In Vivo Half-Life Extension of BMP1/TLL Metalloproteinase Inhibitors Using Small-Molecule Human Serum Albumin Binders.

Reducing the required frequence of drug dosing can improve the adherence of patients to chronic treatments. Hence, drugs with longer in vivo half-lives are highly desirable. One of the most promising approaches to extend the in vivo half-life of drugs is conjugation to human serum albumin (HSA). In this work, we describe the use of AlbuBinder 1, a small-molecule noncovalent HSA binder, to extend the in vivo half-life and pharmacology of small-molecule BMP1/TLL inhibitors in humanized mice (HSA KI/KI). A series of conjugates of AlbuBinder 1 with BMP1/TLL inhibitors were prepared. In particular, conjugate c showed good solubility and a half-life extension of >20-fold versus the parent molecule in the HSA KI/KI mice, reaching half-lives of >48 h with maintained maximal inhibition of plasma BMP1/TLL. The same conjugate showed a half-life of only 3 h in the wild-type mice, suggesting that the half-life extension was principally due to specific interactions with HSA. It is envisioned that conjugation to AlbuBinder 1 should be applicable to a wide range of small molecule or peptide drugs with short half-lives. In this context, AlbuBinders represent a viable alternative to existing half-life extension technologies.

Discovery of renin inhibitors containing a simple aspartate binding moiety that imparts reduced P450 inhibition.

Discovery of potent renin inhibitors which contain a simplified alkylamino Asp-binding group and exhibit improved selectivity for renin over Cyp3A4 is described. Structure-function results in this series are rationalized based on analysis of selected compounds bound to renin, and the contribution of each molecular feature leading to the reduced P450 inhibition is quantified.

GSK114: A selective inhibitor for elucidating the biological role of TNNI3K.

A series of selective TNNI3K inhibitors were developed by modifying the hinge-binding heterocycle of a previously reported dual TNNI3K/B-Raf inhibitor. The resulting quinazoline-containing compounds exhibit a large preference (up to 250-fold) for binding to TNNI3K versus B-Raf, are useful probes for elucidating the biological pathways associated with TNNI3K, and are leads for discovering novel cardiac medicines. GSK114 emerged as a leading inhibitor, displaying significant bias (40-fold) for TNNI3K over B-Raf, exceptional broad spectrum kinase selectivity, and adequate oral exposure to enable its use in cellular and in vivo studies.

Identification of Diarylurea Inhibitors of the Cardiac-Specific Kinase TNNI3K by Designing Selectivity Against VEGFR2, p38α, and B-Raf.

A series of diarylurea inhibitors of the cardiac-specific kinase TNNI3K were developed to elucidate the biological function of TNNI3K and evaluate TNNI3K as a therapeutic target for the treatment of cardiovascular diseases. Utilizing a structure-based design, enhancements in kinase selectivity were engineered into the series, capitalizing on the established X-ray crystal structures of TNNI3K, VEGFR2, p38α, and B-Raf. Our efforts culminated in the discovery of an in vivo tool compound 47 (GSK329), which exhibited desirable TNNI3K potency and rat pharmacokinetic properties as well as promising kinase selectivity against VEGFR2 (40-fold), p38α (80-fold), and B-Raf (>200-fold). Compound 47 demonstrated positive cardioprotective outcomes in a mouse model of ischemia/reperfusion cardiac injury, indicating that optimized exemplars from this series, such as 47, are favorable leads for discovering novel medicines for cardiac diseases.

Improving the developability profile of pyrrolidine progesterone receptor partial agonists.

The previously reported pyrrolidine class of progesterone receptor partial agonists demonstrated excellent potency but suffered from serious liabilities including hERG blockade and high volume of distribution in the rat. The basic pyrrolidine amine was intentionally converted to a sulfonamide, carbamate, or amide to address these liabilities. The evaluation of the degree of partial agonism for these non-basic pyrrolidine derivatives and demonstration of their efficacy in an in vivo model of endometriosis is disclosed herein.

The discovery of tertiary-amine LXR agonists with potent cholesterol efflux activity in macrophages.

The liver X receptors (LXR) play a key role in cholesterol homeostasis and lipid metabolism. SAR studies around tertiary-amine lead molecule 2, an LXR full agonist, revealed that steric and conformational changes to the acetic acid and propanolamine groups produce dramatic effects on agonist efficacy and potency. The new analogs possess good functional activity, demonstrating the ability to upregulate LXR target genes, as well as promote cholesterol efflux in macrophages.

4,6-Diaminopyrimidines as Highly Preferred Troponin I-Interacting Kinase (TNNI3K) Inhibitors.

Structure-guided progression of a purine-derived series of TNNI3K inhibitors directed design efforts that produced a novel series of 4,6-diaminopyrimidine inhibitors, an emerging kinase binding motif. Herein, we report a detailed understanding of the intrinsic conformational preferences of the scaffold, which impart high specificity for TNNI3K. Further manipulation of the template based on the conformational analysis and additional structure-activity relationship studies provided enhancements in kinase selectivity and pharmacokinetics that furnished an advanced series of potent inhibitors. The optimized compounds (e.g., GSK854) are suitable leads for identifying new cardiac medicines and have been employed as in vivo tools in investigational studies aimed at defining the role of TNNI3K within heart failure.

Reverse Hydroxamate Inhibitors of Bone Morphogenetic Protein 1.

Bone Morphogenetic Protein 1 (BMP1) inhibition is a potential method for treating fibrosis because BMP1, a member of the zinc metalloprotease family, is required to convert pro-collagen to collagen. A novel class of reverse hydroxamate BMP1 inhibitors was discovered, and cocrystal structures with BMP1 were obtained. The observed binding mode is unique in that the small molecule occupies the nonprime side of the metalloprotease pocket providing an opportunity to build in metalloprotease selectivity. Structure-guided modification of the initial hit led to the identification of an oral in vivo tool compound with selectivity over other metalloproteases. Due to irreversible inhibition of cytochrome P450 3A4 for this chemical class, the risk of potential drug-drug interactions was managed by optimizing the series for subcutaneous injection.

Substituent Effects on Drug-Receptor H-bond Interactions: Correlations Useful for the Design of Kinase Inhibitors.

Investigation of troponin I-interacting kinase (TNNI3K) as a potential target for the treatment of heart failure has produced a series of substituted N-methyl-3-(pyrimidin-4-ylamino)benzenesulfonamide inhibitors that display excellent potency and selectivity against a broad spectrum of protein kinases. Crystal structures of prototypical members bound to the ATP-binding site of TNNI3K reveal two anchoring hydrogen bond contacts: (1) from the hinge region amide N-H to the pyrimidine nitrogen and (2) from the sulfonamide N-H to the gatekeeper threonine. Evaluation of various para-substituted benzenesulfonamides defined a substituent effect on binding affinity resulting from modulation of the sulfonamide H-bond donor strength. An opposite electronic effect emerged for the hinge NH-pyrimidine H-bond interaction, which is further illuminated in the correlation of calculated H-bond acceptor strength and TNNI3K affinity for a variety of hinge binding heterocycles. These fundamental correlations on drug-receptor H-bond interactions may be generally useful tools for the optimization of potency and selectivity in the design of kinase inhibitors.

4-Aryl-1,2,3-triazole: a novel template for a reversible methionine aminopeptidase 2 inhibitor, optimized to inhibit angiogenesis in vivo.

Inhibitors of human methionine aminopeptidase type 2 (hMetAP2) are of interest as potential treatments for cancer. A new class of small molecule reversible inhibitors of hMetAP2 was discovered and optimized, the 4-aryl-1,2,3-triazoles. Compound 24, a potent inhibitor of cobalt-activated hMetAP2, also inhibits human and mouse endothelial cell growth. Using a mouse matrigel model, this reversible hMetAP2 inhibitor was also shown to inhibit angiogenesis in vivo.

Identification of Purines and 7-Deazapurines as Potent and Selective Type I Inhibitors of Troponin I-Interacting Kinase (TNNI3K).

A series of cardiac troponin I-interacting kinase (TNNI3K) inhibitors arising from 3-((9H-purin-6-yl)amino)-N-methyl-benzenesulfonamide (1) is disclosed along with fundamental structure-function relationships that delineate the role of each element of 1 for TNNI3K recognition. An X-ray structure of 1 bound to TNNI3K confirmed its Type I binding mode and is used to rationalize the structure-activity relationship and employed to design potent, selective, and orally bioavailable TNNI3K inhibitors. Identification of the 7-deazapurine heterocycle as a superior template (vs purine) and its elaboration by introduction of C4-benzenesulfonamide and C7- and C8-7-deazapurine substituents produced compounds with substantial improvements in potency (>1000-fold), general kinase selectivity (10-fold improvement), and pharmacokinetic properties (>10-fold increase in poDNAUC). Optimal members of the series have properties suitable for use in in vitro and in vivo experiments aimed at elucidating the role of TNNI3K in cardiac biology and serve as leads for developing novel heart failure medicines.

A Versatile Enantioselective Strategy Toward L-C-Nucleosides: A Total Synthesis of L-Showdomycin.

Strategies for the synthesis of nucleosides that can provide either L or D isomers become more important as a result of the increasing number of such compounds that are therapeutically useful. The lower toxicity and reduced susceptibility toward metabolism of the L isomers make them particularly interesting. A strategy toward the C-nucleoside analogues has been explored in the context of the synthesis of L-showdomycin. The route involves an asymmetric desymmetrization using palladium catalysis of cis-2,5-diacyloxy-2,5-dihydrofurans available in one step from furan, with carbon nucleophiles. Nucleophilic synthons for a maleimide unit and a methoxycarbonyl unit have been designed. Two sequential palladium-catalyzed reactions introduce both substituents with excellent chemo-, regio-, diastereo-, and enantioselectivity. The presence of a double bond in this doubly alkylated compound at C-3 and C-4 allows easy structural variation. The use of an ester as a hydroxymethyl precursor also introduces a diversity element as well as having importance in its own right. The successful completion of a synthesis of L-showdomycin validates this approach as a viable strategy to C-nucleosides.

Inhibition of the cardiomyocyte-specific kinase TNNI3K limits oxidative stress, injury, and adverse remodeling in the ischemic heart.

Percutaneous coronary intervention is first-line therapy for acute coronary syndromes (ACS) but can promote cardiomyocyte death and cardiac dysfunction via reperfusion injury, a phenomenon driven in large part by oxidative stress. Therapies to limit this progression have proven elusive, with no major classes of new agents since the development of anti-platelets/anti-thrombotics. We report that cardiac troponin I-interacting kinase (TNNI3K), a cardiomyocyte-specific kinase, promotes ischemia/reperfusion injury, oxidative stress, and myocyte death. TNNI3K-mediated injury occurs through increased mitochondrial superoxide production and impaired mitochondrial function and is largely dependent on p38 mitogen-activated protein kinase (MAPK) activation. We developed a series of small-molecule TNNI3K inhibitors that reduce mitochondrial-derived superoxide generation, p38 activation, and infarct size when delivered at reperfusion to mimic clinical intervention. TNNI3K inhibition also preserves cardiac function and limits chronic adverse remodeling. Our findings demonstrate that TNNI3K modulates reperfusion injury in the ischemic heart and is a tractable therapeutic target for ACS. Pharmacologic TNNI3K inhibition would be cardiac-selective, preventing potential adverse effects of systemic kinase inhibition.

Discovery of non-steroidal mifepristone mimetics: pyrazoline-based PR antagonists.

Mifepristone is a non-selective antagonist of 3-oxosteroid receptors with both abortifacient and anti-endometriotic activities. Non-steroidal mimetics of mifepristone and progesterone are important templates for modulation of the progesterone receptor (PR). For our PR program, we sought an unexplored, synthetically accessible non-steroidal mimetic of mifepristone, suitable for parallel synthesis of analogues. Docking of compounds into a PR homology model identified 4-substituted pyrazolines, which, when synthesized and tested, exhibited functional antagonism of PR.