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1.
J Thromb Thrombolysis ; 50(1): 12-19, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32323190

RESUMO

Anticoagulant plasma concentrations and patient characteristics might affect the benefit-risk balance of therapy. The study objective was to assess the impact of model-predicted rivaroxaban exposure and patient characteristics on outcomes in patients receiving rivaroxaban for venous thromboembolism (VTE) prophylaxis (VTE-P) after hip/knee replacement surgery. Post hoc exposure-response analyses were conducted using data from the phase 3 RECORD1-4 studies, in which 12,729 patients were randomized to rivaroxaban 10 mg once daily or enoxaparin for ≤ 39 days. Multivariate regression approaches were used to correlate model-predicted individual rivaroxaban exposures and patient characteristics with outcomes. In the absence of measured rivaroxaban exposure, exposure estimates were predicted based on individual increases in prothrombin time (PT) and by making use of the known correlation between rivaroxaban plasma concentration and dynamics of PT. No significant associations between rivaroxaban exposure and total VTE or major bleeding were identified. A significant association between exposure and a composite of major or non-major clinically relevant (NMCR) bleeding from day 4 after surgery was observed. The relationship was shallow, with an approximate predicted absolute increase in a composite of major or NMCR bleeding from 1.08 [95% confidence interval (CI) 0.76-1.54] to 2.18% (95% CI 1.51-3.17) at the 5th and 95th percentiles of trough plasma concentration, respectively. In conclusion, based on the underlying data and analysis, no reliable target window for exposure with improved benefit-risk could be identified within the investigated exposure range. Hence, monitoring rivaroxaban levels is unlikely to be beneficial in VTE-P.

2.
J Thromb Thrombolysis ; 50(1): 1-11, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32323191

RESUMO

Anticoagulant plasma concentrations and patient characteristics might affect the benefit-risk balance of therapy. This study assessed the impact of model-predicted rivaroxaban exposure and patient characteristics on outcomes in patients receiving rivaroxaban for venous thromboembolism treatment (VTE-T) using data from the phase 3 EINSTEIN-DVT and EINSTEIN-PE studies. In the absence of measured rivaroxaban exposure, exposure estimates were predicted based on individual increases in prothrombin time (PT) and the known correlation between rivaroxaban plasma concentrations and PT dynamics. The composite efficacy outcomes evaluated were recurrent deep-vein thrombosis (DVT) and pulmonary embolism (PE) and recurrent DVT, PE and all-cause death; safety outcomes were major bleeding and the composite of major or non-major clinically relevant (NMCR) bleeding. Exposure-response relationships were evaluated using multivariate logistic and Cox regression for the twice-daily (BID) and once-daily (OD) dosing periods, respectively. Predicted rivaroxaban exposure and CrCl were significantly associated with both efficacy outcomes in the BID period. In the OD period, exposure was significantly associated with recurrent DVT and PE but not recurrent DVT, PE and all-cause death. The statistically significant exposure-efficacy relationships were shallow. Exposure-safety relationships were absent within the investigated exposure range. During both dosing periods, low baseline hemoglobin and prior bleeding were associated with the composite of major or NMCR bleeding. In conclusion, based on the underlying data and analysis, no reliable target window for exposure with improved benefit-risk could be identified within the investigated exposure range. Therefore, monitoring rivaroxaban levels is unlikely to be beneficial in VTE-T.

3.
Haematologica ; 105(5): 1443-1453, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31371418

RESUMO

Pharmacokinetic-based prophylaxis of replacement factor VIII (FVIII) products has been encouraged in recent years, but the relationship between exposure (factor VIII activity) and response (bleeding frequency) remains unclear. The aim of this study was to characterize the relationship between FVIII dose, plasma FVIII activity, and bleeding patterns and individual characteristics in severe hemophilia A patients. Pooled pharmacokinetic and bleeding data during prophylactic treatment with BAY 81-8973 (octocog alfa) were obtained from the three LEOPOLD trials. The population pharmacokinetics of FVIII activity and longitudinal bleeding frequency, as well as bleeding severity, were described using non-linear mixed effects modeling in NONMEM. In total, 183 patients [median age 22 years (range, 1-61); weight 60 kg (11-124)] contributed with 1,535 plasma FVIII activity observations, 633 bleeds and 11 patient/study characteristics [median observation period 12 months (3.1-13.1)]. A parametric repeated time-to-categorical bleed model, guided by plasma FVIII activity from a 2-compartment population pharmacokinetic model, described the time to the occurrence of bleeds and their severity. Bleeding probability decreased with time of study, and a bleed was not found to affect the time of the next bleed. Several covariate effects were identified, including the bleeding history in the 12-month pre-study period increasing the bleeding hazard. However, unexplained inter-patient variability in the phenotypic bleeding pattern remained large (111%CV). Further studies to translate the model into a tool for dose individualization that considers the individual bleeding risk are required. Research was based on a post-hoc analysis of the LEOPOLD studies registered at clinicaltrials.gov identifiers: 01029340, 01233258 and 01311648.

4.
Clin Pharmacokinet ; 59(5): 605-616, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31749076

RESUMO

BACKGROUND: Prophylaxis with factor VIII (FVIII) should be individualized based on patient characteristics, including FVIII pharmacokinetics. Population pharmacokinetic (popPK) modeling simplifies pharmacokinetic studies by obviating the need for multiple samples. OBJECTIVE: The objective of this study was to characterize the pharmacokinetics and inter-individual variability (IIV) of BAY 94-9027 in relation to patient characteristics in support of a popPK-tailored approach, including identifying the optimal number and timing of pharmacokinetic samples. METHODS: Pharmacokinetic samples from 198 males (aged 2‒62 years) with severe hemophilia A, enrolled in BAY 94-9027 clinical trials, were analyzed. Baseline age, height, weight, body mass index, lean body weight (LBW), von Willebrand factor (VWF) level, and race were evaluated. A popPK model was developed and used to simulate pharmacokinetic endpoints difficult to observe from measured FVIII levels, including time to maintain FVIII levels above 1, 3, and 5 IU/dL after different BAY 94-9027 doses. RESULTS: A one-compartment model adequately described BAY 94-9027 pharmacokinetics. Clearance and central volume of distribution were significantly associated with LBW; clearance was inversely correlated with VWF. Due to the monophasic pharmacokinetics and well-understood IIV sources, identification of patient pharmacokinetics was achievable with sparse blood sampling. Median predicted time to maintain FVIII levels > 1 IU/dL in patients aged ≥ 12 years ranged from 120.1 to 127.2 h after single BAY 94-9027 doses of 45‒60 IU/kg. CONCLUSIONS: This analysis evaluated the pharmacokinetics of BAY 94-9027 and its sources of IIV. Using the model, determination of individual patient pharmacokinetics was possible with few FVIII samples, and a sparse sampling design to support pharmacokinetic-guided dosing was identified.

5.
Clin Pharmacokinet ; 59(3): 359-370, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31583611

RESUMO

BACKGROUND: Finerenone (BAY 94-8862) is a potent non-steroidal, selective mineralocorticoid receptor antagonist being developed for the treatment of patients with type 2 diabetes and chronic kidney disease. METHODS: We present the population pharmacokinetics and pharmacodynamics (PD) analysis for efficacy and safety markers based on data from two clinical phase IIb studies: ARTS-DN (NCT01874431) and ARTS-DN Japan (NCT01968668). RESULTS: The pharmacokinetics of finerenone were adequately characterized, with estimated glomerular filtration rate (eGFR) and body weight as influencing covariates. The area under the plasma concentration-time curve in Japanese patients did not differ from that in the global population, and the investigated pharmacokinetics were dose- and time-linear. In addition, the pharmacokinetic model provided robust individual exposure estimates to study exposure-response. The concentration-effect relationship over time for the efficacy marker urinary albumin:creatinine ratio (UACR) was well-characterized by a maximum effect model indicating saturation at high exposures. For the safety markers, a log-linear model and a power model were identified for serum potassium concentration and eGFR, respectively, indicating attenuation of effect gains at high exposures. There was no apparent ethnic effect on the investigated pharmacokinetic-pharmacodynamic relationships. The model-predicted times to reach the full (99%) steady-state drug effect on UACR, serum potassium, and eGFR were 138, 20, and 85 days, respectively, while the pharmacokinetic half-life was 2-3 h and steady state was achieved after 2 days, indicating timescale separation. CONCLUSION: Our dose-exposure-response modeling and simulation indicates effects were largely saturated at finerenone 20 mg and doses of both 10 and 20 mg once daily appear safe and efficacious at reducing albuminuria.

6.
CPT Pharmacometrics Syst Pharmacol ; 8(12): 894-903, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31668021

RESUMO

Bayesian forecasting for dose individualization of prophylactic factor VIII replacement therapy using pharmacokinetic samples is challenged by large interindividual variability in the bleeding risk. A pharmacokinetic-repeated time-to-event model-based forecasting approach was developed to contrast the ability to predict the future occurrence of bleeds based on individual (i) pharmacokinetic, (ii) bleeding, and (iii) pharmacokinetic, bleeding and covariate information using observed data from the Long-Term Efficacy Open-Label Program in Severe Hemophilia A Disease (LEOPOLD) clinical trials (172 severe hemophilia A patients taking prophylactic treatment). The predictive performance assessed by the area under receiver operating characteristic (ROC) curves was 0.67 (95% confidence interval (CI), 0.65-0.69), 0.78 (95% CI, 0.76-0.80), and 0.79 (95% CI, 0.77-0.81) for patients ≥ 12 years when using pharmacokinetics, bleeds, and all data, respectively, suggesting that individual bleed information adds value to the optimization of prophylactic dosing regimens in severe hemophilia A. Further steps to optimize the proposed tool for factor VIII dose adaptation in the clinic are required.

7.
Ther Adv Cardiovasc Dis ; 13: 1753944719863641, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31364490

RESUMO

BACKGROUND: This analysis aimed to evaluate the impact of rivaroxaban exposure and patient characteristics on efficacy and safety outcomes in patients with acute coronary syndrome (ACS) and to determine whether therapeutic drug monitoring might provide additional information regarding rivaroxaban dose, beyond what patient characteristics provide. METHODS: A post hoc exposure-response analysis was conducted using data from the phase III ATLAS ACS 2 Thrombolysis in Myocardial Infarction (TIMI) 51 study, in which 15,526 randomized ACS patients received rivaroxaban (2.5 mg or 5 mg twice daily) or placebo for a mean of 13 months (maximum follow up: 31 months). A multivariate Cox model was used to correlate individual predicted rivaroxaban exposures and patient characteristics with time-to-event clinical outcomes. RESULTS: For the incidence of myocardial infarction (MI), ischemic stroke, or nonhemorrhagic cardiovascular death, hazard ratios (HRs) for steady-state maximum plasma concentration (Cmax) in the 5th and 95th percentiles versus the median were statistically significant but close to 1 for both rivaroxaban doses. For TIMI major bleeding events, a statistically significant association was observed with Cmax [HR, 1.08; 95% CI, 1.06-1.11 (95th percentile versus median, 2.5 mg twice daily)], sex [HR, 0.56; 95% CI, 0.38-0.84 (female versus male)], and previous revascularization [HR, 0.62; 95% CI, 0.44-0.87 (no versus yes)]. CONCLUSIONS: The shallow slopes of the exposure-response relationships and the lack of a clear therapeutic window render it unlikely that therapeutic drug monitoring in patients with ACS would provide additional information regarding rivaroxaban dose beyond that provided by patient characteristics.


Assuntos
Síndrome Coronariana Aguda/tratamento farmacológico , Inibidores do Fator Xa/administração & dosagem , Modelos Biológicos , Rivaroxabana/administração & dosagem , Síndrome Coronariana Aguda/sangue , Síndrome Coronariana Aguda/diagnóstico , Síndrome Coronariana Aguda/mortalidade , Idoso , Isquemia Encefálica/mortalidade , Tomada de Decisão Clínica , Ensaios Clínicos Fase III como Assunto , Relação Dose-Resposta a Droga , Cálculos da Dosagem de Medicamento , Monitoramento de Medicamentos , Inibidores do Fator Xa/efeitos adversos , Inibidores do Fator Xa/farmacocinética , Feminino , Hemorragia/induzido quimicamente , Humanos , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/mortalidade , Ensaios Clínicos Controlados Aleatórios como Assunto , Medição de Risco , Fatores de Risco , Rivaroxabana/efeitos adversos , Rivaroxabana/farmacocinética , Acidente Vascular Cerebral/mortalidade , Resultado do Tratamento
8.
CPT Pharmacometrics Syst Pharmacol ; 8(11): 805-814, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31276324

RESUMO

Prothrombin time (PT) is a measure of coagulation status and was assessed in the majority of patients in the rivaroxaban phase II and III clinical trials as a pharmacodynamic marker. In the absence of sufficient phase III pharmacokinetic (PK) data to provide individual exposure measures for input into rivaroxaban exposure-response analyses, the aim of the present study was to investigate the use of PT-adjustment approaches (i.e., the use of observed individual PT measurements) to enhance the prediction of individual rivaroxaban exposure metrics (derived using a previously developed integrated population PK model) based on the observed linear relationship between PT and rivaroxaban plasma concentrations. The PT-adjustment approaches were established using time-matched PK and PT measurements, which were available from 1,779 patients across four phase II trials and one phase III trial of rivaroxaban. PT-adjusted exposure estimates improved the identification of statistically significant effects when compared with covariate-only exposure estimates.

9.
J Clin Pharmacol ; 58(12): 1639-1654, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30207604

RESUMO

To compare the pharmacokinetics (PK) of the progestin levonorgestrel for various routes of administration, an integrated population PK analysis was performed. This analysis integrated data from 10 clinical pharmacology studies and resulted in a single, comprehensive population PK model (and its applications) describing the PK of levonorgestrel and its variability for 6 levonorgestrel-containing contraceptives: 3 intrauterine systems (IUSs; levonorgestrel [LNG]-IUS 20 [Mirena® ], LNG-IUS 12 [Kyleena® ], and LNG-IUS 8 [Jaydess® /Skyla® ]); 2 oral contraceptives (the progestin-only pill [Microlut® /Norgeston® ] and the combined oral contraceptive [Miranova® ]); and a subdermal implant (Jadelle® ). The levonorgestrel-containing contraceptives administered orally or as an implant act mainly via their systemic (unbound) levonorgestrel exposure, whereas levonorgestrel administered via an IUS is released directly into the uterine cavity, resulting in lower systemic levonorgestrel concentrations. The integrated population PK analysis revealed that the combined oral contraceptive led to the highest levonorgestrel exposure, followed by the progestin-only pill and the implant, which led to similar levonorgestrel exposure, and the IUSs, which led to the lowest levonorgestrel exposure (in decreasing order: LNG-IUS 20, LNG-IUS 12, and LNG-IUS 8). The difference was even more distinct at the end of the indicated duration of use of 3 years (LNG-IUS 8) and 5 years (LNG-IUS 20 and LNG-IUS 12). Comparing the 3 IUSs and the implant, in vivo release rates were highest for the implant, followed by LNG-IUS 20, then LNG-IUS 12, and were lowest for LNG-IUS 8. This is in line with the comparison of the total levonorgestrel concentrations.


Assuntos
Anticoncepcionais Femininos/administração & dosagem , Anticoncepcionais Femininos/farmacocinética , Levanogestrel/administração & dosagem , Levanogestrel/farmacocinética , Administração Oral , Combinação Albuterol e Ipratrópio , Anticoncepcionais Femininos/sangue , Vias de Administração de Medicamentos , Implantes de Medicamento , Liberação Controlada de Fármacos , Feminino , Humanos , Dispositivos Intrauterinos , Levanogestrel/sangue
10.
CPT Pharmacometrics Syst Pharmacol ; 7(5): 309-320, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29660785

RESUMO

The population pharmacokinetics (PK) of rivaroxaban have been evaluated in several population-specific models. We developed an integrated population PK model using pooled data from 4,918 patients in 7 clinical trials across all approved indications. Effects of gender, age, and weight on apparent clearance (CL/F) and apparent volume of distribution (V/F), renal function, and comedication on CL/F, and relative bioavailability as a function of dose (F) were analyzed. Virtual subpopulations for exposure simulations were defined by age, creatinine clearance (CrCL) and body mass index (BMI). Rivaroxaban PK were adequately described by a one-compartment disposition model with a first-order absorption rate constant. Significant effects of CrCL, use of comedications, and study population on CL/F, age, weight, and gender on V/F, and dose on F were identified. CrCL had a modest influence on exposure, whereas age and BMI had a minor influence. The model was suitable to predict rivaroxaban exposure in patient subgroups of special interest.


Assuntos
Rim/efeitos dos fármacos , Rivaroxabana/farmacocinética , Adulto , Peso Corporal , Ensaios Clínicos Fase II como Assunto , Feminino , Humanos , Testes de Função Renal , Masculino , Taxa de Depuração Metabólica , Pessoa de Meia-Idade , Modelos Biológicos , Rivaroxabana/farmacologia
11.
Clin Pharmacokinet ; 56(9): 1045-1055, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28005225

RESUMO

BACKGROUND: BAY 81-8973 is a full-length, unmodified, recombinant human factor VIII (FVIII) for the treatment of hemophilia A. OBJECTIVE: The aim of this study was to compare the pharmacokinetic (PK) profile of BAY 81-8973 with antihemophilic factor (recombinant) plasma/albumin-free method (rAHF-PFM) PATIENTS/METHODS: In this phase I, open-label, crossover study, men aged 18-65 years with severe hemophilia A and ≥150 exposure days to FVIII were randomized to receive a single intravenous infusion of 50 IU/kg BAY 81-8973 or rAHF-PFM, followed by crossover to a single infusion of the other treatment. FVIII levels were measured in plasma over 48 h using one-stage and chromogenic assays. PK parameters, including area under the curve from time zero to the last data point (AUClast; primary outcome) and half-life (t ½) were calculated. A population PK model was developed to simulate various treatment scenarios. RESULTS: Eighteen patients were randomized and analyzed. Using both assays, geometric mean (coefficient of variation [%CV]) AUClast was significantly higher, and t ½ was significantly longer, for BAY 81-8973 versus rAHF-PFM (one-stage, AUClast: 1660 IU·h/dL [29.4] vs. 1310 IU·h/dL [29.0], p < 0.0001; one-stage, t ½: 14.5 [25.7] vs. 11.7 h [27.3], p < 0.0001). Simulations showed that median time to 1 IU/dL was approximately 27% longer for BAY 81-8973 versus rAHF-PFM over doses of 25-50 IU/kg; plasma levels >1 IU/dL could be maintained with 14.4 IU/kg BAY 81-8973 or 39.1 IU/kg rAHF-PFM 3×/week. CONCLUSIONS: BAY 81-8973 showed a superior PK profile versus rAHF-PFM. The same FVIII trough threshold level could be achieved with lower doses of BAY 81-8973 versus rAHF-PFM. ClinicalTrials.gov: NCT02483208.


Assuntos
Fator VIII/administração & dosagem , Fator VIII/farmacocinética , Hemofilia A/sangue , Hemofilia A/tratamento farmacológico , Albumina Sérica/metabolismo , Índice de Gravidade de Doença , Adulto , Estudos Cross-Over , Humanos , Infusões Intravenosas , Masculino , Pessoa de Meia-Idade , Adulto Jovem
12.
J Inorg Biochem ; 105(5): 709-17, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21450275

RESUMO

Decreased influx represents one of the major resistance mechanisms of platinum complexes. In order to address the question if this mechanism of resistance can be overcome by enhancing the lipophilicity of platinum complexes, we investigated the influence of lipophilicity on cellular accumulation and cytotoxicity in a panel of oxaliplatin analogues with different carrier ligands. Cellular accumulation, DNA platination and cytotoxicity were measured in a cisplatin-sensitive and -resistant ovarian carcinoma (A2780/A2780cis) and in an oxaliplatin-sensitive and -resistant ileocecal colorectal adenocarcinoma (HCT-8/HCT-8ox) cell line pair. Platinum concentrations were determined by flameless atomic absorption spectrometry or adsorptive stripping voltammetry. Passive diffusion represented the main influx mechanism of oxaliplatin analogues during the first minutes of incubation as indicated by a correlation between lipophilicity and early influx rate. Afterwards, the predominant influx mechanism was lipophilicity-independent. More lipophilic complexes showed a reduced cytotoxic activity, although the early influx rate was increased. The resistance profiles of the two cell line pairs were found to be different: HCT-8ox cells were less resistant against more lipophilic complexes, whereas A2780cis cells exhibited a comparable degree of resistance against all investigated compounds. However, the reduction in resistance factor of HCT-8ox cells cannot be explained by increased influx suggesting that other resistance mechanisms are circumvented upon exposure to more lipophilic compounds. Though resistance against more lipophilic platinum complexes analogues is lower we conclude that enhancing lipophilicity is not a successful strategy to overcome platinum resistance as higher lipophilicity is also associated with lower cytotoxic activity.


Assuntos
Antineoplásicos/metabolismo , Compostos Organoplatínicos/metabolismo , Platina/química , Antineoplásicos/química , Carcinoma Epitelial do Ovário , Linhagem Celular Tumoral , Sobrevivência Celular , Cisplatino/metabolismo , DNA/química , Resistencia a Medicamentos Antineoplásicos , Endocitose , Humanos , Ligantes , Neoplasias Epiteliais e Glandulares/tratamento farmacológico , Compostos Organoplatínicos/química , Neoplasias Ovarianas/tratamento farmacológico , Platina/metabolismo
13.
Chemotherapy ; 56(1): 1-8, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20185910

RESUMO

BACKGROUND: Cisplatin resistance has been mainly associated with decreased cellular accumulation and increased intracellular glutathione (GSH) levels. ATP is known to increase the membrane permeability of cells and to decrease intracellular GSH levels. Our study aimed at using extracellular ATP to sensitize ovarian carcinoma cells towards cisplatin. METHODS: The MTT assay was used to determine the EC(50) of cisplatin in the human ovarian carcinoma cell line A2780 and its cisplatin-resistant variant A2780cis. Intracellular platinum concentrations were determined using flameless atomic absorption spectrometry. RESULTS: Preincubation and concomitant incubation with ATP did not alter the EC(50) of cisplatin. The presence of 100 muM ATP along with cisplatin decreased cell survival in A2780 but not in A2780cis cells. Extracellular ATP did not increase the cellular accumulation of cisplatin in both A2780 and A2780cis cells. CONCLUSION: The presence of extracellular ATP during treatment with cisplatin leads to additive cytotoxicity in the sensitive A2780 but not in cisplatin-resistant A2780cis cells.


Assuntos
Adenosina Trifosfatases/toxicidade , Protocolos de Quimioterapia Combinada Antineoplásica/toxicidade , Cisplatino/toxicidade , Neoplasias Ovarianas/tratamento farmacológico , Adenosina Trifosfatases/química , Protocolos de Quimioterapia Combinada Antineoplásica/química , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Cisplatino/química , Cisplatino/uso terapêutico , Resistencia a Medicamentos Antineoplásicos , Feminino , Humanos , Microscopia de Força Atômica , Células Tumorais Cultivadas
14.
J Control Release ; 131(2): 100-6, 2008 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-18691617

RESUMO

The development of resistance is one of the major limitations for the use of platinum (Pt) complexes in cancer chemotherapy. As reduced cellular uptake is a well-known resistance mechanism of cisplatin we explored the potential to overcome resistance in cisplatin-resistant A2780 ovarian carcinoma cells by means of macromolecular prodrugs exploiting endocytosis as alternative uptake mechanism. Two Pt-albumin (PL04-HSA, PL07-HSA) complexes and one Pt-polyethylene glycol complex (PEG(10k)-(Mal-Pt-DACH)(2)) were investigated. Intracellular platinum accumulation was quantified by FAAS. Cytotoxic activity was measured using the MTT assay. Endocytosis mechanisms were investigated by co-incubation experiments with bafilomycin A(1) and methyl-beta-cyclodextrin, inhibitors of the clathrin-mediated and caveolae-mediated endocytosis, respectively. Whereas the intracellular accumulation of the low molecular precursors PL04 and PL07 was reduced in the resistant cell variant, no difference between sensitive and resistant cells was observed for the three macromolecular complexes. In the presence of bafilomycin A(1) intracellular accumulation of all investigated macromolecular complexes was decreased whereas methyl-beta-cyclodextrin only affected the Pt-PEG complex. The Pt-PEG complex exhibited a higher cytotoxic activity than the albumin conjugates but also showed cross-resistance with cisplatin. In conclusion, cellular accumulation of macromolecular platinum complexes is not altered in cisplatin-resistant A2780 cells as these complexes enter the cells mainly via endocytotic pathways. Macromolecular platinum complexes specially designed to circumvent reduced cellular accumulation may be a promising approach to overcome cisplatin resistance.


Assuntos
Antineoplásicos , Cisplatino/farmacologia , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Compostos Organoplatínicos , Antineoplásicos/química , Antineoplásicos/farmacocinética , Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , DNA/metabolismo , Portadores de Fármacos/química , Endocitose/efeitos dos fármacos , Fluoresceína-5-Isotiocianato/análogos & derivados , Humanos , Hidrólise , Estrutura Molecular , Compostos Organoplatínicos/química , Compostos Organoplatínicos/farmacocinética , Compostos Organoplatínicos/farmacologia , Polietilenoglicóis/química , Albumina Sérica/química , Soroalbumina Bovina , Espectrofotometria Atômica
15.
Bioconjug Chem ; 15(6): 1349-59, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15546202

RESUMO

Four platinum (II) complexes (13-16) were synthesized by reacting either [Pt trans-DACH](NO(3))(2) with a 6-maleimidocaproic acid, a 15-maleimido-4,7,10,13-tetroxapentadecanoic acid, and a 6-maleimido-4-oxacaproic ester derivative of cyclobutane-1,1-dicarboxylic acid (CDBA) or [Pt(NH(3))(2)](NO(3))(2) with a 6-maleimido-4-oxacaproic ester derivative of CBDA. Both complexes containing the 6-maleimido-4-oxacaproic ester (15, 16) showed good water solubility (>/=8 mg/mL) and CE experiments revealed rapid binding to human serum albumin and the formation of biadducts with dGMP and dAMP. In the MaTu xenograft model in nude mice, both complexes showed an improved antitumor effect at their maximum tolerated dose (2 x 50 mg/kg carboplatin equivalents) compared to therapy with carboplatin at equimolar dose or at its optimal dose (2 x 75 mg/kg).


Assuntos
Antineoplásicos/síntese química , Carboplatina/síntese química , Maleimidas/síntese química , Pró-Fármacos/síntese química , Albumina Sérica/metabolismo , Animais , Antineoplásicos/metabolismo , Carboplatina/análogos & derivados , Carboplatina/metabolismo , Linhagem Celular Tumoral , Feminino , Humanos , Maleimidas/metabolismo , Camundongos , Camundongos Nus , Transplante de Neoplasias , Pró-Fármacos/metabolismo , Ligação Proteica/fisiologia , Solubilidade , Água/metabolismo , Ensaios Antitumorais Modelo de Xenoenxerto/métodos
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