Pyrazole and pyrimidine phenylacylsulfonamides as dual Bcl-2/Bcl-xL antagonists.

5-Butyl-1,4-diphenyl pyrazole and 2-amino-5-chloro pyrimidine acylsulfonamides were developed as potent dual antagonists of Bcl-2 and Bcl-xL. Compounds were optimized for binding to the I88, L92, I95, and F99 pockets normally occupied by pro-apoptotic protein Bim. An X-ray crystal structure confirmed the proposed binding mode. Observation of cytochrome c release from isolated mitochondria in MV-411 cells provides further evidence of target inhibition. Compounds demonstrated submicromolar antiproliferative activity in Bcl-2/Bcl-xL dependent cell lines.

Identification of a phenylacylsulfonamide series of dual Bcl-2/Bcl-xL antagonists.

A series of phenylacylsulfonamides has been prepared as antagonists of Bcl-2/Bcl-xL. In addition to potent binding affinities for both Bcl-2 and Bcl-xL, these compounds were shown to induce classical markers of apoptosis in isolated mitochondria. Overall weak cellular potency was improved by the incorporation of polar functionality resulting in compounds with moderate antiproliferative activity.

Design, synthesis and structure-activity relationships of novel biarylamine-based Met kinase inhibitors.

Biarylamine-based inhibitors of Met kinase have been identified. Lead compounds demonstrate nanomolar potency in Met kinase biochemical assays and significant activity in the Met-driven GTL-16 human gastric carcinoma cell line. X-ray crystallography revealed that these compounds adopt a bioactive conformation, in the kinase domain, consistent with that previously seen with 2-pyridone-based Met kinase inhibitors. Compound 9b demonstrated potent in vivo antitumor activity in the GTL-16 human tumor xenograft model.

The antiangiogenic activity in xenograft models of brivanib, a dual inhibitor of vascular endothelial growth factor receptor-2 and fibroblast growth factor receptor-1 kinases.

Tumor angiogenesis is a complex and tightly regulated network mediated by various proangiogenic factors. The fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF) family of growth factors, and associated tyrosine kinase receptors have a major influence in tumor growth and dissemination and may work synergistically to promote angiogenesis. Brivanib alaninate is the orally active prodrug of brivanib, a selective dual inhibitor of FGF and VEGF signaling. Here, we show that brivanib demonstrates antitumor activity in a broad range of xenograft models over multiple dose levels and that brivanib alaninate shows dose-dependent efficacy equivalent to brivanib in L2987 human tumor xenografts. Brivanib alaninate (107 mg/kg) reduced tumor cell proliferation as determined by a 76% reduction in Ki-67 staining and reduced tumor vascular density as determined by a 76% reduction in anti-CD34 endothelial cell staining. Furthermore, Matrigel plug assays in athymic mice showed that brivanib alaninate inhibited angiogenesis driven by VEGF or basic FGF alone, or combined. Dynamic contrast-enhanced magnetic resonance imaging, used to assess the effects of brivanib alaninate on tumor microcirculation, showed a marked decrease in gadopentetate dimeglumine contrast agent uptake at 107 mg/kg dose, with a reduction in area under the plasma concentration-time curve from time 0 to 60 minutes at 24 and 48 hours of 54% and 64%, respectively. These results show that brivanib alaninate is an effective antitumor agent in preclinical models across a range of doses, and that efficacy is accompanied by changes in cellular and vascular activities.

Discovery of N-(4-(2-amino-3-chloropyridin-4-yloxy)-3-fluorophenyl)-4-ethoxy-1-(4-fluorophenyl)-2-oxo-1,2-dihydropyridine-3-carboxamide (BMS-777607), a selective and orally efficacious inhibitor of the Met kinase superfamily.

Substituted N-(4-(2-aminopyridin-4-yloxy)-3-fluoro-phenyl)-1-(4-fluorophenyl)-2-oxo-1,2-dihydropyridine-3-carboxamides were identified as potent and selective Met kinase inhibitors. Substitution of the pyridine 3-position gave improved enzyme potency, while substitution of the pyridone 4-position led to improved aqueous solubility and kinase selectivity. Analogue 10 demonstrated complete tumor stasis in a Met-dependent GTL-16 human gastric carcinoma xenograft model following oral administration. Because of its excellent in vivo efficacy and favorable pharmacokinetic and preclinical safety profiles, 10 has been advanced into phase I clinical trials.

Discovery of pyrrolopyridine-pyridone based inhibitors of Met kinase: synthesis, X-ray crystallographic analysis, and biological activities.

Conformationally constrained 2-pyridone analogue 2 is a potent Met kinase inhibitor with an IC50 value of 1.8 nM. Further SAR of the 2-pyridone based inhibitors of Met kinase led to potent 4-pyridone and pyridine N-oxide inhibitors such as 3 and 4. The X-ray crystallographic data of the inhibitor 2 bound to the ATP binding site of Met kinase protein provided insight into the binding modes of these inhibitors, and the SAR of this series of analogues was rationalized. Many of these analogues showed potent antiproliferative activities against the Met dependent GTL-16 gastric carcinoma cell line. Compound 2 also inhibited Flt-3 and VEGFR-2 kinases with IC50 values of 4 and 27 nM, respectively. It possesses a favorable pharmacokinetic profile in mice and demonstrates significant in vivo antitumor activity in the GTL-16 human gastric carcinoma xenograft model.

Discovery of orally active pyrrolopyridine- and aminopyridine-based Met kinase inhibitors.

A series of acylurea analogs derived from pyrrolopyridine and aminopyridine scaffolds were identified as potent inhibitors of Met kinase activity. The SAR at various positions of the two kinase scaffolds was investigated. These studies led to the discovery of compounds 3b and 20b, which demonstrated favorable pharmacokinetic properties in mice and significant antitumor activity in a human gastric carcinoma xenograft model.

Discovery and preclinical studies of 5-isopropyl-6-(5-methyl-1,3,4-oxadiazol-2-yl)-N-(2-methyl-1H-pyrrolo[2,3-b]pyridin-5-yl)pyrrolo[2,1-f][1,2,4]triazin-4-amine (BMS-645737), an in vivo active potent VEGFR-2 inhibitor.

We report herein a series of substituted N-(1H-pyrrolo[2,3-b]pyridin-5-yl)pyrrolo[2,1-f][1,2,4]triazin-4-amines as inhibitors of vascular endothelial growth factor receptor-2 tyrosine kinase. Through structure-activity relationship studies, biochemical potency, pharmacokinetics, and kinase selectivity were optimized to afford BMS-645737 (13), a compound with good preclinical in vivo activity against human tumor xenograft models.

Identification of pyrrolo[2,1-f][1,2,4]triazine-based inhibitors of Met kinase.

An amide library derived from the pyrrolo[2,1-f][1,2,4]triazine scaffold led to the identification of modest inhibitors of Met kinase activity. Introduction of polar side chains at C-6 of the pyrrolotriazine core provided significant improvements in in vitro potency. The amide moiety could be replaced with acylurea and malonamide substituents to give compounds with improved potency in the Met-driven GTL-16 human gastric carcinoma cell line. Acylurea pyrrolotriazines with substitution at C-5 demonstrated single digit nanomolar kinase activity. X-ray crystallography revealed that the C-5 substituted pyrrolotriazines bind to the Met kinase domain in an ATP-competitive manner.

Discovery of brivanib alaninate ((S)-((R)-1-(4-(4-fluoro-2-methyl-1H-indol-5-yloxy)-5-methylpyrrolo[2,1-f][1,2,4]triazin-6-yloxy)propan-2-yl)2-aminopropanoate), a novel prodrug of dual vascular endothelial growth factor receptor-2 and fibroblast growth factor receptor-1 kinase inhibitor (BMS-540215).

A series of amino acid ester prodrugs of the dual VEGFR-2/FGFR-1 kinase inhibitor 1 (BMS-540215) was prepared in an effort to improve the aqueous solubility and oral bioavailability of the parent compound. These prodrugs were evaluated for their ability to liberate parent drug 1 in in vitro and in vivo systems. The l-alanine prodrug 8 (also known as brivanib alaninate/BMS-582664) was selected as a development candidate and is presently in phase II clinical trials.

Synthesis, SAR, and Evaluation of 4-[2,4-Difluoro-5-(cyclopropylcarbamoyl)phenylamino]pyrrolo[2,1-f][1,2,4]triazine-based VEGFR-2 kinase inhibitors.

Introduction of the 2,4-difluoro-5-(cyclopropylcarbamoyl)phenylamino group at the C-4 position of the pyrrolo[2,1-f][1,2,4] triazine scaffold led to the discovery of a novel sub-series of inhibitors of VEGFR-2 kinase activity. Subsequent SAR studies on the 1,3,5-oxadiazole ring appended to the C-6 position of this new sub-family of pyrrolotriazines resulted in the identification of low nanomolar inhibitors of VEGFR-2. Antitumor efficacy was observed with compound 37 against L2987 human lung carcinoma xenografts in athymic mice.

Discovery and preclinical studies of (R)-1-(4-(4-fluoro-2-methyl-1H-indol-5-yloxy)-5- methylpyrrolo[2,1-f][1,2,4]triazin-6-yloxy)propan- 2-ol (BMS-540215), an in vivo active potent VEGFR-2 inhibitor.

A series of substituted 4-(4-fluoro-1H-indol-5-yloxy)pyrrolo[2,1-f][1,2,4]triazine-based inhibitors of vascular endothelial growth factor receptor-2 kinase is reported. Structure-activity relationship studies revealed that a methyl group at the 5-position and a substituted alkoxy group at the 6-position of the pyrrolo[2,1-f][1,2,4]triazine core gave potent compounds. Biochemical potency, kinase selectivity, and pharmacokinetics of the series were optimized and in vitro safety liabilities were minimized to afford BMS-540215 (12), which demonstrated robust preclinical in vivo activity in human tumor xenograft models. The l-alanine prodrug of 12, BMS-582664 (21), is currently under evaluation in clinical trials for the treatment of solid tumors.

Design, synthesis, and evaluation of orally active 4-(2,4-difluoro-5-(methoxycarbamoyl)phenylamino)pyrrolo[2,1-f][1,2,4]triazines as dual vascular endothelial growth factor receptor-2 and fibroblast growth factor receptor-1 inhibitors.

A series of substituted 4-(2,4-difluoro-5-(methoxycarbamoyl)phenylamino)pyrrolo[2,1-f][1,2,4]triazines was identified as potent and selective inhibitors of the tyrosine kinase activity of the growth factor receptors VEGFR-2 (Flk-1, KDR) and FGFR-1. The enzyme kinetics associated with the VEGFR-2 inhibition of compound 50 (K(i) = 52 +/- 3 nM) confirmed that the pyrrolo[2,1-f][1,2,4]triazine analogues are competitive with ATP. Several analogues demonstrated low-nanomolar inhibition of VEGF- and FGF-dependent human umbilical vein endothelial cell (HUVEC) proliferation. Replacement of the C6-ester substituent of the pyrrolo[2,1-f][1,2,4]triazine core with heterocyclic bioisosteres, such as substituted 1,3,5-oxadiazoles, afforded compounds with excellent oral bioavailability in mice (i.e., 50 F(po) = 79%). Significant antitumor efficacy was observed with compounds 44, 49, and 50 against established L2987 human lung carcinoma xenografts implanted in athymic mice. A full account of the synthesis, structure-activity relationships, pharmacology, and pharmacokinetic properties of analogues within the series is presented.

Synthesis and SAR of 4-(3-hydroxyphenylamino)pyrrolo[2,1-f][1,2,4]triazine based VEGFR-2 kinase inhibitors.

A versatile synthesis of the suitably functionalized pyrrolo[2,1-f][1,2,4]triazine nucleus is described. SAR at the C-5 and C-6 positions of the 4-(3-hydroxy-4-methylphenylamino)pyrrolo[2,1-f][1,2,4]triazine template led to compounds with good in vitro potency against VEGFR-2 kinase. Glucuronidation of the phenol group is mitigated by incorporation of a basic amino group on the C-6 side chain of the pyrrolotriazine nucleus.

Addition of benzylic and allylic organozinc and Grignard reagents to resin-bound imines to provide alpha-branched secondary amines bearing a wide variety of functional groups. Utility in the synthesis of beta-3 adrenergic receptor agonists.

Benzylic and allylic organozinc and Grignard reagents have been added to resin-bound imines to provide alpha-branched secondary amines. Many functional groups, including electrophilic groups, were compatible with this methodology. Three modules--a resin-bound primary amine, an aromatic aldehyde, and the organometallic--were independently varied to produce a combinatorial library of alpha-branched secondary amines designed as beta-3 adrenergic receptor agonists.

Discovery of aminothiazole inhibitors of cyclin-dependent kinase 2: synthesis, X-ray crystallographic analysis, and biological activities.

High throughput screening identified 2-acetamido-thiazolylthio acetic ester 1 as an inhibitor of cyclin-dependent kinase 2 (CDK2). Because this compound is inactive in cells and unstable in plasma, we have stabilized it to metabolic hydrolysis by replacing the ester moiety with a 5-ethyl-substituted oxazole as in compound 14. Combinatorial and parallel synthesis provided a rapid analysis of the structure-activity relationship (SAR) for these inhibitors of CDK2, and over 100 analogues with IC(50) values in the 1-10 nM range were rapidly prepared. The X-ray crystallographic data of the inhibitors bound to the active site of CDK2 protein provided insight into the binding modes of these inhibitors, and the SAR of this series of analogues was rationalized. Many of these analogues displayed potent and broad spectrum antiproliferative activity across a panel of tumor cell lines in vitro. In addition, A2780 ovarian carcinoma cells undergo rapid apoptosis following exposure to CDK2 inhibitors of this class. Mechanism of action studies have confirmed that the phosphorylation of CDK2 substrates such as RB, histone H1, and DNA polymerase alpha (p70 subunit) is reduced in the presence of compound 14. Further optimization led to compounds such as water soluble 45, which possesses a favorable pharmacokinetic profile in mice and demonstrates significant antitumor activity in vivo in several murine and human models, including an engineered murine mammary tumor that overexpresses cyclin E, the coactivator of CDK2.