autocatalytic activation at pH 3.4. Using a C and N-terminally truncated BACE2 variant, we were able to crystallize and determine the crystal structure of mature BACE2 in complex with a hydroxyethylamine transition-state mimetic inhibitor at 3.1 angstroms resolution. The structure of BACE2 follows the general fold of A1 aspartic proteases. However, similar to BACE1, its C-terminal domain is significantly larger than that of the other family members. Furthermore, the structure of BACE2 reveals differences in the S3, S2, S1' and S2' active site substrate pockets as compared to BACE1, and allows, therefore, for a deeper understanding of the structural features that may facilitate the design of selective BACE1 or BACE2 inhibitors

Trans-3,4-Disubstituted Pyrrolidines as Inhibitors of the Human Aspartyl Protease Renin. Part II: Ether and Carbamate Prime Site Derivatives

Inhibition of the aspartyl protease renin is considered as an efficient approach for treating hypertension. Lately, we described the discovery of a novel class of direct renin inhibitors which comprised a pyrrolidine scaffold (e.g. 2). Based on the X-ray structure of the lead compound 2 bound to renin we reckoned that optimization of binding interactions to the prime site could offer an opportunity to further expand the scope of this chemotype. Pyrrolidine-based inhibitors were synthesized in which the prime site moieties are linked to the pyrrolidine core through an oxygen atom, resulting in an ether or a carbamate linker subseries, respectively. Especially the carbamate derivatives showed a pronounced increase in in vitro potency compared to 2. Here we report the structure-activity relationship of both subclasses and demonstrate blood pressure lowering effects for an advanced prototype in a hypertensive double-transgenic rat model after oral dosing

Discovery of small-molecule reversible Factor D inhibitors targeting the alternative complement pathway

Complement is a key component of the innate immune system, recognizing pathogens and promoting their elimination through cell lysis and/or inflammatory responses1,2. Activation of complement can be initiated by three distinct routes, the classical, lectin and alternative pathways. These converge at the proteolytic cleavage of the third component of complement, C3, generating the C3a and C3b activation fragments. C3b also participates in amplification of its own production via the positive feedback loop of the alternative pathway (AP)2,3. The two proteases Factor D and Factor B are essential for this tightly regulated amplification process. Dysregulation of AP activity predisposes individuals to diverse disorders including age-related macular degeneration (AMD), paroxysmal nocturnal hemoglobinuria (PNH), atypical hemolytic uremic syndrome (aHUS) and C3 nephropathy4-7. Here, using a structure-based design approach, we describe the identification of potent and selective small-molecule reversible inhibitors of Factor D. These inhibitors efficiently blocked AP activation in human whole blood, and prevented both C3 deposition onto, and lysis of, human erythrocytes in an assay that mimics erythrocyte lytic sensitivity. These findings were confirmed with erythrocytes from PNH patients. Oral administration inhibited lipopolysaccharide (LPS)-induced AP activation both systemically and in ocular tissues in Factor D-humanized C57Bl/6 mice. These data demonstrate the feasibility of inhibiting the AP with specific small molecule antagonists and support the development of oral Factor D inhibitors that would enable the systemic treatment of many complement-mediated diseases for which there are currently either no or sub-optimal therapies

The discovery of 4-((2S,4S)-4-ethoxy-1-((5-methoxy-7-methyl-1H-indol-4-yl)methyl)piperidin-2-yl)benzoic acid (LNP023), a Factor B inhibitor, specifically designed to be applicable to treating a diverse array of complement mediated diseases

The alternative pathway (AP) of the complement system is a key contributor to the pathogenesis of several human diseases including age-related macular degeneration, paroxysmal nocturnal hemoglobinuria (PNH), atypical hemolytic uremic syndrome (aHUS) and various glomerular diseases. The serine protease Factor B (FB) is a key node in the AP and is integral to the formation of C3 and C5 convertase. Despite the prominent role of FB in the AP pathway selective, orally bioavailable inhibitors has not been reported previously. Herein we describe our efforts to identify FB inhibitors by leveraging insights from several X-ray co-crystal structures. This work culminated in the discovery of LNP023 (41), which is currently being evaluated clinically in several diverse indications

Structure-based design and pre-clinical characterization of selective and orally bioavailable Factor XIa inhibitors: Demonstrating the power of an integrated S1 protease family approach

The serine protease Factor XI (FXI) is a prominent drug target as it holds promise to deliver efficacious anti-coagulation without an enhanced risk of major bleeds. Several efforts have been described targeting the active form of the enzyme, FXIa. Herein we disclose our efforts to identify potent, selective, and orally bioavailable inhibitors of FXIa. Compound 1, identified from a diverse library of internal serine protease inhibitors, was originally designed as a complement Factor D inhibitor and exhibited sub-micromolar FXIa activity and an encouraging ADME profile while being devoid of peptidomimetic architecture. Optimization of interactions in the S1, S1β, and S1` pockets of FXIa through a combination of structure-based drug design and traditional medicinal chemistry led to the discovery of compound 23 with sub-nanomolar potency on FXIa, enhanced selectivity over other coagulation proteases, and a pre-clinical PK profile consistent with bid dosing in patients