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1.
NPJ Breast Cancer ; 8(1): 68, 2022 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-35610260

RESUMO

Trastuzumab acts in part through the adaptive immune system. Previous studies showed that enrichment of immune-related gene expression was associated with improved outcomes in HER2-positive (HER2+) breast cancer. However, the role of the immune system in response to lapatinib is not fully understood. Gene expression analysis was performed in 1,268 samples from the North Central Cancer Treatment Group (NCCTG) N9831 and 244 samples from the NeoALTTO trial. In N9831, enrichment of CD45 and immune-subset signatures were significantly associated with improved outcomes. We identified a novel 17-gene adaptive immune signature (AIS), which was found to be significantly associated with improved RFS among patients who received adjuvant trastuzumab (HR 0.66, 95% CI 0.49-0.90, Cox regression model p = 0.01) but not in patients who received chemotherapy alone (HR 0.96, 95% CI 0.67-1.40, Cox regression model p = 0.97). This result was validated in NeoALTTO. Overall, AIS-low patients had a significantly lower pathologic complete response (pCR) rate compared with AIS-high patients (χ2 p < 0.0001). Among patients who received trastuzumab alone, pCR was observed in 41.7% of AIS-high patients compared with 9.8% in AIS-low patients (OR of 6.61, 95% CI 2.09-25.59, logistic regression model p = 0.003). More importantly, AIS-low patients had a higher pCR rate with an addition of lapatinib (51.1% vs. 9.8%, OR 9.65, 95% CI 3.24-36.09, logistic regression model p < 0.001). AIS-low patients had poor outcomes, despite receiving adjuvant trastuzumab. However, these patients appear to benefit from an addition of lapatinib. Further studies are needed to validate the significance of this signature to identify patients who are more likely to benefit from dual anti-HER2 therapy. ClinicalTrials.gov Identifiers: NCT00005970 (NCCTG N9831) and NCT00553358 (NeoALTTO).

2.
Methods Mol Biol ; 2055: 273-300, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31502157

RESUMO

Biomarkers based on transcriptional profiling can be useful in the measurement of complex and/or dynamic physiological states where other profiling strategies such as genomic or proteomic characterization are not able to adequately measure the biology. One particular advantage of transcriptional biomarkers is the ease with which they can be measured in the clinical setting using robust platforms such as the NanoString nCounter system. The nCounter platform enables digital quantitation of multiplexed RNA from small amounts of blood, formalin-fixed, paraffin-embedded tumors, or other such biological samples that are readily available from patients, and the chapter uses it as the primary example for diagnostic assay development. However, development of diagnostic assays based on RNA biomarkers on any platform requires careful consideration of all aspects of the final clinical assay a priori, as well as design and execution of the development program in a way that will maximize likelihood of future success. This chapter introduces transcriptional biomarkers and provides an overview of the design and development process that will lead to a locked diagnostic assay that is ready for validation of clinical utility.


Assuntos
Biomarcadores Tumorais/genética , Perfilação da Expressão Gênica/instrumentação , Neoplasias/genética , Regulação Neoplásica da Expressão Gênica , Humanos , Análise de Sequência com Séries de Oligonucleotídeos/instrumentação , Inclusão em Parafina , Fixação de Tecidos
3.
JCI Insight ; 4(24)2019 12 19.
Artigo em Inglês | MEDLINE | ID: mdl-31852845

RESUMO

Immune checkpoint inhibitor (ICI) treatment has recently become a first-line therapy for many non-small cell lung cancer (NSCLC) patients. Unfortunately, most NSCLC patients are refractory to ICI monotherapy, and initial attempts to address this issue with secondary therapeutics have proven unsuccessful. To identify entities precluding CD8+ T cell accumulation in this process, we performed unbiased analyses on flow cytometry, gene expression, and multiplexed immunohistochemical data from a NSCLC patient cohort. The results revealed the presence of a myeloid-rich subgroup, which was devoid of CD4+ and CD8+ T cells. Of all myeloid cell types assessed, neutrophils were the most highly associated with the myeloid phenotype. Additionally, the ratio of CD8+ T cells to neutrophils (CD8/PMN) within the tumor mass optimally distinguished between active and myeloid cases. This ratio was also capable of showing the separation of patients responsive to ICI therapy from those with stable or progressive disease in 2 independent cohorts. Tumor-bearing mice treated with a combination of anti-PD1 and SX-682 (CXCR1/2 inhibitor) displayed relocation of lymphocytes from the tumor periphery into a malignant tumor, which was associated with induction of IFN-γ-responsive genes. These results suggest that neutrophil antagonism may represent a viable secondary therapeutic strategy to enhance ICI treatment outcomes.


Assuntos
Antineoplásicos Imunológicos/farmacologia , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Neoplasias Pulmonares/tratamento farmacológico , Linfócitos do Interstício Tumoral/imunologia , Neutrófilos/imunologia , Idoso , Animais , Antineoplásicos Imunológicos/uso terapêutico , Linfócitos T CD8-Positivos/imunologia , Carcinoma Pulmonar de Células não Pequenas/sangue , Carcinoma Pulmonar de Células não Pequenas/imunologia , Estudos de Coortes , Conjuntos de Dados como Assunto , Modelos Animais de Doenças , Feminino , Citometria de Fluxo , Perfilação da Expressão Gênica , Humanos , Imuno-Histoquímica , Contagem de Leucócitos , Neoplasias Pulmonares/sangue , Neoplasias Pulmonares/imunologia , Masculino , Camundongos , Pessoa de Meia-Idade , Neutrófilos/metabolismo , Receptor de Morte Celular Programada 1/antagonistas & inibidores , Receptor de Morte Celular Programada 1/imunologia , Receptores de Interleucina-8A/antagonistas & inibidores , Receptores de Interleucina-8B/antagonistas & inibidores , Falha de Tratamento
4.
J Clin Oncol ; 37(35): 3425-3435, 2019 12 10.
Artigo em Inglês | MEDLINE | ID: mdl-31622131

RESUMO

PURPOSE: Recent trials have shown potential benefit of extended adjuvant endocrine therapy and relatively high risk of recurrence (RoR) after 5 years in hormone receptor-positive (HR+) human epidermal growth factor receptor 2-negative (HER2-) breast cancer. Although risk of late relapse in HR+ HER2- breast cancer is fairly well defined, the risk in HER2-positive (HER2+) breast cancer treated with adjuvant trastuzumab-based chemotherapy remains largely unknown. METHODS: We included 3,177 patients with HER2+ breast cancer treated with adjuvant chemotherapy alone or with trastuzumab from the North Central Cancer Treatment Group N9831 (ClinicalTrials.gov identifier: NCT00005970) and National Surgical Adjuvant Breast and Bowel Project B-31 (ClinicalTrials.gov identifier: NCT00004067) trials. RESULTS: Overall, HR+ breast cancer was significantly associated with improved recurrence-free survival (RFS) during the first 5 years (hazard ratio, 0.65; 95% CI, 0.56 to 0.77; P < .001). Among patients treated with trastuzumab, cumulative hazard for RFS was lower in patients with HR+ HER2+ breast cancer during the first 5 years (10.96% v 17.48%; hazard ratio, 0.60; 95% CI, 0.45 to 0.79; P < .001). However, there was no significant difference in RFS based on HR status during years 5 to 10 (hazard ratio, 1.32; 95% CI, 0.93 to 1.88; P = .12). A comparable degree of trastuzumab benefit was observed in HR+ and HR- breast cancers ( P for interaction = .87). Furthermore, we observed low RoR in years 5 to 10 among patients with HR+ HER2+ breast cancer: 3.23% in patients without lymph node involvement (N0) and 6.39% in patients with involvement of one to three lymph nodes (N1). CONCLUSION: The benefit of adjuvant trastuzumab persists for a long time. A distinct pattern of recurrence was observed between HR+ and HR- HER2+ disease but with similar degree of benefit from adjuvant trastuzumab. RoR in years 5 to 10 in HR+ HER2+ breast cancer is low, particularly in patients with N0 or N1 disease.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Neoplasias da Mama/tratamento farmacológico , Recidiva Local de Neoplasia/epidemiologia , Receptor ErbB-2/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Ciclofosfamida/administração & dosagem , Doxorrubicina/administração & dosagem , Feminino , Seguimentos , Humanos , Incidência , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/induzido quimicamente , Recidiva Local de Neoplasia/diagnóstico , Paclitaxel/administração & dosagem , Prognóstico , Taxa de Sobrevida , Trastuzumab/administração & dosagem , Estados Unidos/epidemiologia , Adulto Jovem
5.
Front Immunol ; 10: 14, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30761123

RESUMO

Natural killer (NK) cells are innate cytotoxic and immunoregulatory lymphocytes that have a central role in anti-tumor immunity and play a critical role in mediating cellular immunity in advanced cancer immunotherapies, such as dendritic cell (DC) vaccines. Our group recently tested a novel recombinant adenovirus-transduced autologous DC-based vaccine that simultaneously induces T cell responses against three melanoma-associated antigens for advanced melanoma patients. Here, we examine the impact of this vaccine as well as the subsequent systemic delivery of high-dose interferon-α2b (HDI) on the circulatory NK cell profile in melanoma patients. At baseline, patient NK cells, particularly those isolated from high-risk patients with no measurable disease, showed altered distribution of CD56dim CD16+ and CD56dim CD16- NK cell subsets, as well as elevated serum levels of immune suppressive MICA, TN5E/CD73 and tactile/CD96, and perforin. Surprisingly, patient NK cells displayed a higher level of activation than those from healthy donors as measured by elevated CD69, NKp44 and CCR7 levels, and enhanced K562 killing. Elevated cytolytic ability strongly correlated with increased representation of CD56dim CD16+ NK cells and amplified CD69 expression on CD56dim CD16+ NK cells. While intradermal DC immunizations did not significantly impact circulatory NK cell activation and distribution profiles, subsequent HDI injections enhanced CD56bright CD16- NK cell numbers when compared to patients that did not receive HDI. Phenotypic analysis of tumor-infiltrating NK cells showed that CD56dim CD16- NK cells are the dominant subset in melanoma tumors. NanoString transcriptomic analysis of melanomas resected at baseline indicated that there was a trend of increased CD56dim NK cell gene signature expression in patients with better clinical response. These data indicate that melanoma patient blood NK cells display elevated activation levels, that intra-dermal DC immunizations did not effectively promote systemic NK cell responses, that systemic HDI administration can modulate NK cell subset distributions and suggest that CD56dim CD16- NK cells are a unique non-cytolytic subset in melanoma patients that may associate with better patient outcome.


Assuntos
Vacinas Anticâncer/administração & dosagem , Vacinas Anticâncer/imunologia , Interferon-alfa/uso terapêutico , Células Matadoras Naturais/imunologia , Melanoma/imunologia , Melanoma/terapia , Apresentação de Antígeno/imunologia , Células Apresentadoras de Antígenos/imunologia , Células Apresentadoras de Antígenos/metabolismo , Biomarcadores , Antígeno CD56/metabolismo , Ensaios Clínicos Fase I como Assunto , Terapia Combinada , Citotoxicidade Imunológica , Humanos , Imunofenotipagem , Imunoterapia , Interferon-alfa/farmacologia , Células Matadoras Naturais/metabolismo , Ativação Linfocitária/imunologia , Melanoma/diagnóstico , Melanoma/metabolismo , Estadiamento de Neoplasias , Receptores de IgG/metabolismo , Resultado do Tratamento , Microambiente Tumoral/imunologia
6.
Clin Cancer Res ; 25(14): 4422-4430, 2019 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-30808774

RESUMO

PURPOSE: Young age has been shown to be an independent predictor of poor outcome in breast cancer. In HER2-positive breast cancer, the effects of aging remain largely unknown. EXPERIMENTAL DESIGN: A total of 4,547 patients were included [3,132 from North Central Cancer Treatment Group (NCCTG) N9831 and 1,415 from National Surgical Adjuvant Breast and Bowel Project (NSABP) B-31]. Pathologic stromal tumor-infiltrating lymphocyte (sTIL) and molecular tumor infiltrating lymphocyte (mTIL) signatures were evaluated. RESULTS: In NCCTG N9831, comparable benefit of trastuzumab was observed in all patients [age ≤ 40; HR, 0.43; 95% confidence interval (CI), 0.28-0.66; P < 0.001; and age > 40; HR, 0.56; 95% CI, 0.45-0.69; P < 0.001]. Similar results were observed in NSABP B-31 (age ≤ 40; HR, 0.45; 95% CI, 0.29-0.68; P < 0.001; and age > 40; HR, 0.42; 95% CI, 0.33-0.54; P < 0.001). Among patients who received chemotherapy alone, younger age was associated with poor outcome in the hormone receptor-positive subset, but not the hormone receptor-negative subset, in both trials. Although there was no association between sTILs and age, a small, but significant increase in mTIL CD45 and some immune subset signatures were observed. Among patients who received chemotherapy alone, patients over 40 years of age with lymphocyte-predominant breast cancer had excellent outcome, with 95% remaining recurrence free at 15 years. CONCLUSIONS: Among patients treated with trastuzumab, there was no significant difference in outcome related to age. Our study suggests that trastuzumab can negate the poor prognosis associated with young age.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Biomarcadores Tumorais/metabolismo , Neoplasias da Mama/mortalidade , Linfócitos do Interstício Tumoral/imunologia , Recidiva Local de Neoplasia/mortalidade , Receptor ErbB-2/metabolismo , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/imunologia , Neoplasias da Mama/patologia , Quimioterapia Adjuvante , Ciclofosfamida/administração & dosagem , Intervalo Livre de Doença , Doxorrubicina/administração & dosagem , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/tratamento farmacológico , Recidiva Local de Neoplasia/imunologia , Recidiva Local de Neoplasia/patologia , Paclitaxel/administração & dosagem , Taxa de Sobrevida , Trastuzumab/administração & dosagem , Adulto Jovem
7.
J Natl Cancer Inst ; 109(2)2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27794124

RESUMO

Background: Genomic data from human epidermal growth factor receptor 2-positive (HER2+) tumors were analyzed to assess the association between intrinsic subtype and clinical outcome in a large, well-annotated patient cohort. Methods: Samples from the NCCTG (Alliance) N9831 trial were analyzed using the Prosigna algorithm on the NanoString platform to define intrinsic subtype, risk of recurrence scores, and risk categories for 1392 HER2+ tumors. Subtypes were evaluated for recurrence-free survival (RFS) using Kaplan-Meier and Cox model analysis following adjuvant chemotherapy (n = 484) or chemotherapy plus trastuzumab (n = 908). All statistical tests were two-sided. Results: Patients with HER2+ tumors from N9831 were primarily scored as HER2-enriched (72.1%). These individuals received statistically significant benefit from trastuzumab (hazard ratio [HR] = 0.68, 95% confidence interval [CI] = 0.52 to 0.89, P = .005), as did the patients (291 of 1392) with luminal-type tumors (HR = 0.52, 95% CI = 0.32 to 0.85, P = .01). Patients with basal-like tumors (97 of 1392) did not have statistically significantly better RFS when treated with trastuzumab and chemotherapy compared with chemotherapy alone (HR = 1.06, 95% CI = 0.53 to 2.13, P = .87). Conclusions: The majority of clinically defined HER2-positive tumors were classified as HER2-enriched or luminal using the Prosigna algorithm. Intrinsic subtype alone cannot replace conventional histopathological evaluation of HER2 status because many tumors that are classified as luminal A or luminal B will benefit from adjuvant trastuzumab if that subtype is accompanied by HER2 overexpression. However, among tumors that overexpress HER2, we speculate that assessment of intrinsic subtype may influence treatment, particularly with respect to evaluating alternative therapeutic approaches for that subset of HER2-positive tumors of the basal-like subtype.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/genética , Receptor ErbB-2/genética , Algoritmos , Neoplasias da Mama/classificação , Neoplasias da Mama/patologia , Quimioterapia Adjuvante , Ciclofosfamida/administração & dosagem , Intervalo Livre de Doença , Doxorrubicina/administração & dosagem , Feminino , Humanos , Paclitaxel/administração & dosagem , Receptor ErbB-2/análise , Trastuzumab/administração & dosagem , Carga Tumoral
8.
Cancer Res ; 75(18): 3738-46, 2015 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-26216548

RESUMO

Pancreatic cancer is characterized by extensive stromal desmoplasia, which decreases blood perfusion and impedes chemotherapy delivery. Breaking the stromal barrier could both increase perfusion and permeabilize the tumor, enhancing chemotherapy penetration. Mechanical disruption of the stroma can be achieved using ultrasound-induced bubble activity-cavitation. Cavitation is also known to result in microstreaming and could have the added benefit of actively enhancing diffusion into the tumors. Here, we report the ability to enhance chemotherapeutic drug doxorubicin penetration using ultrasound-induced cavitation in a genetically engineered mouse model (KPC mouse) of pancreatic ductal adenocarcinoma. To induce localized inertial cavitation in pancreatic tumors, pulsed high-intensity focused ultrasound (pHIFU) was used either during or before doxorubicin administration to elucidate the mechanisms of enhanced drug delivery (active vs. passive drug diffusion). For both types, the pHIFU exposures that were associated with high cavitation activity resulted in disruption of the highly fibrotic stromal matrix and enhanced the normalized doxorubicin concentration by up to 4.5-fold compared with controls. Furthermore, normalized doxorubicin concentration was associated with the cavitation metrics (P < 0.01), indicating that high and sustained cavitation results in increased chemotherapy penetration. No significant difference between the outcomes of the two types, that is, doxorubicin infusion during or after pHIFU treatment, was observed, suggesting that passive diffusion into previously permeabilized tissue is the major mechanism for the increase in drug concentration. Together, the data indicate that pHIFU treatment of pancreatic tumors when resulting in high and sustained cavitation can efficiently enhance chemotherapy delivery to pancreatic tumors. .


Assuntos
Antibióticos Antineoplásicos/administração & dosagem , Carcinoma Ductal Pancreático/tratamento farmacológico , Doxorrubicina/administração & dosagem , Sistemas de Liberação de Medicamentos/métodos , Ondas de Choque de Alta Energia , Neoplasias Pancreáticas/tratamento farmacológico , Fonoforese/métodos , Animais , Antibióticos Antineoplásicos/farmacocinética , Carcinoma Ductal Pancreático/genética , Carcinoma Ductal Pancreático/patologia , Difusão , Doxorrubicina/farmacocinética , Sistemas de Liberação de Medicamentos/instrumentação , Desenho de Equipamento , Camundongos , Camundongos Transgênicos , Microscopia de Fluorescência , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/patologia , Fonoforese/instrumentação , Distribuição Aleatória , Células Estromais/patologia , Espectrometria de Massas em Tandem
9.
BMC Res Notes ; 2: 80, 2009 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-19426535

RESUMO

BACKGROUND: We assessed NanoString's nCounter Analysis System for its ability to quantify gene expression of forty-eight genes in a single reaction with 100 ng of total RNA or an equivalent amount of tissue lysate. In the nCounter System, multiplexed gene expression target levels are directly detected, without enzymatic reactions, via two sequence-specific probes. The individual mRNA is captured with one mRNA target sequence-specific capture probe that is used in a post-hybridization affinity purification procedure. The second mRNA target specific-sequence and fluorescent-labeled colored coded probe is then used in the detection with the 3-component complex separated on a surface via an applied electric field followed by imaging. We evaluated reproducibility, accuracy, concordance with quantitative RT-PCR, linearity, dynamic range, and the ability of the system to assay different inputs (matched samples of total RNA from Flash Frozen (FF) and Formalin Fixed Paraffin Embedded Tissues (FFPET), and crude tissue lysates (CTL)). FINDINGS: The nCounter Analysis System provided data equivalent to that produced by Taqman(R)-based assays for genes expressed within the ranges of the calibration curves (above ~0.5 mRNA copies per human cell based on an assumption of 10 pg of total RNA per cell). System response was linear over more than two orders of magnitude with typical CVs of ~6% for concentrations above 1 fM (105 molecules per mL). Profiling the industry-standard MAQC data set yielded correlation coefficients of >0.83 for intensity values and >0.99 for measured ratios. Ninety percent of nCounter ratio measurements were within 1.27-1.33 fold changes of the Taqman(R) data (0.34-0.41 in log2 scale) for FF total RNA samples. CONCLUSION: The nCounter Analysis System generated robust data for multi-gene expression signatures across three different sample preparation conditions.

10.
Lab Chip ; 8(4): 557-64, 2008 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18369510

RESUMO

A microfluidic device known to mix bulk solutions, the herringbone microchannel, was incorporated into a surface-binding assay to determine if the recirculation of solution altered the binding of a model protein (streptavidin) to the surface. Streptavidin solutions were pumped over surfaces functionalized with its ligand, biotin, and the binding of streptavidin to those surfaces was monitored using surface plasmon resonance imaging. Surface binding was compared between a straight microchannel and herringbone microchannels in which the chevrons were oriented with and against the flow direction. A 3-dimensional finite-element model of the surface binding reaction was developed for each of the geometries and showed strong qualitative agreement with the experimental results. Experimental and model results indicated that the forward and reverse herringbone microchannels substantially altered the distribution of protein binding (2-dimensional binding profile) as a function of time when compared to a straight microchannel. Over short distances (less than 1.5 mm) down the length of the microchannel, the model predicted no additional protein binding in the herringbone microchannel compared to the straight microchannel, consistent with previous findings in the literature.


Assuntos
Técnicas Biossensoriais/métodos , Técnicas Analíticas Microfluídicas/métodos , Proteínas/química , Técnicas Biossensoriais/instrumentação , Análise de Elementos Finitos , Técnicas Analíticas Microfluídicas/instrumentação , Modelos Biológicos , Ligação Proteica , Proteínas/metabolismo , Soluções/química , Estreptavidina/química , Estreptavidina/metabolismo , Ressonância de Plasmônio de Superfície/métodos , Fatores de Tempo
11.
Anal Chim Acta ; 611(1): 80-8, 2008 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-18298971

RESUMO

Patterning substrates with biological reagents is a critical component of biosensor development. Many applications require multi-analyte patterning capabilities, with a need to deposit several species reproducibly with a high degree of precision. We demonstrate a piezoelectric inkjet printing system that is capable of creating sub-millimeter (down to 150microm) patterns of aqueous and nonaqueous reagents with precise placement for biosensor applications. The size, shape, and density of the patterns may be modified by simple adjustments of the patterning parameters. Using this system, two methods of multi-analyte protein patterning for use in biosensor assays are demonstrated. The first method involves the deposition of multiple proteins directly onto a gold substrate. Specific binding of an antibody to the deposited antigen is demonstrated, although nonspecific adsorption of the antibody may limit the utility of this simple method in quantitative biosensor applications. A second, more sophisticated multi-analyte patterning method involves two sequential patterning steps, consisting of an initial deposition onto gold of a mixed thiol layer to provide oriented binding capabilities in a nonfouling background and a second deposition of multiple biotinylated proteins. Highly specific antibody binding to this patterned multi-analyte surface was demonstrated, with minimal nonspecific adsorption to the surrounding regions. Thus, this method produces high-quality, localized, and customizable sub-millimeter patterns in a nonfouling background for multi-analyte bioassay development.


Assuntos
Técnicas Biossensoriais , Complexo Antígeno-Anticorpo , Sítios de Ligação de Anticorpos , Eletrônica , Ouro/química , Proteínas/química , Reprodutibilidade dos Testes
12.
Anal Chem ; 79(10): 3549-53, 2007 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-17437333

RESUMO

A novel microfluidic surface-based competition immunoassay, termed the concentration gradient immunoassay (described in detail in a companion paper (Nelson, K.; Foley, J.; Yager, P. Anal. Chem. 2007, 79, 3542-3548.) uses surface plasmon resonance (SPR) imaging to rapidly measure the concentration of small molecules. To conduct this assay, antibody and analyte are introduced into the two inlets of a T-sensor (Weigl, B. H.; Yager, P. Science 1999, 283, 346-347. Kamholz, A. E.; Weigl, B. H.; Finlayson, B. A.; Yager, P. Anal. Chem. 1999, 71, 5340-5347). Several millimeters downstream, antibody molecules with open binding sites can bind to a surface functionalized with immobilized antigen. This space- and time-dependent binding can be sensitively observed using SPR imaging. In this paper, we describe a complex three-dimensional finite element model developed to better understand the dynamic processes occurring with this assay. The model shows strong qualitative agreement with experimental results for small-molecule detection. The model confirms the experimental finding that the position within the microchannel at which the antibody binds to the immobilized analyte may be used to quantify the concentration of analyte in the sample. In addition, the model was used to explore the sensitivity of assay performance to parameters such as antibody and analyte concentrations, thereby giving insight into ways to optimize analysis speed and accuracy. Given the experimental verification of the computational results, this model serves as an efficient method to explore the influence of the flow rate, microchannel dimensions, and antibody concentration on the sensitivity of the assay.


Assuntos
Anticorpos , Análise de Elementos Finitos , Imunoensaio/métodos , Ressonância de Plasmônio de Superfície , Reações Antígeno-Anticorpo , Técnicas Biossensoriais/métodos , Imunoensaio/normas , Compostos Orgânicos/análise
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