RESUMO
Drug discovery is a multi-disciplinary effort in which groups with expertise in a range of areas combine in a unified way to achieve a common goal: to deliver a clinical candidate to evaluate a hypothesis for improving human health. As a medicinal chemist this environment has provided multiple opportunities to be involved in cross-discipline interactions that have been both rewarding and led to outcomes that would not have been possible without an intimate interdisciplinary curiosity. Within this article I aim to share some of my experiences with the ß2-adrenoceptor that have fostered such synergistic relationships with several disciplines, but in particular with in vitro pharmacologists looking at different ways to stimulate this G protein-coupled receptor (GPCR). This interest now spans over a quarter of a century and has been intertwined with the delivery of three clinical candidates.
Assuntos
Receptores Adrenérgicos beta 2 , Humanos , Receptores Adrenérgicos beta 2/metabolismo , Descoberta de Drogas , Receptores Acoplados a Proteínas G/metabolismo , Agonistas de Receptores Adrenérgicos beta 2/farmacologiaRESUMO
In this study, we report the ß1 -adrenoceptor binding kinetics of several clinically relevant ß1/2 -adrenoceptor (ß1/2 AR) agonists and antagonists. [3 H]-DHA was used to label CHO-ß1 AR for binding studies. The kinetics of ligand binding was assessed using a competition association binding method. Ligand physicochemical properties, including logD7.4 and the immobilized artificial membrane partition coefficient (KIAM ), were assessed using column-based methods. Protein Data Bank (PDB) structures and hydrophobic and electrostatic surface maps were constructed in PyMOL. We demonstrate that the hydrophobic properties of a molecule directly affect its kinetic association rate (kon ) and affinity for the ß1 AR. In contrast to our findings at the ß2 -adrenoceptor, KIAM , reflecting both hydrophobic and electrostatic interactions of the drug with the charged surface of biological membranes, was no better predictor than simple hydrophobicity measurements such as clogP or logD7.4 , at predicting association rate. Bisoprolol proved kinetically selective for the ß1 AR subtype, dissociating 50 times slower and partly explaining its higher measured affinity for the ß1 AR. We speculate that the association of positively charged ligands at the ß1 AR is curtailed somewhat by its predominantly neutral/positive charged extracellular surface. Consequently, hydrophobic interactions in the ligand-binding pocket dominate the kinetics of ligand binding. In comparison at the ß2 AR, a combination of hydrophobicity and negative charge attracts basic, positively charged ligands to the receptor's surface promoting the kinetics of ligand binding. Additionally, we reveal the potential role kinetics plays in the on-target and off-target pharmacology of clinically used ß-blockers.
Assuntos
Antagonistas Adrenérgicos beta , Antagonistas Adrenérgicos beta/farmacologia , Cinética , LigantesRESUMO
Balanced pan-class I phosphoinositide 3-kinase inhibition as an approach to cancer treatment offers the prospect of treating a broad range of tumor types and/or a way to achieve greater efficacy with a single inhibitor. Taking buparlisib as the starting point, the balanced pan-class I PI3K inhibitor 40 (NVP-CLR457) was identified with what was considered to be a best-in-class profile. Key to the optimization to achieve this profile was eliminating a microtubule stabilizing off-target activity, balancing the pan-class I PI3K inhibition profile, minimizing CNS penetration, and developing an amorphous solid dispersion formulation. A rationale for the poor tolerability profile of 40 in a clinical study is discussed.
Assuntos
Antineoplásicos , Fosfatidilinositol 3-Quinases , Aminopiridinas/farmacologia , Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Compostos Orgânicos , Inibidores de Fosfoinositídeo-3 Quinase , Inibidores de Proteínas Quinases/farmacologia , Inibidores de Proteínas Quinases/uso terapêuticoRESUMO
[This corrects the article DOI: 10.1021/acsmedchemlett.7b00485.].
RESUMO
FGF19 signaling through the FGFR4/ß-klotho receptor complex has been shown to be a key driver of growth and survival in a subset of hepatocellular carcinomas, making selective FGFR4 inhibition an attractive treatment opportunity. A kinome-wide sequence alignment highlighted a poorly conserved cysteine residue within the FGFR4 ATP-binding site at position 552, two positions beyond the gate-keeper residue. Several strategies for targeting this cysteine to identify FGFR4 selective inhibitor starting points are summarized which made use of both rational and unbiased screening approaches. The optimization of a 2-formylquinoline amide hit series is described in which the aldehyde makes a hemithioacetal reversible-covalent interaction with cysteine 552. Key challenges addressed during the optimization are improving the FGFR4 potency, metabolic stability, and solubility leading ultimately to the highly selective first-in-class clinical candidate roblitinib.
Assuntos
Piperazinas/química , Inibidores de Proteínas Quinases/química , Piridinas/química , Receptor Tipo 4 de Fator de Crescimento de Fibroblastos/antagonistas & inibidores , Sequência de Aminoácidos , Animais , Sítios de Ligação , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Cisteína/química , Cães , Desenho de Fármacos , Meia-Vida , Hepatócitos/citologia , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Neoplasias Hepáticas/tratamento farmacológico , Camundongos , Microssomos Hepáticos/metabolismo , Simulação de Dinâmica Molecular , Piperazinas/metabolismo , Piperazinas/farmacologia , Piperazinas/uso terapêutico , Inibidores de Proteínas Quinases/metabolismo , Inibidores de Proteínas Quinases/farmacologia , Inibidores de Proteínas Quinases/uso terapêutico , Piridinas/metabolismo , Piridinas/farmacologia , Piridinas/uso terapêutico , Ratos , Receptor Tipo 4 de Fator de Crescimento de Fibroblastos/metabolismo , Relação Estrutura-Atividade , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Hepatocellular carcinoma (HCC) is the most common primary malignancy of the liver and it is the third leading cause of cancer-related deaths worldwide. Recently, aberrant signaling through the FGF19/FGFR4 axis has been implicated in HCC. Here, we describe the development of FGF401, a highly potent and selective, first in class, reversible-covalent small-molecule inhibitor of the kinase activity of FGFR4. FGF401 is exquisitely selective for FGFR4 versus the other FGFR paralogues FGFR1, FGFR2, FGFR3, and all other kinases in the kinome. FGF401 has excellent drug-like properties showing a robust pharmacokinetic/pharmacodynamics/efficacy relationship, driven by a fraction of time above the phospho-FGFR4 IC90 value. FGF401 has remarkable antitumor activity in mice bearing HCC tumor xenografts and patient-derived xenograft models that are positive for FGF19, FGFR4, and KLB. FGF401 is the first FGFR4 inhibitor to enter clinical trials, and a phase I/II study is currently ongoing in HCC and other solid malignancies.
Assuntos
Fatores de Crescimento de Fibroblastos/genética , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/terapia , Receptor Tipo 4 de Fator de Crescimento de Fibroblastos/antagonistas & inibidores , Animais , Humanos , Neoplasias Hepáticas/patologia , Camundongos , Camundongos Nus , Transdução de SinaisRESUMO
The anabolic effects of ß 2-adrenoceptor (ß 2-AR) agonists on skeletal muscle have been demonstrated in various species. However, the clinical use of ß 2-AR agonists for skeletal muscle wasting conditions has been limited by their undesired cardiovascular effects. Here, we describe the preclinical pharmacological profile of a novel 5-hydroxybenzothiazolone (5-HOB) derived ß 2-AR agonist in comparison with formoterol as a representative ß 2-AR agonist that have been well characterized. In vitro, 5-HOB has nanomolar affinity for the human ß 2-AR and selectivity over the ß 1-AR and ß 3-AR. 5-HOB also shows potent agonistic activity at the ß 2-AR in primary skeletal muscle myotubes and induces hypertrophy of skeletal muscle myotubes. Compared with formoterol, 5-HOB demonstrates comparable full-agonist activity on cAMP production in skeletal muscle cells and skeletal muscle tissue-derived membranes. In contrast, a greatly reduced intrinsic activity was determined in cardiomyocytes and cell membranes prepared from the rat heart. In addition, 5-HOB shows weak effects on chronotropy, inotropy, and vascular relaxation compared with formoterol. In vivo, 5-HOB significantly increases hind limb muscle weight in rats with attenuated effects on heart weight and ejection fraction, unlike formoterol. Furthermore, changes in cardiovascular parameters after bolus subcutaneous treatment in rats and rhesus monkeys are significantly lower with 5-HOB compared with formoterol. In conclusion, the pharmacological profile of 5-HOB indicates superior tissue selectivity compared with the conventional ß 2-AR agonist formoterol in preclinical studies and supports the notion that such tissue-selective agonists should be investigated for the safe treatment of muscle-wasting conditions without cardiovascular limiting effects.
Assuntos
Benzotiazóis/química , Benzotiazóis/farmacologia , Sistema Cardiovascular/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Receptores Adrenérgicos beta 2/metabolismo , Segurança , Agonistas de Receptores Adrenérgicos beta 2/efeitos adversos , Agonistas de Receptores Adrenérgicos beta 2/química , Agonistas de Receptores Adrenérgicos beta 2/farmacologia , Agonistas de Receptores Adrenérgicos beta 2/uso terapêutico , Anabolizantes/efeitos adversos , Anabolizantes/química , Anabolizantes/farmacologia , Anabolizantes/uso terapêutico , Animais , Benzotiazóis/efeitos adversos , Benzotiazóis/uso terapêutico , Células CHO , Cricetulus , Coração/efeitos dos fármacos , Humanos , Hipertrofia/tratamento farmacológico , Cinética , Macaca mulatta , Masculino , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Miócitos Cardíacos/efeitos dos fármacos , RatosRESUMO
As part of a project to identify FGFR4 selective inhibitors, scaffold morphing of a 2-formylquinoline amide hit identified series of 2-formylpyridine ureas (2-FPUs) with improved potency and physicochemical properties. In particular, tetrahydronaphthyridine urea analogues with cellular activities below 30 nM have been identified. Consistent with the hypothesized reversible-covalent mechanism of inhibition, the 2-FPUs exhibited slow binding kinetics, and the aldehyde, as the putative electrophile, could be demonstrated to be a key structural element for activity.
RESUMO
The FGF19- fibroblast growth factor receptor (FGFR4)-ßKlotho (KLB) pathway plays an important role in the regulation of bile acid (BA) homeostasis. Aberrant activation of this pathway has been described in the development and progression of a subset of liver cancers including hepatocellular carcinoma, establishing FGFR4 as an attractive therapeutic target for such solid tumors. FGF401 is a highly selective FGFR4 kinase inhibitor being developed for hepatocellular carcinoma, currently in phase I/II clinical studies. In preclinical studies in mice and dogs, oral administration of FGF401 led to induction of Cyp7a1, elevation of its peripheral marker 7alpha-hydroxy-4-cholesten-3-one, increased BA pool size, decreased serum cholesterol and diarrhea in dogs. FGF401 was also associated with increases of serum aminotransferases, primarily alanine aminotransferase (ALT), in the absence of any observable adverse histopathological findings in the liver, or in any other organs. We hypothesized that the increase in ALT could be secondary to increased BAs and conducted an investigative study in dogs with FGF401 and coadministration of the BA sequestrant cholestyramine (CHO). CHO prevented and reversed FGF401-related increases in ALT in dogs in parallel to its ability to reduce BAs in the circulation. Correlation analysis showed that FGF401-mediated increases in ALT strongly correlated with increases in taurolithocholic acid and taurodeoxycholic acid, the major secondary BAs in dog plasma, indicating a mechanistic link between ALT elevation and changes in BA pool hydrophobicity. Thus, CHO may offer the potential to mitigate elevations in serum aminotransferases in human subjects that are caused by targeted FGFR4 inhibition and elevated intracellular BA levels.
Assuntos
Alanina Transaminase/sangue , Ácidos e Sais Biliares/sangue , Resina de Colestiramina/farmacologia , Fígado/efeitos dos fármacos , Inibidores de Proteínas Quinases/toxicidade , Receptor Tipo 4 de Fator de Crescimento de Fibroblastos/antagonistas & inibidores , Alanina Transaminase/biossíntese , Animais , Ácidos e Sais Biliares/biossíntese , Cães , Relação Dose-Resposta a Droga , Feminino , Fígado/enzimologia , Masculino , Piperazinas/farmacologia , Inibidores de Proteínas Quinases/sangue , Piridinas/farmacologia , Testes de Toxicidade , ToxicocinéticaRESUMO
A diverse range of selective FGFR4 inhibitor hit series were identified using unbiased screening approaches and by the modification of known kinase inhibitor scaffolds. In each case the origin of the selectivity was consistent with an interaction with a poorly conserved cysteine residue within the middle-hinge region of the kinase domain of FGFR4, at position 552. Targeting this region identified a non-covalent diaminopyrimidine series differentiating by size, an irreversible-covalent inhibitor in which Cys552 undergoes an SNAr reaction with a 2-chloropyridine, and a reversible-covalent inhibitor series in which Cys552 forms a hemithioacetal adduct with a 2-formyl naphthalene. In addition, the introduction of an acrylamide into a known FGFR scaffold identified a pan-FGFR inhibitor which reacted with both Cys552 and a second poorly conserved cysteine on the P-loop of FGFR4 at position 477 which is present in all four FGFR family members.
RESUMO
In vitro metabolic identification studies with a PI3K-α inhibitor lead molecule 1 identified a single predominant site of oxidative metabolism to be occurring within a tert.butyl moiety. Modification of the tert.butyl group within the lead molecule 1, to the corresponding d9-tert.butyl analogue 2, led to an increase in both the in vitro and in vivo metabolic stability. This increase in metabolic stability resulted in a 2-fold increase in the oral bioavailability measured in the rat, and a 3-fold increase in potency in a chronic in vivo study in the mouse, for 2 when compared to 1.
Assuntos
Deutério/metabolismo , Inibidores Enzimáticos/farmacologia , Fosfatidilinositol 3-Quinases/metabolismo , Amidas/química , Animais , Disponibilidade Biológica , Classe I de Fosfatidilinositol 3-Quinases , Inibidores Enzimáticos/metabolismo , Inibidores Enzimáticos/farmacocinética , Cinética , Inibidores de Fosfoinositídeo-3 Quinase , Prolina/química , Ratos , Tiazóis/química , Ureia/químicaRESUMO
Ligand binding to membrane proteins may be significantly influenced by the interaction of ligands with the membrane. In particular, the microscopic ligand concentration within the membrane surface solvation layer may exceed that in bulk solvent, resulting in overestimation of the intrinsic protein-ligand binding contribution to the apparent/measured affinity. Using published binding data for a set of small molecules with the ß2 adrenergic receptor, we demonstrate that deconvolution of membrane and protein binding contributions allows for improved structure-activity relationship analysis and structure-based drug design. Molecular dynamics simulations of ligand bound membrane protein complexes were used to validate binding poses, allowing analysis of key interactions and binding site solvation to develop structure-activity relationships of ß2 ligand binding. The resulting relationships are consistent with intrinsic binding affinity (corrected for membrane interaction). The successful structure-based design of ligands targeting membrane proteins may require an assessment of membrane affinity to uncouple protein binding from membrane interactions.
Assuntos
Membrana Celular/metabolismo , Ligantes , Receptores Adrenérgicos beta 2/metabolismo , Sítios de Ligação , Relação Dose-Resposta a Droga , Humanos , Modelos Moleculares , Estrutura Molecular , Relação Estrutura-AtividadeRESUMO
Taking the pyrrolopyrimidine derived IGF-1R inhibitor NVP-AEW541 as the starting point, the benzyl ether back-pocket binding moiety was replaced with a series of 2-cyclic ether methyl ethers leading to the identification of novel achiral [2.2.1]-bicyclic ether methyl ether containing analogues with improved IGF-1R activities and kinase selectivities. Further exploration of the series, including a fluorine scan of the 5-phenyl substituent, and optimisation of the sugar-pocket binding moiety identified compound 33 containing (S)-2-tetrahydrofuran methyl ether 6-fluorophenyl ether back-pocket, and cis-N-Ac-Pip sugar-pocket binding groups. Compound 33 showed improved selectivity and pharmacokinetics compared to NVP-AEW541, and produced comparable in vivo efficacy to linsitinib in inhibiting the growth of an IGF-1R dependent tumour xenograft model in the mouse.
Assuntos
Antineoplásicos/farmacologia , Imidazóis/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Pirazinas/farmacologia , Pirimidinas/farmacologia , Pirróis/farmacologia , Receptor IGF Tipo 1/antagonistas & inibidores , Animais , Antineoplásicos/síntese química , Antineoplásicos/química , Proliferação de Células/efeitos dos fármacos , Relação Dose-Resposta a Droga , Humanos , Imidazóis/síntese química , Imidazóis/química , Camundongos , Camundongos Nus , Estrutura Molecular , Células NIH 3T3 , Neoplasias Experimentais/tratamento farmacológico , Neoplasias Experimentais/patologia , Inibidores de Proteínas Quinases/síntese química , Inibidores de Proteínas Quinases/química , Pirazinas/síntese química , Pirazinas/química , Pirimidinas/síntese química , Pirimidinas/química , Pirróis/síntese química , Pirróis/química , Receptor IGF Tipo 1/metabolismo , Relação Estrutura-Atividade , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Super agonists produce greater functional responses than endogenous agonists in the same assay, and their unique pharmacology is the subject of increasing interest and debate. We propose that receptor residence time and the duration of receptor signaling contribute to the pharmacology of super agonism. We have further characterized the novel ß2 adrenoceptor agonist C26 (7-[(R)-2-((1R,2R)-2-benzyloxycyclopentylamino)-1-hydroxyethyl]-4-hydroxybenzothiazolone), which displays higher intrinsic activity than the endogenous ligand adrenaline in cAMP accumulation, ß-arrestin-2 recruitment, and receptor internalization assays. C26 recruited ß-arrestin-2, and internalized the Green Fluorescent Protein (GFP)-taggedß2 adrenoceptor at a slow rate, with half-life (t1/2) values of 0.78 ± 0.1 and 0.78 ± 0.04 hours, respectively. This was compared with 0.31 ± 0.04 and 0.34 ± 0.01 hours for adrenaline-mediated ß-arrestin-2 recruitment and GFP-ß2 internalization, respectively. The slower rate for C26 resulted in levels of ß-arrestin-2 recruitment increasing up to 4-hour agonist incubation, at which point the intrinsic activity was determined to be 124.3 ± 0.77% of the adrenaline response. In addition to slow functional kinetics, C26 displayed high affinity with extremely slow receptor dissociation kinetics, giving a receptor residence half-life of 32.7 minutes at 37°C, which represents the slowest dissociation rate we have observed for any ß2 adrenoceptor agonist tested to date. In conclusion, we propose that the gradual accumulation of long-lived active receptor complexes contributes to the increased intrinsic activity of C26 over time. This highlights the need to consider the temporal aspects of agonist binding and signaling when characterizing ligands as super agonists.
Assuntos
Agonistas de Receptores Adrenérgicos beta 2/química , Agonistas de Receptores Adrenérgicos beta 2/metabolismo , Receptores Adrenérgicos beta 2/metabolismo , Agonistas de Receptores Adrenérgicos beta 2/farmacologia , Animais , Células CHO , Linhagem Celular Tumoral , Cricetinae , Cricetulus , Relação Dose-Resposta a Droga , Cobaias , Humanos , Masculino , Técnicas de Cultura de Órgãos , Ligação Proteica/fisiologia , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Traqueia/efeitos dos fármacos , Traqueia/metabolismoRESUMO
Exploring the affinity-pocket binding moiety of a 2-aminothiazole (S)-proline-amide-urea series of selective PI3Kα inhibitors using a parallel-synthesis approach led to the identification of a novel 4',5-bisthiazole sub-series. The synthesis and optimisation of both the affinity pocket and (S)-proline amide moieties within this 4',5-bisthiazole sub-series are described. From this work a number of analogues, including 14 (A66) and 24, were identified as potent and selective PI3Kα inhibitor in vitro tool compounds.
Assuntos
Inibidores de Fosfoinositídeo-3 Quinase , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/farmacologia , Tiazóis/química , Tiazóis/farmacologia , Ureia/análogos & derivados , Ureia/farmacologia , Animais , Classe I de Fosfatidilinositol 3-Quinases , Humanos , Modelos Moleculares , Simulação de Dinâmica Molecular , Fosfatidilinositol 3-Quinases/química , Fosfatidilinositol 3-Quinases/metabolismo , FosfatidilinositóisRESUMO
A cyclisation within a 4',5-bisthiazole (S)-proline-amide-urea series of selective PI3Kα inhibitors led to a novel 4,5-dihydrobenzo[1,2-d:3,4-d]bisthiazole tricyclic sub-series. The synthesis and optimisation of this 4,5-dihydrobenzo[1,2-d:3,4-d]bisthiazole sub-series and the expansion to a related tricyclic 4,5-dihydrothiazolo[4,5-h]quinazoline sub-series are described. From this work analogues including 11, 12, 19 and 23 were identified as potent and selective PI3Kα inhibitor in vivo tool compounds.
Assuntos
Inibidores de Fosfoinositídeo-3 Quinase , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/farmacologia , Quinazolinas/química , Quinazolinas/farmacologia , Tiazóis/química , Tiazóis/farmacologia , Animais , Células CACO-2 , Classe I de Fosfatidilinositol 3-Quinases , Feminino , Humanos , Camundongos Nus , Modelos Moleculares , Neoplasias/tratamento farmacológico , Neoplasias/enzimologia , Fosfatidilinositol 3-Quinases/química , Fosfatidilinositol 3-Quinases/metabolismo , Inibidores de Proteínas Quinases/farmacocinética , Inibidores de Proteínas Quinases/uso terapêutico , Quinazolinas/farmacocinética , Quinazolinas/uso terapêutico , Relação Estrutura-Atividade , Tiazóis/farmacocinética , Tiazóis/uso terapêuticoRESUMO
A novel, previously undescribed 4H-thiazolo[5',4':4,5]pyrano[2,3-c]pyridine tricyclic scaffold has been discovered. The application of this novel chemotype leading to a potent and selective prototype PI3Kα inhibitor with favorable physicochemical and PK-properties is described.
Assuntos
Inibidores de Fosfoinositídeo-3 Quinase , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/farmacologia , Piridinas/química , Piridinas/farmacologia , Tiazóis/química , Tiazóis/farmacologia , Aminação , Animais , Classe I de Fosfatidilinositol 3-Quinases , Humanos , Modelos Moleculares , Neoplasias/tratamento farmacológico , Neoplasias/enzimologia , Fosfatidilinositol 3-Quinases/química , Fosfatidilinositol 3-Quinases/metabolismo , Inibidores de Proteínas Quinases/farmacocinética , Piridinas/farmacocinética , Ratos , Tiazóis/farmacocinéticaRESUMO
The optimisation of two series of 4-hydroxybenzothiazolone derived ß2-adrenoceptor agonists, bearing α-substituted cyclopentyl and ß-phenethyl amino-substituents, as inhaled long-acting bronchodilators is described. Analogues were selected for synthesis using a lipophilicity based hypothesis to achieve the targeted rapid onset of action in combination with a long duration of action. The profiling of the two series led to identification of the α-substituted cyclopentyl analogue 2 as the optimal compound with a comparable profile to the inhaled once-daily long-acting ß2-adrenoceptor agonist indacaterol. On the basis of these data 2 was promoted as the backup development candidate to indacaterol from the Novartis LABA project.
Assuntos
Agonistas de Receptores Adrenérgicos beta 2/administração & dosagem , Agonistas de Receptores Adrenérgicos beta 2/farmacologia , Benzotiazóis/administração & dosagem , Benzotiazóis/farmacologia , Receptores Adrenérgicos beta 2/metabolismo , Administração por Inalação , Agonistas de Receptores Adrenérgicos beta 2/química , Animais , Benzotiazóis/química , Relação Dose-Resposta a Droga , Cobaias , Estrutura MolecularRESUMO
Current pharmacological models for determining affinity and kinetics of drugs for membrane receptors assume the interacting molecules are homogeneously distributed in the bulk aqueous phase. The phospholipid membrane can, however, provide a second compartment into which drugs can partition, particularly lipophilic/basic compounds. In this study we measured the phospholipid affinity and receptor binding kinetics of several clinically relevant ß2-adrenoceptor agonists and antagonists and demonstrated that the degree of phospholipid interaction directly affects the observed kinetic association rate (k on) and dissociation constant (Kd), but not the dissociation rate (k off) from the target, by concentrating drug in the local environment around the receptor. When the local drug concentration was accounted for, the k on was comparable across the cohort and the corrected Kd was directly related to the k off. In conclusion, we propose a new approach to determining the pharmacology of drugs for membrane targets that accounts for differences in local drug concentration brought about by direct affinity for phospholipids, establishing "micro-pharmacokinetic/pharmacodynamic relationships" for drugs.
Assuntos
Agonistas de Receptores Adrenérgicos beta 2/farmacologia , Antagonistas de Receptores Adrenérgicos beta 2/farmacologia , Membrana Celular/metabolismo , Modelos Biológicos , Receptores Adrenérgicos beta 2/metabolismo , Agonistas de Receptores Adrenérgicos beta 2/química , Agonistas de Receptores Adrenérgicos beta 2/farmacocinética , Antagonistas de Receptores Adrenérgicos beta 2/química , Antagonistas de Receptores Adrenérgicos beta 2/farmacocinética , Animais , Ligação Competitiva , Células CHO , Cricetinae , Cricetulus , Humanos , Ligantes , Membranas Artificiais , Fosfolipídeos/química , Fosfolipídeos/metabolismo , Ensaio RadioliganteRESUMO
Phosphatidylinositol-3-kinase α (PI3Kα) is a therapeutic target of high interest in anticancer drug research. On the basis of a binding model rationalizing the high selectivity and potency of a particular series of 2-aminothiazole compounds in inhibiting PI3Kα, a medicinal chemistry program has led to the discovery of the clinical candidate NVP-BYL719.