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1.
Stat Med ; 36(2): 225-241, 2017 01 30.
Artigo em Inglês | MEDLINE | ID: mdl-26891942

RESUMO

In oncology, combinations of drugs are often used to improve treatment efficacy and/or reduce harmful side effects. Dual-agent phase I clinical trials assess drug safety and aim to discover a maximum tolerated dose combination via dose-escalation; cohorts of patients are given set doses of both drugs and monitored to see if toxic reactions occur. Dose-escalation decisions for subsequent cohorts are based on the number and severity of observed toxic reactions, and an escalation rule. In a combination trial, drugs may be administered concurrently or non-concurrently over a treatment cycle. For two drugs given non-concurrently with overlapping toxicities, toxicities occurring after administration of the first drug yet before administration of the second may be attributed directly to the first drug, whereas toxicities occurring after both drugs have been given some present ambiguity; toxicities may be attributable to the first drug only, the second drug only or the synergistic combination of both. We call this mixture of attributable and non-attributable toxicity semi-attributable toxicity. Most published methods assume drugs are given concurrently, which may not be reflective of trials with non-concurrent drug administration. We incorporate semi-attributable toxicity into Bayesian modelling for dual-agent phase I trials with non-concurrent drug administration and compare the operating characteristics to an approach where this detail is not considered. Simulations based on a trial for non-concurrent administration of intravesical Cabazitaxel and Cisplatin in early-stage bladder cancer patients are presented for several scenarios and show that including semi-attributable toxicity data reduces the number of patients given overly toxic combinations. © 2016 The Authors. Statistics in Medicine Published by John Wiley & Sons Ltd.


Assuntos
Antineoplásicos/administração & dosagem , Antineoplásicos/toxicidade , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Protocolos de Quimioterapia Combinada Antineoplásica/toxicidade , Ensaios Clínicos Fase I como Assunto/métodos , Algoritmos , Bioestatística , Ensaios Clínicos Fase I como Assunto/estatística & dados numéricos , Estudos de Coortes , Simulação por Computador , Relação Dose-Resposta a Droga , Esquema de Medicação , Humanos , Bloqueio Interatrial , Modelos Estatísticos , Neoplasias/tratamento farmacológico
2.
Trials ; 24(1): 776, 2023 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-38037105

RESUMO

BACKGROUND: Highly effective, short-course, bedaquiline-containing treatment regimens for multidrug-resistant tuberculosis (MDR-TB) and integrase strand transfer inhibitor (INSTI)-containing fixed dose combination antiretroviral therapy (ART) have radically transformed treatment for MDR-TB and HIV. However, without advances in adherence support, we may not realize the full potential of these therapeutics. The primary objective of this study is to compare the effect of adherence support interventions on clinical and biological endpoints using an adaptive randomized platform. METHODS: This is a prospective, adaptive, randomized controlled trial comparing the effectiveness of four adherence support strategies on a composite clinical outcome in adults with MDR-TB and HIV initiating bedaquiline-containing MDR-TB treatment regimens and receiving ART in KwaZulu-Natal, South Africa. Trial arms include (1) enhanced standard of care, (2) psychosocial support, (3) mHealth using cellular-enabled electronic dose monitoring, and (4) combined mHealth and psychosocial support. The level of support will be titrated using a differentiated service delivery (DSD)-informed assessment of treatment support needs. The composite primary outcome will include survival, negative TB culture, retention in care, and undetectable HIV viral load at month 12. Secondary outcomes will include individual components of the primary outcome and quantitative evaluation of adherence on TB and HIV treatment outcomes. DISCUSSION: This trial will evaluate the contribution of different modes of adherence support on MDR-TB and HIV outcomes with WHO-recommended all-oral MDR-TB regimens and ART in a high-burden operational setting. We will also assess the utility of a DSD framework to pragmatically adjust levels of MDR-TB and HIV treatment support. TRIAL REGISTRATION: ClinicalTrials.gov NCT05633056. Registered on 1 December 2022.


Assuntos
Infecções por HIV , Tuberculose Resistente a Múltiplos Medicamentos , Adulto , Humanos , Infecções por HIV/diagnóstico , Infecções por HIV/tratamento farmacológico , Infecções por HIV/complicações , Estudos Prospectivos , Ensaios Clínicos Controlados Aleatórios como Assunto , África do Sul/epidemiologia , Resultado do Tratamento , Tuberculose Resistente a Múltiplos Medicamentos/diagnóstico , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico
3.
Health Psychol ; 40(4): 230-241, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33856830

RESUMO

OBJECTIVE: Personalized trials have the potential to improve the precision of treatment selection and foster patient involvement in clinical decision making. Little is known about the attitudes of patients with multimorbidities. To address this, stakeholders designed and conducted a national survey that determined general attitudes and features of personalized trials that may increase their use among patients with multimorbidities in clinical and research practice. METHOD: A multistakeholder collaboratory of patients, clinicians, scientists, methodologists, statisticians, and research disseminators designed a survey to determine the conditions, symptoms, and design attributes most applicable to personalized trials according to patients. A sample of U.S. patients with two or more prespecified personalized-trial-amenable chronic conditions completed the online survey. RESULTS: Multimorbid participants (N = 501; M age = 56.1 years) showed that some conditions, symptoms or use cases for personalized trials include pain (57.6%), hypertension (38.8%), diabetes (28.8%), sleep problems (27.4%), and depression (23.0%). Overall, 82.0% of the participants with multimorbidities were interested in participating in personalized trials. The percentage that were interested varied by trial attributes, including physician involvement (86.4%), patient-driven treatment selection (88.0%), clinician blinding (59.2%), placebo treatment options (57.5%), and out-of-pocket costs (41.8%). CONCLUSION: Participants with multimorbidities identified prevalent use cases that are suited to personalized trials. Participants also identified design features of such trials, including patient-driven treatment selection, active comparators, and nonblinding. This study demonstrates that eliciting input from a collaboratory and patients with multimorbidities can inform research priorities for this rapidly growing patient population and increase adoption by researchers and clinicians alike. (PsycInfo Database Record (c) 2021 APA, all rights reserved).


Assuntos
Participação do Paciente/métodos , Seleção de Pacientes/ética , Medicina de Precisão/métodos , Participação dos Interessados/psicologia , Humanos , Masculino , Pessoa de Meia-Idade , Pesquisadores , Inquéritos e Questionários
4.
JAMA Netw Open ; 3(11): e2025134, 2020 11 02.
Artigo em Inglês | MEDLINE | ID: mdl-33175177

RESUMO

Importance: Adults who belong to racial/ethnic minority groups are more likely than White adults to receive a diagnosis of chronic disease in the United States. Objective: To evaluate which health indicators have improved or become worse among Black and Hispanic middle-aged and older adults since the Minority Health and Health Disparities Research and Education Act of 2000. Design, Setting, and Participants: In this repeated cross-sectional study, a total of 4 856 326 records were extracted from the Behavioral Risk Factor Surveillance System from January 1999 through December 2018 of persons who self-identified as Black (non-Hispanic), Hispanic (non-White), or White and who were 45 years or older. Exposure: The 1999 legislation to reduce racial/ethnic health disparities. Main Outcomes and Measures: Poor health indicators and disparities including major chronic diseases, physical inactivity, uninsured status, and overall poor health. Results: Among the 4 856 326 participants (2 958 041 [60.9%] women; mean [SD] age, 60.4 [11.8] years), Black adults showed an overall decrease indicating improvement in uninsured status (ß = -0.40%; P < .001) and physical inactivity (ß = -0.29%; P < .001), while they showed an overall increase indicating deterioration in hypertension (ß = 0.88%; P < .001), diabetes (ß = 0.52%; P < .001), asthma (ß = 0.25%; P < .001), and stroke (ß = 0.15%; P < .001) during the last 20 years. The Black-White gap (ie, the change in ß between groups) showed improvement (2 trend lines converging) in uninsured status (-0.20%; P < .001) and physical inactivity (-0.29%; P < .001), while the Black-White gap worsened (2 trend lines diverging) in diabetes (0.14%; P < .001), hypertension (0.15%; P < .001), coronary heart disease (0.07%; P < .001), stroke (0.07%; P < .001), and asthma (0.11%; P < .001). Hispanic adults showed improvement in physical inactivity (ß = -0.28%; P = .02) and perceived poor health (ß = -0.22%; P = .001), while they showed overall deterioration in hypertension (ß = 0.79%; P < .001) and diabetes (ß = 0.50%; P < .001). The Hispanic-White gap showed improvement in coronary heart disease (-0.15%; P < .001), stroke (-0.04%; P < .001), kidney disease (-0.06%; P < .001), asthma (-0.06%; P = .02), arthritis (-0.26%; P < .001), depression (-0.23%; P < .001), and physical inactivity (-0.10%; P = .001), while the Hispanic-White gap worsened in diabetes (0.15%; P < .001), hypertension (0.05%; P = .03), and uninsured status (0.09%; P < .001). Conclusions and Relevance: This study suggests that Black-White disparities increased in diabetes, hypertension, and asthma, while Hispanic-White disparities remained in diabetes, hypertension, and uninsured status.


Assuntos
Asma/etnologia , Diabetes Mellitus/etnologia , Disparidades nos Níveis de Saúde , Hipertensão/etnologia , Pessoas sem Cobertura de Seguro de Saúde/etnologia , Saúde das Minorias/tendências , Comportamento Sedentário/etnologia , Negro ou Afro-Americano/estatística & dados numéricos , Idoso , Artrite/etnologia , Doença das Coronárias/etnologia , Estudos Transversais , Depressão/etnologia , Feminino , Indicadores Básicos de Saúde , Hispânico ou Latino/estatística & dados numéricos , Humanos , Seguro Saúde/tendências , Nefropatias/etnologia , Masculino , Pessoa de Meia-Idade , Acidente Vascular Cerebral/etnologia , Estados Unidos/epidemiologia , População Branca/estatística & dados numéricos
5.
Contemp Clin Trials ; 84: 105826, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31419605

RESUMO

BACKGROUND: Elevated depressive symptoms among survivors of acute coronary syndromes (ACS) confer recurrent cardiovascular events and mortality, worse quality of life, and higher healthcare costs. While multiple scientific groups advise routine depression screening for ACS survivors, no randomized trials exist to inform this screening recommendation. We aimed to assess the effect of screening for depression on change in quality of life over 18 months among ACS patients. METHODS: The Comparison of Depression Identification after Acute Coronary Syndrome on Quality of Life and Cost Outcomes (CODIACS-QoL) trial is a pragmatic, 3-arm trial that randomized ACS patients to 1) systematic depression screening using the 8-item Patient Health Questionnaire (PHQ-8) and if positive screen (PHQ-8 ≥ 10), notification of primary care providers (PCPs) and invitation to participate in centralized, patient-preference, stepped depression care (Screen, Notify, and Treat, N = 499); 2) systematic depression screening and PCP notification only (Screen and Notify, N = 501); and 3) usual care (No Screen, N = 500). Adults hospitalized for ACS in the previous 2-12 months without prior history of depression were eligible for participation. Key outcomes will be quality-adjusted life years (primary), cost of health care utilization, and depression-free days across 18 months. RESULTS: A total of 1500 patients were randomized in the CODIACS-QOL trial (28.3% women; 16.3% Hispanic; mean age 65.9 (11.5) years). Only 7% of ACS survivors had elevated depressive symptoms. CONCLUSIONS: Using a novel randomization schema and pragmatic design principles, the CODIACS-QoL trial achieved its enrollment target. Eventual results of this trial will inform future depression screening recommendations in cardiac patients. TRIAL REGISTRATION: ClinicalTrials.gov (NCT01993017).


Assuntos
Síndrome Coronariana Aguda/complicações , Depressão/diagnóstico , Depressão/etiologia , Programas de Rastreamento/métodos , Atenção Primária à Saúde/métodos , Síndrome Coronariana Aguda/psicologia , Fatores Etários , Idoso , Algoritmos , Antidepressivos/uso terapêutico , Análise Custo-Benefício , Aconselhamento/métodos , Depressão/terapia , Feminino , Nível de Saúde , Humanos , Masculino , Programas de Rastreamento/economia , Saúde Mental , Pessoa de Meia-Idade , Aceitação pelo Paciente de Cuidados de Saúde , Atenção Primária à Saúde/economia , Qualidade de Vida , Encaminhamento e Consulta , Fatores Sexuais , Método Simples-Cego , Fatores Socioeconômicos
6.
J Am Heart Assoc ; 7(20): e008658, 2018 10 16.
Artigo em Inglês | MEDLINE | ID: mdl-30371272

RESUMO

Background Obtaining out-of-clinic blood pressure ( BP ) measurements to confirm a diagnosis of hypertension is recommended before initiating treatment. There are few empiric data available on the number of measurements required to reliably estimate BP on home BP monitoring ( HBPM ). Methods and Results We analyzed data from 316 community-dwelling adults not taking antihypertensive medication from the IDH (Improving the Detection of Hypertension) study who performed HBPM for 14 days. The reliability of home BP measurements was assessed using the intraclass correlation coefficient and as the percentage of participants with an absolute difference in home BP <10 mm Hg between weeks. The reliability of home hypertension status was assessed by the κ statistic. In the IDH study, 13.6% of participants had clinic hypertension and 18.0% had home hypertension. Mean home systolic and diastolic BP exhibited excellent reliability and sufficient agreement using the average of 2 morning and 2 evening BP readings for a minimum of 2 days of HBPM and a single morning and single evening or 2 morning BP readings for a minimum of 3 days. For diagnosing home hypertension, there was good agreement with a minimum of 3 days of HBPM using the average of 2 morning and 2 evening measurements or a single morning and single evening BP reading. A greater number of days was required for the other HBPM strategies. Conclusions Using the average of morning and evening readings, 3 days of HBPM are needed to reliably estimate mean home BP and diagnose out-of-clinic hypertension.


Assuntos
Monitorização Ambulatorial da Pressão Arterial/normas , Hipertensão/diagnóstico , Adulto , Análise de Variância , Monitorização Ambulatorial da Pressão Arterial/estatística & dados numéricos , Feminino , Humanos , Hipertensão/fisiopatologia , Masculino , Reprodutibilidade dos Testes
7.
J Clin Epidemiol ; 102: 12-22, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-29859242

RESUMO

OBJECTIVE: Despite their promise for increasing treatment precision, Personalized Trials (i.e., N-of-1 trials) have not been widely adopted. We aimed to ascertain patient preferences for Personalized Trials. STUDY DESIGN AND SETTING: We recruited 501 adults with ≥2 common chronic conditions from Harris Poll Online. We used Sawtooth Software to generate 45 plausible Personalized Trial designs comprising combinations of eight key attributes (treatment selection, treatment type, clinician involvement, blinding, time commitment, self-monitoring frequency, duration, and cost) at different levels. Conditional logistic regression was used to assess relative importance of different attributes using a random utility maximization model. RESULTS: Overall, participants preferred Personalized Trials with no costs vs. $100 cost (utility difference 1.52 [standard error 0.07], P < 0.001) and with less vs. more time commitment/day (0.16 [0.07], P < 0.015) but did not hold preferences for the other six attributes. In subgroup analyses, participants ≥65 years, white, and with income ≤$50,000 were more averse to costs than their counterparts (P all <0.05). CONCLUSION: To optimize dissemination, Personalized Trial designers should seek to minimize out-of-pocket costs and time burden of self-monitoring. They should also consider adaptive designs that can accommodate subgroup differences in design preferences.


Assuntos
Ensaios Clínicos como Assunto/economia , Preferência do Paciente/psicologia , Medicina de Precisão/economia , Adulto , Fatores Etários , Idoso , Ensaios Clínicos como Assunto/psicologia , Estudos Transversais , Medicina Baseada em Evidências , Feminino , Gastos em Saúde , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Medicina de Precisão/psicologia , Fatores Socioeconômicos , Inquéritos e Questionários
8.
Cancer Genomics Proteomics ; 4(5): 341-8, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17993718

RESUMO

BACKGROUND: African-American women develop more aggressive breast cancers and at an earlier age compared with Caucasian women. MATERIALS AND METHODS: We compared gene expression profiles of breast cancer cell lines that were developed from African-American and Caucasian patients to identify biological differences in breast cancers that develop in these groups. Real-time PCR was used to evaluate mRNA expression in cell lines and in a series of breast cancer cases. Gene microarray signal intensities were also analyzed in the International Genomics Consortium Expression Project for Oncology (expO) dataset. RESULTS: 17,-Hydroxysteroid dehydrogenase type 2 (17HSD 2) gene and mRNA expression were significantly higher in the African-American cell lines (p<0.05). However, 17HSD 2 expression did not differ significantly between the two cohorts in either our clinical series or the expO dataset. 17HSD 2 expression was found to be predictive of younger age at diagnosis and estrogen receptor status. CONCLUSION: Overexpression of 17HSD 2 in African-American breast cancer may contribute to the increased proportion of estrogen receptor-negative breast cancers and worse clinical outcome among African-American patients.


Assuntos
17-Hidroxiesteroide Desidrogenases/metabolismo , Negro ou Afro-Americano , Neoplasias da Mama/enzimologia , Receptores de Estrogênio/metabolismo , 17-Hidroxiesteroide Desidrogenases/biossíntese , 17-Hidroxiesteroide Desidrogenases/genética , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Estradiol Desidrogenases , Feminino , Humanos , Invasividade Neoplásica , Fenótipo
9.
AMIA Annu Symp Proc ; 2017: 930-939, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29854160

RESUMO

Psychological stress is a major contributor to the adoption of unhealthy behaviors, which in turn accounts for 41% of global cardiovascular disease burden. While the proliferation of mobile health apps has offered promise to stress management, these apps do not provide micro-level feedback with regard to how to adjust one's behaviors to achieve a desired health outcome. In this paper, we formulate the task of multi-stage stress management as a sequential decision-making problem and explore the application of reinforcement learning to provide micro-level feedback for stress reduction. Specifically, we incorporate a multi-stage threshold selection into Q-learning to derive an interpretable form of a recommendation policy for behavioral coaching. We apply this method on an observational dataset that contains Fitbit ActiGraph measurements and self-reported stress levels. The estimated policy is then used to understand how exercise patterns may affect users' psychological stress levels and to perform coaching more effectively.


Assuntos
Algoritmos , Terapia Comportamental , Monitores de Aptidão Física , Estresse Psicológico/terapia , Actigrafia , Conjuntos de Dados como Assunto , Exercício Físico , Retroalimentação , Humanos , Aprendizagem , Estudos Longitudinais , Aplicativos Móveis , Autorrelato
10.
Cancer ; 116(23): 5432-9, 2010 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-20665890

RESUMO

BACKGROUND: Bortezomib has preclinical and clinical in B-cell lymphomas, both alone and in combination with other agents. A phase 1 evaluation was conducted of bortezomib with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) in patients with untreated diffuse large B-cell lymphoma (DLBCL) or mantle cell lymphoma (MCL). METHODS: Twenty patients (16 with DLBCL and 4 with MCL) with a median age of 66 years (range, 29-84 years) were enrolled. Eleven subjects (55%) had an elevated lactate dehydrogenase level, and 10 patients (50%) had International Prognostic Index scores of 3 to 5. Standard R-CHOP was administered on a 21-day cycle for 6 cycles, with 1 of 3 dose levels of bortezomib (0.7 mg/m2 [n=4 patients], 1.0 mg/m2 [n=9 patients], or 1.3 mg/m2 [n=7 patients]) administered on Days 1 and 4 of each cycle. RESULTS: The maximum tolerated dose of bortezomib with R-CHOP was not reached, and the 1.3-mg/m2 dose level had acceptable tolerability. A dose-limiting toxicity (pulmonary) was only observed in 1 patient receiving 1.0 mg/m2 of bortezomib. Neuropathy occurred in 13 patients (65%), but was mostly grade 1 (45%) and reached grade 3 in only 1 patient (all toxicities were graded using the Common Terminology Criteria for Adverse Events, version 3.0). Grade 4 hematologic toxicity occurred in 7 patients (35%). Of 19 evaluable patients, all responded, with 18 (95%) cases of complete response/complete response unconfirmed achieved and 1 (5%) partial response reported. At a median follow-up of 56 months, overall survival at 4 years was 75% and progression-free survival was 58%. CONCLUSIONS: Bortezomib at a dose of 1.3 mg/m2 twice per cycle can be added to R-CHOP chemotherapy with acceptable toxicity. Multi-institutional and cooperative group follow-up studies of this regimen are currently ongoing.


Assuntos
Anticorpos Monoclonais Murinos/administração & dosagem , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Ácidos Borônicos/administração & dosagem , Linfoma Difuso de Grandes Células B/tratamento farmacológico , Linfoma de Célula do Manto/tratamento farmacológico , Pirazinas/administração & dosagem , Adulto , Idoso , Idoso de 80 Anos ou mais , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Ácidos Borônicos/efeitos adversos , Bortezomib , Ciclofosfamida/efeitos adversos , Ciclofosfamida/uso terapêutico , Doxorrubicina/efeitos adversos , Doxorrubicina/uso terapêutico , Esquema de Medicação , Feminino , Humanos , Masculino , Dose Máxima Tolerável , Pessoa de Meia-Idade , Prednisona/efeitos adversos , Prednisona/uso terapêutico , Pirazinas/efeitos adversos , Rituximab , Vincristina/efeitos adversos , Vincristina/uso terapêutico
11.
Cancer ; 112(5): 1139-46, 2008 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-18246536

RESUMO

BACKGROUND: The prognosis for patients with recurrent high-grade gliomas is poor and treatment options are limited. Current chemotherapeutic regimens can improve clinical outcomes, but extend survival by only a few months. Temozolomide is a methylating agent that is typically administered once daily. Because preclinical studies suggested that a twice-daily dosing schedule might be more effective, the safety and efficacy of twice-daily dosing of temozolomide were studied in patients with recurrent gliomas at their first, second, or third recurrence. METHODS: This multi-institutional trial enrolled 120 patients with recurrent glioblastoma multiforme (GBM), anaplastic astrocytoma (AA), or anaplastic oligodendroglioma (AO). An initial oral dose of 200 mg/m(2) of temozolomide was followed by 9 consecutive doses of 90-mg/m(2) every 12 hours. Treatment cycles were repeated every 28 days. Doses were escalated to 100 mg/m(2) twice daily in the absence of unacceptable toxicity or were reduced if unacceptable toxicity occurred. RESULTS: For GBM, AA, and AO patients, respectively, the median progression-free survival (PFS) was 4.2 months, 5.8 months, and 7.7 months, whereas the median overall survival (OS) was 8.8 months, 14.6 months, and 18 months. The overall response rate (partial and complete) for the GBM, AA, and AO patients was 31%, 46%, and 46%, respectively. Grade 3/4 toxicities included neutropenia (1.1%), thrombocytopenia (3.6%), and anemia (0.3%) (graded according to the World Health Organization grading system). CONCLUSIONS: Twice-daily dosing may enhance the efficacy of temozolomide in the treatment of recurrent gliomas without increasing toxicity. This regimen compares favorably with other dosing schedules of temozolomide reported in the literature.


Assuntos
Antineoplásicos Alquilantes/administração & dosagem , Neoplasias Encefálicas/tratamento farmacológico , Dacarbazina/análogos & derivados , Glioma/tratamento farmacológico , Administração Oral , Adulto , Idoso , Antineoplásicos Alquilantes/toxicidade , Dacarbazina/administração & dosagem , Dacarbazina/toxicidade , Esquema de Medicação , Avaliação de Medicamentos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Temozolomida
12.
J Neurooncol ; 76(1): 85-92, 2006 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-16402278

RESUMO

BACKGROUND: P-glycoprotein (Pgp) mediates, in part, resistance to natural product chemotherapy drugs which constitute over half of the available drugs for cancer treatment. Tamoxifen (TAM) enhances intracellular deposition of natural product chemotherapy in human cell lines by inhibition of Pgp. Pgp is highly expressed in the choroid plexus and is thought to be a key component of the blood-cerebrospinal fluid barrier (BCSFB). We conducted a prospective, randomized study to assess if Pgp inhibition by TAM alters deposition of paclitaxel in cerebrospinal fluid (CSF). METHODS: Ten patients with either primary or metastatic brain tumors were randomized to: paclitaxel alone (175 mg/m2/IV) or a course of TAM (160 mg/m2 PO BID on Days 1-5) followed by paclitaxel (175 mg/m2/IV on Day 5). CSF and plasma samples were obtained following paclitaxel infusion; paclitaxel and TAM concentrations were measured by high-performance liquid chromatography assays. RESULTS: Paclitaxel was detected in the CSF of six of the 10 patients. Peak CSF paclitaxel concentrations of the paclitaxel and paclitaxel-TAM groups ranged between 3.5-57.4 and 2.3-24.6 nM, respectively. Though there was a 2.4-fold higher mean CSF paclitaxel concentration and a 3.7-fold higher median peak CSF:plasma paclitaxel ratio for those who received paclitaxel alone as compared to combined paclitaxel-TAM, it was not statistically significant (P = 0.22). In one patient enrolled to both arms, higher CSF concentrations of paclitaxel and higher paclitaxel CSF: plasma ratios were observed when given paclitaxel alone. CONCLUSIONS: The trend towards lower paclitaxel CSF concentrations when given with TAM is consistent with the published finding that Pgp's localization in the endothelial cells of the choroid plexus works in an opposite direction and keeps drugs in the CSF. Thus, agents which inhibit Pgp, such as TAM, may increase efflux of Pgp substrates out of the BCSFB and may paradoxically lower CSF concentrations of natural product chemotherapy drugs. Conceptually, this finding implies that the Pgp in the BBB and BCSFB keeps natural toxins such as paclitaxel, from entering the brain (BBB) and, if they do enter the brain, keeps them in the CSF (BCSFB) where they may be less harmful than if they re-entered the brain. Thus, our work supports this novel idea and adds to the understanding of the functions of the BCSFB.


Assuntos
Antineoplásicos Hormonais/farmacologia , Antineoplásicos Fitogênicos/líquido cefalorraquidiano , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias Encefálicas/tratamento farmacológico , Paclitaxel/líquido cefalorraquidiano , Tamoxifeno/farmacologia , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/antagonistas & inibidores , Administração Oral , Adulto , Idoso , Neoplasias Encefálicas/secundário , Cromatografia Líquida de Alta Pressão , Feminino , Humanos , Infusões Intravenosas , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos
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