Purpose: Hypoxia inducible factor-1 (HIF-1), the central mediator of the cellular response to low oxygen, functions as a transcription factor for a broad range of genes that provide adaptive responses to oxygen deprivation. HIF-1 is overexpressed in cancer and has become an important therapeutic target in solid tumors. In this study, a novel HIF-1α inhibitor was identified and its molecular mechanism was investigated. Experimental Design: Using a HIF-responsive reporter cell-based assay, a 10,000-member natural product-like chemical compound library was screened to identify novel HIF-1 inhibitors. This led us to discover KC7F2, a lead compound with a central structure of cystamine. The effects of KC7F2 on HIF-1 transcription, translation, and protein degradation processes were analyzed. Results: KC7F2 markedly inhibited HIF-mediated transcription in cells derived from different tumor types, including glioma, breast, and prostate cancers, and exhibited enhanced cytotoxicity under hypoxia. KC7F2 prevented the activation of HIF-target genes such as carbonic anhydrase IX, matrix metalloproteinase 2 (MMP2), endothelin 1, and enolase 1. An investigation into the mechanism of action of KC7F2 showed that it worked through the down-regulation of HIF-1α protein synthesis, an effect accompanied by the suppression of the phosphorylation of eukaryotic translation initiation factor 4E binding protein 1 and p70 S6 kinase, key regulators of HIF-1α protein synthesis. Conclusion: These results show that KC7F2 is a potent HIF-1 pathway inhibitor and its potential as a cancer therapy agent warrants further study. (Clin Cancer Res 2009;15 (19):6128-36) Hypoxia, a reduction in partial oxygen pressure, is a major hindrance to effective solid tumor therapy. The microenvironment of rapidly growing solid tumors shows increased energy demand and diminished vascular supply, resulting in focal areas of prominent hypoxia (1). The hypoxic fraction of tumors is resistant to traditional therapies. Radiotherapy is compromised because of the reduced reaction of oxygen with radiationinduced DNA free radicals (2). Chemotherapy is hampered by the diffusion-limited drug delivery to hypoxic regions from distant vasculature. Moreover, many anticancer drugs are most effective against rapidly proliferating cells, and hypoxia (and deficiencies in other nutrients such as glucose) can cause a reduction in cell proliferation rate (3). This is compounded by the induction of the multidrug resistance (MDR1) gene product P-glycoprotein in hypoxic tissue (4), further reducing drug efficacy. Hypoxic tumor regions also impede immune responses, and may promote the growth of cancer stem cells (5,6).Hypoxia drives malignant tumor progression. Tumor hypoxia increases malignant progression and metastasis by promoting angiogenesis through the induction of proangiogenic proteins such as vascular endothelial growth factor (VEGF) and metabolic adaptation through elevation of glycolytic enzymes (7,8). Hypoxia also generates selective pressure for cells to acquir...

The synthesis and preclinical characterization of novel 4-(R)-methyl-6,7-dihydro-4H-triazolo[4,5-c]pyridines that are potent and selective brain penetrant P2X7 antagonists are described. Optimization efforts based on previously disclosed unsubstituted 6,7-dihydro-4H-triazolo[4,5-c]pyridines, methyl substituted 5,6,7,8-tetrahydro[1,2,4]triazolo[4,3-a]pyrazines, and several other series lead to the identification of a series of 4-(R)-methyl-6,7-dihydro-4H-triazolo[4,5-c]pyridines that are selective P2X7 antagonists with potency at the rodent and human P2X7 ion channels. These novel P2X7 antagonists have suitable physicochemical properties, and several analogs have an excellent pharmacokinetic profile, good partitioning into the CNS and show robust in vivo target engagement after oral dosing. Improvements in metabolic stability led to the identification of JNJ-54175446 (14) as a candidate for clinical development. The drug discovery efforts and strategies that resulted in the identification of the clinical candidate are described herein.

Complement factor D (FD), a highly specific S1 serine protease, plays a central role in the amplification of the alternative complement pathway (AP) of the innate immune system. Dysregulation of AP activity predisposes individuals to diverse disorders such as age-related macular degeneration, atypical hemolytic uremic syndrome, membranoproliferative glomerulonephritis type II, and paroxysmal nocturnal hemoglobinuria. Previously, we have reported the screening efforts and identification of reversible benzylamine-based FD inhibitors (1 and 2) binding to the open active conformation of FD. In continuation of our drug discovery program, we designed compounds applying structure-based approaches to improve interactions with FD and gain selectivity against S1 serine proteases. We report herein the design, synthesis, and medicinal chemistry optimization of the benzylamine series culminating in the discovery of 12, an orally bioavailable and selective FD inhibitor. 12 demonstrated systemic suppression of AP activation in a lipopolysaccharide-induced AP activation model as well as local ocular suppression in intravitreal injection-induced AP activation model in mice expressing human FD.

A devised synthetic strategy toward the QRSTU ring system 4 of the marine-derived biotoxin maitotoxin (1) delivered, in addition to 4, its diastereoisomers 85-epi-QRSTU and 86-epi-QRSTU ring systems 5 and 6. The convergent route to these maitotoxin fragments involved coupling of UT and Q building blocks 9 (obtained from 2-deoxy-D-ribose) and 10 (obtained from D-ribose) followed by ring-closing metathesis to afford enol ether 8, whose elaboration to the targeted QRSTU ring system 4 required its conversion to hydroxy ketone 7. The latter compound (7) was transformed to the final product through a hydroxy dithioketal cyclization, followed by oxidationmethylation of the resulting O,S-mixed ketal to install the last of the five methyl groups contained within the target molecule (4). 13 C NMR spectroscopic analysis of synthesized fragments 4, 5 and 6, and comparisons with maitotoxin, provided strong support for the originally assigned structure of the QRSTU domain of the natural product.

A single pot dipolar cycloaddition reaction/Cope elimination sequence was developed to access novel 1,4,6,7-tetrahydro-5H-[1,2,3]triazolo[4,5-c]pyridine P2X7 antagonists that contain a synthetically challenging chiral center. The structure-activity relationships of the new compounds are described. Two of these compounds, (S)-(2-fluoro-3-(trifluoromethyl)phenyl)(1-(5-fluoropyrimidin-2-yl)-6-methyl-1,4,6,7-tetrahydro-5H-[1,2,3]triazolo[4,5-c]pyridin-5-yl)methanone (compound 29) and (S)-(3-fluoro-2-(trifluoromethyl)pyridin-4-yl)(1-(5-fluoropyrimidin-2-yl)-6-methyl-1,4,6,7-tetrahydro-5H-[1,2,3]triazolo[4,5-c]pyridin-5-yl)methanone (compound 35), were found to have robust P2X7 receptor occupancy at low doses in rat with ED values of 0.06 and 0.07 mg/kg, respectively. Compound 35 had notable solubility compared to 29 and showed good tolerability in preclinical species. Compound 35 was chosen as a clinical candidate for advancement into phase I clinical trials to assess safety and tolerability in healthy human subjects prior to the initiation of proof of concept studies for the treatment of mood disorders.

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A concise and efficient cascade-based total synthesis of artochamins F, H, I, and J is described. The potential biogenetic connection between artochamin F, or a derivative thereof, and artochamins H, I, and J, through an unusual formal [2+2] cycloaddition process, was shown to be feasible. An alternative mechanism for this transformation is also proposed.

Dedicated to Masakatsu Shibasaki on the occasion of his 60th birthdayThe Artocarpus genus encompasses approximately 60 species of trees that are distributed throughout the tropical regions of Asia. Selected members of this family of plants have been used as traditional folk medicines in Sri Lanka, Taiwan, Thailand, and Indonesia. [1][2][3][4] A search for the bioactive ingredients of these plants led to the isolation of several bioactive prenylated flavanoids from the roots of Artocarpus chama, [5] and more recently a number of weakly cytotoxic prenylated stilbenes and their derivatives.[6] Artochamins F, H, I, and J (1-4, Scheme 1) are among the most structurally fascinating members of this group of compounds. Herein we describe the total synthesis of all four natural products through an expedient route that involves a cascade sequence featuring a novel formal [2+2] thermal cycloaddition reaction.The unique bicyclo[3.2.0]heptane carbon frameworks of artochamins H-J (2-4) would appear to be biogenetically derived from artochamin F (1), or a derivative thereof, through a formal [2+2] cycloaddition reaction between the stilbene alkene and one of the prenyl groups.[6] Furthermore, the racemic nature [7] of 2-4 could implicate a non-enzymatic process for this transformation, given the pairwise enantiotopic relationship between both the top and bottom faces of the two prenyl moieties. We were intrigued by the possibility of accomplishing the required cycloaddition under thermal conditions [8] since we speculated that the realization of such a reaction would lead to a concise synthetic approach to the artochamins from stilbenes 5 a and/or 5 b through a cascade sequence that involved, in addition to the key cyclobutaneforming process, two consecutive Claisen rearrangements. Furthermore, protecting-group design on the intermediates was expected to modulate the cascade reaction and allow selective pathways so as to deliver any of the four targeted natural products (1-4).The first objective was the stereoselective construction of an appropriately functionalized stilbene derivative from which the formal [2+2] cycloaddition reaction within the projected cascade could be investigated. The Julia-Kocienski olefination [9] was chosen [10] as the key step for this initial construction as shown in Scheme 2.Thus, the substituted phenyltetrazolesulfones 7 a and 7 b were prepared from 3,4-dihydroxybenzaldehyde (6) in a straightforward manner that involved protection (either as the corresponding Boc derivative or silyl ether), reduction with NaBH 4 , and Mitsunobu coupling with 1-phenyl-1H-tetrazole-5-thiol, followed by molybdenum-catalyzed oxidation of the resulting sulfides to the desired sulfones 7 a (73 % overall yield from 6) and 7 b (77 % overall yield from 6). The preparation of the other required coupling partner, aldehyde 10, began with methyl ester 8, [11] which was converted into the corresponding bis-reversed prenylated ester 9 through a copper-catalyzed etherification [12] with 1,1-dimethylpropynyl carbonate and Lindlar h...