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1.
J Pharmacol Exp Ther ; 370(2): 269-277, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31175220

RESUMO

Cabotegravir, a novel integrase inhibitor under development for treatment and prevention of HIV, is primarily metabolized by UDP-glucuronosyltransferase (UGT)1A1 and UGT1A9 to a direct ether glucuronide metabolite. The aim of these studies was to elucidate the mechanistic basis of cabotegravir-glucuronide disposition in humans. Cabotegravir glucuronidation was predominantly hepatic (>95%) with minimal intestinal and renal contribution. Rat liver perfusions demonstrated that cabotegravir-glucuronide formed in the liver undergoes comparable biliary and sinusoidal excretion, consistent with high concentrations of the glucuronide in human bile and urine. Cabotegravir-glucuronide biliary excretion was mediated by multidrug resistance-associated protein (MRP)2 (not transported by breast cancer resistance protein or P-glycoprotein), whereas hepatic basolateral excretion into sinusoidal blood was via both MRP3 [fraction transport (Ft) = 0.81] and MRP4 (Ft = 0.19). Surprisingly, despite high urinary recovery of hepatically-formed cabotegravir-glucuronide, metabolite levels in circulation were negligible, a phenomenon consistent with rapid metabolite clearance. Cabotegravir-glucuronide was transported by hepatic uptake transporters organic anion-transporting (OAT) polypeptide (OATP)1B1 and OATP1B3; however, metabolite clearance by hepatic uptake from circulation was low (2.7% of hepatic blood flow) and unable to explain the minimal systemic exposure. Instead, circulating cabotegravir-glucuronide undergoes efficient renal clearance, where uptake into the proximal tubule would be mediated by OAT3 (not transported by OAT1), and subsequent secretion into urine by MRP2 (Ft = 0.66) and MRP4 (Ft = 0.34). These studies provide mechanistic insight into the disposition of cabotegravir-glucuronide, a hepatically-formed metabolite with appreciable urinary recovery and minimal systemic exposure, including fractional contribution of redundant transporters to any given process based on quantitative proteomics. SIGNIFICANCE STATEMENT: The role of membrane transporters in metabolite disposition, especially glucuronides, and as sites of unexpected drug-drug interactions, which alter drug efficacy and safety, has been established. Cabotegravir-glucuronide, formed predominantly by direct glucuronidation of parent drug in liver, was the major metabolite recovered in human urine (27% of oral dose) but was surprisingly not detected in systemic circulation. To our knowledge, this is the first mechanistic description of this phenomenon for a major hepatically-formed metabolite to be excreted in the urine to a large extent, but not circulate at detectable levels. The present study elucidates the mechanistic basis of cabotegravir-glucuronide disposition in humans. Specific hepatic and renal transporters involved in the disposition of cabotegravir-glucuronide, with their fractional contribution, have been provided.

2.
Drug Metab Dispos ; 47(8): 890-898, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31167838

RESUMO

Preliminary analysis of ongoing birth surveillance study identified evidence of potential increased risk for neural tube defects (NTDs) in newborns associated with exposure to dolutegravir at the time of conception. Folate deficiency is a common cause of NTDs. Dolutegravir and other HIV integrase inhibitor drugs were evaluated in vitro for inhibition of folate transport pathways: proton-coupled folate transporter (PCFT), reduced folate carrier (RFC), and folate receptor α (FRα)-mediated endocytosis. Inhibition of folate transport was extrapolated to the clinic by using established approaches for transporters in intestine, distribution tissues, and basolateral and apical membranes of renal proximal tubules (2017 FDA Guidance). The positive controls, methotrexate and pemetrexed, demonstrated clinically relevant inhibition of PCFT, RFC, and FRα in folate absorption, distribution, and renal sparing. Valproic acid was used as a negative control that elicits folate-independent NTDs; valproic acid did not inhibit PCFT, RFC, or FRα At clinical doses and exposures, the observed in vitro inhibition of FRα by dolutegravir and cabotegravir was not flagged as clinically relevant; PCFT and RFC inhibition was not observed in vitro. Bictegravir inhibited both PCFT and FRα, but the observed inhibition did not reach the criteria for clinical relevance. Elvitegravir and raltegravir inhibited PCFT, but only raltegravir inhibition of intestinal PCFT was flagged as potentially clinically relevant at the highest 1.2-g dose (not the 400-mg dose). These studies showed that dolutegravir is not a clinical inhibitor of folate transport pathways, and it is not predicted to elicit clinical decreases in maternal and fetal folate levels. Clinically relevant HIV integrase inhibitor drug class effect on folate transport pathways was not observed. SIGNIFICANCE STATEMENT: Preliminary analysis of ongoing birth surveillance study identified evidence of potential increased risk for neural tube defects (NTDs) in newborns associated with exposure to the HIV integrase inhibitor dolutegravir at the time of conception; folate deficiency is a common cause of NTDs. Dolutegravir and other HIV integrase inhibitor drugs were evaluated in vitro for inhibition of the major folate transport pathways: proton-coupled folate transporter, reduced folate carrier, and folate receptor α-mediated endocytosis. The present studies showed that dolutegravir is not a clinical inhibitor of folate transport pathways, and it is not predicted to elicit clinical decreases in maternal and fetal folate levels. Furthermore, clinically relevant HIV integrase inhibitor drug class effect on folate transport pathways was not observed.

3.
Clin Pharmacol Ther ; 104(5): 836-864, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30347454

RESUMO

Drug transporters can govern the absorption, distribution, metabolism, and excretion of substrate drugs and endogenous substances. Investigations to examine their potential impact to pharmacokinetic (PK) drug-drug interactions (DDIs) are an integral part of the risk assessment in drug development. To evaluate a new molecular entity as a potential perpetrator of transporters, use of well characterized and/or clinically relevant probe substrates with good selectivity and sensitivity are critical for robust clinical DDI assessment that could inform DDI management strategy in the product labeling. The availability of endogenous biomarkers to monitor transporter-mediated DDIs in early phases of clinical investigations would greatly benefit downstream clinical plans. This article reviews the state-of-the-art in transporter clinical probe drugs and emerging biomarkers, including current challenges and limitations, delineates methods and workflows to identify and validate novel endogenous biomarkers to support clinical DDI evaluations, and proposes how these probe drugs or biomarkers could be used in drug development.

5.
Clin Pharmacol Ther ; 104(5): 890-899, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30091177

RESUMO

This white paper provides updated International Transporter Consortium (ITC) recommendations on transporters that are important in drug development following the 3rd ITC workshop. New additions include prospective evaluation of organic cation transporter 1 (OCT1) and retrospective evaluation of organic anion transporting polypeptide (OATP)2B1 because of their important roles in drug absorption, disposition, and effects. For the first time, the ITC underscores the importance of transporters involved in drug-induced vitamin deficiency (THTR2) and those involved in the disposition of biomarkers of organ function (OAT2 and bile acid transporters).

6.
Clin Pharmacol Ther ; 104(5): 781-784, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29761830

RESUMO

Metformin drug-drug interaction (DDI) studies are conducted during development of drugs that inhibit organic cation transporters and/or multidrug and toxin extrusion proteins (OCTs/MATEs). Monitoring solely changes in systemic exposure, the typical DDI study endpoint appears inadequate for metformin, which is metabolically stable, has poor passive membrane permeability, and undergoes transporter-mediated tissue distribution and clearance. Evaluation of renal clearance, antihyperglycemic effects, and potentially lactate as an exploratory safety marker, can support rational metformin dose adjustment. The proposed DDI study design aims to adequately inform metformin dosing during comedication.

7.
J Pharmacol Exp Ther ; 366(1): 37-45, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29653960

RESUMO

Atovaquone, an antiprotozoal and antipneumocystic agent, is predominantly cleared by biliary excretion of unchanged parent drug. Atovaquone is ≥10,000-fold concentrated in human bile relative to unbound plasma. Even after correcting for apparent nonspecific binding and incomplete solubility in bile, atovaquone is still concentrated ≥100-fold in bile, consistent with active biliary excretion. Mechanisms of atovaquone hepatobiliary disposition were studied using a multiexperimental in vitro and in vivo approach. Atovaquone uptake was not elevated in HEK293 cells singly overexpressing OATP1B1, OATP1B3, OATP2B1, OCT1, NTCP, or OAT2. Hepatocyte uptake of atovaquone was not impaired by OATP and OCT inhibitor cocktail (rifamycin and imipramine). Atovaquone liver-to-blood ratio at distributional equilibrium was not reduced in Oatp1a/1b and Oct1/2 knockout mice. Atovaquone exhibited efflux ratios of approximately unity in P-gp and BCRP overexpressing MDCK cell monolayers and did not display enhanced uptake in MRP2 vesicles. Biliary and canalicular clearance were not decreased in P-gp, Bcrp, Mrp2, and Bsep knockout rats. In the present study, we rule out the involvement of major known basolateral uptake and bile canalicular efflux transporters in the hepatic uptake and biliary excretion of atovaquone. This is the first known example of a drug cleared by biliary excretion in humans, with extensive biliary concentration, which is not transported by the mechanisms investigated herein.

8.
Clin Pharmacol Ther ; 103(5): 758-760, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29193038

RESUMO

Hepatic organic cation transporter 1 (OCT1) can be a determinant of drug clearance and distribution, which can impact drug exposure and response. OCT1 was shown recently to be the rate-determining step in the clearance of several drugs in humans, and thereby a mechanism of pharmacogenetic variability and drug-drug interactions (DDIs). OCT1 mediates metformin distribution to the liver (key biophase). As OCT1 modulation impacts metformin response, but not pharmacokinetics (PK), metformin DDI studies require pharmacodynamic endpoint(s) to inform rational metformin dose adjustment.

9.
J Pharm Sci ; 106(12): 3442-3452, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-28927987

RESUMO

Regulatory agencies have recently issued drug-drug interaction guidelines, which require determination of plasma protein binding (PPB). To err on the conservative side, the agencies recommend that a 0.01 lower limit of fraction unbound (fu) be used for highly bound compounds (>99%), irrespective of the actual measured values. While this may avoid false negatives, the recommendation would likely result in a high rate of false positive predictions, resulting in unnecessary clinical studies and more stringent inclusion/exclusion criteria, which may add cost and time in delivery of new medicines to patients. In this perspective, we provide a review of current approaches to measure PPB, and important determinants in enabling the accuracy and precision in these measurements. The ability to measure fu is further illustrated by a cross-company data comparison of PPB for warfarin and itraconazole, demonstrating good concordance of the measured fu values. The data indicate that fu values of ≤0.01 may be determined accurately across laboratories when appropriate methods are used. These data, along with numerous other examples presented in the literature, support the use of experimentally measured fu values for drug-drug interaction predictions, rather than using the arbitrary cutoff value of 0.01 as recommended in current regulatory guidelines.


Assuntos
Proteínas Sanguíneas/metabolismo , Interações de Medicamentos/fisiologia , Preparações Farmacêuticas/química , Preparações Farmacêuticas/normas , Ligação Proteica/fisiologia , Animais , Indústria Farmacêutica/normas , Humanos , Preparações Farmacêuticas/metabolismo , Plasma/metabolismo
10.
J Clin Pharmacol ; 56 Suppl 7: S23-39, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-27385177

RESUMO

This review provides a practical clinical perspective on the relevance of hepatic transporters in pharmacokinetics and drug-drug interactions (DDIs). Special emphasis is placed on transporters with clear relevance to clinical DDIs, efficacy, and safety. Basolateral OATP1B1 and 1B3 emerged as important hepatic drug uptake pathways, sites for systemic DDIs, and sources of pharmacogenetic variability. As the first step in hepatic drug removal from the circulation, OATPs are an important determinant of systemic pharmacokinetics, specifically influencing systemic absorption, clearance, and hepatic distribution for subsequent metabolism and/or excretion. Biliary excretion of parent drugs is a less prevalent clearance pathway than metabolism or urinary excretion, but BCRP and MRP2 are critically important to biliary/fecal elimination of drug metabolites. Inhibition of biliary excretion is typically not apparent at the level of systemic pharmacokinetics but can markedly increase liver exposure. Basolateral efflux transporters MRP3 and MRP4 mediate excretion of parent drugs and, more commonly, polar metabolites from hepatocytes into blood. Basolateral excretion is an area in need of further clinical investigation, which will necessitate studies more complex than just systemic pharmacokinetics. Clinical relevance of hepatic uptake is relatively well appreciated, and clinical consequences of hepatic excretion (biliary and basolateral) modulation remain an active research area.


Assuntos
Fígado/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Preparações Farmacêuticas/metabolismo , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/metabolismo , Animais , Transporte Biológico/efeitos dos fármacos , Transporte Biológico/fisiologia , Interações de Medicamentos/fisiologia , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Humanos , Fígado/efeitos dos fármacos , Proteínas Associadas à Resistência a Múltiplos Medicamentos/metabolismo , Proteínas de Neoplasias/metabolismo , Transportadores de Ânions Orgânicos/metabolismo , Preparações Farmacêuticas/administração & dosagem
11.
J Acquir Immune Defic Syndr ; 72(4): 400-7, 2016 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-26974526

RESUMO

BACKGROUND: Dolutegravir is an integrase strand transfer inhibitor (INSTI) licensed for use in HIV-1 infection and is an inhibitor of organic cation transporter 2 (OCT2). This study assessed the effect of dolutegravir on the pharmacokinetics of metformin, an OCT2 substrate. DESIGN: This was an open-label, parallel-group, 3-period crossover study in healthy adult subjects. Subjects were enrolled into 1 of 2 treatment cohorts (15 subjects/cohort) receiving metformin 500 mg q12h for 5 days in period 1; metformin 500 mg q12h plus dolutegravir 50 mg q24h (cohort 1) or 50 mg q12h (cohort 2) for 7 days in period 2; and metformin 500 mg q12h for 10 days in period 3. There were no washout periods between treatments. Effects of dolutegravir on metformin transport and paracellular permeability were evaluated in vitro. RESULTS: Co-administration of dolutegravir 50 mg q24h increased metformin area under the curve(0-τ) by 79% and Cmax by 66%, whereas dolutegravir 50 mg q12h increased metformin area under the curve(0-τ) and Cmax by 145% and 111%, respectively. Metformin t(1/2) remained unchanged. Increased metformin exposure during dolutegravir co-administration returned to period 1 levels after dolutegravir discontinuation in period 3. Co-administration of dolutegravir and metformin was well tolerated. In vitro, dolutegravir was not a clinically relevant inhibitor of OCT1, OCT3, multidrug and toxin extrusion protein 1, multidrug and toxin extrusion protein 2-K, or plasma membrane monoamine transporter, and it did not affect metformin paracellular permeability or uptake into an intestinal cell line. CONCLUSIONS: Dolutegravir significantly increased metformin plasma exposure, which can be partially explained by OCT2 inhibition. It is recommended that dose adjustments of metformin be considered to maintain optimal glycemic control when patients are starting/stopping dolutegravir while taking metformin.


Assuntos
Glicemia/efeitos dos fármacos , Inibidores de Integrase de HIV/farmacologia , Compostos Heterocíclicos com 3 Anéis/farmacologia , Hipoglicemiantes/farmacocinética , Metformina/farmacocinética , Adulto , Área Sob a Curva , Glicemia/metabolismo , Estudos Cross-Over , Esquema de Medicação , Interações de Medicamentos , Feminino , Inibidores de Integrase de HIV/administração & dosagem , Voluntários Saudáveis , Compostos Heterocíclicos com 3 Anéis/administração & dosagem , Humanos , Hipoglicemiantes/administração & dosagem , Masculino , Metformina/administração & dosagem , Segurança do Paciente , Resultado do Tratamento
12.
Eur J Cancer ; 56: 1-9, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26798966

RESUMO

BACKGROUND: Notch signalling regulates stem cell development and survival and is deregulated in multiple malignancies. LY900009 is a small molecule inhibitor of Notch signalling via selective inhibition of the γ-secretase protein. We report the first-in-human phase I trial of LY900009. METHODS: Dose escalation (Part A) was performed in cohorts of three advanced cancer patients using a modified continual reassessment method and dose confirmation (Part B) was performed in ovarian cancer patients. LY900009 was taken orally thrice weekly (every Monday, Wednesday, and Friday) during a 28-d cycle. The primary objective determined the maximum tolerated dose (MTD); secondary end-points included toxicity, pharmacokinetics, pharmacodynamics, and antitumour activity. RESULTS: Thirty-five patients received LY900009 at dose levels ranging from 2-60 mg. Study drug-related adverse events were diarrhoea (46%), vomiting (34%), anorexia (31%), nausea (31%), and fatigue (23%). At 30 mg, a dose-limiting toxicity (grade III mucosal inflammation) was observed. LY900009 absorption was rapid, with median tmax at 1-4 h post-dose. LY900009 inhibited plasma levels of amyloid-ß peptide in a dose-dependent manner with 80-90% inhibition observed in the 30- to 60-mg cohorts. No responses were seen, but five patients had stable disease. Two patients (5.7%) with leiomyosarcoma and ovarian cancer received four cycles of therapy. One patient (15 mg) showed markedly increased glandular mucin consistent with pharmacologic inhibition of the Notch pathway. CONCLUSIONS: The recommended MTD schedule for future studies was 30 mg thrice weekly, which exceeds the target inhibition level observed in preclinical models to promote tumour regression in humans.


Assuntos
Alanina/análogos & derivados , Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Antineoplásicos/administração & dosagem , Dibenzazepinas/administração & dosagem , Neoplasias/tratamento farmacológico , Inibidores de Proteases/administração & dosagem , Receptores Notch/antagonistas & inibidores , Administração Oral , Adulto , Idoso , Alanina/administração & dosagem , Alanina/efeitos adversos , Alanina/farmacocinética , Secretases da Proteína Precursora do Amiloide/metabolismo , Antineoplásicos/efeitos adversos , Antineoplásicos/farmacocinética , Dibenzazepinas/efeitos adversos , Dibenzazepinas/farmacocinética , Relação Dose-Resposta a Droga , Esquema de Medicação , Feminino , Humanos , Masculino , Dose Máxima Tolerável , Pessoa de Meia-Idade , Neoplasias/enzimologia , Neoplasias/patologia , Neoplasias Ovarianas/tratamento farmacológico , Neoplasias Ovarianas/enzimologia , Neoplasias Ovarianas/patologia , Inibidores de Proteases/efeitos adversos , Inibidores de Proteases/farmacocinética , Receptores Notch/metabolismo , Transdução de Sinais/efeitos dos fármacos , Resultado do Tratamento , Estados Unidos , Adulto Jovem
13.
Invest New Drugs ; 33(6): 1187-96, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26403509

RESUMO

PURPOSE: LY2090314 (LY) is a glycogen synthase kinase 3 inhibitor with preclinical efficacy in xenograft models when combined with platinum regimens. A first-in-human phase 1 dose-escalation study evaluated the combination of LY with pemetrexed/carboplatin. PATIENTS AND METHODS: Forty-one patients with advanced solid tumors received single-dose LY monotherapy lead-in and 37 patients received LY (10-120 mg) plus pemetrexed/carboplatin (500 mg/m(2) and 5-6 AUC, respectively) across 8 dose levels every 21 days. Primary objective was maximum tolerated dose (MTD) determination; secondary endpoints included safety, antitumor activity, pharmacokinetics, and beta-catenin pharmacodynamics. RESULTS: MTD of LY with pemetrexed/carboplatin was 40 mg. Eleven dose-limiting toxicities (DLTs) occurred in ten patients. DLTs during LY monotherapy occurred at ≥ 40 mg: grade 2 visual disturbance (n = 1) and grade 3/4 peri-infusional thoracic pain during or shortly post infusion (n = 4; chest, upper abdominal, and back pain). Ranitidine was added after de-escalation to 80 mg LY to minimize peri-infusional thoracic pain. Following LY with pemetrexed/carboplatin therapy, DLTs included grade 3/4 thrombocytopenia (n = 4) and grade 4 neutropenia (n = 1). Best overall response by RECIST included 5 confirmed partial responses (non-small cell lung cancer [n = 3], mesothelioma, and breast cancer) and 19 patients having stable disease. Systemic LY exposure was approximately linear over dose range studied. Transient upregulation of beta-catenin measured in peripheral blood mononuclear cells (PBMCs) occurred at 40 mg LY. CONCLUSIONS: The initial safety profile of LY2090314 was established. MTD LY dose with pemetrexed/carboplatin is 40 mg IV every 3 weeks plus ranitidine. Efficacy of LY plus pemetrexed/carboplatin requires confirmation in randomized trials.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Carboplatina/administração & dosagem , Quinase 3 da Glicogênio Sintase/antagonistas & inibidores , Compostos Heterocíclicos com 3 Anéis/administração & dosagem , Maleimidas/administração & dosagem , Pemetrexede/administração & dosagem , Administração Intravenosa , Adulto , Idoso , Protocolos de Quimioterapia Combinada Antineoplásica/farmacocinética , Carboplatina/farmacocinética , Estudos de Coortes , Relação Dose-Resposta a Droga , Feminino , Seguimentos , Quinase 3 da Glicogênio Sintase/metabolismo , Compostos Heterocíclicos com 3 Anéis/farmacocinética , Humanos , Masculino , Maleimidas/farmacocinética , Pessoa de Meia-Idade , Neoplasias/tratamento farmacológico , Neoplasias/enzimologia , Pemetrexede/farmacocinética
14.
J Pharmacol Exp Ther ; 354(2): 225-9, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26062557

RESUMO

Blood cells are considered an important distributional compartment for metformin based on the high blood-to-plasma partition ratio (B/P) in humans (>10 at Cmin). However, literature reports of metformin's intrinsic in vitro B/P values are lacking. At present, the extent and rate of metformin cellular partitioning was determined in incubations of fresh human and rat blood with [(14)C]metformin for up to 1 week at concentrations spanning steady-state plasma Cmin, Cmax, and a concentration associated with lactic acidosis. The results showed that metformin's intrinsic equilibrium B/P was ∼0.8-1.4 in blood, which is <10% of the reported clinical value. Kinetics of metformin partitioning into human blood cells and repartitioning back into plasma were slow (repartitioning half-life ∼32-39 hours). These data, along with in vivo rapid and efficient renal clearance of plasma metformin (plasma renal extraction ratio ∼90%-100%), explain why the clinical terminal half-life of metformin in plasma (6 hours) is 3- to 4-fold shorter than the half-life in whole blood (18 hours) and erythrocytes (23 hours). The rate constant for metformin repartitioning from blood cells to plasma (∼0.02 h(-1)) is far slower than the clinical renal elimination rate constant (0.3 h(-1)). Blood distributional rate constants were incorporated into a metformin physiologically-based pharmacokinetic model, which predicted the differential elimination half-life in plasma and blood. The present study demonstrates that the extent of cellular drug partitioning in blood observed in a dynamic in vivo system may be very different from the static in vitro values when repartitioning from blood cells is far slower than clearance of drug in plasma.


Assuntos
Hipoglicemiantes/sangue , Metformina/sangue , Plasma/metabolismo , Animais , Humanos , Hipoglicemiantes/farmacologia , Masculino , Metformina/farmacologia , Plasma/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley
15.
Drug Metab Dispos ; 43(4): 490-509, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25587128

RESUMO

Breast cancer resistance protein (BCRP; ABCG2) limits intestinal absorption of low-permeability substrate drugs and mediates biliary excretion of drugs and metabolites. Based on clinical evidence of BCRP-mediated drug-drug interactions (DDIs) and the c.421C>A functional polymorphism affecting drug efficacy and safety, both the US Food and Drug Administration and European Medicines Agency recommend preclinical evaluation and, when appropriate, clinical assessment of BCRP-mediated DDIs. Although many BCRP substrates and inhibitors have been identified in vitro, clinical translation has been confounded by overlap with other transporters and metabolic enzymes. Regulatory recommendations for BCRP-mediated clinical DDI studies are challenging, as consensus is lacking on the choice of the most robust and specific human BCRP substrates and inhibitors and optimal study design. This review proposes a path forward based on a comprehensive analysis of available data. Oral sulfasalazine (1000 mg, immediate-release tablet) is the best available clinical substrate for intestinal BCRP, oral rosuvastatin (20 mg) for both intestinal and hepatic BCRP, and intravenous rosuvastatin (4 mg) for hepatic BCRP. Oral curcumin (2000 mg) and lapatinib (250 mg) are the best available clinical BCRP inhibitors. To interrogate the worst-case clinical BCRP DDI scenario, study subjects harboring the BCRP c.421C/C reference genotype are recommended. In addition, if sulfasalazine is selected as the substrate, subjects having the rapid acetylator phenotype are recommended. In the case of rosuvastatin, subjects with the organic anion-transporting polypeptide 1B1 c.521T/T genotype are recommended, together with monitoring of rosuvastatin's cholesterol-lowering effect at baseline and DDI phase. A proof-of-concept clinical study is being planned by a collaborative consortium to evaluate the proposed BCRP DDI study design.


Assuntos
Transportadores de Cassetes de Ligação de ATP/antagonistas & inibidores , Interações de Medicamentos , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos/metabolismo , Proteínas de Neoplasias/antagonistas & inibidores , Preparações Farmacêuticas/metabolismo , Farmacocinética , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP , Transportadores de Cassetes de Ligação de ATP/genética , Ensaios Clínicos como Assunto , Resistência a Múltiplos Medicamentos , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos/genética , Humanos , Proteínas de Neoplasias/genética , Polimorfismo de Nucleotídeo Único , Guias de Prática Clínica como Assunto , Projetos de Pesquisa , Especificidade por Substrato
16.
Mol Cancer Ther ; 14(2): 480-90, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25504752

RESUMO

Emerging evidence demonstrates that stromal cell-derived factor 1 (SDF-1) and CXCR4, a chemokine and chemokine receptor pair, play important roles in tumorigenesis. In this report, we describe a small cyclic peptide, LY2510924, which is a potent and selective CXCR4 antagonist currently in phase II clinical studies for cancer. LY2510924 specifically blocked SDF-1 binding to CXCR4 with IC50 value of 0.079 nmol/L, and inhibited SDF-1-induced GTP binding with Kb value of 0.38 nmol/L. In human lymphoma U937 cells expressing endogenous CXCR4, LY2510924 inhibited SDF-1-induced cell migration with IC50 value of 0.26 nmol/L and inhibited SDF-1/CXCR4-mediated intracellular signaling. LY2510924 exhibited a concentration-dependent inhibition of SDF-1-stimulated phospho-ERK and phospho-Akt in tumor cells. Biochemical and cellular analyses revealed that LY2510924 had no apparent agonist activity. Pharmacokinetic analyses suggested that LY2510924 had acceptable in vivo stability and a pharmacokinetic profile similar to a typical small-molecular inhibitor in preclinical species. LY2510924 showed dose-dependent inhibition of tumor growth in human xenograft models developed with non-Hodgkin lymphoma, renal cell carcinoma, lung, and colon cancer cells that express functional CXCR4. In MDA-MB-231, a breast cancer metastatic model, LY2510924 inhibited tumor metastasis by blocking migration/homing process of tumor cells to the lung and by inhibiting cell proliferation after tumor cell homing. Collectively, the preclinical data support further investigation of LY2510924 in clinical studies for cancer.


Assuntos
Antineoplásicos/farmacologia , Neoplasias Mamárias Experimentais/patologia , Metástase Neoplásica/patologia , Peptídeos Cíclicos/farmacologia , Receptores CXCR4/antagonistas & inibidores , Animais , Antineoplásicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Quimiocina CXCL12 , Modelos Animais de Doenças , Cães , Estabilidade de Medicamentos , Feminino , Humanos , Macaca fascicularis , Masculino , Camundongos Endogâmicos C57BL , Peptídeos Cíclicos/química , Peptídeos Cíclicos/farmacocinética , Ratos Sprague-Dawley , Receptores CXCR4/agonistas , Receptores CXCR4/metabolismo , Transdução de Sinais/efeitos dos fármacos , Ensaios Antitumorais Modelo de Xenoenxerto
18.
Drug Metab Dispos ; 42(11): 1780-4, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25106415

RESUMO

Ketoconazole is no longer available for clinical determination of worst-case victim drug-drug interaction (DDI) potential for cytochrome P450 3A (CYP3A)-substrate drugs; clarithromycin and itraconazole are the proposed replacements. Ketoconazole DDIs are described by unbound systemic exposures due to absence of carrier-facilitated hepatic uptake, but this aspect of clarithromycin and itraconazole disposition has not been investigated. At present, transport of clarithromycin, itraconazole, and hydroxyitraconazole by hepatic organic anion transporting polypeptides (OATPs) and organic cation transporter 1 (OCT1) was examined in vitro and in vivo. As for ketoconazole, uptake of clarithromycin, itraconazole, and hydroxyitraconazole into OATP1B1, OATP1B3, OATP2B1, and OCT1 expressing human embryonic kidney 293 (HEK293) cells was not greater than in vector controls. Uptake into these HEK293 cells and human hepatocytes was not impaired by the prototypical OATP, OCT, and sodium/taurocholate cotransporting polypeptide inhibitors bromosulfophthalein, imipramine, and taurocholate, respectively. In contrast, uptake of the positive controls, atorvastatin for OATPs and metformin for OCT1, was significantly enhanced by relevant transporter expression, and uptake into both these HEK293 cells and human hepatocytes was significantly impaired by prototypical inhibitors. In Oatp1a/1b gene cluster knockout mice, which lack the major hepatic Oatps, and in Oct1/2 knockout mice, ketoconazole, clarithromycin, itraconazole, and hydroxyitraconazole oral exposure was not increased, and the liver-to-blood partition coefficient (Kp) was not decreased. By contrast relative to wild-type mice, in Oatp1a/1b- and Oct1/2-knockout mice, atorvastatin and metformin oral exposure was significantly increased, and liver Kp was significantly decreased. The present studies provide in vitro and in vivo evidence that, like ketoconazole, clarithromycin, itraconazole, and hydroxyitraconazole are not transported into the liver by hepatic uptake transporters, including OATPs and OCT1.


Assuntos
Inibidores do Citocromo P-450 CYP3A/farmacologia , Fígado/metabolismo , Transportadores de Ânions Orgânicos/metabolismo , Transportador 1 de Cátions Orgânicos/metabolismo , Animais , Claritromicina/farmacologia , Inibidores do Citocromo P-450 CYP3A/farmacocinética , Itraconazol/farmacologia , Cetoconazol/farmacologia , Masculino , Camundongos , Camundongos Knockout
19.
Drug Metab Dispos ; 42(6): 1008-15, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24658455

RESUMO

The glycogen synthase kinase-3 inhibitor LY2090314 specifically impaired CYP2B6 activity during in vitro evaluation of cytochrome P450 (P450) enzyme induction in human hepatocytes. CYP2B6 catalytic activity was significantly decreased following 3-day incubation with 0.1-10 µM LY2090314, on average by 64.3% ± 5.0% at 10 µM. These levels of LY2090314 exposure were not cytotoxic to hepatocytes and did not reduce CYP1A2 and CYP3A activities. LY2090314 was not a time-dependent CYP2B6 inhibitor, did not otherwise inhibit enzyme activity at concentrations ≤10 µM, and was not metabolized by CYP2B6. Thus, mechanism-based inactivation or other direct interaction with the enzyme could not explain the observed reduction in CYP2B6 activity. Instead, LY2090314 significantly reduced CYP2B6 mRNA levels (Imax = 61.9% ± 1.4%; IC50 = 0.049 ± 0.043 µM), which were significantly correlated with catalytic activity (r(2) = 0.87, slope = 0.77; Imax = 57.0% ± 10.8%, IC50 = 0.057 ± 0.027 µM). Direct inhibition of constitutive androstane receptor by LY2090314 is conceptually consistent with the observed CYP2B6 transcriptional suppression (Imax = 100.0% ± 10.8% and 57.1% ± 2.4%; IC50 = 2.5 ± 1.2 and 2.1 ± 0.4 µM for isoforms 1 and 3, respectively) and may be sufficiently extensive to overcome the weak but potent activation of pregnane X receptor by ≤10 µM LY2090314 (19.3% ± 2.2% of maximal rifampin response, apparent EC50 = 1.2 ± 1.1 nM). The clinical relevance of these findings was evaluated through physiologically based pharmacokinetic model simulations. CYP2B6 suppression by LY2090314 is not expected clinically, with a projected <1% decrease in hepatic enzyme activity and <1% decrease in hydroxybupropion exposure following bupropion coadministration. However, simulations showed that observed CYP2B6 suppression could be clinically relevant for a drug with different pharmacokinetic properties from LY2090314.


Assuntos
Citocromo P-450 CYP2B6/biossíntese , Citocromo P-450 CYP2B6/genética , Inibidores do Citocromo P-450 CYP2D6/farmacologia , Drogas em Investigação/farmacologia , Transcrição Genética/efeitos dos fármacos , Transcrição Genética/fisiologia , Bupropiona/farmacologia , Linhagem Celular Tumoral , Relação Dose-Resposta a Droga , Interações de Medicamentos/fisiologia , Drogas em Investigação/química , Feminino , Hepatócitos/efeitos dos fármacos , Hepatócitos/enzimologia , Compostos Heterocíclicos com 3 Anéis/farmacologia , Humanos , Masculino , Maleimidas/farmacologia
20.
Drug Metab Dispos ; 42(4): 650-64, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24346835

RESUMO

Recent analyses demonstrated that metabolites are unlikely to contribute significantly to clinical inhibition of cytochrome P450 (P450)-mediated drug metabolism, and that only ∼2% of this type of drug interaction could not be predicted from the parent drug alone. Due to generally increased polarity and decreased permeability, metabolites are less likely to interact with P450s, but their disposition is instead more likely to involve transporters. This commentary presents case studies illustrating the potential importance of transporters as determinants of metabolite disposition, and as sites of drug interactions, which may alter drug efficacy and safety. Many of these examples are hydrophilic phase II conjugates involved in enterohepatic cycling, where modulation of transporter-dependent disposition may alter pharmacokinetics/pharmacodynamics. The case studies suggest that characterization of metabolite disposition, toxicology, and pharmacology should not focus solely on metabolites with appreciable systemic exposure, but should take into consideration major excretory metabolites. A more thorough understanding of metabolite (phase I and II; circulating and excreted) transport properties during drug development may provide an improved understanding of complex drug-drug interactions (DDIs) that can alter drug and/or metabolite systemic and intracellular exposure. Knowledge and capability gaps remain in clinical translation of in vitro and animal data regarding metabolite disposition. To this end, useful experimental and modeling approaches are highlighted. Application of these tools may lead to a better understanding of metabolite victim and perpetrator DDI potential, and ultimately the establishment of approaches for prediction of pharmacodynamic and toxicodynamic consequences of metabolite transport modulation.


Assuntos
Proteínas de Transporte/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Descoberta de Drogas , Preparações Farmacêuticas/metabolismo , Interações de Medicamentos , Humanos , Modelos Biológicos , Preparações Farmacêuticas/sangue , Preparações Farmacêuticas/urina , Distribuição Tecidual
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