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Immune escape is a prerequisite for tumor growth. We previously described a decline in intratumor activated cytotoxic T cells and T cell receptor (TCR) clonotype diversity in invasive breast carcinomas compared to ductal carcinoma in situ (DCIS), implying a central role of decreasing T cell responses in tumor progression. To determine potential associations between peripheral immunity and breast tumor progression, here, we assessed the peripheral blood TCR clonotype of 485 breast cancer patients diagnosed with either DCIS or de novo stage IV disease at younger (<45) or older (≥45) age. TCR clonotype diversity was significantly lower in older compared to younger breast cancer patients regardless of tumor stage at diagnosis. In the younger age group, TCR-α clonotype diversity was lower in patients diagnosed with de novo stage IV breast cancer compared to those diagnosed with DCIS. In the older age group, DCIS patients with higher TCR-α clonotype diversity were more likely to have a recurrence compared to those with lower diversity. Whole blood transcriptome profiles were distinct depending on the TCR-α Chao1 diversity score. There were more CD8+ T cells and a more active immune environment in DCIS tumors of young patients with higher peripheral blood TCR-α Chao1 diversity than in those with lower diversity. These results provide insights into the role that host immunity plays in breast cancer development across different age groups.
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Neoplasias de la Mama , Carcinoma Ductal de Mama , Carcinoma Intraductal no Infiltrante , Humanos , Anciano , Femenino , Neoplasias de la Mama/patología , Carcinoma Intraductal no Infiltrante/genética , Carcinoma Intraductal no Infiltrante/patología , Linfocitos T CD8-positivos/patología , Biomarcadores de Tumor/genética , Receptores de Antígenos de Linfocitos T/genética , Procesos Neoplásicos , Receptores de Antígenos de Linfocitos T alfa-beta/genética , Carcinoma Ductal de Mama/patologíaRESUMEN
BACKGROUND: Patients with inflammatory breast cancer (IBC) have overall poor clinical outcomes, with triple-negative IBC (TN-IBC) being associated with the worst survival, warranting the investigation of novel therapies. Preclinical studies implied that ruxolitinib (RUX), a JAK1/2 inhibitor, may be an effective therapy for TN-IBC. METHODS: We conducted a randomized phase II study with nested window-of-opportunity in TN-IBC. Treatment-naïve patients received a 7-day run-in of RUX alone or RUX plus paclitaxel (PAC). After the run-in, those who received RUX alone proceeded to neoadjuvant therapy with either RUX + PAC or PAC alone for 12 weeks; those who had received RUX + PAC continued treatment for 12 weeks. All patients subsequently received 4 cycles of doxorubicin plus cyclophosphamide prior to surgery. Research tumor biopsies were performed at baseline (pre-run-in) and after run-in therapy. Tumors were evaluated for phosphorylated STAT3 (pSTAT3) by immunostaining, and a subset was also analyzed by RNA-seq. The primary endpoint was the percent of pSTAT3-positive pre-run-in tumors that became pSTAT3-negative. Secondary endpoints included pathologic complete response (pCR). RESULTS: Overall, 23 patients were enrolled, of whom 21 completed preoperative therapy. Two patients achieved pCR (8.7%). pSTAT3 and IL-6/JAK/STAT3 signaling decreased in post-run-in biopsies of RUX-treated samples, while sustained treatment with RUX + PAC upregulated IL-6/JAK/STAT3 signaling compared to RUX alone. Both treatments decreased GZMB+ T cells implying immune suppression. RUX alone effectively inhibited JAK/STAT3 signaling but its combination with PAC led to incomplete inhibition. The immune suppressive effects of RUX alone and in combination may negate its growth inhibitory effects on cancer cells. CONCLUSION: In summary, the use of RUX in TN-IBC was associated with a decrease in pSTAT3 levels despite lack of clinical benefit. Cancer cell-specific-targeting of JAK2/STAT3 or combinations with immunotherapy may be required for further evaluation of JAK2/STAT3 signaling as a cancer therapeutic target. TRIAL REGISTRATION: www. CLINICALTRIALS: gov , NCT02876302. Registered 23 August 2016.
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Neoplasias Inflamatorias de la Mama , Nitrilos , Paclitaxel , Pirazoles , Pirimidinas , Neoplasias de la Mama Triple Negativas , Femenino , Humanos , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Neoplasias Inflamatorias de la Mama/tratamiento farmacológico , Neoplasias Inflamatorias de la Mama/patología , Interleucina-6 , Terapia Neoadyuvante , Nitrilos/uso terapéutico , Paclitaxel/uso terapéutico , Pirazoles/uso terapéutico , Pirimidinas/uso terapéutico , Resultado del Tratamiento , Neoplasias de la Mama Triple Negativas/tratamiento farmacológico , Neoplasias de la Mama Triple Negativas/patologíaRESUMEN
Daratumumab is an anti-CD38 monoclonal antibody approved for multiple myeloma. The initial infusion is administered over a median of 7.5 hours with subsequent infusions given over 3 to 4 hours. Studies show high incidence of infusion related reactions (IRRs) with the initial dose which decreases with subsequent infusions. Accelerated 90 minute daratumumab infusions following the second dose of standard administration are widely accepted in practice including at Beth Israel Deaconess Medical Center (BIDMC) despite limited data from small safety studies. The objective of this study is to evaluate the safety of accelerated daratumumab administration compared to standard administration. The primary outcome is the incidence of common terminology criteria for adverse events (CTCAE) version 5.0 grade 1 or higher for IRRs in accelerated and standard infusions. Secondary outcomes include non-IRR adverse events and amount of supportive care medications used pre- and post- and during accelerated and standard infusions. A total of seventy five patients received a daratumumab infusion between November 2015 and August 2019. There were a total of 420 daratumumab infusions evaluated, 317 (75.5%) were standard infusions of which 152 infusions were standard infusions that preceded an accelerated infusion. There were a total of 103 (24.5%) accelerated infusions. IRRs occurred in a total of 38 (9%) of the infusions with CTCAE grade 2 reactions occurring in total of 21 (5%) infusions and grade 1 occurring in 15 (3.6%) infusions. Overall accelerated daratumumab administration is safe and well tolerated when given following at least two standard infusions.
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Antineoplásicos , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos , Mieloma Múltiple , Anticuerpos Monoclonales/efectos adversos , Antineoplásicos/efectos adversos , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos/tratamiento farmacológico , Humanos , Mieloma Múltiple/tratamiento farmacológico , Estudios RetrospectivosRESUMEN
We describe rapid spread of multidrug-resistant gram-negative bacteria among patients in dedicated coronavirus disease care units in a hospital in Maryland, USA, during May-June 2020. Critical illness, high antibiotic use, double occupancy of single rooms, and modified infection prevention practices were key contributing factors. Surveillance culturing aided in outbreak recognition and control.
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Antibacterianos , COVID-19 , Enfermedad Crítica , Bacterias Gramnegativas , Control de Infecciones , Pautas de la Práctica en Enfermería , Sobreinfección , Antibacterianos/clasificación , Antibacterianos/uso terapéutico , COVID-19/epidemiología , COVID-19/fisiopatología , COVID-19/terapia , Enfermedad Crítica/epidemiología , Enfermedad Crítica/terapia , Farmacorresistencia Bacteriana Múltiple , Bacterias Gramnegativas/clasificación , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Gramnegativas/aislamiento & purificación , Humanos , Control de Infecciones/métodos , Control de Infecciones/organización & administración , Unidades de Cuidados Intensivos/organización & administración , Maryland/epidemiología , Técnicas Microbiológicas/métodos , Técnicas Microbiológicas/estadística & datos numéricos , Pautas de la Práctica en Enfermería/organización & administración , Pautas de la Práctica en Enfermería/normas , Factores Desencadenantes , Factores de Riesgo , SARS-CoV-2 , Sobreinfección/diagnóstico , Sobreinfección/microbiologíaRESUMEN
Receptors expressed on the plasma membrane and their interacting partners critically regulate cellular communication during homeostasis and disease, and as such represent main therapeutic targets. Despite its importance for drug development, receptor-ligand proteomics has remained a daunting field, in part because of the challenges associated to the study of membrane-expressed proteins. Here, to enable sensitive detection of receptor-ligand interactions in high throughput, we implement a new platform, the Conditioned Media AlphaScreen, for interrogation of a library consisting of most single transmembrane human proteins. Using this method to study key immune receptors, we identify and further validate the interleukin receptor IL20RA as the first binding partner for the checkpoint inhibitor B7-H3. Further, KIR2DL5, a natural killer cell protein that had remained orphan, is uncovered as a functional binding partner for the poliovirus receptor (PVR). This interaction is characterized using orthogonal assays, which demonstrate that PVR specifically engages KIR2DL5 on natural killer cells leading to inhibition of cytotoxicity. Altogether, these results reveal unappreciated links between protein families that may importantly influence receptor-driven functions during disease. Applicable to any target of interest, this technology represents a versatile and powerful approach for elucidation of receptor-ligand interactomes, which is essential to understand basic aspects of the biology of the plasma membrane proteins and ultimately inform the development of novel therapeutic strategies.
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Antígenos B7/metabolismo , Matriz Extracelular/metabolismo , Células Asesinas Naturales/metabolismo , Receptores de Interleucina/metabolismo , Receptores KIR2DL5/metabolismo , Receptores Virales/metabolismo , Comunicación Celular , Células HEK293 , Humanos , Células Asesinas Naturales/citología , Células Asesinas Naturales/inmunología , Ligandos , Unión Proteica , Mapas de Interacción de ProteínasRESUMEN
PURPOSE: Clonal hematopoiesis of indeterminate potential (CHIP) is frequent in patients with solid tumors. Prospective data about CHIP prevalence at breast cancer diagnosis and its dynamic evolution under treatment selective pressure are limited. PATIENTS AND METHODS: We performed targeted error-corrected sequencing on 614 samples from 380 patients with breast cancer. We investigated the dynamics of CHIP on prospectively collected paired samples from patients with early breast cancer (eBC) receiving chemotherapy (CT) or endocrine therapy (ET). We assessed the correlation of CHIP with survival in patients with metastatic triple-negative breast cancer (mTNBC). We estimated the risk of progression to treatment-related myeloid neoplasms (t-MN) according to the clonal hematopoiesis risk score (CHRS). In exploratory analyses, we considered clonal hematopoiesis (CH) with variant allele fraction (VAF) ≥0.005. RESULTS: CHIP was identified in 15% of patients before treatment. Few CHIP emerged after treatment, and the risk of developing new mutations was similar for patients receiving CT versus ET (odds ratio [OR], 1.16; P = .820). However, CT increased the risk of developing new CH with VAF ≥0.005 (OR, 3.45; P = .002). Five TP53-mutant CH with VAF ≥0.005 emerged among patients receiving CT. Most patients had low risk of t-MN according to the CHRS score. CHIP did not correlate with survival in mTNBC. CONCLUSION: CHIP is frequent in patients with breast cancer. In this study, CT did not lead to emergence of new CHIP, and most patients had low risk of developing t-MN. This finding is reassuring, given long life expectancy of patients with eBC and the association of CHIP with morbidity and mortality. However, TP53-mutant CH with VAF ≥0.005 emerged with CT, which carries high risk of t-MN. Evolution of these small clones and their clinical significance warrant further investigation.
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BACKGROUND: Hospital-onset bacteraemia and fungaemia (HOB) is being explored as a surveillance and quality metric. The objectives of the current study were to determine sources and preventability of HOB in hospitalised patients in the USA and to identify factors associated with perceived preventability. METHODS: We conducted a cross-sectional study of HOB events at 10 academic and three community hospitals using structured chart review. HOB was defined as a blood culture on or after hospital day 4 with growth of one or more bacterial or fungal organisms. HOB events were stratified by commensal and non-commensal organisms. Medical resident physicians, infectious disease fellows or infection preventionists reviewed charts to determine HOB source, and infectious disease physicians with training in infection prevention/hospital epidemiology rated preventability from 1 to 6 (1=definitely preventable to 6=definitely not preventable) using a structured guide. Ratings of 1-3 were collectively considered 'potentially preventable' and 4-6 'potentially not preventable'. RESULTS: Among 1789 HOB events with non-commensal organisms, gastrointestinal (including neutropenic translocation) (35%) and endovascular (32%) were the most common sources. Overall, 636/1789 (36%) non-commensal and 238/320 (74%) commensal HOB events were rated potentially preventable. In logistic regression analysis among non-commensal HOB events, events attributed to intravascular catheter-related infection, indwelling urinary catheter-related infection and surgical site infection had higher odds of being rated preventable while events with neutropenia, immunosuppression, gastrointestinal sources, polymicrobial cultures and previous positive blood culture in the same admission had lower odds of being rated preventable, compared with events without those attributes. Of 636 potentially preventable non-commensal HOB events, 47% were endovascular in origin, followed by gastrointestinal, respiratory and urinary sources; approximately 40% of those events would not be captured through existing healthcare-associated infection surveillance. DISCUSSION: Factors identified as associated with higher or lower preventability should be used to guide inclusion, exclusion and risk adjustment for an HOB-related quality metric.
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Bacteriemia , Infección Hospitalaria , Fungemia , Humanos , Estudios Transversales , Bacteriemia/epidemiología , Bacteriemia/prevención & control , Estados Unidos/epidemiología , Infección Hospitalaria/prevención & control , Infección Hospitalaria/epidemiología , Masculino , Femenino , Fungemia/epidemiología , Persona de Mediana Edad , Indicadores de Calidad de la Atención de Salud , AncianoRESUMEN
Delivering heat in vivo could enhance a wide range of biomedical therapeutic and diagnostic technologies, including long-term drug delivery devices and cancer treatments. To date, providing thermal energy is highly power-intensive, rendering it oftentimes inaccessible outside of clinical settings. We developed an in vivo heating method based on the exothermic reaction between liquid-metal-activated aluminum and water. After establishing a method for consistent activation, we characterized the heat generation capabilities with thermal imaging and heat flux measurements. We then demonstrated one application of this reaction: to thermally actuate a gastric resident device made from a shape-memory alloy called Nitinol. Finally, we highlight the advantages and future directions for leveraging this novel in situ heat generation method beyond the showcased example.
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PURPOSE: Young women treated for breast cancer with cytotoxic therapies are at risk for clonal hematopoiesis of indeterminate potential (CHIP), a condition in which blood cells carrying a somatic mutation associated with hematologic malignancy comprise at least 4% of the total blood system. CHIP has primarily been studied in older patient cohorts with limited clinical phenotyping. EXPERIMENTAL DESIGN: We performed targeted sequencing on longitudinal blood samples to characterize the clonal hematopoietic landscape of 878 women treated for breast cancer enrolled in the prospective Young Women's Breast Cancer Study. RESULTS: We identified somatic driver mutations in 252 study subjects (28.7%), but only 24 (2.7%) had clones large enough to meet criteria for CHIP. The most commonly mutated genes were DNMT3A and TET2, similar to mutations observed in noncancer cohorts. At 9-year median follow-up, we found no association between the presence of a somatic blood mutation (regardless of clone size) and adverse breast cancer (distant relapse-free survival) or non-breast cancer-related outcomes in this cohort. A subset of paired blood samples obtained over 4 years showed no evidence of mutant clonal expansion, regardless of genotype. Finally, we identified a subset of patients with likely germline mutations in genes known to contribute to inherited cancer risk, such as TP53 and ATM. CONCLUSIONS: Our data show that for young women with early-stage breast cancer, CHIP is uncommon after cytotoxic exposure, is unlikely to contribute to adverse outcomes over the decade-long follow-up and may not require additional monitoring if discovered incidentally.
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Neoplasias de la Mama , Hematopoyesis Clonal , Humanos , Femenino , Anciano , Hematopoyesis Clonal/genética , Estudios Prospectivos , Hematopoyesis/genética , Evolución Clonal/genética , Recurrencia Local de Neoplasia , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/genética , MutaciónRESUMEN
Actively triggerable materials, which break down upon introduction of an exogenous stimulus, enable precise control over the lifetime of biomedical technologies, as well as adaptation to unforeseen circumstances, such as changes to an established treatment plan. Yet, most actively triggerable materials are low-strength polymers and hydrogels with limited long-term durability. By contrast, metals possess advantageous functional properties, including high mechanical strength and conductivity, that are desirable across several applications within biomedicine. To realize actively triggerable metals, a mechanism called liquid metal embrittlement is leveraged, in which certain liquid metals penetrate the grain boundaries of certain solid metals and cause them to dramatically weaken or disintegrate. In this work, it is demonstrated that eutectic gallium indium (EGaIn), a biocompatible alloy of gallium, can be formulated to reproducibly trigger the breakdown of aluminum within different physiologically relevant environments. The breakdown behavior of aluminum after triggering can further be readily controlled by manipulating its grain structure. Finally, three possible use cases of biomedical devices constructed from actively triggerable metals are demonstrated.
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Aluminio , Galio , Aleaciones , Galio/química , Indio/química , Conductividad EléctricaRESUMEN
Purpose: To examine circulating tumor DNA (ctDNA) and its association with residual cancer burden (RCB) using an ultrasensitive assay in patients with triple-negative breast cancer (TNBC) receiving neoadjuvant chemotherapy (NAT). Patients and Methods: We identified responders (RCB-0/1) and matched non-responders (RCB-2/3) from the phase II TBCRC 030 prospective study of neoadjuvant paclitaxel vs. cisplatin in TNBC. We collected plasma samples at baseline, three weeks, and twelve weeks (end of therapy). We created personalized ctDNA assays utilizing MAESTRO mutation enrichment sequencing. We explored associations between ctDNA and RCB status and disease recurrence. Results: Of 139 patients, 68 had complete samples and no additional NAT. Twenty-two were responders and 19 of those had sufficient tissue for whole-genome sequencing. We identified an additional 19 non-responders for a matched case-control analysis of 38 patients using a MAESTRO ctDNA assay tracking 319-1000 variants (median 1000) to 114 plasma samples from 3 timepoints. Overall, ctDNA positivity was 100% at baseline, 79% at week 3, and 55% at week 12. Median tumor fraction (TFx) was 3.7 × 10 -4 (range: 7.9 × 10 -7 to 4.9 × 10 -1 ). TFx decreased 285-fold from baseline to week 3 in responders and 24-fold in non-responders. Week 12 ctDNA clearance correlated with RCB: clearance was observed in 10/11 patients with RCB-0, 3/8 with RCB-1, 4/15 with RCB-2, and 0/4 with RCB-3. Among 6 patients with known recurrence five had persistent ctDNA at week 12. Conclusion: NAT for TNBC reduced ctDNA TFx by 285-fold in responders and 24-fold in non-responders. In 58% (22/38) of patients, ctDNA TFx dropped below the detection level of a commercially available test, emphasizing the need for sensitive tests. Additional studies will determine if ctDNA-guided approaches can improve outcomes.
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Introduction Glaucoma is characterized by the loss of retinal nerve fiber tissues and the loss of the neuroretinal rim of the optic nerve head is termed glaucomatous optic neuropathy (GON). The early diagnosis of glaucoma requires measurement of intraocular pressure (IOP) by tonometry. The gold standard method widely used in clinical settings to measure IOP is Goldmann applanation tonometry (GAT). Myopia is also considered a risk factor for glaucoma. Population-based and hospital-based evidence suggests that the prevalence of GON is higher in high myopic eyes than in emmetropic eyes. The present study aims to document the association between myopia and elevated IOP. Materials and methods A total of 400 medium and high myopic patients attending the ophthalmology outpatient department, in a tertiary care hospital, were measured for IOP using GAT and underwent a detailed clinical evaluation. All the patients also underwent slit lamp biomicroscopic examination and fundus examination. Other data included details on demographic, socio-economic, and occupational history. Results A detailed refractive error examination revealed that amongst 400 right eyes, 67.5% had medium myopia, while 66.75% of the left eye were medium myopic. Amongst the medium myopic eyes, the average IOP was 15.51±3.68 mm of Hg, while in high myopic, the average IOP was 16.19±3.33 mm of Hg. A difference of 0.68 mm of Hg with high myopic eyes having higher IOP values than medium myopic eyes was observed, and it was significant statistically with a p-value <0.05. Conclusion There is a statistically significant association between elevated IOP and the high myopic group. In comparison to IOP measured in medium myopic and high myopic patients, elevated IOP was observed in the high myopic group than in the medium myopic group.
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PURPOSE: To examine the prevalence and dynamics of circulating tumor DNA (ctDNA) and its association with metastatic recurrence in patients with high-risk early-stage hormone receptor-positive breast cancer (HR+ BC) more than 5 years from diagnosis. METHODS: We enrolled 103 patients with high-risk stage II-III HR+ BC diagnosed more than 5 years prior without clinical evidence of recurrence. We performed whole-exome sequencing (WES) on primary tumor tissue to identify somatic mutations tracked via a personalized, tumor-informed ctDNA test to detect minimal residual disease (MRD). We collected plasma at the time of consent and at routine visits every 6-12 months. Patients were followed for clinical recurrence. RESULTS: In total, 85 of 103 patients had sufficient tumor tissue; of them, 83 of 85 (97.6%) patients had successful whole-exome sequencing. Personalized ctDNA assays were designed targeting a median of 36 variants to test 219 plasma samples. The median time from diagnosis to first sample was 8.4 years. The median follow-up was 10.4 years from diagnosis and 2.0 years from first sample. The median number of plasma samples per patient was two. Eight patients (10%) had positive MRD testing at any time point. Six patients (7.2%) developed distant metastatic recurrence, all of whom were MRD-positive before overt clinical recurrence, with median ctDNA lead time of 12.4 months. MRD was not identified in one patient (1.2%) with local recurrence. Two of eight MRD-positive patients had not had clinical recurrence at last follow-up. CONCLUSION: In this prospective study, in patients with high-risk HR+ BC in the late adjuvant setting, ctDNA was identified a median of 1 year before all cases of distant metastasis. Future studies will determine if ctDNA-guided intervention in patients with HR+ BC can alter clinical outcomes.
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ADN Tumoral Circulante , Neoplasias de la Mama Triple Negativas , Biomarcadores de Tumor/genética , ADN Tumoral Circulante/genética , Humanos , Mutación , Recurrencia Local de Neoplasia/patología , Neoplasia Residual , Estudios Prospectivos , Receptor ErbB-2RESUMEN
A 91-year-old man with a history of intravesicular BCG therapy for recurrent bladder cancer and bilateral total hip arthroplasty (THA) presented with left hip pain. He was noted to have a fluid collection over the left lateral hip and hip X-ray showed loosening of the prosthetic hip stem indicative of a prosthetic joint infection (PJI). He subsequently underwent removal of the THA and insertion of an antibiotic spacer. He was discharged on intravenous ceftriaxone for presumed culture negative PJI. Intraoperative acid fast bacillus culture later grew Mycobacterium tuberculosis complex, which was then differentiated to M. bovis The M. bovis infection was thought to be a complication of the patient's prior BCG therapy. He was initially started on isoniazid, rifampin, pyrazinamide and ethambutol pending cultures and sensitivities; pyrazinamide was discontinued after M. bovis was isolated on culture and susceptibility data confirmed the expected inherent resistance of M. bovis to pyrazinamide. The patient underwent successful THA revision and remains symptom-free at 1 year.
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Adyuvantes Inmunológicos/efectos adversos , Vacuna BCG/efectos adversos , Prótesis de Cadera , Mycobacterium bovis/aislamiento & purificación , Recurrencia Local de Neoplasia , Infecciones Relacionadas con Prótesis/diagnóstico , Neoplasias de la Vejiga Urinaria , Adyuvantes Inmunológicos/administración & dosificación , Administración Intravesical , Anciano de 80 o más Años , Animales , Antituberculosos/uso terapéutico , Vacuna BCG/administración & dosificación , Bovinos , Terapia Combinada , Diagnóstico Diferencial , Humanos , Masculino , Infecciones Relacionadas con Prótesis/diagnóstico por imagen , Infecciones Relacionadas con Prótesis/terapia , Pirazinamida/uso terapéutico , Tuberculosis Bovina/diagnóstico , Tuberculosis Bovina/diagnóstico por imagen , Tuberculosis Bovina/terapiaRESUMEN
Substantial efforts have been made to understand the interactions between immune checkpoint receptors and their ligands targeted in immunotherapies against cancer. To carefully characterize the complete network of interactions involved and the binding affinities between their extracellular domains, an improved kinetic assay is needed to overcome limitations with surface plasmon resonance (SPR). Here, we present a magneto-nanosensor platform integrated with a microfluidic chip that allows measurement of dissociation constants in the micromolar-range. High-density conjugation of magnetic nanoparticles with prey proteins allows multivalent receptor interactions with sensor-immobilized bait proteins, more closely mimicking natural-receptor clustering on cells. The platform has advantages over traditional SPR in terms of insensitivity of signal responses to pH and salinity, less consumption of proteins and better sensitivities. Using this platform, we characterized the binding affinities of the PD-1-PD-L1/PD-L2 co-inhibitory receptor system, and discovered an unexpected interaction between the two known PD-1 ligands, PD-L1 and PD-L2.