The role of antibody-based troponin detection in cardiovascular disease: A critical assessment.

Cardiovascular disease has remained the world's biggest killer for 30 years. To aid in the diagnosis and prognosis of patients suffering cardiovascular-related disease accurate detection methods are essential. For over 20 years, the cardiac-specific troponins, I (cTnI) and T (cTnT), have acted as sensitive and specific biomarkers to assist in the diagnosis of various types of heart diseases. Various cardiovascular complications were commonly detected in patients with COVID-19, where cTn elevation is detectable, which suggested potential prognostic value of cTn in COVID-19-infected patients. Detection of these biomarkers circulating in the bloodstream is generally facilitated by immunoassays employing cTnI- and/or cTnT-specific antibodies. While several anti-troponin assays are commercially available, there are still obstacles to overcome to achieve optimal troponin detection. Such obstacles include the proteolytic degradation of N and C terminals on cTnI, epitope occlusion of troponin binding-sites by the cTnI/cTnT complex, cross reactivity of antibodies with skeletal troponins or assay interference caused by human anti-species antibodies. Therefore, further research into multi-antibody based platforms, multi-epitope targeting and rigorous validation of immunoassays is required to ensure accurate measurements. Moreover, in combination with various technical advances (e.g. microfluidics), antibody-based troponin detection systems can be more sensitive and rapid for incorporation into portable biosensor systems to be used at point-of care.

An assessment of potential biomarkers of environment enteropathy and its association with age and microbial infections among children in Bangladesh.

Interventional studies targeting environment enteropathy (EE) are impeded by the lack of appropriate, validated, non-invasive biomarkers of EE. Thus, we aimed to validate the association of potential biomarkers for EE with enteric infections and nutritional status in a longitudinal birth cohort study. We measured endotoxin core antibody (EndoCab) and soluble CD14 (sCD14) in serum, and myeloperoxidase (MPO) in feces using commercially available enzyme-linked immunosorbent assay (ELISA) kits. We found that levels of serum EndoCab and sCD14 increase with the cumulative incidence of enteric infections. We observed a significant correlation between the fecal MPO level in the children at 24 months of age with the total number of bacterial and viral infections, the total number of parasitic infections, and the total number of diarrheal episodes and diarrheal duration. We observed that the levels of serum EndoCab, sCD14, and fecal MPO at 3 months of age were significantly associated with whether children were malnourished at 18 months of age or not. Biomarkers such as fecal MPO, serum EndoCab and sCD14 in children at an early age may be useful as a measure of cumulative burden of preceding enteric infections, which are predictive of subsequent malnutrition status and may be useful non-invasive biomarkers for EE.

Exame de dosagem de anticorpo anti-receptor de acetilcolina para diagnóstico da Miastenia Gravis / Anti-receptor antibody dosagem test Acetylcholine for diagnosis of Myasthenia Gravis

INTRODUÇÃO: A MG é uma doença autoimune da junção neuromuscular que se apresenta com fraqueza muscular localizada ou generalizada. Na maioria dos casos, a doença é causada por anticorpos contra receptores de acetilcolina (anti-AChR), que estão presentes em cerca de 85% e 50% dos pacientes com as formas generalizadas e ocular, respectivamente. O diagnóstico de MG é definido de acordo com manifestações clínicas, além de provas sorológicas ou eletroneuromiográficas, que apresentam sensibilidade e especificidade variadas de acordo com a apresentação da doença. A estimulação nervosa repetitiva é o estudo eletroneuromiográfico complementar atualmente disponível no Sistema Único de Saúde (SUS) para diagnóstico de MG. TECNOLOGIA: Dosagem de anticorpo anti-receptor de acetilcolina. PERGUNTA: o exame diagnóstico de dosagem de anticorpos anti-acetilcolina pode ser uma alternativa à eletroneuromiografia (estimulação nervosa repetitiva ­ ENR) para o diagnóstico da MG? EVIDÊNCIAS CIENTÍFICAS: Uma revisão sistemática (RS) e dois estudos clínicos prospectivos de avaliação de métodos diagnósticos de MG foram incluídos. A RS incluiu sete estudos de avaliação de anticorpos anti-AChR e sete estudos de avaliação da ENR. As estimativas de acurácia do anti-AChR na RS foram agrupadas de acordo com o delineamento dos estudos, evidenciando sensibilidade de 44% a 66% na MG ocular e de 90% a 96% na MG generalizada, sem variação na especificidade (98% a 99% em ambas as apresentações). Os estudos da ENR foram muitos heterogêneos e evidenciaram sensibilidade entre 11% a 39% no diagnóstico da MG ocular, e entre 32% a 98% na MG generalizada, com especificidade elevada em ambos os casos (94% a 97%). Os estudos individuais evidenciaram sensibilidade de 73% a 74% para MG generalizada e de 38% a 70% para MG ocular para o anti-AChR, e sensibilidade de 80% a 83% para MG generalizada e de 45% a 62% para MG ocular. As avaliações do risco de viés dos estudos incluídos demonstraram alto risco de viés para a RS e baixo risco para a maioria dos domínios avaliados nos estudos de coorte. AVALIAÇÃO DE IMPACTO ORÇAMENTÁRIO: A estimativa de custo global anual do exame anti-AChR no cenário base foi de aproximadamente 155 mil reais, com impacto cumulativo em 5 anos de 788 mil reais. Considerando que uma parcela dos indivíduos necessitará submeter-se adicionalmente ao exame eletroneuromiográfico, o que implicaria em aproximadamente 15 mil reais a mais por ano, o custo total do diagnóstico da doença foi de cerca de 170 mil reais a mais por ano, e de cerca de 867 mil reais ao final do quinto ano de incorporação. Na análise de sensibilidade, foram observados valores de custo total de 165 mil reais no cenário mais otimista e acima de 2 milhões de reais no cenário mais pessimista, para o diagnóstico de MG no período de 5 anos. A variável de maior impacto nos resultados foi a população inicial, seguida do custo do exame anti-AChR. CONSIDERAÇÕES FINAIS: A dosagem de anticorpos anti-AChR é um exame confirmatório essencial para diagnóstico de MG. De maneira geral, os estudos evidenciam sensibilidade superior à ENR, tanto no diagnóstico da forma ocular quanto generalizada da doença, com elevada especificidade. Os estudos de ENR foram heterogêneos e evidenciaram diferentes níveis de acurácia de acordo com o número e localização dos estímulos avaliados, o que não ocorre no cenário da dosagem de anticorpos. As avaliações do risco de viés dos estudos incluídos demonstraram alto risco de viés para a RS e baixo risco para a maioria dos domínios avaliados nos estudos de coorte. Não foram identificadas recomendações de diagnóstico de MG em agências de ATS, mas diretrizes internacionais recomendam o exame como etapa inicial no diagnóstico da doença. RECOMENDAÇÃO PRELIMINAR: A Conitec, em sua 93ª reunião ordinária, realizada no dia 08 de dezembro de 2020, deliberou que a matéria fosse disponibilizada em consulta pública com recomendação preliminar favorável à incorporação do exame de dosagem de anticorpos anti-acetilcolina para diagnóstico da Miastenia Gravis no Sistema Único de Saúde. Considerouse, entre outros fatores, que, o exame de avaliação de anticorpos anti-AChR possui uma maior sensibilidade diagnóstica em comparação ao exame eletroneuromiográfico, além disso eletroneuromiografia é um exame demorado e requer um treinamento específico para sua realização. Consequentemente, o tratamento precoce da miastenia gravis poderia ser comprometido. CONSULTA PÚBLICA: A consulta pública nº 68 ficou vigente entre os dias 05/01/2021 e 25/01/2021. Foram recebidas nove contribuições, sendo cinco pelo formulário para contribuições técnico-científicas e quatro pelo formulário para contribuições sobre experiência ou opinião. Estas foram provenientes de pacientes, familiares, amigos ou cuidadores de pacientes, profissionais de saúde ou pessoas interessadas no tema. A maioria das contribuições (77,8%) concordou com a recomendação preliminar da Conitec. Uma contribuição foi neutra (nem concorda e nem discorda) e uma contribuição discordou da recomendação preliminar da Conitec, no entanto, ambas estas contribuições não apresentaram justificativa. As contribuições abordaram, principalmente, os pontos positivos da incorporação da dosagem de anticorpos anti-AChR para o diagnóstico de MG. Não foram solicitadas alterações no texto ou apresentadas referências ou anexos. Houve apenas um argumento sobre a possibilidade de inclusão de anti MUSK para melhoria do atendimento dos demais casos negativos do anticorpo anti-receptor de acetilcolina. Porém, como não houve uma demanda ou pergunta de pesquisa priorizada no escopo, a tecnologia não foi avaliada formalmente pela Conitec. RECOMENDAÇÃO FINAL: Os membros da Conitec presentes na 95ª reunião ordinária, no dia 03 de março de 2021, consideraram que o procedimento possui um corpo de evidências que favorece o exame de dosagem de anticorpos antiacetilcolina para diagnóstico da Miastenia Gravis. Considerou-se a maior sensibilidade e facilidade deste exame comparado à eletroneuromiografia. Diante do exposto, o Plenário deliberou por unanimidade recomendar a incorporação do exame de dosagem de anticorpo anti-receptor de acetilcolina para diagnóstico de Miastenia Gravis. Foi assinado o Registro de Deliberação nº 593/2021. DECISÃO: incorporar o exame de dosagem de anticorpo antirreceptor de acetilcolina para diagnóstico de Miastenia Gravis, do Sistema Único de Saúde - SUS, conforme Portaria nº 11, publicada no Diário Oficial da União nº 74, seção 1, página 235, em 19 de abril de 2021

Presence of Anti-MDA5 Antibody and Its Value for the Clinical Assessment in Patients With COVID-19: A Retrospective Cohort Study.

Background: Striking similarities have been found between coronavirus disease 2019 (COVID-19) and anti-melanoma differentiation-associated gene 5 (MDA5) antibody (Ab)-related dermatomyositis, implying a shared autoinflammatory aberrance. Herein, we aim to investigate whether the anti-MDA5 Ab is present in COVID-19 and correlates with the severity and adverse outcome of COVID-19 patients. Methods and Findings: We retrospectively recruited 274 adult inpatients with COVID-19 in this study, including 48, 164, and 62 cases of deaths, severe, and non-severe patients respectively. The anti-MDA5 Ab was determined by ELISA and verified by Western Blotting, which indicated that the positive rate of anti-MDA5 Ab in COVID-19 patients was 48.2% (132/274). The clinical and laboratory features, as well as outcomes between patients with positive and negative anti-MDA5 Ab were compared and we found that the anti-MDA5 Ab positive patients tended to represent severe disease (88.6% vs 66.9%, P<0.0001). We also demonstrated that the titer of anti-MDA5 Ab was significantly elevated in the non-survivals (5.95 ± 5.16 vs 8.22 ± 6.64, P=0.030) and the positive rate was also higher than that in the survivals (23.5% vs 12.0%, P=0.012). Regarding severe COVID-19 patients, we found that high titer of anti-MDA5 Ab (≥10.0 U/mL) was more prevalent in the non-survivals (31.2% vs 14.0%, P=0.006). Moreover, a dynamic analysis of anti-MDA5 Ab was conducted at different time-points of COVID-19, which revealed that early profiling of anti-MDA5 Ab could distinguish severe patients from those with non-severe ones. Conclusions: Anti-MDA5 Ab was prevalent in the COVID-19 patients and high titer of this antibody is correlated with severe disease and unfavorable outcomes.

Rapid and accurate Bayesian diagnosis of heparin-induced thrombocytopenia.

Prompt diagnostic evaluation of suspected heparin-induced thrombocytopenia (HIT) is critical for guiding initial patient management. We assessed the performance of 3 immunoassays detecting anti-platelet factor 4 (PF4)/heparin antibodies, derived a diagnostic algorithm with a short analytical turnaround time (TAT), and prospectively validated the algorithm. Plasma samples were analyzed by Zymutest-HIA-IgG, HemosIL-AcuStar-HIT-IgG, and ID-H/PF4-PaGIA in retrospective (n = 221) and prospective (n = 305) derivation cohorts. We calculated likelihood ratios of result intervals and cutoff values with 100% negative (NPV) and positive (PPV) predictive values for a positive gold standard functional assay (heparin-induced platelet activation [HIPA]). A diagnostic algorithm was established based on the Bayesian combination of pretest probability and likelihood ratios of first- and second-line immunoassays. Cutoffs with 100% PPV for positive HIPA were >3.0 U/mL (HemosIL-AcuStar-HIT-IgG) and titer ≥16 (ID-H/PF4-PaGIA); cutoffs with 100% NPV were <0.13 U/mL and ≤1, respectively. During the prospective validation of the derived algorithm (n = 687), HemosIL-AcuStar-HIT-IgG was used as unique testing in 566 (82.4%) of 687 cases (analytical TAT, 30 minutes). In 121 (17.6%) of 687 unresolved cases, ID-H/PF4-PaGIA was used as second-line testing (additional TAT, 30 minutes). The algorithm accurately predicted HIT in 51 (7.4%) of 687 patients and excluded it in 604 (87.9%) of 687 patients, leaving only 20 (2.9%) cases unresolved. We also identified 12 (1.7%) of 687 positive predictions not confirmed by HIPA: 10 patients with probable HIT despite negative HIPA and 2 possible false-positive algorithm predictions. The combination of pretest probability with first- and second-line immunoassays for anti-PF4/heparin antibodies is accurate for ruling in or out HIT in ≥95% of cases within 60 minutes. This diagnostic approach improves initial management of patients with suspected HIT.

Heparin-induced thrombocytopenia: An international assessment of the quality of laboratory testing.

BACKGROUND: Accurate diagnosis of heparin-induced thrombocytopenia (HIT) is essential to ensure timely treatment and prevent complications. Current diagnostic assays include enzyme-linked immunosorbent assays (ELISAs) and rapid immunoassays (RIs). RIs offer fast turnaround times but were not significantly represented in previous external proficiency testing challenges. OBJECTIVES: To use external proficiency testing to assess qualitative concordance for heparin/PF4 antibody detection. METHODS: From 2013 to 2017, the External Quality Control for Assays and Tests (ECAT) Foundation distributed 10 samples internationally. RESULTS: In total, 437 laboratories submitted 3149 results. ELISAs accounted for 1484 (47%) responses with RIs accounting for 1665 (53%) responses. RI use increased over the 5-year period. ELISAs classified 96% of both consensus positive and consensus negative samples concordantly. The coefficient of variation (CV) for positive sample optical densities (ODs) ranged from 35% to 50% when combining ELISA assay methods together. Quantitative RIs classified 97% of consensus-positive and 98% of consensus-negative samples concordantly. Qualitative RIs had a higher proportion of discordant responses and classified 88% of consensus-positive samples and 73% of consensus-negative samples concordantly. Of RIs only latex immunoassays and IgG specific chemiluminescent assays identified > 95% of samples concordantly with consensus. CONCLUSION: Quantitative RIs and ELISAs classify > 95% of samples concordantly. The ODs from different ELISA methods vary considerably and are not interchangeable. Qualitative RI use is increasing despite a greater proportion of discordant classifications. This includes a higher than expected number of negative classifications for consensus-positive samples among many RIs, challenging their use as "rule out" tests.

Incidence and Management of Olaratumab Infusion-Related Reactions.

PURPOSE: Olaratumab is a human monoclonal immunoglobulin G1 antibody against platelet-derived growth factor receptor-α. We report the nature and frequency of infusion-related reactions (IRRs) with olaratumab in clinical trials and postmarketing reports. METHODS: Data from patients exposed to olaratumab across nine clinical trials were reviewed for IRRs. Blood samples were also analyzed for pre-existing immunoglobulin E anti-galactose-α-1,3-galactose (anti-α-Gal) antibodies. RESULTS: In the clinical trials, IRRs were identified in 70 of 485 patients (14.4%). The most frequent symptoms included flushing, fever or chills, and dyspnea. For 68 of 70 patients (97.1%), the first IRR occurred during the first two cycles of treatment. Grade 3 or worse IRRs were reported in 11 patients (2.3%), all during the first infusion and usually within 15 minutes of the start of the infusion. One IRR-related fatality (0.2%) occurred in a nonpremedicated patient with grade 3 or worse cardiac comorbidities. There was an association between grade 3 or worse IRRs and pre-existing anti-α-Gal antibodies, with a trend toward higher IRR rates in US geographies known to have a higher prevalence of anti-α-Gal antibodies. IRRs in postmarketing reports were consistent in nature and severity with those in the clinical trials. CONCLUSION: Premedication with corticosteroids and antihistamines should occur in all patients before olaratumab infusion, as indicated in labels in the United States and the European Union. Patients receiving olaratumab should be monitored for IRRs in a setting where resuscitation equipment is available for the treatment of IRRs.

BCG scar, socioeconomic and nutritional status: a study of newborns in urban area of Makassar, Indonesia.

OBJECTIVE: To investigate factors that determine the response to Bacille Calmette-Guérin (BCG) vaccination in urban environments with respect to socioeconomic status (SES), prenatal exposure to infections or newborn's nutritional status. METHODS: The study was conducted in an urban area, in Makassar, Indonesia. At baseline, 100 mother and newborns pair from high and low SES communities were included. Intestinal protozoa, soil transmitted helminths, total IgE, anti-Hepatitis A Virus IgG and anti-Toxoplasma IgG were measured to determine exposure to infections. Information on gestational age, birth weight/height and delivery status were collected. Weight-for-length z-score, a proxy for newborns adiposity, was calculated. Leptin and adiponectin from cord sera were also measured. At 10 months of age, BCG scar size was measured from 59 infants. Statistical modelling was performed using multiple linear regression. RESULTS: Both SES and birth nutritional status shape the response towards BCG vaccination at 10 months of age. Infants born to low SES families have smaller BCG scar size compared to infants born from high SES families and total IgE contributed to the reduced scar size. On the other hand, infants born with better nutritional status were found to have bigger BCG scar size but this association was abolished by leptin levels at birth. CONCLUSION: This study provides new insights into the importance of SES and leptin levels at birth on the development of BCG scar in 10 months old infants.

OBJECTIF: Investiguer les facteurs qui déterminent la réponse à la vaccination par le BCG en milieu urbain en ce qui concerne le statut socioéconomique (SSE), l'exposition prénatale aux infections ou l'état nutritionnel du nouveau-né. MÉTHODES: L'étude a été menée dans une zone urbaine, à Makassar, en Indonésie. Au départ, 100 paires mère-nouveau-né issues de communautés à statut social élevé et faible ont été incluses. Les protozoaires intestinaux, les helminthes transmis par le sol, les IgE totales, les IgG anti-virus de l'hépatite A et anti- Toxoplasma ont été mesurés pour déterminer l'exposition aux infections. Des informations sur l'âge gestationnel, le poids/taille à la naissance et l'état d'accouchement ont été collectées. Le z-score poids-pour la taille, un indicateur indirect de l'adiposité du nouveau-né a été calculé. La leptine et l'adiponectine provenant de sérum des cordons ont également été mesurées. A l'âge de 10 mois, la taille des cicatrices de BCG a été mesurée chez 59 nourrissons. La modélisation statistique a été réalisée à l'aide d'une régression linéaire multiple. RÉSULTATS: Le statut socioéconomique et l'état nutritionnel à la naissance déterminent la réponse à la vaccination par le BCG à l'âge de 10 mois. La taille des cicatrices de BCG est plus petite chez les nourrissons nés de familles à statut socioéconomique faible comparée à celles chez ceux de familles à statut socioéconomique élevé et les IgE totales ont contribué à la réduction de la taille de ces cicatrices. En revanche, les bébés nés avec un meilleur état nutritionnel avaient une taille de cicatrice du BCG plus grande, mais cette association était supprimée par les niveaux de leptine à la naissance. CONCLUSION: Cette étude fournit de nouvelles informations sur l'importance du SSE et des niveaux de leptine à la naissance sur le développement d'une cicatrice du BCG chez des nourrissons âgés de 10 mois.

The value of anti-JCV antibody index assessment in multiple sclerosis patients treated with natalizumab with respect to demographic, clinical and radiological findings.

BACKGROUND: Natalizumab-related progressive multifocal leukoencephalopathy (PML) is associated with the presence of anti-John Cunningham virus (JCV) antibodies. The aim of this investigation was to evaluate the long-term stability of anti-JCV antibody serum levels and their relation to various demographic, clinical and radiological characteristics in patients suffering from multiple sclerosis (MS). METHODS: Seventy-eight relapsing-remitting MS patients treated with natalizumab and evaluated for the presence of serum anti-JCV antibodies over a time period of 1-6 years (3-11 samples) were included in the study. Anti-JCV antibody levels and their changes were correlated with various demographic, clinical and radiological findings. RESULTS: Median follow-up time was 43.5 months, with a median of 5.3 samples available per patient. At baseline, 46 (59%) of the patients were seropositive. During follow-up, anti-JCV antibody status changed from negative to positive or vice versa in 23% of patients. Baseline anti-JCV antibody index correlated positively with age (p = 0.03). PATIENTS: with stable positive anti-JCV antibody index had more T2 hyperintensities (20.2 vs. 13.1; p < 0.007) on cerebral magnetic resonance imaging (MRI) and were also older than the stable negative anti-JCV antibody index group of patients (45.2.vs. 40.3 years; p < 0.01). No significant increase in T2 hyperintensities after seroconversion was revealed. Average duration from beginning of natalizumab therapy to seroconversion (n = 13) was 33 months. Annual seroconversion rate of anti-JCV antibody status was 6.5%. A baseline anti-JCV antibody index of >0.90 (n = 33) predicted stable seropositivity (100%), while baseline anti-JCV antibody index <0.20 did not predicted stable seronegativity (59%). PML was not diagnosed in any of the patients studied during the follow-up. CONCLUSIONS: A positive baseline anti-JCV antibody index of >0.90 predicts stable positive JCV serostatus, in contrast with a baseline anti-JCV antibody index of <0.20, which remained negative in 59% of cases. Stable positive anti-JCV index patients have more MRI T2 hyperintensities and are older compared with stable negative anti-JCV index patients.

An international external quality assessment for laboratory diagnosis of heparin-induced thrombocytopenia.

Essentials A pilot study for External Quality Assessment for testing of HIT is described. The qualitative accordance for the PF4/heparin IgG test was 97.6%. The qualitative accordance for functional HIT tests was considerably lower. External Quality Assessment for functional HIT tests is required. SUMMARY: Objective Heparin-induced thrombocytopenia (HIT) is a potentially life-threatening complication of heparin exposure. Diagnosis is most reliable using a combination of an enzyme immunoassay (EIA) that detects antibodies against platelet factor 4 (PF4)/heparin complexes ("antigen" assay) and a "functional" assay that detects platelet-activating properties of the pathogenic HIT antibodies. No External Quality Assessment (EQA) is available for a combination of the tests. Here we report on the results of the first international EQA. Methods The pilot EQA was organized by the Department of Transfusion Medicine, Universitätsmedizin Greifswald, Germany. Six serum samples of patients, which were referred to Greifswald for HIT diagnosis, and one negative control sample were distributed to seven participants in Germany, Canada, and Singapore. Participants were asked to report the optical density (OD) values of their local EIA test for IgG-specific antibodies against the PF4/heparin complexes and the results for a functional assay (HIPA or SRA). Consensus was defined as a minimum 70% agreement, i.e., agreement among at least five of the seven participating laboratories. Results and conclusion Six out of seven participants reported results for EIA, with a high quantitative accordance (97.6%). For the functional assay, consensus was reached for all samples except the negative control, for which some participants reported nonspecific reactivity. All HIT-negative samples were correctly diagnosed by all participants; for HIT-positive samples, consensus of 70% was reached. Although the limited availability of sample material is an obstacle to overcome, an EQA combining both EIA and functional testing is feasible.

Immunogenicity assessment of tbo-filgrastim in cancer patients receiving chemotherapy.

AIM: This integrated analysis examined the immunogenicity of tbo-filgrastim and its potential clinical impact in three Phase III randomized studies in patients with breast cancer, lung cancer and non-Hodgkin lymphoma receiving chemotherapy. RESULTS: Treatment-emergent antidrug antibodies (ADA) occurred in 3/213 (1.4%) breast cancer patients, 2/160 (1.3%) lung cancer patients and 1/63 (1.6%) patients with non-Hodgkin lymphoma. None of the treatment-emergent ADA showed cross-reactivity toward native granulocyte-colony stimulating factors or exhibited neutralizing activity against tbo-filgrastim. Among patients with treatment-emergent ADA, there was no treatment-related hypersensitivity or anaphylaxis and no evidence of loss of clinical efficacy. CONCLUSION: Tbo-filgrastim has demonstrated low immunogenicity in cancer patients receiving chemotherapy and ADA response does not impact safety and efficacy in the patients.

A compact, low-cost, quantitative and multiplexed fluorescence detection platform for point-of-care applications.

An effective method of combating infectious diseases is the deployment of hand-held devices at the point-of-care (POC) for screening or self-monitoring applications. There is a need for very sensitive, low-cost and quantitative diagnostic devices. In this study, we present a low-cost, multiplexed fluorescence detection platform that has a high sensitivity and wide dynamic range. Our system features inexpensive 3 × 3 mm interference filters with a high stopband rejection, sharp transition edges, and greater than 90% transmission in the passband. In addition to the filters, we improve signal-to-noise ratio by leveraging time for accuracy using a charge-integration-based readout. The fluorescence sensing platform provides a sensitivity to photon flux of ∼1×104photons/mm2sec and has the potential for 2-3 orders of magnitude improvement in sensitivity over standard colorimetric detection that uses colored latex microspheres. We also detail the design, development, and characterization of our low-cost fluorescence detection platform and demonstrate 100% and 97.96% reduction in crosstalk probability and filter cost, respectively. This is achieved by reducing filter dimensions and ensuring appropriate channel isolation in a 2 × 2 array configuration. Practical considerations with low-cost interference filter system design, analysis, and system performance are also discussed. The performance of our platform is compared to that of a standard laboratory array scanner. We also demonstrate the detection of antibodies to human papillomavirus (HPV16) E7 protein, as a potential biomarker for early cervical cancer detection in human plasma.

PET response assessment in apatinib-treated radioactive iodine-refractory thyroid cancer.

This work evaluated the use of the positron emission tomography (PET)/computed tomography (CT) technique to assess the early therapeutic response and predict the prognosis of patients with radioactive iodine-refractory differentiated thyroid cancer (RAIR-DTC) who underwent apatinib therapy. Standardised uptake value (SUV), metabolic tumour volume (MTV) and total lesion glycolysis (TLG), derived from 18F-FDG PET/CT and SUV from 68Ga-NOTA-PRGD2 PET/CT were evaluated. Tumour response was evaluated using the Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. Sixteen of 20 patients achieved partial response (PR) and four of 20 had stable disease (SD) after apatinib therapy. Six progression-free survival (PFS) events occurred. A strong correlation was observed between the best change in the sum of the longest diameters of target lesions (ΔCT%) and 18F-FDG PET/CT indices after the completion of the first treatment cycle (ΔMTV% (P = 0.0019), ΔTLG% (P = 0.0021) and ΔSUVmax% (P = 0.0443)). A significant difference in PFS was observed between patients with ΔMTV% <-45% and ≥-45% (P = 0.0019) and between patients with ΔTLG% <-80% and ≥-80% (P = 0.0065). Ten of 11 patients presented a decrease in SUVmax on 68Ga-NOTA-PRGD2 PET/CT after two cycles of apatinib therapy and showed PR, whereas one patient presenting an increase in SUVmax only showed SD as the best response. When a cut-off value of the target/background ratio at -20% was used, two PFS curves showed a significant difference (P = 0.0016). Hence, early assessment by 18F-FDG and 68Ga-NOTA-PRGD2 PET/CT was effective in the prediction and evaluation of RAIR-DTC treated with apatinib.

Evaluation of a Decision Tree for Efficient Antenatal Red Blood Cell Antibody Screening.

BACKGROUND: Hemolytic disease of the fetus and newborn due to maternal red blood cell alloimmunization can have serious consequences. Because early detection enables careful monitoring of affected pregnancies, programs to routinely screen all pregnant women have been widely adopted. Due to the low prevalence of alloimmunization, these require large investments of resources to detect a small number of cases. METHODS: We conducted a validation study of a decision tree developed in the Netherlands for determining whether to screen for alloimmunization. In a Swedish cohort, we compared the performance of that decision tree to two alternative models that used maternal characteristics, obstetric history, and transfusion history to identify high-risk women for screening or low-risk women who might be exempt from screening. The models were compared for predictive ability and potential reduction in the volume of screening. RESULTS: The decision tree applied to our study population identified 89% of alloimmunized women with a negative predictive value (NPV) of 99.7% by screening 62% of the population. To achieve the same NPV, our model exempting low-risk women captured 90% of alloimmunizations by screening 63% of the population. In contrast, the model identifying high-risk women for screening while maintaining a similar NPV captured 63% of alloimmunized women by screening 20% of the population. CONCLUSIONS: We validated that an existing decision tree for selecting women for maternal screening performed well in our population, identifying a large proportion of women who became alloimmunized, with a predictive performance almost identical to that of a more elaborate model.

Clinical relevance of detecting anti-infliximab antibodies with a drug-tolerant assay: post hoc analysis of the TAXIT trial.

OBJECTIVE: To evaluate the clinical relevance of antidrug antibodies (ADAs) measured using a drug-tolerant assay in a post hoc analysis of the Trough Concentration (TC) Adapted Infliximab Treatment (TAXIT) randomised controlled trial. DESIGN: ADA in serum samples (n=221) of 76 patients enrolled in TAXIT, who presented with an infliximab TC <3 µg/mL at screening, were reanalysed after optimisation and at the end of the study using a drug-tolerant ADA assay. Patients underwent dose escalation to achieve therapeutic TCs between 3 µg/mL and 7 µg/mL prior to randomisation. Patients were grouped into quartiles (Q1-4) according to ADA concentration at screening. RESULTS: Using a drug-tolerant assay, the immunogenicity detection rate increased from 21% (drug-sensitive assay) to 63% at screening, from 0% to 51% after optimisation and from 3% to 42% at the end of TAXIT. Patients in ADA Q4 required a higher cumulative infliximab dose (2390 (880-2998) mg) to achieve target TCs, resulting in a higher drug cost (€10 712 (4120-13 596)) compared with ADA-negative patients (€2060 (1648-3296)) and patients in ADA Q1/Q2 (€2060 (1648-4120)/€2060 (1751-3296), p<0.001). However, all but one patient belonging to ADA Q4 were also ADA-positive using a drug-sensitive assay. CONCLUSIONS: Upon dose intensification, low concentration ADAs, not detectable using a drug-sensitive assay, disappear in more than half of the patients over time and are clinically non-relevant. In contrast, high concentration ADAs which are typically also detected in a drug-sensitive assay, persist over time and necessitate a higher cumulative dose and drug cost. In the latter group, proactive drug switching may be more cost-efficient. CLINICAL TRIALS REGISTER: 2011-002061-38; Post-results.

Quartz crystal microbalance as an assay to detect anti-drug antibodies for the immunogenicity assessment of therapeutic biologics.

Because of their biological origins, therapeutic biologics can trigger an unwanted deleterious immune response with some patients. The immunogenicity of therapeutic biologics can affect drug efficacy and patient safety by the production of circulating anti-drug antibodies (ADA). In this study, quartz crystal microbalance (QCM) was developed as an assay to detect ADA. Etanercept (Enbrel®) was covalently grafted to dextran-modified QCM surfaces. Rabbits were immunized with etanercept to generate ADA. Results showed the QCM assay could detect purified ADA from rabbits at concentrations as low as 50 ng/mL, within the sensitivity range of ELISA. The QCM assay could also assess the ADA isotype. It was shown that the ADA were composed of the IgG isotype, but not IgM, as expected. Furthermore, it was shown that QCM surfaces that had been used to detect ADA could be regenerated in glycine-HCl solution and reused. The QCM assay was also demonstrated to detect ADA in crude serum samples. Serum was collected from the rabbits and analyzed before and after etanercept immunization. ADA were clearly detected in serum from rabbits after immunization, but not in serum before immunization. Serum from patients administered with etanercept for rheumatoid arthritis (RA) treatment was also analyzed and compared to serum from healthy donors. Sera from 10 RA patients were analyzed. Results showed one of the RA patient serum samples may have ADA present. In conclusion, QCM appears to be a viable assay to detect ADA for the immunogenicity assessment of therapeutic biologics.

Assessment of Anti-Tumor Cytotoxic Activity of Naturally Occurring Antibodies in Human Serum or Plasma.

A small percentage of the Western population carries antibodies in the peripheral blood, which are able to kill human tumors such as neuroblastoma or melanoma. Several observations indicate that these antibodies, preferentially of IgM isotype, belong to the class of naturally occurring antibodies. Here, we describe two screening methods for the detection and quantification of such antibodies in human blood samples: a cellular ELISA technique and a flow cytometric assay, based on intercalation of fluorescent propidium iodide into the DNA of dying or dead cells.

Assessment of the immunogenicity of gonadotrophins during controlled ovarian stimulation.

PROBLEM: Gonadotrophin hormones are used for the controlled ovarian stimulation (COS) as part of the in vitro fertilization techniques. Therapeutic proteins have the potential to induce an unwanted immune response. METHOD OF STUDY: The presence of anti-FSH, anti-LH and anti-hCG antibodies were determined in patients from two different clinical trials after the repeated administration of hMG or FSH. RESULTS: In the first study, 27 subjects were screening for the presence of anti-FSH antibodies. From the 27 patients, only one patient showed the presence of low levels of antibodies. In a second study, 25 patients were screened for the presence of anti-FSH, anti-LH and anti-hCG antibodies. At the end of the study, no patients showed the presence of antibodies. CONCLUSION: The results of this study suggest that repeated treatment cycles with FSH or hMG in patients undergoing COS for in vitro fertilization can be safely and effectively applied without concerns for immunogenicity.

Assessment of Anti-vinculin and Anti-cytolethal Distending Toxin B Antibodies in Subtypes of Irritable Bowel Syndrome.

BACKGROUND: Antibodies to cytolethal distending toxin B (CdtB) and vinculin are novel biomarkers that rule-in and differentiate irritable bowel syndrome with diarrhea (IBS-D) from other causes of diarrhea and healthy controls. AIM: To determine whether these antibodies can also diagnose and differentiate other IBS subtypes. METHODS: Subjects with IBS-D based on Rome III criteria (n = 2375) were recruited from a large-scale multicenter clinical trial (TARGET 3). Healthy subjects without gastrointestinal (GI) diseases or symptoms (n = 43) and subjects with mixed IBS (IBS-M) (n = 25) or IBS with constipation (IBS-C) (n = 30) were recruited from two major medical centers. Plasma levels of anti-CdtB and anti-vinculin antibodies in all subjects were determined by enzyme-linked immunosorbent assay. Optical densities of ≥1.68 and ≥2.80 were considered positive for anti-vinculin and anti-CdtB, respectively. Plasma levels of anti-CdtB and anti-vinculin antibodies were highest in IBS-D and lowest in IBS-C and healthy controls (P < 0.001). Levels in IBS-C subjects were not statistically different from controls (P > 0.1). Positivity for anti-CdtB or anti-vinculin resulted in a statistically significant negative gradient from IBS-D (58.1%) to IBS-M (44.0%), IBS-C (26.7%), and controls (16.3%) (P < 0.001). CONCLUSIONS: Anti-CdtB and anti-vinculin titers and positivity rates differ in IBS subtypes, with higher antibody levels and positivity rates in IBS-D and IBS-M, and lower levels in IBS-C subjects that are similar to those in healthy controls. These antibodies appear useful in the diagnosis of IBS-M and IBS-D, but not IBS-C. Furthermore, these findings suggest that IBS-C is pathophysiologically distinct from subtypes with diarrheal components (i.e., IBS-M and IBS-D).

Biosimilar Infliximab in Inflammatory Bowel Disease: Outcomes of a Managed Switching Programme.

BACKGROUND AND AIMS: Biosimilar infliximab CT-P13 offers the potential for large drug acquisition cost savings. However, there are limited published data regarding its efficacy, safety, and immunogenicity in inflammatory bowel disease [IBD], particularly in switching IBD patients from originator to biosimilar infliximab. We present the outcomes of a service evaluation of switching IBD patients established on originator infliximab to biosimilar, using a managed switching programme funded via a gain share agreement in a UK teaching hospital. METHODS: Evaluation outcomes included drug persistence, changes in drug acquisition costs, patient-reported side effects, adverse events, patient outcomes assessed using the IBD-control Patient-Reported Outcome Measures [PROM] questionnaire, serum drug and antibody levels, and routinely collected biochemical markers. RESULTS: A total of 143 patients with IBD [118 Crohn's disease, 23 ulcerative colitis, 2 IBD unclassified] were switched from originator infliximab to CT-P13. Patients reported a similar incidence of side effects before and after switch. No clinically significant differences were observed in mean C-reactive protein [CRP], albumin, haemoglobin levels, or platelet and white cell counts after the switch to CT-P13, whereas mean IBD-control-8 score improved from 10.4 to 11.2 [p = 0.041]. There was no significant difference in drug persistence between biosimilar and originator infliximab [p = 0.94] and no increase in immunogenicity was found. Drug acquisition costs decreased by £40,000-60,000 per month. CONCLUSIONS: A managed switching programme from originator infliximab to biosimilar CT-P13 in IBD, using a gain-share agreement, delivers significant cost savings and investment in clinical services while maintaining similar patient-reported outcomes, biochemical response, drug persistence, and adverse event profile.