Alterations of the phosphoinositide-3 kinase (PI3K)/Akt signaling pathway occur broadly in cancer... more Alterations of the phosphoinositide-3 kinase (PI3K)/Akt signaling pathway occur broadly in cancer via multiple mechanisms including mutation of the PIK3CA gene, loss or mutation of phosphatase and tensin homolog(PTEN), and deregulation of mammaliantargetof rapamycin (mTOR) complexes. The dysregulation of this pathway has been implicated in tumor initiation, cell growth and survival, invasion and angiogenesis, thus, PI3K and mTOR are promising therapeutic targets for cancer. We discovered GDC-0980, a selective, potent, orally bioavailable inhibitor of Class I PI3 kinase and mTOR kinase (TORC1/2) with excellent pharmacokinetic and pharmaceuticalproperties. GDC-0980potently inhibitssignaltransductiondownstream of both PI3K and mTOR, as measured by pharmacodynamic (PD) biomarkers, thereby acting upon two key pathway nodes to produce the strongest attainable inhibition of signaling in the pathway. Correspondingly, GDC-0980waspotentacrossabroadpanelofcancercelllines,withthegreatestpotency...
Because the phosphatidylinositol 3-kinase (PI3K) signaling pathway plays a crucial role in many a... more Because the phosphatidylinositol 3-kinase (PI3K) signaling pathway plays a crucial role in many aspects of cell growth and survival, inhibitors of the pathway offer great potential in the treatment of cancer. We have recently reported the discovery of potent and orally bioavailable pan inhibitors of PI3K, including the inhibitor GDC-0941. As part of our continued interest in the design of novel PI3K inhibitors, we embarked on a program to further probe key binding pockets in PI3K as well as increase structural diversity of our inhibitors. Through structure based design driven by crystallography in PI3Kgamma and systematic modification of our lead chemical series, new inhibitors that take advantage of alternative binding interactions in the PI3K ATP site have been identified. Because of the enhanced affinity of some new interactions, potent (IC50-p110a Citation Information: In: Proc Am Assoc Cancer Res; 2009 Apr 18-22; Denver, CO. Philadelphia (PA): AACR; 2009. Abstract nr 2707.
Inhibitors of the Class I phosphoinositide 3-kinase (PI3K) isoform PI3Kα have received substantia... more Inhibitors of the Class I phosphoinositide 3-kinase (PI3K) isoform PI3Kα have received substantial attention for their potential use in cancer therapy. Despite the particular attraction of targeting PI3Kα, achieving selectivity for the inhibition of this isoform has proved challenging. Herein we report the discovery of inhibitors of PI3Kα that have selectivity over the other Class I isoforms and all other kinases tested. In GDC-0032 (3, taselisib), we previously minimized inhibition of PI3Kα relative to the other Class I insoforms. Subsequently, we extended our efforts to identify PI3Kα-specific inhibitors using PI3Kα crystal structures to inform the design of benzoxazepin inhibitors with selectivity for PI3Kα through interactions with a non-conserved residue. Several molecules selective for PI3Kα relative to the other Class I isoforms, as well as other kinases, were identified. Optimization of properties related to drug metabolism then culminated in the identification of the clinic...
Modifications of the phosphoinositide-3 kinase (PI3K)/Akt signaling pathway are frequent in cance... more Modifications of the phosphoinositide-3 kinase (PI3K)/Akt signaling pathway are frequent in cancer due to multiple mechanisms, including activating mutations of the alpha isoform of PI3K. The dysregulation of this pathway has been implicated in many processes involved in oncogenesis. Thus, PI3K is a promising therapeutic target for cancer. Previously we have disclosed GDC-0941, a class 1 selective PI3K inhibitor and our class 1 PI3K/mTOR kinase inhibitor, GDC-0980. In this presentation we describe the design and discovery of a new class of PI3K inhibitors, which selectively inhibit the activated PI3Kα isoform relative to the PI3Kβ isoform. A lead was identified from a high throughput screen (HTS) that resulted in a novel chemical series of kinase inhibitors. Through a structure-based approach, this lead was optimized to provide very potent inhibitors of PI3K. In addition, this chemical series allowed for designing molecules that have different selectivity patterns with respect to th...
Alterations of the phosphoinositide-3 kinase (PI3K)/Akt signaling pathway occur broadly in cancer... more Alterations of the phosphoinositide-3 kinase (PI3K)/Akt signaling pathway occur broadly in cancer via multiple mechanisms including mutation of the PIK3CA gene, loss or mutation of phosphatase and tensin homolog (PTEN), and deregulation of mammalian target of rapamycin (mTOR) complexes. The dysregulation of this pathway has been implicated in tumor initiation, cell growth and survival, invasion and angiogenesis, thus, PI3K and mTOR are promising therapeutic targets for cancer. We discovered GDC-0980, a selective, potent, orally bioavailable inhibitor of Class I PI3 kinase and mTOR kinase (TORC1/2) with excellent pharmacokinetic and pharmaceutical properties. GDC-0980 potently inhibits signal transduction downstream of both PI3K and mTOR, as measured by pharmacodynamic (PD) biomarkers, thereby acting upon two key pathway nodes to produce the strongest attainable inhibition of signaling in the pathway. Correspondingly, GDC-0980 was potent across a broad panel of cancer cell lines, wit...
Introduction: The phosphoinositide-3 kinase (PI3K)/Akt signaling pathway is deregulated in a wide... more Introduction: The phosphoinositide-3 kinase (PI3K)/Akt signaling pathway is deregulated in a wide variety of cancers. Somatic activating mutations and amplifications in PI3K are common in multiple cancers including breast, colon, and lung cancer. PTEN, a phosphatase that converts PIP3 to PIP2 and thus has an opposing function to PI3K, is a commonly mutated tumor suppressor in multiple cancers including prostate and glioblastoma. Alterations of this pathway have been implicated in tumor initiation, progression, survival, angiogenesis, and metastasis. PI3K/Akt pathway activation has also been implicated in therapeutic resistance. Thus PI3K is considered to be a promising therapeutic target for cancer. Summary of Results: Medicinal chemistry efforts resulted in the discovery of GDC-0980, a selective, orally bioavailable inhibitor of PI3 Kinase and mTOR kinase with promising pharmacokinetic and pharmaceutical properties. Here we report the first pre-clinical profile of GDC-0980. This co...
The phosphatidylinositol-3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathw... more The phosphatidylinositol-3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathway plays a key role in the regulation of cellular growth, survival, and proliferation. Inappropriate activation of the pathway as a result of mutations and amplifications has been implicated in a variety of human cancers. Pathway dysregulation drives tumorigenesis through phosphorylation of proteins that directly regulate protein synthesis, cell cycle, and metabolism. The complexity of the mTOR and PI3K pathways, which include two functionally distinct mTOR complexes, feedback loops, and parallel regulatory pathways, clearly invokes a need for functional assays that can clarify the mechanism of action for drugs targeting mTOR and PI3K either as single agents or in combination. In this work, we used three different types of cell based assays to investigate the effects of PI3K versus mTORc1 inhibition on signaling pathways, cell cycle, and autophagy. The first set of assays differentiates ...
The PI3K/AKT/mTOR pathway has been shown to play an important role in cancer. Starting with compo... more The PI3K/AKT/mTOR pathway has been shown to play an important role in cancer. Starting with compounds 1 and 2 (GDC-0941) as templates, (thienopyrimidin-2-yl)aminopyrimidines were discovered as potent inhibitors of PI3K or both PI3K and mTOR. Structural information derived from PI3Kγ-ligand cocrystal structures of 1 and 2 were used to design inhibitors that maintained potency for PI3K yet improved metabolic stability and oral bioavailability relative to 1. The addition of a single methyl group to the optimized 5 resulted in 21, which had significantly reduced potency for mTOR. The lead compounds 5 (GNE-493) and 21 (GNE-490) have good pharmacokinetic (PK) parameters, are highly selective, demonstrate knock down of pathway markers in vivo, and are efficacious in xenograft models where the PI3K pathway is deregulated. Both compounds were compared in a PI3KR mutated MCF7.1 xenograft model and were found to have equivalent efficacy when normalized for exposure.
Inhibition of PI3Kδ is considered to be an attractive mechanism for the treatment of inflammatory... more Inhibition of PI3Kδ is considered to be an attractive mechanism for the treatment of inflammatory diseases and leukocyte malignancies. Using a structure-based design approach, we have identified a series of potent and selective benzimidazole-based inhibitors of PI3Kδ. These inhibitors do not occupy the selectivity pocket between Trp760 and Met752 that is induced by other families of PI3Kδ inhibitors. Instead, the selectivity of the compounds for inhibition of PI3Kδ relative to other PI3K isoforms appears to be due primarily to the strong interactions these inhibitors are able to make with Trp760 in the PI3Kδ binding pocket. The pharmacokinetic properties and the ability of compound 5 to inhibit the function of B-cells in vivo are described.
PI3Kδ is a lipid kinase and a member of a larger family of enzymes, PI3K class IA(α, β, δ) and IB... more PI3Kδ is a lipid kinase and a member of a larger family of enzymes, PI3K class IA(α, β, δ) and IB (γ), which catalyze the phosphorylation of PIP2 to PIP3. PI3Kδ is mainly expressed in leukocytes, where it plays a critical, nonredundant role in B cell receptor mediated signaling and provides an attractive opportunity to treat diseases where B cell activity is essential, e.g., rheumatoid arthritis. We report the discovery of novel, potent, and selective PI3Kδ inhibitors and describe a structural hypothesis for isoform (α, β, γ) selectivity gained from interactions in the affinity pocket. The critical component of our initial pharmacophore for isoform selectivity was strongly associated with CYP3A4 time-dependent inhibition (TDI). We describe a variety of strategies and methods for monitoring and attenuating TDI. Ultimately, a structure-based design approach was employed to identify a suitable structural replacement for further optimization.
Novel arylpiperazines were identified as alpha 1-adrenoceptor (AR) subtype-selective antagonists ... more Novel arylpiperazines were identified as alpha 1-adrenoceptor (AR) subtype-selective antagonists by functional in vitro screening. 3-[4-(ortho-Substituted phenyl)piperazin-1-yl]propylamines were derivatized with N,N-dimethyl anthranilamides, nicotinamides, as well as carboxamides of quinoline, 1,8-naphthyridine, pyrazolo[3,4-b]pyridine, isoxazolo[3,4-b]pyridine, imidazo[4,5-b]pyridine, and pyrazolo[1,5-a]pyrimidines. Strips of rabbit bladder neck were employed as a predictive assay for antagonism in the human lower tract. Rings of rat aorta were used as a "negative screen" for the test antagonists. Binding to alpha 1-ARs was relatively sensitive to size and electronic features of the arylpiperazine portion of the antagonists and permissive to these features on the heteroaryl carboxamide side. These structure-affinity findings were exploited to produce nicotinamides (e.g. 13ii and 25x) and pyrazolo[3,4-b]pyridines (e.g. 37f and 37y) ligands with nanomolar affinity at the alpha 1-AR subtype prevalent in the human lower urinary tract(pA2 values: 8.8, 10.7, 9.3, and 9.9, respectively) and displaying 2-3 orders of magnitude selectivity over the alpha 1D-AR.
We have isolated and characterized from human prostate novel splice variants of the human α1A‐adr... more We have isolated and characterized from human prostate novel splice variants of the human α1A‐adrenoceptor, several of which generate truncated products and one isoform, α1A‐4, which has the identical splice site as the three previously described isoforms. Long‐PCR on human genomic DNA showed that the α1A‐4 exon is located between those encoding the α1A‐1 and α1A‐3 variants. CHO‐K1 cells stably expressing α1A‐4 showed ligand binding properties similar to those of the other functional isoforms as well as agonist‐stimulated inositol phosphate accumulation. Quantitative PCR analyses revealed that α1A‐4 is the most abundant isoform expressed in the prostate with high levels also detected in liver and heart.
The recombinant a-adrenoceptor displays a distinct pharmacological profile 'classical a-adrenocep... more The recombinant a-adrenoceptor displays a distinct pharmacological profile 'classical a-adrenoceptor' in homogenate binding 1L 1A All rights reserved.
PI3 Kinase and mTOR have been identified as promising targets for the treatment of cancer. These ... more PI3 Kinase and mTOR have been identified as promising targets for the treatment of cancer. These enzymes participate in related, but not redundant, signaling networks to transmit cellular growth and survival signals, which are hallmarks of tumor growth. An interest in targeting both of these two important points along this critical signaling pathway, and the ability to leverage the high degree of structural similarity in the active sites of PI3K and mTOR kinase, has resulted in the discovery of GDC-0980 as a Class I PI3K and mTOR kinase inhibitor for oncology indications. The structure, efficacy, and medicinal chemistry behind the discovery of this compound is described. Beginning with the morpholin-4-yl-thieno[3,2-d]pyrimidine core of the Class I PI3K inhibitor GDC-0941, structural substitutions were made external to the core that added mTOR potency, improved the metabolic stability in vitro and in vivo, and lowered the plasma protein binding of the scaffold. Homology models of mTOR using PI3Kγ structures with bound inhibitors provided hypotheses for increasing mTOR potency relative to previous compounds. The solubility of the modified compounds was improved through the addition of polar functionality in the solvent exposed region of the scaffold, resulting in GDC-0980. GDC-0980 is potent across Class I isoforms with IC509s of 5, 27, 7, and 14 nM for PI3Kα, β, Δ, and γ, and inhibits mTOR with a Ki of 17 nM. The compound is highly selective versus a large panel of kinases including others in the PIK family. Based on the excellent PK profile, linear increase in exposure, strong potency in a broad range of cancer cells, and high free fraction, GDC-0980 is efficacious in animal models of cancer when dosed orally at low doses. Furthermore, this compound is efficacious when dosed intermittently as well as on a daily schedule. These preclinical data provide compelling support for GDC-0980 as a clinical candidate, and early stage clinical trials are underway. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2787. doi:10.1158/1538-7445.AM2011-2787
Three fully-de®ned a 1-adrenoceptors (a 1A , a 1B and a 1D) have been established in pharmacologi... more Three fully-de®ned a 1-adrenoceptors (a 1A , a 1B and a 1D) have been established in pharmacological and molecular studies. A fourth a 1-adrenoceptor, the putative a 1L-adrenoceptor, has been de®ned in functional but not molecular studies, and has been proposed to mediate contraction of human lower urinary tract tissues; its relationship to the three fully characterized a 1-adrenoceptors is not known. 2 In the present study, binding anities were estimated by displacement of [ 3 H]-prazosin in membrane homogenates of Chinese hamster ovary (CHO-K1) cells stably expressing the human a 1A-, a 1B-and a 1Dadrenoceptors and were compared with anity estimates obtained functionally in identical cells by measuring inhibition of noradrenaline (NA)-stimulated accumulation of [ 3 H]-inositol phosphates. 3 For the a 1A-adrenoceptor, binding studies revealed a pharmacological pro®le typical for the classically de®ned a 1A-adrenoceptor, such that prazosin, RS-17053, WB 4101, 5-methylurapidil, Rec 15/ 2739 and S-niguldipine all displayed subnanomolar anity. A dierent pro®le of anity estimates was obtained in inositol phosphates accumulation studies: prazosin, WB 4101, 5-methylurapidil, RS-17053 and S-niguldipine showed 10 to 40 fold lower anity than in membrane binding. However, anity estimates were not`frameshifted', as tamsulosin, indoramin and Rec 15/2739 yielded similar, high anity estimates in binding and functional assays. 4 In contrast, results from human a 1B-and a 1D-adrenoceptors expressed in CHO-K1 cells gave antagonist anity pro®les in binding and functional assays that were essentially identical. 5 A concordance of anity estimates from the functional (inositol phosphates accumulation) studies of the a 1A-adrenoceptor in CHO-K1 cells was found with estimates published recently from contractile studies in human lower urinary tract tissues (putative a 1L-adrenoceptor). These data show that upon functional pharmacological analysis, the cloned a 1A-adrenoceptor displays pharmacological recognition properties consistent with those of the putative a 1L-adrenoceptor. Why this pro®le diers from that obtained in membrane binding, and whether it explains the a 1L-adrenoceptor pharmacology observed in many native tissues, requires further investigation.
We investigated the cardiovascular effects of rilmenidine, moxonidine and clonidine in conscious ... more We investigated the cardiovascular effects of rilmenidine, moxonidine and clonidine in conscious wild‐type and D79N α2A‐adrenoceptor mice. The in vitro pharmacology of these agonists was determined at recombinant (human) α2‐adrenoceptors and at endogenous (dog) α2A‐adrenoceptors. In wild‐type mice, rilmenidine, moxonidine (100, 300 and 1000 μg kg−1, i.v.) and clonidine (30, 100 and 300 μg kg−1, i.v.) dose‐dependently decreased blood pressure and heart rate. In D79N α2A‐adrenoceptor mice, responses to rilmenidine and moxonidine did not differ from vehicle control. Clonidine‐induced hypotension was absent, but dose‐dependent hypertension and bradycardia were observed. In wild‐type mice, responses to moxonidine (1 mg kg−1, i.v.) were antagonized by the non‐selective, non‐imidazoline α2‐adrenoceptor antagonist, RS‐79948‐197 (1 mg kg−1, i.v.). Affinity estimates (pKi) at human α2A‐, α2B‐ and α2C‐adrenoceptors, respectively, were: rilmenidine (5.80, 5.76 and 5.33), moxonidine (5.37, <5...
Alterations of the phosphoinositide-3 kinase (PI3K)/Akt signaling pathway occur broadly in cancer... more Alterations of the phosphoinositide-3 kinase (PI3K)/Akt signaling pathway occur broadly in cancer via multiple mechanisms including mutation of the PIK3CA gene, loss or mutation of phosphatase and tensin homolog(PTEN), and deregulation of mammaliantargetof rapamycin (mTOR) complexes. The dysregulation of this pathway has been implicated in tumor initiation, cell growth and survival, invasion and angiogenesis, thus, PI3K and mTOR are promising therapeutic targets for cancer. We discovered GDC-0980, a selective, potent, orally bioavailable inhibitor of Class I PI3 kinase and mTOR kinase (TORC1/2) with excellent pharmacokinetic and pharmaceuticalproperties. GDC-0980potently inhibitssignaltransductiondownstream of both PI3K and mTOR, as measured by pharmacodynamic (PD) biomarkers, thereby acting upon two key pathway nodes to produce the strongest attainable inhibition of signaling in the pathway. Correspondingly, GDC-0980waspotentacrossabroadpanelofcancercelllines,withthegreatestpotency...
Because the phosphatidylinositol 3-kinase (PI3K) signaling pathway plays a crucial role in many a... more Because the phosphatidylinositol 3-kinase (PI3K) signaling pathway plays a crucial role in many aspects of cell growth and survival, inhibitors of the pathway offer great potential in the treatment of cancer. We have recently reported the discovery of potent and orally bioavailable pan inhibitors of PI3K, including the inhibitor GDC-0941. As part of our continued interest in the design of novel PI3K inhibitors, we embarked on a program to further probe key binding pockets in PI3K as well as increase structural diversity of our inhibitors. Through structure based design driven by crystallography in PI3Kgamma and systematic modification of our lead chemical series, new inhibitors that take advantage of alternative binding interactions in the PI3K ATP site have been identified. Because of the enhanced affinity of some new interactions, potent (IC50-p110a Citation Information: In: Proc Am Assoc Cancer Res; 2009 Apr 18-22; Denver, CO. Philadelphia (PA): AACR; 2009. Abstract nr 2707.
Inhibitors of the Class I phosphoinositide 3-kinase (PI3K) isoform PI3Kα have received substantia... more Inhibitors of the Class I phosphoinositide 3-kinase (PI3K) isoform PI3Kα have received substantial attention for their potential use in cancer therapy. Despite the particular attraction of targeting PI3Kα, achieving selectivity for the inhibition of this isoform has proved challenging. Herein we report the discovery of inhibitors of PI3Kα that have selectivity over the other Class I isoforms and all other kinases tested. In GDC-0032 (3, taselisib), we previously minimized inhibition of PI3Kα relative to the other Class I insoforms. Subsequently, we extended our efforts to identify PI3Kα-specific inhibitors using PI3Kα crystal structures to inform the design of benzoxazepin inhibitors with selectivity for PI3Kα through interactions with a non-conserved residue. Several molecules selective for PI3Kα relative to the other Class I isoforms, as well as other kinases, were identified. Optimization of properties related to drug metabolism then culminated in the identification of the clinic...
Modifications of the phosphoinositide-3 kinase (PI3K)/Akt signaling pathway are frequent in cance... more Modifications of the phosphoinositide-3 kinase (PI3K)/Akt signaling pathway are frequent in cancer due to multiple mechanisms, including activating mutations of the alpha isoform of PI3K. The dysregulation of this pathway has been implicated in many processes involved in oncogenesis. Thus, PI3K is a promising therapeutic target for cancer. Previously we have disclosed GDC-0941, a class 1 selective PI3K inhibitor and our class 1 PI3K/mTOR kinase inhibitor, GDC-0980. In this presentation we describe the design and discovery of a new class of PI3K inhibitors, which selectively inhibit the activated PI3Kα isoform relative to the PI3Kβ isoform. A lead was identified from a high throughput screen (HTS) that resulted in a novel chemical series of kinase inhibitors. Through a structure-based approach, this lead was optimized to provide very potent inhibitors of PI3K. In addition, this chemical series allowed for designing molecules that have different selectivity patterns with respect to th...
Alterations of the phosphoinositide-3 kinase (PI3K)/Akt signaling pathway occur broadly in cancer... more Alterations of the phosphoinositide-3 kinase (PI3K)/Akt signaling pathway occur broadly in cancer via multiple mechanisms including mutation of the PIK3CA gene, loss or mutation of phosphatase and tensin homolog (PTEN), and deregulation of mammalian target of rapamycin (mTOR) complexes. The dysregulation of this pathway has been implicated in tumor initiation, cell growth and survival, invasion and angiogenesis, thus, PI3K and mTOR are promising therapeutic targets for cancer. We discovered GDC-0980, a selective, potent, orally bioavailable inhibitor of Class I PI3 kinase and mTOR kinase (TORC1/2) with excellent pharmacokinetic and pharmaceutical properties. GDC-0980 potently inhibits signal transduction downstream of both PI3K and mTOR, as measured by pharmacodynamic (PD) biomarkers, thereby acting upon two key pathway nodes to produce the strongest attainable inhibition of signaling in the pathway. Correspondingly, GDC-0980 was potent across a broad panel of cancer cell lines, wit...
Introduction: The phosphoinositide-3 kinase (PI3K)/Akt signaling pathway is deregulated in a wide... more Introduction: The phosphoinositide-3 kinase (PI3K)/Akt signaling pathway is deregulated in a wide variety of cancers. Somatic activating mutations and amplifications in PI3K are common in multiple cancers including breast, colon, and lung cancer. PTEN, a phosphatase that converts PIP3 to PIP2 and thus has an opposing function to PI3K, is a commonly mutated tumor suppressor in multiple cancers including prostate and glioblastoma. Alterations of this pathway have been implicated in tumor initiation, progression, survival, angiogenesis, and metastasis. PI3K/Akt pathway activation has also been implicated in therapeutic resistance. Thus PI3K is considered to be a promising therapeutic target for cancer. Summary of Results: Medicinal chemistry efforts resulted in the discovery of GDC-0980, a selective, orally bioavailable inhibitor of PI3 Kinase and mTOR kinase with promising pharmacokinetic and pharmaceutical properties. Here we report the first pre-clinical profile of GDC-0980. This co...
The phosphatidylinositol-3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathw... more The phosphatidylinositol-3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathway plays a key role in the regulation of cellular growth, survival, and proliferation. Inappropriate activation of the pathway as a result of mutations and amplifications has been implicated in a variety of human cancers. Pathway dysregulation drives tumorigenesis through phosphorylation of proteins that directly regulate protein synthesis, cell cycle, and metabolism. The complexity of the mTOR and PI3K pathways, which include two functionally distinct mTOR complexes, feedback loops, and parallel regulatory pathways, clearly invokes a need for functional assays that can clarify the mechanism of action for drugs targeting mTOR and PI3K either as single agents or in combination. In this work, we used three different types of cell based assays to investigate the effects of PI3K versus mTORc1 inhibition on signaling pathways, cell cycle, and autophagy. The first set of assays differentiates ...
The PI3K/AKT/mTOR pathway has been shown to play an important role in cancer. Starting with compo... more The PI3K/AKT/mTOR pathway has been shown to play an important role in cancer. Starting with compounds 1 and 2 (GDC-0941) as templates, (thienopyrimidin-2-yl)aminopyrimidines were discovered as potent inhibitors of PI3K or both PI3K and mTOR. Structural information derived from PI3Kγ-ligand cocrystal structures of 1 and 2 were used to design inhibitors that maintained potency for PI3K yet improved metabolic stability and oral bioavailability relative to 1. The addition of a single methyl group to the optimized 5 resulted in 21, which had significantly reduced potency for mTOR. The lead compounds 5 (GNE-493) and 21 (GNE-490) have good pharmacokinetic (PK) parameters, are highly selective, demonstrate knock down of pathway markers in vivo, and are efficacious in xenograft models where the PI3K pathway is deregulated. Both compounds were compared in a PI3KR mutated MCF7.1 xenograft model and were found to have equivalent efficacy when normalized for exposure.
Inhibition of PI3Kδ is considered to be an attractive mechanism for the treatment of inflammatory... more Inhibition of PI3Kδ is considered to be an attractive mechanism for the treatment of inflammatory diseases and leukocyte malignancies. Using a structure-based design approach, we have identified a series of potent and selective benzimidazole-based inhibitors of PI3Kδ. These inhibitors do not occupy the selectivity pocket between Trp760 and Met752 that is induced by other families of PI3Kδ inhibitors. Instead, the selectivity of the compounds for inhibition of PI3Kδ relative to other PI3K isoforms appears to be due primarily to the strong interactions these inhibitors are able to make with Trp760 in the PI3Kδ binding pocket. The pharmacokinetic properties and the ability of compound 5 to inhibit the function of B-cells in vivo are described.
PI3Kδ is a lipid kinase and a member of a larger family of enzymes, PI3K class IA(α, β, δ) and IB... more PI3Kδ is a lipid kinase and a member of a larger family of enzymes, PI3K class IA(α, β, δ) and IB (γ), which catalyze the phosphorylation of PIP2 to PIP3. PI3Kδ is mainly expressed in leukocytes, where it plays a critical, nonredundant role in B cell receptor mediated signaling and provides an attractive opportunity to treat diseases where B cell activity is essential, e.g., rheumatoid arthritis. We report the discovery of novel, potent, and selective PI3Kδ inhibitors and describe a structural hypothesis for isoform (α, β, γ) selectivity gained from interactions in the affinity pocket. The critical component of our initial pharmacophore for isoform selectivity was strongly associated with CYP3A4 time-dependent inhibition (TDI). We describe a variety of strategies and methods for monitoring and attenuating TDI. Ultimately, a structure-based design approach was employed to identify a suitable structural replacement for further optimization.
Novel arylpiperazines were identified as alpha 1-adrenoceptor (AR) subtype-selective antagonists ... more Novel arylpiperazines were identified as alpha 1-adrenoceptor (AR) subtype-selective antagonists by functional in vitro screening. 3-[4-(ortho-Substituted phenyl)piperazin-1-yl]propylamines were derivatized with N,N-dimethyl anthranilamides, nicotinamides, as well as carboxamides of quinoline, 1,8-naphthyridine, pyrazolo[3,4-b]pyridine, isoxazolo[3,4-b]pyridine, imidazo[4,5-b]pyridine, and pyrazolo[1,5-a]pyrimidines. Strips of rabbit bladder neck were employed as a predictive assay for antagonism in the human lower tract. Rings of rat aorta were used as a &amp;amp;quot;negative screen&amp;amp;quot; for the test antagonists. Binding to alpha 1-ARs was relatively sensitive to size and electronic features of the arylpiperazine portion of the antagonists and permissive to these features on the heteroaryl carboxamide side. These structure-affinity findings were exploited to produce nicotinamides (e.g. 13ii and 25x) and pyrazolo[3,4-b]pyridines (e.g. 37f and 37y) ligands with nanomolar affinity at the alpha 1-AR subtype prevalent in the human lower urinary tract(pA2 values: 8.8, 10.7, 9.3, and 9.9, respectively) and displaying 2-3 orders of magnitude selectivity over the alpha 1D-AR.
We have isolated and characterized from human prostate novel splice variants of the human α1A‐adr... more We have isolated and characterized from human prostate novel splice variants of the human α1A‐adrenoceptor, several of which generate truncated products and one isoform, α1A‐4, which has the identical splice site as the three previously described isoforms. Long‐PCR on human genomic DNA showed that the α1A‐4 exon is located between those encoding the α1A‐1 and α1A‐3 variants. CHO‐K1 cells stably expressing α1A‐4 showed ligand binding properties similar to those of the other functional isoforms as well as agonist‐stimulated inositol phosphate accumulation. Quantitative PCR analyses revealed that α1A‐4 is the most abundant isoform expressed in the prostate with high levels also detected in liver and heart.
The recombinant a-adrenoceptor displays a distinct pharmacological profile 'classical a-adrenocep... more The recombinant a-adrenoceptor displays a distinct pharmacological profile 'classical a-adrenoceptor' in homogenate binding 1L 1A All rights reserved.
PI3 Kinase and mTOR have been identified as promising targets for the treatment of cancer. These ... more PI3 Kinase and mTOR have been identified as promising targets for the treatment of cancer. These enzymes participate in related, but not redundant, signaling networks to transmit cellular growth and survival signals, which are hallmarks of tumor growth. An interest in targeting both of these two important points along this critical signaling pathway, and the ability to leverage the high degree of structural similarity in the active sites of PI3K and mTOR kinase, has resulted in the discovery of GDC-0980 as a Class I PI3K and mTOR kinase inhibitor for oncology indications. The structure, efficacy, and medicinal chemistry behind the discovery of this compound is described. Beginning with the morpholin-4-yl-thieno[3,2-d]pyrimidine core of the Class I PI3K inhibitor GDC-0941, structural substitutions were made external to the core that added mTOR potency, improved the metabolic stability in vitro and in vivo, and lowered the plasma protein binding of the scaffold. Homology models of mTOR using PI3Kγ structures with bound inhibitors provided hypotheses for increasing mTOR potency relative to previous compounds. The solubility of the modified compounds was improved through the addition of polar functionality in the solvent exposed region of the scaffold, resulting in GDC-0980. GDC-0980 is potent across Class I isoforms with IC509s of 5, 27, 7, and 14 nM for PI3Kα, β, Δ, and γ, and inhibits mTOR with a Ki of 17 nM. The compound is highly selective versus a large panel of kinases including others in the PIK family. Based on the excellent PK profile, linear increase in exposure, strong potency in a broad range of cancer cells, and high free fraction, GDC-0980 is efficacious in animal models of cancer when dosed orally at low doses. Furthermore, this compound is efficacious when dosed intermittently as well as on a daily schedule. These preclinical data provide compelling support for GDC-0980 as a clinical candidate, and early stage clinical trials are underway. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2787. doi:10.1158/1538-7445.AM2011-2787
Three fully-de®ned a 1-adrenoceptors (a 1A , a 1B and a 1D) have been established in pharmacologi... more Three fully-de®ned a 1-adrenoceptors (a 1A , a 1B and a 1D) have been established in pharmacological and molecular studies. A fourth a 1-adrenoceptor, the putative a 1L-adrenoceptor, has been de®ned in functional but not molecular studies, and has been proposed to mediate contraction of human lower urinary tract tissues; its relationship to the three fully characterized a 1-adrenoceptors is not known. 2 In the present study, binding anities were estimated by displacement of [ 3 H]-prazosin in membrane homogenates of Chinese hamster ovary (CHO-K1) cells stably expressing the human a 1A-, a 1B-and a 1Dadrenoceptors and were compared with anity estimates obtained functionally in identical cells by measuring inhibition of noradrenaline (NA)-stimulated accumulation of [ 3 H]-inositol phosphates. 3 For the a 1A-adrenoceptor, binding studies revealed a pharmacological pro®le typical for the classically de®ned a 1A-adrenoceptor, such that prazosin, RS-17053, WB 4101, 5-methylurapidil, Rec 15/ 2739 and S-niguldipine all displayed subnanomolar anity. A dierent pro®le of anity estimates was obtained in inositol phosphates accumulation studies: prazosin, WB 4101, 5-methylurapidil, RS-17053 and S-niguldipine showed 10 to 40 fold lower anity than in membrane binding. However, anity estimates were not`frameshifted', as tamsulosin, indoramin and Rec 15/2739 yielded similar, high anity estimates in binding and functional assays. 4 In contrast, results from human a 1B-and a 1D-adrenoceptors expressed in CHO-K1 cells gave antagonist anity pro®les in binding and functional assays that were essentially identical. 5 A concordance of anity estimates from the functional (inositol phosphates accumulation) studies of the a 1A-adrenoceptor in CHO-K1 cells was found with estimates published recently from contractile studies in human lower urinary tract tissues (putative a 1L-adrenoceptor). These data show that upon functional pharmacological analysis, the cloned a 1A-adrenoceptor displays pharmacological recognition properties consistent with those of the putative a 1L-adrenoceptor. Why this pro®le diers from that obtained in membrane binding, and whether it explains the a 1L-adrenoceptor pharmacology observed in many native tissues, requires further investigation.
We investigated the cardiovascular effects of rilmenidine, moxonidine and clonidine in conscious ... more We investigated the cardiovascular effects of rilmenidine, moxonidine and clonidine in conscious wild‐type and D79N α2A‐adrenoceptor mice. The in vitro pharmacology of these agonists was determined at recombinant (human) α2‐adrenoceptors and at endogenous (dog) α2A‐adrenoceptors. In wild‐type mice, rilmenidine, moxonidine (100, 300 and 1000 μg kg−1, i.v.) and clonidine (30, 100 and 300 μg kg−1, i.v.) dose‐dependently decreased blood pressure and heart rate. In D79N α2A‐adrenoceptor mice, responses to rilmenidine and moxonidine did not differ from vehicle control. Clonidine‐induced hypotension was absent, but dose‐dependent hypertension and bradycardia were observed. In wild‐type mice, responses to moxonidine (1 mg kg−1, i.v.) were antagonized by the non‐selective, non‐imidazoline α2‐adrenoceptor antagonist, RS‐79948‐197 (1 mg kg−1, i.v.). Affinity estimates (pKi) at human α2A‐, α2B‐ and α2C‐adrenoceptors, respectively, were: rilmenidine (5.80, 5.76 and 5.33), moxonidine (5.37, <5...
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