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Supplemental Tables S1-S3. Table S1 describes the antiproliferative activity of SAR125844 on a panel of cell lines and the known genetic alterations of MET and other oncogenes or tumor suppressor genes for these cell lines. Table S2 describes the antiproliferative activity of SAR125844 upon various times of exposure in Hs 746T MET-amplified tumor cell line. Table S3 describes tumor exposure over plasma exposure ratios for SAR125844, JNJ-38877605 and PF-04217903 MET inhibitors.

Bengamide, aus marinen Schwammen stammende und als Inhibitoren der Methionin-Aminopeptidase (MetAP) charakterisierte Naturstoffe, wurden intensiv als Wirkstoffe gegen Krebs erforscht. In einem multidisziplinaren Forschungsprojekt haben wir die Bereitstellung von Bengamiden uber Fermentation des terrestrischen Myxobakteriums M. virescens, die Aufklarung ihrer Biosynthese und die Optimierung ihrer Eigenschaften als Arzneistoff-Leitstrukturen untersucht. Die Charakterisierung des Biosyntheseweges zeigte auf, dass bakterielle Resistenz gegenuber Bengamiden durch Leu154 des myxobakteriellen MetAP-Proteins vermittelt wird, und ermoglichte den Transfer des gesamten Biosynthesegenclusters in den geeigneteren Produktionsstamm M. xanthus DK1622. Eine Kombination aus Semisynthese mikrobiell gewonnener Bengamide und Totalsynthese fuhrte zum optimierten Derivat 8 a. Die nanomolare zellulare Wirksamkeit und die hohe metabolische Stabilitat waren mit einer verbesserten Halbwertszeit in Mausen sowie mit Antitumor-Effizienz in einem Melanom-Mausmodell verbunden.

The bengamides, sponge-derived natural products that have been characterized as inhibitors of methionine aminopeptidases (MetAPs), have been intensively investigated as anticancer compounds. We embarked on a multidisciplinary project to supply bengamides by fermentation of the terrestrial myxobacterium M. virescens, decipher their biosynthesis, and optimize their properties as drug leads. The characterization of the biosynthetic pathway revealed that bacterial resistance to bengamides is conferred by Leu 154 of the myxobacterial MetAP protein, and enabled transfer of the entire gene cluster into the more suitable production host M. xanthus DK1622. A combination of semisynthesis of microbially derived bengamides and total synthesis resulted in an optimized derivative that combined high cellular potency in the nanomolar range with high metabolic stability, which translated to an improved half-life in mice and antitumor efficacy in a melanoma mouse model.

Activation of the MET/HGF pathway is common in human cancer and is thought to promote tumor initiation, metastasis, angiogenesis, and resistance to diverse therapies. We report here the pharmacologic characterization of the triazolopyridazine derivative SAR125844, a potent and highly selective inhibitor of the MET receptor tyrosine kinase (RTK), for intravenous administration. SAR125844 displayed nanomolar activity against the wild-type kinase (IC50 value of 4.2 nmol/L) and the M1250T and Y1235D mutants. Broad biochemical profiling revealed that SAR125844 was highly selective for MET kinase. SAR125844 inhibits MET autophosphorylation in cell-based assays in the nanomolar range, and promotes low nanomolar proapoptotic and antiproliferative activities selectively in cell lines with MET gene amplification or pathway addiction. In two MET-amplified human gastric tumor xenograft models, SNU-5 and Hs 746T, intravenous treatment with SAR125844 leads to potent, dose- and time-dependent inhibition of the MET kinase and to significant impact on downstream PI3K/AKT and RAS/MAPK pathways. Long duration of MET kinase inhibition up to 7 days was achieved with a nanosuspension formulation of SAR125844. Daily or every-2-days intravenous treatment of SAR125844 promoted a dose-dependent tumor regression in MET-amplified human gastric cancer models at tolerated doses without treatment-related body weight loss. Our data demonstrated that SAR125844 is a potent and selective MET kinase inhibitor with a favorable preclinical toxicity profile, supporting its clinical development in patients with MET-amplified and MET pathway–addicted tumors. Mol Cancer Ther; 14(2); 384–94. ©2014 AACR.

From a screening of 27 106 covalent DNA-encoded compound library, a novel KRAS G12C chemical series has been identified. Original hit series compound displayed low µM covalent binding activity to KRAS G12C under GDP form associated with a k(inact)/Ki of 1,03 M-1.s-1, a stable electrophilic covalent warhead (T1/2 in 5mM GSH > 24h), +12°C stabilization Delta Tm in DSF assay and 3 µM IC50 value in GEF assay, while no detectable covalent binding to KRAS G12C under GTP form and to KRAS WT or KRAS G12D under GDP form. From 3 µM, it also induced significant pERK inhibition in H358 KRAS-G12C but not in A549 KRAS G12S NSCLC cell lines. Unique binding mode to SII pocket was demonstrated by Xray crystallography. Multi-parametric and structural biology guided chemical optimization yielded potent KRAS G12C lead compounds which combine k(inact)/Ki > 500 M-1.s-1, Delta Tm=20°C, 10 nM range pERK IC50 values with correlated direct KRAS G12C selective covalent modification. They also exhibited 100 nM range KRAS G12C allele-specific anti-proliferative activity and triggered significant apoptosis induction. In vivo treatment of mice bearing H358 tumour xenografts through oral route with optimized candidates showed a marked and prolonged inhibition of both pERK and DUSP6 mRNA as well as consistent direct KRAS-G12C covalent modification as evidenced by LC-MS in tumor samples. Altogether, these data demonstrate the power of DNA-encoded library approach to deliver potential drug candidates with selective cysteine-targeted irreversible mechanism of action on challenging oncology targets such as KRAS. Citation Format: Gary McCort, Rosalia Arrebola, Loreley Calvet, Baptiste Ronan, Fabrice Vergne, Francis Duffieux, Alexey Rak, Isabelle Meaux, David Papin, Florence Fassy, Cecile Delorme, Magali Matthieu, Jean-Paul Nicolas, Christophe Marcireau, Valerie Steier, Pierre-Yves Abecassis, Valerie Czepczor, Heather A. Thomson, Christopher D. Hupp, J.P. Guilinger, Ying Zhang, Anthony D. Keefe, John W. Cuozzo, Julie Liu, Laurent Debussche. Discovery of novel potent allele-selective KRAS-G12C covalent inhibitors stemming from DNA-encoded library [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3070.

Compelling molecular biology publications have reported the implication of phosphoinositide kinase PI3Kβ in PTEN-deficient cell line growth and proliferation. These findings supported a scientific rationale for the development of PI3Kβ-specific inhibitors for the treatment of PTEN-deficient cancers. This paper describes the discovery of 2-[2-(2,3-dihydro-indol-1-yl)-2-oxo-ethyl]-6-morpholin-4-yl-3H-pyrimidin-4-one (7) and the optimization of this new series of active and selective pyrimidone indoline amide PI3Kβ inhibitors. 2-[2-(2-Methyl-2,3-dihydro-indol-1-yl)-2-oxo-ethyl]-6-morpholin-4-yl-3H-pyrimidin-4-one (28), identified following a carefully designed methyl scan, displayed improved physicochemical and in vitro pharmacokinetic properties. Structural biology efforts enabled the acquisition of the first X-ray cocrystal structure of p110β with the selective inhibitor compound 28 bound to the ATP site. The nonplanar binding mode described herein is consistent with observed structure-activity relationship for the series. Compound 28 demonstrated significant in vivo activity in a UACC-62 xenograft model in mice, warranting further preclinical investigation. Following successful development, compound 28 entered phase I/Ib clinical trial in patients with advanced cancer.

From a HTS campaign, a new series of pyrimidone anilides exemplified by compound 1 has been identified with good inhibitory activity for the PI3Kβ isoform. The structure of compound 1 in PI3Kγ was solved revealing a binding mode in agreement with the SAR observed on PI3Kβ. These compounds displayed inhibition in the nanomolar range in the biochemical assay and were also potent p-Akt inhibitors in a PTEN-deficient PC3 prostate cancer cell line. Optimization of in vitro pharmocokinetic properties led to compound 25 exhibiting 52% bioavailability in mice and target engagement in an acute PK/PD study.

Most of the phosphoinositide-3 kinase (PI3K) kinase inhibitors currently in clinical trials for cancer treatment exhibit pan PI3K isoform profiles. Single PI3K isoforms differentially control tumorigenesis, and PI3Kβ has emerged as the isoform involved in the tumorigenicity of PTEN-deficient tumors. Herein we describe the discovery and optimization of a new series of benzimidazole- and benzoxazole-pyrimidones as small molecular mass PI3Kβ-selective inhibitors. Starting with compound 5 obtained from a one-pot reaction via a novel intermediate 1, medicinal chemistry optimization led to the discovery of compound 8, which showed a significant activity and selectivity for PI3Kβ and adequate in vitro pharmacokinetic properties. The X-ray costructure of compound 8 in PI3Kδ showed key interactions and structural features supporting the observed PI3Kβ isoform selectivity. Compound 8 achieved sustained target modulation and tumor growth delay at well tolerated doses when administered orally to SCID mice implanted with PTEN-deficient human tumor xenografts.

Neuropeptide Y (NPY) has several receptors; one of them, the neuropeptide Y5 receptor (NPY5) seems involved in feeding behavior in mammals. Although this particular receptor has been extensively studied in the literature, the difficulties encountered to obtain a stable cell line expressing this recombinant receptor have impaired the development of tools necessary to establish its molecular pharmacology. We thus established a method for the functional study of new ligands. It is based upon the cotransfection in human melatonin receptor 1 (MT1)-overexpressing HEK293 cells of three plasmids encoding melanocortin receptor (MC5), neuropeptide Y5 receptor (NPY5) and a cyclic AMP response element-controlled luciferase. Once challenged with αMSH, the MC5 receptor activates the cyclic AMP response, through the coupling protein subunit Gs. In contrast, NPY5 agonists, through the NPY5 receptor which is negatively coupled to the same pathway, counteract the αMSH-mediated effect on cyclic AMP level. Using appropriate controls, this method can pinpoint compounds with antagonistic activity. Simple and straightforward, this system permits reproducible measurements of agonist or antagonist effects in the presence of neuropeptide Y, the natural agonist. This method has the advantage over already existing methods and beyond its apparent complexity, to enhance the cyclic AMP concentration at a ‘physiological’ level, by opposition to a forskolin-induced adenylate cyclase activation. Finally, to further validate this assay, we showed results from (1) a series of natural peptidic agonists that permitted the standardization and (2) a series of potent nonpeptidic antagonists (affinity >10−9 M) that form a new class of active NPY5 receptor antagonists.

Our aim was to specify the 5-HT2 subtype selectivity of EGIS-7625 (1-benzyl-4-[(2-nitro-4-methyl-5-amino)-phenyl]-piperazine), a new 5-HT2B ligand, in receptor binding studies and characterize its pharmacology at 5-HT2A, 5-HT2B and 5-HT2C receptors in in vivo experiments and in isolated organs, in vitro. EGIS-7625 had high affinity for recombinant human 5-HT2B receptors (pK i = 9.0) but much weaker affinity for 5-HT2A and 5-HT2C receptors (pK i = 6.2 and 7.7, respectively). In the classic 5-HT2B test, EGIS-7625 produced a concentration-related parallel rightward shift in the concentration-response relationship for the 5-HT-induced smooth muscle constriction in rat stomach fundus strips with a pA2 of 9.4. On the other hand, EGIS-7625 was a weak competitive antagonist at 5-HT2A receptors as it shifted 5-HT-induced concentration-response curves to the right at high concentrations (pA2 = 6.7) in rabbit pulmonary artery strips. The m-chlorophenylpiperazine-induced hypomotility and hypophagia was only partially attenuated by EGIS-7625 even at a dose of 30 mg/kg i.p. while mianserin, a non-selective 5-HT antagonist was almost fully effective in these tests at 3 mg/kg i.p., suggesting weak antagonistic effect of EGIS-7625 at neuronal 5-HT2C receptors, in vivo. In conclusion, EGIS-7625 is a potent, selective and competitive 5-HT2B antagonist that seems to be a good research tool for the separation of the functional roles of vascular 5-HT2A and 5-HT2B receptors.

Amido derivatives 10-18 of the corresponding oxyamines were synthesised as melatoninergic ligands by the reaction of hydroxyphtalimide with the halogeno derivatives or the corresponding alcohols using Mitsunobu reaction conditions. The affinity of the compounds for chicken brain melatonin receptors and recombinant human MT(1) and MT(2) receptors was evaluated using 2-[125I]-iodomelatonin as the radioligand. Overall, the introduction of an oxygen atom in the amido chain was not a favourable parameter as the compounds were less potent than the corresponding deoxy derivatives. However, nanomolar compounds were obtained with the arylethyloxy derivatives (13c (R'=nPr), chicken brain, hMT(1), hMT(2), K(i) values: 4.8, 3.86, 2.4 nM, respectively) and the 2,7-dimethoxynaphthalene derivatives (17c (R'=nPr), chicken brain, hMT(1), hMT(2), K(i) values: 0.04, 0.13, 0.1 nM, respectively). The functional activity of these compounds was evaluated by the aggregation of melanophores in Xenopus laevis tadpoles and the potency was related to the affinity of the molecules for melatonin receptors. The compounds were found to be full agonists and compound 17a was 20-fold more potent than melatonin in this bioassay.

The neuropeptide Y Y5 receptor gene generates two splice variants, referred to here as Y5L (long isoform) and Y5S (short isoform). Y5L mRNA differs from Y5S mRNA in its 5′ end, generating a putative open reading frame with 30 additional nucleotides upstream of the initiator AUG compared with the Y5S mRNA. The purpose of the present work was to investigate the existence of the Y5L mRNA. The authenticity of this transcript was confirmed by isolating part of its 5′ untranslated region through 5′ rapid amplification of cDNA ends and analysing its tissue distribution. To study the initiation of translation on Y5L mRNA, we cloned the Y5L cDNA and two Y5L cDNA mutants lacking the first or the second putative initiation start codon. Transient expression of the three plasmids in COS-7 cells and saturation binding experiments using 125I-labelled polypeptide YY (PYY) as a ligand showed that initiation of translation on Y5L mRNA could start at the first AUG, giving rise to a Y5L receptor with an N-terminal 10-amino-acid extension when compared with the Y5S receptor. The human Y5L and Y5S receptor isoforms displayed similar affinity constants (1.3nM and 1.5nM respectively). [125I]PYY binding to COS-7 cells expressing either the Y5L or the Y5S isoform was inhibited with the same rank order of potency by a selection of six chemically diverse compounds: PYY>neuropeptide Y>pancreatic polypeptide>CGP71683A>Synaptic 34>Banyu 6. Comparison of the tissue distribution of Y5L and Y5S mRNAs, as determined by reverse transcription—PCR analysis, indicated that expression of Y5L mRNA occurs in a tissue-specific manner. Finally, we have shown that the two AUG triplets contained in the 5′ untranslated region of Y5L mRNA did not affect receptor expression.

Melanin-concentrating hormone (MCH) is a cyclic peptide, mainly involved in the regulation of skin pigmentation in teleosts and feeding behavior in mammals. The human keratinocyte SVK14 cell line has been previously shown to express binding sites for the MCH analog [125I]-[Phe13,3-iodo-Tyr19]MCH. We report here that: (1) this binding site similarly recognized [125I]-[3-iodo-Tyr13]MCH; (2) its pharmacological profile clearly differed from those observed at the two human MCH receptor subtypes, MCH1-R and MCH2-R; (3) MCH did not induce any effect on second messenger systems (including cAMP, calcium, and MAP kinase signaling pathways), and (4) no mRNAs corresponding to the MCH receptors were found. In conclusion, the binding site characterized in the SVK14 cell line is distinct from the MCH1 and MCH2 receptors and deserves therefore further investigation.

The Aurora family of serine/threonine kinases is essential for mitosis. Their crucial role in cell cycle regulation and aberrant expression in a broad range of malignancies have been demonstrated and have prompted intensive search for small molecule Aurora inhibitors. Indeed, over 10 of them have reached the clinic as potential anticancer therapies. We report herein the discovery and optimization of a novel series of tricyclic molecules that has led to SAR156497, an exquisitely selective Aurora A, B, and C inhibitor with in vitro and in vivo efficacy. We also provide insights into its mode of binding to its target proteins, which could explain its selectivity.

The neurohormone melatonin is the central switch of the circadian rhythm and presumably exerts its activities through a series of receptors among which MT1 and MT2 have been widely studied. The third binding site of melatonin, MT3, has been recently characterized as a melatonin-sensitive form of the quinone reductase 2 (QR2, EC 1.6.99.2). In the present work, we showed that the binding of melatonin at MT3/QR2 was better described with 2-[125I]-iodomethoxy-carbonylamino-N-acetyltryptamine (2-[125I]-I-MCA-NAT) and, most importantly, that it was measurable at 20 degrees while it has been initially described and thoroughly studied using 2-[125I]-iodomelatonin at 4 degrees. Under these novel conditions, binding to MT3 could be traced without cross-reactivity with MT1 and MT2 receptors and, moreover, under conditions similar to those used to measure MT3/QR2 catalytic activity. The pharmacology established here on hamster kidney samples using the reference compounds remained essentially as already described using other experimental conditions. A new series of compounds with nanomolar affinity for the MT3 binding site and a high MT3 selectivity versus MT1 and MT2 is reported. In addition, we further document the MT3/QR2 binding site by demonstrating that it was widely distributed among mammals, although inter-species and inter-tissues differences exist. The present report details new experimental conditions for the pharmacological study of melatonin-sensitive QR2 isoforms, and suggests that, in addition to an already demonstrated inter-species difference, inter-tissues differences in QR2 sensitivity to melatonin may exist in primates and, therefore, represent an original and interesting route of investigation on the effect of melatonin on MT3/QR2.

Several series of low-molecular-mass ligands of the neuropeptide receptor subtype Y5 were prepared using a mixed strategy of synthesis on solid phase and in solution. Collections of single compounds were obtained by an automated parallel procedure which allowed quick variation and investigation of the central spacer moiety, as well as of the aromatic substituents on each side. The strategy of parallel synthesis and screening of partially purified analogs helped to select rapidly potent and selective leads which displayed comparable antagonistic potency against neuropeptide Y activity on the Y5 receptor and better receptor selectivity than the original reference compounds.

The present study evaluated, via a combined electrophysiological and dialysis approach, the potential influence of serotonin (5-HT)2C as compared to 5-HT2A and 5-HT2B receptors on dopaminergic, adrenergic, and serotonergic transmission in frontal cortex (FCX). Whereas the selective 5-HT2A antagonist MDL100,907 failed to modify extracellular levels of dopamine (DA), noradrenaline (NA) or 5-HT simultaneously quantified in single dialysate samples of freely-moving rats, the 5-HT2B/5-HT2C antagonist SB206,553 dose-dependently increased levels of DA and NA without affecting those of 5-HT. This action was attributable to 5-HT2C receptor blockade inasmuch as the selective 5-HT2C antagonist SB242,084 likewise increased FCX levels of DA and NA, whereas the selective 5-HT2B antagonist SB204,741 was ineffective. Further, the preferential 5-HT2C receptor agonist Ro60-0175 dose-dependently depressed FCX levels of DA. The suppressive influence of 5-HT2C receptors on DA release was also expressed on mesolimbic and nigrostriatal dopaminergic pathways, in that levels of DA in nucleus accumbens and striatum were likewise reduced by Ro60-0175 and elevated, though less markedly, by SB206,553. In line with the above findings, Ro60-0175 dose-dependently decreased the firing rate of ventrotegmental dopaminergic and locus coeruleus (LC) adrenergic perikarya, whereas their activity was dose-dependently enhanced by SB206,553. Furthermore, SB206,553 transformed the firing pattern of ventrotegmental dopaminergic neurons into a burst mode. In contrast to SB206,553, MDL100,907 had little affect on the firing rate of dopaminergic or adrenergic neurons. In conclusion, as compared to 5-HT2A and 5-HT2B receptors, 5-HT2C receptors exert a tonic, suppressive influence on the activity of mesocortical — as well as mesolimbic and nigrostriatal — dopaminergic pathways, likely via indirect actions expressed at the level of their cell bodies. Frontocortical adrenergic, but not serotonergic, transmission is also tonically suppressed by 5-HT2C receptors. Synapse 36:205–221, 2000. © 2000 Wiley-Liss, Inc.

The novel benzopyranopyrrolidine and potential antipsychotic, S16924 ((+)-2-[[1-[2-(2,3-dihydrobenzo[ 1,4] dioxin-5-yloxy)-ethyl]-pyrrolidin-3yl]]-1-(4-fluoro-ph enyl)-ethanone), displays marked affinity for serotonin (5-HT)1A, 5-HT2A and dopamine D2 receptors. Herein, we show that it also possesses high affinity for the cloned, INI isoform of h5-HT2c receptors (pKi=8.28) stably expressed in CHO cells. Similarly, clozapine (8.04) was a potent ligand, whereas haloperidol (

Mirtazapine displayed marked affinity for cloned, human alpha2A-adrenergic (AR) receptors at which it blocked noradrenaline (NA)-induced stimulation of guanosine-5'-O-(3-[35S]thio)-triphosphate ([35S]-GTPgammaS) binding. Similarly, mirtazapine showed high affinity for cloned, human serotonin (5-HT)2C receptors at which it abolished 5-HT-induced phosphoinositide generation. Alpha2-AR antagonist properties were revealed in vivo by blockade of UK-14,304-induced antinociception, while antagonist actions at 5-HT2C receptors were demonstrated by blockade of Ro 60 0175-induced penile erections and discriminative stimulus properties. Mirtazapine showed negligible affinity for 5-HT reuptake sites, in contrast to the selective 5-HT reuptake inhibitor, citalopram. In freely moving rats, in the dorsal hippocampus, frontal cortex (FCX), nucleus accumbens and striatum, citalopram increased dialysate levels of 5-HT, but not dopamine (DA) and NA. On the contrary, mirtazapine markedly elevated dialysate levels of NA and, in FCX, DA, whereas 5-HT was not affected. Citalopram inhibited the firing rate of serotonergic neurons in dorsal raphe nucleus, but not of dopaminergic neurons in the ventral tegmental area, nor adrenergic neurons in the locus coeruleus. Mirtazapine, in contrast, enhanced the firing rate of dopaminergic and adrenergic, but not serotonergic, neurons. Following 2 weeks administration, the facilitatory influence of mirtazapine upon dialysate levels of DA and NA versus 5-HT in FCX was maintained, and the influence of citalopram upon FCX levels of 5-HT versus DA and NA was also unchanged. Moreover, citalopram still inhibited, and mirtazapine still failed to influence, dorsal raphe serotonergic neurons. In conclusion, in contrast to citalopram, mirtazapine reinforces frontocortical dopaminergic and corticolimbic adrenergic, but not serotonergic, transmission. These actions reflect antagonist properties at alpha2A-AR and 5-HT2C receptors.

Herein, we evaluate the interaction of the alpha(2)-AR antagonist, yohimbine, as compared to fluparoxan, at multiple monoaminergic receptors and examine their roles in the modulation of adrenergic, dopaminergic and serotonergic transmission in freely-moving rats. Yohimbine displays marked affinity at human (h)alpha(2A)-, halpha(2B)- and halpha(2C)-ARs, significant affinity for h5-HT(1A), h5-HT(1B), h5-HT(1D), and hD(2) receptors and weak affinity for hD(3) receptors. In [(35)S]GTPgammaS binding protocols, yohimbine exerts antagonist actions at halpha(2A)-AR, h5-HT(1B), h5-HT(1D), and hD(2) sites, yet partial agonist actions at h5-HT(1A) sites. In vivo, agonist actions of yohimbine at 5-HT(1A) sites are revealed by WAY100,635-reversible induction of hypothermia in the rat. In guinea pigs, antagonist actions of yohimbine at 5-HT(1B) receptors are revealed by blockade of hypothermia evoked by the 5-HT(1B) agonist, GR46,611. In distinction to yohimbine, fluparoxan shows only modest partial agonist actions at h5-HT(1A) sites versus marked antagonist actions at halpha(2)-ARs. While fluparoxan selectively enhances hippocampal noradrenaline (NAD) turnover, yohimbine also enhances striatal dopamine (DA) turnover and suppresses striatal turnover of 5-HT. Further, yohimbine decreases firing of serotonergic neurones in raphe nuclei, an action reversed by WAY100,635. Fluparoxan increases extracellular levels of DA and NAD, but not 5-HT, in frontal cortex. In analogy, yohimbine enhances FCX levels of DA and NAD, yet suppresses those of 5-HT, the latter effect being antagonized by WAY100,635. The induction by fluoxetine of FCX levels of 5-HT, DA, and NAD is potentiated by fluparoxan. Yohimbine likewise facilitates the influence of fluoxetine upon DA and NAD levels, but not those of 5-HT. In conclusion, the alpha(2)-AR antagonist properties of yohimbine increase DA and NAD levels both alone and in association with fluoxetine. However, in contrast to the selective alpha(2)-AR antagonist, fluparoxan, the 5-HT(1A) agonist actions of yohimbine suppress 5-HT levels alone and underlie its inability to augment the influence of fluoxetine upon 5-HT levels.

We have identified from human liver eight alpha(1A)-adrenoceptor (alpha(1A)-AR) splice variants that were also expressed in human heart, prostate and hippocampus. Three of these alpha(1A)-AR isoforms (alpha(1A-1)-AR, alpha(1A-2a)-AR and alpha(1A-3a)-AR) gave rise to receptors with seven transmembrane domains (7TMalpha(1A)-AR). The other five (alpha(1A-2b)-AR, alpha(1A-2c)-AR, alpha(1A-3c)-AR, alpha(1A-5)-AR and alpha(1A-6)-AR) led to truncated receptors lacking transmembrane domain VII (6TMalpha(1A)-AR). The 7TMalpha(1A)-AR isoforms transiently expressed in COS-7 cells bound [(3)H]prazosin with high affinity (K(d) 0.2 nM) and mediated a noradrenaline (norepinephrine)-induced increase in cytoplasmic free Ca(2+) concentration, whereas the 6TMalpha(1A)-AR isoforms were incapable of ligand binding and signal transduction. Immunocytochemical studies with N-terminal epitope-tagged alpha(1A)-AR isoforms showed that the 7TMalpha(1A)-AR isoforms were present both at the cell surface and in intracellular compartments, whereas the 6TMalpha(1A)-AR isoforms were exclusively localized within the cell. Interestingly, in co-transfected cells, each truncated alpha(1A)-AR isoform inhibited [(3)H]prazosin binding and cell-surface trafficking of the co-expressed 'original' 7TMalpha(1A-1)-AR. However, there was no modification of either the [(3)H]prazosin-binding affinity or the pharmacological properties of alpha(1A-1)-AR. Immunoblotting experiments revealed that co-expression of the alpha(1A-1)-AR with 6TMalpha(1A)-AR isoforms did not impair alpha(1A-1)-AR expression. Therefore the expression in human tissues of many truncated isoforms constitutes a new regulation pathway of biological properties of alpha(1A)-AR.

1. The purpose of this work was to verify the hypothesis that the rabbit ileum is a selective preparation for the NPY Y5 receptor by using new selective antagonists recently synthesized. Spontaneous contractions of the rabbit isolated ileum were recorded and binding experiments were performed in cells expressing the human NPY Y1, Y2, Y4 or Y5 receptor subtype. 2. NPY analogues produced a concentration-dependent transient inhibition of the spontaneous contractions of the rabbit ileum with the following order of potency hPP > rPP > PYY > or = [Leu31,-Pro34]-NPY > NPY >> NPY13-36. Pre-exposure to rPP, PYY, [Leu31,Pro34]-NPY or NPY (but not NPY13-36) inhibited the effect of subsequent administration of hPP suggesting cross-desensitization of the preparation. The apparent affinity of the various agonists studied was correlated to the affinity reported for the human Y4 receptor subtype (and to a lesser extent for the rat Y4 subtype) but not to the affinity for the Y5 receptor subtype. 3. BIBO 3304, a selective NPY Y1 receptor antagonist, and CGP 71683A, a selective NPY Y5 receptor antagonist, did not affect the response to hPP. JCF 109, another NPY Y5 receptor antagonist, produced an inhibition of the response to hPP but only at the highest dose tested (10 microM) which also, by itself, produced intrinsic inhibitory effects. 4. 1229U91, a non-selective ligand for Y1, Y2, Y4 and Y5 receptors with high affinity toward the Y1 and Y4 receptor subtypes, produced a concentration-dependent transient inhibition of the spontaneous contractions of the rabbit ileum and a dose-dependent inhibition of the response to hPP (apparent pKB: 7.2). 5. These results suggest that in the rabbit ileum, the NPY receptor involved in the inhibition of the spontaneous contractile activity is a NPY Y4 receptor subtype.

This study examined the activity of chemically diverse alpha2 adrenoceptor ligands at recombinant human (h) and native rat (r) alpha2A adrenoceptors compared with 5-HT1A receptors. First, in competition binding experiments at h alpha2A and h5-HT1A receptors expressed in CHO cells, several compounds, including the antagonists 1-(2-pyrimidinyl)piperazine (1-PP), (+/-)-idazoxan, benalfocin (SKF 86466), yohimbine and RX 821,002, displayed preference for h alpha2A versus h5-HT1A receptors of only 1.4-, 3.6-, 4-, 10- and 11-fold, respectively (based on differences in pKi values). Clonidine, brimonidine (UK 14304), the benzopyrrolidine fluparoxan and the guanidines guanfacine and guanabenz exhibited intermediate selectivity (22- to 31-fold) for h alpha2A receptors. Only the antagonist atipamezole and the agonist dexmedetomidine (DMT) displayed high preference for alpha2 adrenoceptors (1290- and 91-fold, respectively). Second, the compounds were tested for their ability to induce h5-HT1A receptor-mediated G-protein activation, as indicated by the stimulation of [35S]GTPgammaS binding. All except atipamezole and RX 821,002 exhibited agonist activity, with potencies which correlated with their affinity for h5-HT1A receptors. Relative efficacies (Emax values) were 25-35% for guanabenz, guanfacine, WB 4101 and benalfocin, 50-65% for 1-PP, (+/-)-idazoxan and clonidine, and over 70% for fluparoxan, oxymetazoline and yohimbine (relative to 5-HT = 100%). Yohimbine-induced [35S]GTPgammaS binding was inhibited by the selective 5-HT1A receptor antagonist WAY 100,635. In contrast, RX 821,002 was the only ligand which exhibited antagonist activity at h5-HT1A receptors, inhibiting 5-HT-stimulated [35S]GTPgammaS binding. Atipamezole, which exhibited negligeable affinity for 5-HT1A receptors, was inactive. Third, the affinities for r alpha2A differed considerably from the affinities for h alpha2A receptors whereas the affinities for r5-HT1A differed much less from the affinities for h5-HT1A receptors. This affected markedly the affinity ratios of certain compounds. For example, (+/-)-idazoxan was only 3.6-fold selective for h alpha2A versus h5-HT1A but 51-fold selective for r alpha2A versus r5-HT1A receptors. Conversely, yohimbine was tenfold selective for h alpha2A versus h5-HT1A adrenoceptors but 4.2-fold selective for r alpha2A versus r5-HT1A receptors. Nevertheless, both atipamezole and DMT were highly selective for both rat and human alpha2A versus rat or human 5-HT1A receptors. In conclusion, these data indicate that: (1) the agonist DMT and the antagonist atipamezole are the ligands of choice to distinguish alpha2-mediated from 5-HT1A-mediated actions, whilst several of the other compounds show only low or modest selectivity for alpha2A over 5-HT1A receptors; (2) caution should be exercised in experimental and clinical interpretation of the actions of traditionally employed alpha2 ligands, such as clonidine, yohimbine and (+/-)-idazoxan, which exhibit marked agonist activity at 5-HT1A receptors.

In our continuous efforts to identify and develop novel targeted cancer treatments, a new morpholino-thiazole scaffold active against PI3Kβ has been identified. This Letter reports the optimization of this compound class to develop PI3Kβ isoform-selective inhibitors with suitable pharmacological properties.

We have shown previously that neurotoxic venom secretory phospholipases A2 (sPLA2s) have specific receptors in brain membranes called N-type receptors that are likely to play a role in the molecular events leading to neurotoxicity of these proteins. The sPLA2 found in honey bee venom is neurotoxic and binds to this receptor with high affinity. In this paper, we have used a number of mutants of bee venom sPLA2 produced in Escherichia coli to determine the structural elements of this protein that are involved in its binding to N-type receptors. Mutations in the interfacial binding surface, in the Ca2+-binding loop and in the hydrophobic channel lead to a dramatic decrease in binding to N-type receptors, whereas mutations of surface residues localized in other parts of the sPLA2 structure do not significantly modify the binding properties. Neurotoxicity experiments show that mutants with low affinity for N-type receptors are devoid of neurotoxic properties, even though some of them retain high enzymatic activity. These results provide further evidence for the involvement of N-type receptors in neurotoxic processes associated with venom sPLA2s and identify the surface region surrounding the hydrophobic channel of bee venom sPLA2 as the N-type receptor recognition domain.

The accompanying multivariate analysis of the binding profiles of antiparkinson agents revealed contrasting patterns of affinities at diverse classes of monoaminergic receptor. Herein, we characterized efficacies at human (h)D(2SHORT(S)), hD(2LONG(L)), hD(3), and hD(4.4) receptors and at halpha(2A)-, halpha(2B)-, halpha(2C)-, and halpha(1A)-adrenoceptors (ARs). As determined by guanosine 5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPgammaS) binding, no ligand displayed "full" efficacy relative to dopamine (100%) at all "D(2)-like" sites. However, at hD(2S) receptors quinpirole, pramipexole, ropinirole, quinerolane, pergolide, and cabergoline were as efficacious as dopamine (E(max)100%); TL99, talipexole, and apomorphine were highly efficacious (79-92%); piribedil, lisuride, bromocriptine, and terguride showed intermediate efficacy (40-55%); and roxindole displayed low efficacy (11%). For all drugs, efficacies were lower at hD(2L) receptors, with terguride and roxindole acting as antagonists. At hD(3) receptors, efficacies ranged from 33% (roxindole) to 94% (TL99), whereas, for hD(4) receptors, highest efficacies (approximately 70%) were seen for quinerolane, quinpirole, and TL99, whereas piribedil and terguride behaved as antagonists and bromocriptine was inactive. Although efficacies at hD(2S) versus hD(2L) sites were highly correlated (r = 0.79), they correlated only modestly to hD(3)/hD(4) sites (r = 0.44-0.59). In [(35)S]GTPgammaS studies of halpha(2A)-ARs, TL99 (108%), pramipexole (52%), talipexole (51%), pergolide (31%), apomorphine (16%), and quinerolane (11%) were agonists and ropinirole and roxindole were inactive, whereas piribedil and other agents were antagonists. Similar findings were obtained at halpha(2B)- and halpha(2C)-ARs. Using [(3)H]phosphatidylinositol depletion, roxindole, bromocriptine, lisuride, and terguride displayed potent antagonist properties at halpha(1A)-ARs. In conclusion, antiparkinson agents display diverse agonist and antagonist properties at multiple subtypes of D(2)-like receptor and alpha(1)/alpha(2)-AR, actions, which likely contribute to their contrasting functional profiles.

A series of N-(2-phenylbenzofuran-3-yl) ethyl amide and N-(2-arylalkylbenzofuran-3-yl) ethyl amide derivatives were synthesized and evaluated as melatonin receptor ligands. The affinity of each compound for the two MT(1) and MT(2) melatonin receptor subtypes was determined by binding studies using 2-[(125)I]iodomelatonin on human embryonic kidney cell line HEK293 membrane homogenates. The intrinsic activity of the most interesting compounds was evaluated on the [(35)S]GTPgammaS binding assay. Introduction of a 2-phenyl substituent in the C-2 benzofuran position leads to an agonist compound, 10q, which binds more strongly than melatonin itself to both MT(1) and MT(2) subtypes. On the other hand, a 2-benzyl group in the same position allows MT(2) antagonist selective ligands to be obtained. The MT(2) selectivity and antagonist potency can be modulated with suitable modifications on the N-acyl and benzyl substituents, and the most selective compounds 10c and 19 show affinity ratios of 123 and 192, respectively, and bind to the MT(2) subtype similarly to melatonin itself (0.1 nM). Nevertheless, 10c acts as an MT(1) and MT(2) antagonist, whereas 19 is a partial agonist.

Melanin-concentrating hormone (MCH) is a cyclic neuropeptide of nineteen amino acids in mammals. Its involvement in the feeding behaviour has been well established during the last few years. A first receptor subtype, now termed MCH1R, was discovered in 1999, following the desorphanisation of the SLC1 orphan receptor, using either reverse pharmacology or systematic screening of agonist candidates. A second MCH receptor, MCH2R, has been discovered recently, by several groups working on data mining of genomic banks. The molecular pharmacology of these two receptors is only described on the basis of the action of peptides derived from MCH. The present review tentatively summarizes the knowledge on these two receptors and presents the first attempts to discover new classes of antagonists that might have major roles in the control of obesity and feeding behaviour.Key words: melanin-concentrating hormone, melanin-concentrating hormone receptor, SLC-1, food intake, obesity.

Disruption of the interaction between p53 and MDM2 with small molecules, and subsequent reactivation of p53, is an attractive treatment strategy for p53 wild-type tumors that has shown striking pre-clinical activity in models exhibiting genomic amplification of the MDM2 gene. However, MDM2 amplified tumors represent only a small proportion of the p53 wild-type tumor population, and single agent regressions may be limited outside of the MDM2 amplified context. In order to increase the potential clinical benefit of MDM2-p53 protein-protein interaction (PPI) inhibitors beyond tumors exhibiting amplification of MDM2, we performed an enhancer library combination screen to identify optimal combination partners for MDM2-p53 PPI inhibitors in p53 wild-type, MDM2 non-amplified tumor cells. The MDM2-p53 PPI inhibitor SAR405838 and a related molecule were examined in combination with an enhancer library of 200 oncology drugs representing a broad molecular diversity of targets across a panel of twenty p53 wild-type cancer cell lines. Analysis results showed that MEK inhibitors were the most statistically significant synergistic combination partners in this screen, with synergy observed in cell lines harboring mutations that activated MAP kinase pathway signaling. These synergy results were validated in independent experiments using the ray design methodology, and extended to multiple K-ras, N-ras and B-raf mutant contexts in vitro. In K-ras, N-ras or B-raf mutant cell lines, the combination of SAR405838 with the MEK inhibitor pimasertib resulted in p53 pathway activation, inhibition of pERK levels, induction of the apoptotic mediators PUMA and BIM, induction of phosphatidyl serine exposure, and induction of caspase activity. In the Ras/Raf wild-type cell line MCF7, no synergy was observed. In cell line and patient-derived xenografts in vivo, the combination of SAR405838 and pimasertib resulted in greater anti-tumor activity than single agents and induced regression in K-ras, N-ras and B-raf mutant tumor models derived from different tissue types, including complete regressions in multiple models. These data indicate that MEK inhibitors synergize with MDM2-p53 PPI inhibitors in tumor models that exhibit activated MAP kinase pathway signaling and p53 wild-type status. Given the relative lack of overlapping clinically significant toxicities of MDM2-p53 PPI inhibitors and MEK inhibitors, such a combination merits further investigation for the treatment of K-ras, N-ras, or B-raf mutant, p53 wild-type tumors, representing a large patient population with significant unmet medical need. Citation Format: Isabelle Meaux, Jean-Paul Nicolas, Steve Rowley, Sukhvinder Sidhu, Francoise Herve, Laurent Dassencourt, Fanny Windenberger, Dimitri Gorge-Bernat, Pascal Pannier, Donald Bergstrom, Laurent Debussche, James Watters. Disruption of the MDM2-p53 interaction synergizes with MEK inhibition to induce cell death and promote tumor regression in p53 wild-type, Ras or Raf-mutant tumor models. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 805. doi:10.1158/1538-7445.AM2014-805

Conformationally restricted phenalene and acenaphthene derivatives 5 were synthesized from phenalen-1-one and acenaphthen-1-one derivatives using the Horner-Emmons reaction. The amines were prepared through the corresponding isocyanates by the Curtius reaction on the acids or by the reduction of the nitriles. Amido derivatives (R(3) = Me, Et, n-Pr, c-Pr) were prepared by acylation of the amines with the appropriate anhydrides or acid chlorides or by the reductive acylation of the nitriles. The affinities of the compounds for melatonin binding sites were evaluated in vitro in binding assays using chicken brain melatonin and the human mt(1) and MT(2) receptors expressed in HEK-293 cells. The functionality of the compounds was determined by the potency to lighten the skin of Xenopus laevis tadpoles. Highly potent compounds were obtained. The data highlighted the role of the methoxy group located in the ortho position to the ethylamido chain as compounds with picomolar affinities such as 14c were obtained (chicken brain, hmt(1), hMT(2) K(i) values = 0.02, 0.008, 0.069 nM, respectively). Compound 14c was equipotent to the corresponding dimethoxy derivative 15c (chicken brain, hmt(1), hMT(2) K(i) values = 0.07, 0.016, 0.1 nM, respectively). On the other hand, the restricted conformation of the amido chain did not influence selectivity for the cloned hmt(1) and hMT(2) receptors. These compounds were also potent agonists of melanophore aggregation in X. laevis. 15a,c were several hundred fold more potent than melatonin (EC(50) = 0.025, 0.004 nM, respectively). Conformational studies indicated that the minimum energy folded conformation of the ethylamido chain could constitute the putative active form in the receptor site in agreement with previous results.

Focused small libraries of melatonin receptor ligands from arylalkylamine derivatives were synthesised by combinatorial chemistry using the mix and split method in the solid phase. A library of 108 compounds was then synthesised from 12 arylalkyl amines and nine carboxylic acids. The compound mixtures were evaluated on chicken brain melatonin and recombinant human mt1 and MT2 receptors. Deconvolution of the most potent mixture demonstrated the superiority of 3-methoxy and 2,5-dimethoxy substitution on the phenyl ring with isopropyl, propyl and ethyl amido chains. Several compounds with nanomolar affinity for human melatonin receptors were obtained.

The screening of combinatorial libraries requires a deconvolution procedure to obtain, in fine, the most active compound of the starting library. The standard screening assays used in regular molecular pharmacology, have been poorly assessed when transposed to combinatorial chemistry-related experiments, particularly those involving large numbers of chemicals in a single assay. One key issue is the effect of the inactive analogs on the identification of the active ligand in mixtures. We chose melatonin receptors to measure the apparent affinity of a single ligand when tested alone or in mixtures of non-peptide low molecular weight compounds. Using ligands with IC50 from the micro- to the picomolar range, mixed with increasingly complex mixtures of 5 to 20 or 25 inactive compounds, we analyzed the displacements from the mt1 and MT2 melatonin receptor subtypes of the radioligand 2-iodomelatonin (KD= 25 pmol/l and 200 pmol/l, respectively) . The behavior of equimolar mixtures in displacement curves led to the conclusion that the observed binding affinity reflects the dilution effect of mixing the active component with inactive compounds but does not reveal noticeable interactions which would interfere with the binding process. From the practical point of view, the concentrations of the active species in the binding assay should be large enough to displace significantly the radioligand, a requirement which may be limited by the solubility of the ligand mixtures. In contrast, previous observations with peptide libraries report that the dilution effect is often compensated by additive or synergic action of structurally related analogs, thus making possible the deconvolution of very large (typically up to 10(7) compounds) peptide libraries.

Experiments were designed to determine the receptor subtype(s) involved in the contraction of the rat proximal colon to NPY. In this tissue, mRNA of Y 2 and Y 4 NPY receptor subtypes were highly expressed, whereas Y 5 mRNA levels were very low and Y 1 mRNA levels were intermediate. NPY analogues induced contractions with the following order of potency: rPP>hPP=PYY=NPY=[Leu 31 , Pro 34 ]NPY>NPY (2–36) =[ d -Trp 32 ]NPY>NPY (13–36) . Responses to NPY, PYY and NPY (13–36) were not or partially affected by tetrodotoxin, in contrast to the responses to [Leu 31 ,Pro 34 ]NPY, rPP, hPP and [ d -Trp 32 ]NPY which were fully blocked. Atropine did not inhibit the contractions to NPY, PYY and [Leu 31 ,Pro 34 ]NPY but significantly affected those to NPY (13–36) , [ d -Trp 32 ]NPY, rPP and hPP. The specific Y 1 receptor antagonist BIBP 3226 was ineffective but JCF 104 and JCF 105 (two compounds with preferential affinity toward the hY 5 receptor versus the hY 1 or hY 2 receptor) abolished the contractions provoked by the NPY analogues. These results suggest that NPY activates three receptor subtypes, a Y 2 subtype possibly by a direct action on the smooth muscle cells, as well as a Y 4 and a Y 5 (or `Y 5 -like') subtype which, respectively, release acetylcholine and an unknown neurotransmitter.

Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase belonging to the insulin receptor superfamily. Activating mutations in ALK are oncogenic and cause 10% to 15% of neuroblastoma cases. Similarly, activating ALK fusions have been detected in several cancers, including ALCL (NPM-ALK in 70% of patients) and NSCLC (EML4-ALK in 3% to 7% of patients). Several ALK inhibitors are currently undergoing clinical development, among which crizotinib has recently received marketing approval from the U.S. FDA under the name Xalkori. This nonselective ALK inhibitor has provided clinical benefit to lung cancer patients, but its sustained efficacy seems to be impaired by acquired drug resistance and several publications have already described ALK secondary mutations identified in patients who progressed while on crizotinib therapy. In this study, we have: Identified EML4-ALK mutations able to confer resistance to crizotinib. A screen using the Ba/F3 system found 24 residues in the ALK kinase domain where mutations can cause crizotinib resistance. Some of these mutations (L1152R, C1156Y, F1174L, G1202R, S1206F) have been identified in lung cancer patients progressing under crizotinib treatment Evaluated the activity of novel in-house and reference ALK kinase inhibitors against Ba/F3 cell lines stably expressing wild-type EML4-ALK and selected crizotinib-allele resistant mutantsPerformed in vivo head to head studies with a representative in-house ALK inhibitor and crizotinib to compare their pharmacodynamic properties This work resulted in the identification of an ALK kinase inhibitor with similar potency against wild-type EML4-ALK and crizotinib-allele resistant mutants and displaying significant target coverage in in vivo settings.

SAR125844 is a potent MET kinase inhibitor for intravenous (IV) administration, with nanomolar activity against the wild-type enzyme (IC50 = 4.2 nM) and some kinase domain mutants, such as M1250T and Y1235D. It is highly selective for MET kinase in a panel of 275 kinases tested, with only 5 other protein kinases inhibited at IC50 values below 300 nM. In cellular assays, SAR125844 inhibits MET autophosphorylation at the nanomolar range (IC50 from 1.4 to 5.1 nM), translating into antiproliferative activity selectively in MET-driven cell lines such as MET-amplified cell lines, with IC50 values in the low nanomolar range and induction of apoptosis. SAR125844 induces a G1 block in the two MET-amplified tumor cell lines tested. Moreover, the compound is also able to inhibit HGF-induced cell migration in PC-3 prostate tumor cell line. In two MET-amplified human gastric tumor xenograft models tested, SNU-5 and Hs 746T, SAR125844 intravenous treatment leads to potent impact on the MET signaling pathway in a dose and time dependent manner, with potent inhibition of MET autophosphorylation, as well as a significant effect on downstream PI3K/AKT and RAS/MAPK pathways. As a single agent, this translates into a dose-dependent antitumor activity in these two xenograft models, with tumor stasis at the lowest active dose and tumor regression at the highly active doses. High loading single dose administration of SAR125844 using a nanosuspension formulation allowed a sustained P-MET inhibition in tumors up to 7 days. In all models, antitumor activity was achieved at well tolerated doses without significant effect on body weight. The observed correlation between P-MET inhibition in the tumor and antitumor activity in preclinical settings suggests that P-MET evaluation in tumor biopsies could be a direct pharmacodynamic biomarker of SAR125844 activity in patients. In order to investigate whether a non-invasive biomarker could also be used as pharmacodynamic read-out, we measured shed-MET (soluble extracellular domain of the MET receptor) in the plasma of tumor-bearing mice and showed that its level correlates with tumor burden in 2 MET-amplified xenograft models. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 845. doi:1538-7445.AM2012-845

Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase belonging to the insulin receptor superfamily. Activating mutations in ALK are oncogenic and cause 10 to 15% of neuroblastoma cases. Similarly, activating ALK fusions have been detected in several cancers, including ALCL (NPM-ALK in 70% of patients) and NSCLC (EML4-ALK in 3–7% of patients). ALK inhibitors from different compound classes and kinase selectivity profiles are currently undergoing clinical development, among which crizotinib has recently received marketing approval from the US FDA. This non-selective ALK inhibitor has provided clinical benefit to lung cancer patients, but its sustained efficacy seems to be impaired by acquired drug resistance and several publications have already described ALK secondary mutations identified in patients who progressed while on crizotinib therapy. In this study, we have used the Ba/F3 system to identify EML4-ALK mutations able to confer resistance to crizotinib. To this end, we have generated a cDNA library containing random mutations in EML4-ALK using an E. Coli strain deficient in DNA repair pathways. The library was then subcloned in a retroviral vector and used to infect Ba/F3 cells. The cells were plated in 96 well microplates at an appropriate dilution and allowed to grow in the presence of 500 nM of crizotinib. The resistant cells were cultured and EML4-ALK was sequenced. Overall, this screen identified mutations at 24 positions in the ALK kinase domain. Some of these mutations (L1152R, C1156Y, F1174L) correspond to the ones known to cause resistance in lung cancer patients treated with crizotinib. Ba/F3 cell lines stably expressing a selected number of the 24 mutations have been generated and used to evaluate the activity of in-house and reference ALK kinase modulators. This work has shown that several mutations known to activate ALK in neuroblastoma are also able to confer resistance to crizotinib. The Ba/F3 cell lines expressing EML4-ALK mutants have been useful tools to characterize the activity profile of a range of ALK kinase inhibitors and several of our in-house compounds have been identified as active against the crizotinib-allele resistant mutants. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B76.

Abnormal PI3K pathway activation plays a major role in cancer, as a result of either RTK activation or somatic mutations of major components of the pathway, including activating point mutations and amplification of the PIK3CA gene as well as loss of negative regulatory proteins such as PTEN. Most of the ATP-competitive PI3K inhibitors currently in clinical development inhibit all class I PI3K isoforms: however, several recent reports support the development of isoform-specific inhibitors. In particular, while PI3Kα specific inhibitors are predicted to inhibit growth of tumors with PIK3CA mutations, PTEN-deficient tumors have been shown to depend on PI3Kβ. In addition, isoform specific PI3K inhibitors may exhibit better safety profiles compared to pan-selective PI3K inhibitors, and thus may be easier to combine with other targeted or cytotoxic therapies. Here we report the discovery of ATP-competitive inhibitors with selectivity for PI3Kα, PI3Kα/mTOR, or PI3Kβ, which were identified and optimized by means of high-throughput screening and medicinal chemistry. These inhibitors exhibit biochemical IC50 values below 100 nM and good selectivity over other PI3K isoforms and a diverse panel of protein kinases. Cellular assays demonstrate that PI3Kα or PI3Kα/mTOR compounds inhibit phosphorylation of targets downstream of PI3K (Akt) and mTOR (S6 and p70S6 kinase) in the PI3Kα-activated MCF7 cell line, and that effects on PI3K pathway readouts are less pronounced in PC3 cells lacking PTEN. In contrast, PI3Kβ compounds potently inhibit phosphorylation of AKT (cellular IC50s < 200 nM) in the PTEN-deficient PC3 tumor cell line, and the most PI3Kβ-selective inhibitors are inactive on AKT phosphorylation in PI3Kα-activated H460 cells. In vivo pharmacodynamic analyses following oral administration of these isoform-selective inhibitors to mice bearing xenografted tumors demonstrate dose-dependent inhibition of phosphorylation of PI3K and mTOR effectors at well-tolerated doses. These results strongly argue for the development of isoform-selective PI3K inhibitors for the treatment of cancer patients harboring tumors with PTEN- deficient or PI3Kα-activated specific genotypes. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4475.

A 25. μg dose of prazosin infused over 2.0 min either intracerebroventricularly (i.c.v.) or intravenously (i.v.) in the chloralose—urethane-anasethetised cat produced a long-lasting fall in aortic blood pressure without significantly changing the heart rate. This effect appeared earlier and was significanlty more pronouced following i.v. than i.c.v. administration. However, the rate at which the decreased blood pressure returned to baseline level was independent of the route of administration. In the pithed cat both i.v. and i.c.v. prazosin significantly inhibited the increase in blood pressure, but not that in heart rate, elicited by spinal cord stimulation although a smaller inhibition was observed with the central route of injection. These experiments suggested a significant and rapid leakage of prazosin into the systemic circulation and this was confirmed when significant plasma prazosin levels were detected immediately after the central infusion of the compound. The peripheral availability of i.c.v. prazosin was estimated to be 48% of that obtained withe the same i.v. dose. These resutls suggest that the blood pressure lowering effects of i.v. and i.c.v. prazosin were probably due to an impairment of the sympathetic nervous system at the level of the postsynaptic vascular α-adrenoceptors. Furthermore, these findings indicte that certain compounds given i.c.v. may rapidly pass from the cerebrospinal fluid into the systemic circulation and produce peripheral pharmacological effects. Therefore, great discretion shold be used in employing this route of administration to study effects possibly mediated by the central nervous system. The monitoring of drug plasma and tissue concentrations after central administration is as important as are basic pharmacological tests which may not always be suitably sensitive or designed to detect all the possible peripheral actions of a centrally administered compound.