Metabolic targeting of cancer by a ubiquinone uncompetitive inhibitor of mitochondrial complex I.

SMIP004-7 is a small molecule inhibitor of mitochondrial respiration with selective in vivo anti-cancer activity through an as-yet unknown molecular target. We demonstrate here that SMIP004-7 targets drug-resistant cancer cells with stem-like features by inhibiting mitochondrial respiration complex I (NADH:ubiquinone oxidoreductase, complex I [CI]). Instead of affecting the quinone-binding site targeted by most CI inhibitors, SMIP004-7 and its cytochrome P450-dependent activated metabolite(s) have an uncompetitive mechanism of inhibition involving a distinct N-terminal region of catalytic subunit NDUFS2 that leads to rapid disassembly of CI. SMIP004-7 and an improved chemical analog selectively engage NDUFS2 in vivo to inhibit the growth of triple-negative breast cancer transplants, a response mediated at least in part by boosting CD4+ and CD8+ T cell-mediated immune surveillance. Thus, SMIP004-7 defines an emerging class of ubiquinone uncompetitive CI inhibitors for cell autonomous and microenvironmental metabolic targeting of mitochondrial respiration in cancer.

Identification of potent and selective VEGFR receptor tyrosine kinase inhibitors having new amide isostere headgroups.

A novel series of malonamide-type dual VEGFR2/c-Met inhibitors in which one of the amide bonds was replaced by an amide isostere-a trifluoroethylamine unit, was designed, synthesized, and evaluated for their enzymatic and cellular inhibition of VEGFR2 and c-Met enzymes. Optimization of these molecular entities resulted in identification of potent and selective inhibitors of VEGFR2 enzyme.

Identification of a novel series of potent RON receptor tyrosine kinase inhibitors.

A novel series of N-(3-fluoro-4-(2-substituted-thieno[3,2-b]pyridin-7-yloxy)phenyl)-1-phenyl-5-(trifluoromethyl)-1H-pyrazole-4-carboxamides targeting RON receptor tyrosine kinase was designed and synthesized. SAR study of the series allowed us to identify compounds possessing either inhibitory activity of RON kinase enzyme in the low nanomolar range with low residual activity against the closely related c-Met or potent dual inhibitory activity against RON and c-Met, with no significant activity against VEGFR2 in both cases.

Constrained (l-)-S-adenosyl-l-homocysteine (SAH) analogues as DNA methyltransferase inhibitors.

Potent SAH analogues with constrained homocysteine units have been designed and synthesized as inhibitors of human DNMT enzymes. The five membered (2S,4S)-4-mercaptopyrrolidine-2-carboxylic acid, in 1a, was a good replacement for homocysteine, while the corresponding six-member counterpart was less active. Further optimization of 1a, changed the selectivity profile of these inhibitors. A Chloro substituent at the 2-position of 1a, compound 1d, retained potency against DNMT1, while N(6) alkylation, compound 7a, conserved DNMT3b2 activity. The concomitant substitutions of 1a at both 2- and N(6) positions reduced activity against both enzymes.

SAR around (l)-S-adenosyl-l-homocysteine, an inhibitor of human DNA methyltransferase (DNMT) enzymes.

The inhibitory activity of base-modified SAH analogues and the specificity of inhibiting human DNMT1 and DNMT3b2 enzymes was explored. The 6-amino group was essential while the 7-N of the adenine ring of SAH could be replaced by CH- without loss of activity against both enzymes. The introduction of small groups at the 2-position of the adenine moiety favors DNMT1 over DNMT3b2 inhibition whereas alkylation of the N(6)-amino moiety favors the inhibition of DNMT3b2 enzyme.

N-(4-(6,7-Disubstituted-quinolin-4-yloxy)-3-fluorophenyl)-2-oxo-3-phenylimidazolidine-1-carboxamides: a novel series of dual c-Met/VEGFR2 receptor tyrosine kinase inhibitors.

A series of N-(4-(6,7-disubstituted-quinolin-4-yloxy)-3-fluorophenyl)-2-oxo-3-phenylimidazolidine-1-carboxamides targeting c-Met and VEGFR2 tyrosine kinases was designed and synthesized. The compounds were potent against these two enzymes with IC(50) values in the low nanomolar range in vitro, possessed favorable pharmacokinetic profiles and showed high efficacy in vivo in several human tumor xenograft models in mice.

N3-arylmalonamides: a new series of thieno[3,2-b]pyridine based inhibitors of c-Met and VEGFR2 tyrosine kinases.

A family of thieno[3,2-b]pyridine based small molecule inhibitors of c-Met and VEGFR2 were designed based on lead structure 2. These compounds were shown to have IC(50) values in the low nanomolar range in vitro and were efficacious in human tumor xenograft models in mice in vivo.

N-(3-fluoro-4-(2-arylthieno[3,2-b]pyridin-7-yloxy)phenyl)-2-oxo-3-phenylimidazolidine-1-carboxamides: a novel series of dual c-Met/VEGFR2 receptor tyrosine kinase inhibitors.

A series of N-(3-fluoro-4-(2-arylthieno[3,2-b]pyridin-7-yloxy)phenyl)-2-oxo-3-phenylimidazolidine-1-carboxamides targeting c-Met and VEGFR2 tyrosine kinases was designed and synthesized. The compounds were potent against these two enzymes with IC(50) values in the low nanomolar range in vitro, possessed favorable pharmacokinetic profiles and showed high efficacy in vivo in several human tumor xenograft models in mice.

SAR and biological evaluation of analogues of a small molecule histone deacetylase inhibitor N-(2-aminophenyl)-4-((4-(pyridin-3-yl)pyrimidin-2-ylamino)methyl)benzamide (MGCD0103).

Analogues of the clinical compound MGCD0103 (A) were designed and synthesized. These compounds inhibit recombinant human HDAC1 with IC(50) values in the sub-micromolar range. In human cancer cells growing in culture these compounds induce hyperacetylation of histones, cause expression of the tumor suppressor protein p21(WAF1/CIP1), and inhibit cellular proliferation. Lead molecule of the series, compound 25 is metabolically stable, possesses favorable pharmacokinetic characteristics and is orally active in vivo in different mouse tumor xenograft models.

4-(Heteroarylaminomethyl)-N-(2-aminophenyl)-benzamides and their analogs as a novel class of histone deacetylase inhibitors.

The synthesis and biological evaluation of a variety of 4-(heteroarylaminomethyl)-N-(2-aminophenyl)-benzamides and their analogs is described. Some of these compounds were shown to inhibit HDAC1 with IC(50) values below the micromolar range, induce hyperacetylation of histones, upregulate expression of the tumor suppressor p21(WAF1/Cip1), and inhibit proliferation of human cancer cells. In addition, certain compounds of this class were active in several human tumor xenograft models in vivo.

Design and synthesis of 4-[(s-triazin-2-ylamino)methyl]-N-(2-aminophenyl)-benzamides and their analogues as a novel class of histone deacetylase inhibitors.

Inhibition of histone deacetylases (HDAC) is emerging as a new strategy in human cancer therapy. The synthesis and biological evaluation of a variety of 4-(heteroarylaminomethyl)-N-(2-aminophenyl)-benzamides is presented herein. From the different series bearing a six-membered heteroaromatic ring studied, the s-triazine series showed the best HDAC1 enzyme and in vitro anti-proliferative activities with IC(50) values below micromolar range. Some of these compounds can also significantly reduce tumor growth in human tumor xenograft models in mice.

Discovery of a novel and potent series of thieno[3,2-b]pyridine-based inhibitors of c-Met and VEGFR2 tyrosine kinases.

A series of thieno[3,2-b]pyridine-based inhibitors of c-Met and VEGFR2 tyrosine kinases is described. The compounds demonstrated potency with IC(50) values in the low nanomolar range in vitro while the lead compound also showed in vivo activity against various human tumor xenograft models in mice. Further exploration of this class of compounds is underway.

Novel aminophenyl benzamide-type histone deacetylase inhibitors with enhanced potency and selectivity.

Significant effort is being made to understand the role of HDAC isotypes in human cancer and to develop antitumor agents with better therapeutic windows. A part of this endeavor was the exploration of the 14 A internal cavity adjacent to the enzyme catalytic site, which led to the design and synthesis of compound 4 with the unusual bis(aryl)-type pharmacophore. SAR studies around this lead resulted in optimization to potent, selective, nonhydroxamic acid HDAC inhibitors.

N-(2-Amino-phenyl)-4-(heteroarylmethyl)-benzamides as new histone deacetylase inhibitors.

A variety of N-(2-amino-phenyl)-4-(heteroarylmethyl)-benzamides were designed and synthesized. These compounds were shown to inhibit recombinant human HDAC1 with IC(50) values in the sub-micromolar range. In human cancer cells growing in culture these compounds induced hyperacetylation of histones, induced the expression of the tumor suppressor protein p21(WAF1/Cip1), and inhibited cellular proliferation. Certain compounds of this class also showed in vivo activity in various human tumor xenograft models in mice.

Histone deacetylase inhibitors: latest developments, trends and prospects.

Histone deacetylases (HDACs) and histone acetyltransferases (HATs) are enzymes that catalyze the deacetylation and acetylation of lysine residues located in the NH(2) terminal tails of histones and non-histone proteins. Perturbation of this balance is often observed in human cancers and inhibition of HDACs has emerged as a novel therapeutic strategy against cancer. To date, more that 30 groups, academic and industrial, are involved in research related to these target enzymes. Over the past year, dozens of research papers and patent applications describing new HDAC inhibitors belonging to different structural classes have been disclosed. The present review highlights the latest developments in design and synthesis of HDAC inhibitors -- potential anti-cancer drugs.

Structurally simple trichostatin A-like straight chain hydroxamates as potent histone deacetylase inhibitors.

A series of new, structurally simple trichostatin A (TSA)-like straight chain hydroxamates were prepared and evaluated for their ability to inhibit partially purified human histone deacetylase 1 (HDAC-1). Some of these compounds such as 8m, 8n, 12, and 15b exhibited potent HDAC inhibitory activity with low nanomolar IC(50) values, comparable to natural TSA. These compounds induce hyperacetylation of histones in T24 human cancer cells and significantly inhibit proliferation in various human cancer cells. They also induce expression of p21 and cause cell cycle blocks in human cancer cells. In this paper, we describe the synthesis of these new compounds as well as structure-activity relationship results from enzyme inhibition and alterations in cellular function.

Identification of a Novel Series of Potent TrkA Receptor Tyrosine Kinase Inhibitors.

A novel series of N-(3-(6-substituted-aminopyridin-3-yloxy)phenyl)-2-oxo-3-phenylimidazolidine-1-carboxamides targeting TrkA receptor tyrosine kinase was identified. SAR study of the series allowed us to design and synthesize compounds possessing inhibitory activity of TrkA kinase enzyme in the low nanomolar range with low residual activity against c-Met and with no significant activity against VEGFR2.

Histone deacetylase inhibitors in cancer therapy: new compounds and clinical update of benzamide-type agents.

Histone deacetylase (HDAC) inhibitors constitute a novel and growing class of anticancer agents that function by altering intracellular patterns of histone acetylation, the so-called epigenetic "histone code," thereby producing changes in cell cycle arrest, differentiation, and/or apoptosis in tumor cells. This overview describes the chemistry and preliminary characterization of recently disclosed molecules in three major classes of HDAC inhibitors: hydroxamic acids, 2-amino- benzanilides, and cyclic peptides. In addition, results from recent clinical trials on isotype-selective HDAC inhibitors are reviewed. It is clear from the plethora of new molecules and the encouraging results from clinical trials that HDAC inhibitors hold a great deal of promise, particularly as add-on therapy, for the treatment of a variety of solid and hematologic cancers.

Discovery of N-(2-aminophenyl)-4-[(4-pyridin-3-ylpyrimidin-2-ylamino)methyl]benzamide (MGCD0103), an orally active histone deacetylase inhibitor.

The design, synthesis, and biological evaluation of N-(2-aminophenyl)-4-[(4-pyridin-3-ylpyrimidin-2-ylamino)methyl]benzamide 8 (MGCD0103) is described. Compound 8 is an isotype-selective small molecule histone deacetylase (HDAC) inhibitor that selectively inhibits HDACs 1-3 and 11 at submicromolar concentrations in vitro. 8 blocks cancer cell proliferation and induces histone acetylation, p21 (cip/waf1) protein expression, cell-cycle arrest, and apoptosis. 8 is orally bioavailable, has significant antitumor activity in vivo, has entered clinical trials, and shows promise as an anticancer drug.

Substituted N-(2-aminophenyl)-benzamides, (E)-N-(2-aminophenyl)-acrylamides and their analogues: novel classes of histone deacetylase inhibitors.

Inhibition of histone deacetylases (HDACs) is emerging as a new strategy in human cancer therapy. Novel 2-aminophenyl benzamides and acrylamides, that can inhibit human HDAC enzymes and induce hyperacetylation of histones in human cancer cells, have been designed and synthesized. These compounds selectively inhibit proliferation and cause cell cycle arrest in various human cancer cells but not in normal cells. The growth inhibition of 2-aminophenyl benzamides and acrylamides against human cancer cells in vitro is reversible and is dependent on the induction of histone acetylation. Compounds of this class can significantly reduce tumor growth in human tumor xenograft models.