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AIMS: This open label study was conducted to assess the effect of renal impairment (RI) on the pharmacokinetics (PK) of peginterferon lambda-1a (Lambda). METHODS: Subjects (age 18-75 years, BMI 18-35 kg m(-2) ) were enrolled into one of five renal function groups: normal (n = 12), mild RI (n = 8), moderate RI (n = 8), severe RI (n = 7), end-stage renal disease (ESRD, n = 8) based on estimated glomerular filtration rate (eGFR) calculated using the Modification of Diet in Renal Disease (MDRD) equation. Subjects received a single dose of Lambda (180 µg) subcutaneously on day 1 followed by PK serum sample collections through day 29. Safety, tolerability and immunogenicity data were collected through day 43. PK parameters were estimated and summarized by group. Geometric mean ratios (GMR) and 90% confidence intervals (CIs) were calculated between normal and RI groups. RESULTS: With decreasing eGFR, Lambda exposure (Cmax , AUC) increased while apparent clearance (CL/F) and apparent volume of distribution (V/F) decreased. Relative to subjects with normal renal function (geometric mean AUC = 99.5 ng ml(-1) h), Lambda exposure estimates (AUC) were slightly increased in the mild RI group (geometric mean [90% CI]: 1.20 [0.82, 1.77]) and greater in the moderate (1.95 [1.35, 2.83]), severe RI (1.95 [1.30, 2.93]) and ESRD (1.88 [1.30, 2.73]) groups. Lambda was generally well tolerated. CONCLUSIONS: The results demonstrated that RI reduces the clearance of Lambda and suggests that dose modifications may not be required in patients with mild RI but may be required in patients with moderate to severe RI or ESRD.
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Antivirales/farmacocinética , Tasa de Filtración Glomerular/efectos de los fármacos , Interleucinas/farmacocinética , Fallo Renal Crónico/sangre , Polietilenglicoles/farmacocinética , Adolescente , Adulto , Anciano , Antivirales/administración & dosificación , Antivirales/efectos adversos , Antivirales/sangre , Área Bajo la Curva , Humanos , Interleucinas/administración & dosificación , Interleucinas/efectos adversos , Interleucinas/sangre , Fallo Renal Crónico/fisiopatología , Modelos Lineales , Persona de Mediana Edad , Polietilenglicoles/administración & dosificación , Polietilenglicoles/efectos adversos , Índice de Severidad de la Enfermedad , Adulto JovenRESUMEN
Evolving immunogenicity assay performance expectations and a lack of harmonized neutralizing antibody validation testing and reporting tools have resulted in significant time spent by health authorities and sponsors on resolving filing queries. A team of experts within the American Association of Pharmaceutical Scientists' Therapeutic Product Immunogenicity Community across industry and the Food and Drug Administration addressed challenges unique to cell-based and non-cell-based neutralizing antibody assays. Harmonization of validation expectations and data reporting will facilitate filings to health authorities and are described in this manuscript. This team provides validation testing and reporting strategies and tools for the following assessments: (1) format selection; (2) cut point; (3) assay acceptance criteria; (4) control precision; (5) sensitivity including positive control selection and performance tracking; (6) negative control selection; (7) selectivity/specificity including matrix interference, hemolysis, lipemia, bilirubin, concomitant medications, and structurally similar analytes; (8) drug tolerance; (9) target tolerance; (10) sample stability; and (11) assay robustness.
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Anticuerpos Neutralizantes , Preparaciones Farmacéuticas , Tolerancia a MedicamentosRESUMEN
The COVID-19 pandemic has strained the biological matrix supply chain. An upsurge in demand driven by numerous COVID-19 therapeutic and vaccine development programs to combat the pandemic, along with logistical challenges sourcing and transporting matrix, has led to increased lead times for multiple matrices. Biological matrix shortages can potentially cause significant delays in drug development programs across the pharmaceutical and biotechnology industry. Given the current circumstances, discussion is warranted around what will likely be increased use of surrogate matrices in support of pharmacokinetic (PK), immunogenicity, and biomarker assays for regulatory filings. Regulatory authorities permit the use of surrogate matrix in bioanalytical methods in instances where matrix is rare or difficult to obtain, as long as the surrogate is appropriately selected and scientifically justified. Herein, the scientific justification and possible regulatory implications of employing surrogate matrix in PK, immunogenicity, and biomarker assays are discussed. In addition, the unique challenges that cell and gene therapy (C>) and other innovative therapeutic modalities place on matrix supply chains are outlined. Matrix suppliers and contract research organizations (CROs) are actively implementing mitigation strategies to alleviate the current strain on the matrix supply chain and better prepare the industry for any future unexpected strains. To maintain ethical standards, these mitigation strategies include projecting matrix needs with suppliers at least 6 months in advance and writing or updating study protocols to allow for additional matrix draws from study subjects and/or re-purposing of subject matrix from one drug development program to another.
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COVID-19 , Pandemias , HumanosRESUMEN
Evolving immunogenicity assay performance expectations and a lack of harmonized anti-drug antibody validation testing and reporting tools have resulted in significant time spent by health authorities and sponsors on resolving filing queries. Following debate at the American Association of Pharmaceutical Sciences National Biotechnology Conference, a group was formed to address these gaps. Over the last 3 years, 44 members from 29 organizations (including 5 members from Europe and 10 members from FDA) discussed gaps in understanding immunogenicity assay requirements and have developed harmonization tools for use by industry scientists to facilitate filings to health authorities. Herein, this team provides testing and reporting strategies and tools for the following assessments: (1) pre-study validation cut point; (2) in-study cut points, including procedures for applying cut points to mixed populations; (3) system suitability control criteria for in-study plate acceptance; (4) assay sensitivity, including the selection of an appropriate low positive control; (5) specificity, including drug and target tolerance; (6) sample stability that reflects sample storage and handling conditions; (7) assay selectivity to matrix components, including hemolytic, lipemic, and disease state matrices; (8) domain specificity for multi-domain therapeutics; (9) and minimum required dilution and extraction-based sample processing for titer reporting.
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Anticuerpos , Bioensayo , Europa (Continente) , Estados UnidosRESUMEN
Aim: Globally, neurodegeneration accounts for significant morbidity and mortality among the elderly. Millions of people are afflicted with neurodegenerative diseases, with the most notable cases attributed to Alzheimer's, Huntington's, amyotrophic lateral sclerosis and Parkinson's diseases. Sensitive assays that can detect proteopathic anomalies indicative of early neurodegeneration have remained elusive. Therefore, there is an urgent need for sensitive diagnostic and prognostic biomarker assays that can guide the therapeutic regimen in the clinic. Materials & methods: Single molecule array digital immunoassay platform has sensitivity about 1000-fold higher than traditional ligand binding assays. Consequently, we are now beginning to implement ultrasensitive techniques in bioanalysis. Conclusion: In the current study, we evaluated single molecule array technology and report specifications to quantitate neurofilament light chain, a bona-fide biomarker for neurodegeneration. Preliminary neurofilament light screening results from 100 human geriatric cerebrospinal fluid samples displayed huge biological variation and warrants further investigation.
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Inmunoensayo/métodos , Pruebas Inmunológicas/métodos , Proteínas de Neurofilamentos/metabolismo , HumanosRESUMEN
Over the last decade, several regulatory guidelines on bioanalytical method validation (BMV) have been issued by regulatory agencies around the world. This has left the bioanalytical community struggling with regional differences in regulatory expectations when preparing for global pharmaceutical submissions. The International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) has the mission to achieve greater harmonization worldwide to ensure that safe, effective, and high-quality medicines are developed and registered in the most resource-efficient manner. Following calls for harmonization, ICH-selected bioanalytical method validation and sample analysis among its topics for guidance development and earlier this year released a draft guideline (M10) on BMV for public consultation. In response, the American Association of Pharmaceutical Scientists (AAPS) held a 3-day workshop to provide a forum for regulatory, industry, and academic scientists to discuss the guideline and hear various points of view on key aspects. While there was agreement that the draft guideline is generally well written and comprehensive, specific topics generated considerable discussion and, in some cases, revision recommendations for consideration by the expert working group (EWG) responsible for the guideline content. This report provides a summary of the workshop proceedings.
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Desarrollo de Medicamentos/normas , Investigación Farmacéutica/normas , Estudios de Validación como AsuntoRESUMEN
Biological drug products may elicit an antidrug antibody (ADA) response. The current widely used bridging ligand binding assay (LBA) is the gold standard for ADA assessments in drug development, which is a qualitative assay followed by a quasi-quantitative titer analysis but can be prone to interferences from biological matrices, drug targets and circulating drugs. We present our perspectives and findings in exploring a hybrid LBA/LC-MS as an orthogonal bioanalytical tool for clinical immunogenicity assessments. The hybrid LBA/LC-MS is a semiquantitative assay with acceptable specificity, drug tolerance and the capability of multiplexed detection of ADA isotypes. The assay results suggest this technology to be a promising and complementary bioanalytical tool that can provide informative immunogenicity data in drug development.
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Técnicas Inmunológicas/métodos , Espectrometría de Masas , Artefactos , Cromatografía Liquida , Humanos , Límite de Detección , Control Social FormalRESUMEN
In September 2018, the American Association of Pharmaceutical Scientists (AAPS) conducted an Annual Guidance Forum on the considerations related to immunogenicity testing for therapeutic protein products. In addition to a broad representation by the pharmaceutical industry, the event included strong representation by leading scientists from the US Food and Drug Administration (FDA). The agency and industry perspectives and updates to the guidance were presented. Specific topics that were discussed included the strategies of anti-drug antibody (ADA) assay cut-point assessments, the selection of ADA-positive controls (PCs), and the evaluation of PC performance. Assessment strategies and relevance of ADA assay attributes were also discussed, including assay drug tolerance and ADA assay sensitivity. The following is a summary of the discussion.
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Anticuerpos/análisis , Productos Biológicos/inmunología , Guías como Asunto , Proteínas/inmunología , Animales , Descubrimiento de Drogas , Estados Unidos , United States Food and Drug AdministrationRESUMEN
PEGylation is a modification commonly used to increase the half-life of therapeutic proteins. The strategy for immunogenicity testing of these compounds should include methods to detect both anti-protein and anti-PEG antibodies. We previously reported a method for the detection of anti-PEG antibodies using ProterixBio's (formerly BioScale) acoustic membrane microparticle (AMMP) technology. Our initial method development work showed the assay was capable of detecting antibodies in human serum with a sensitivity of 1 µg/mL with good reproducibility (CV < 7%). Since the publication of this initial paper, additional experimentation was performed in an effort to validate the assay for support of clinical sample analysis. This additional data indicate that the method has high variability (CV% > 20) and is unsuitable to support clinical sample analysis.
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Anticuerpos/inmunología , Ensayo de Inmunoadsorción Enzimática/métodos , Polietilenglicoles/metabolismo , Anticuerpos/sangre , Química Farmacéutica/métodos , Humanos , Límite de Detección , Reproducibilidad de los ResultadosRESUMEN
AIM: A ligand-binding assay (LBA) was used to measure exposure of PRM-151, the recombinant form of human pentraxin-2 (PTX-2), a complex pentamer with multiple binding partners. However, the assay showed a lack of dose-dependent exposure in select preclinical species and it could not differentiate the infused PRM-151 from the endogenous PTX-2 in nonhuman primates. MATERIALS & METHODS: Instead of assessing interference from its multiple binding partners, which could be time consuming and laborious, a LC-MS assay avoid of these interference was implemented to measure 'total' drug without the use of immunoaffinity capture reagents. RESULTS & CONCLUSION: The resultant LC-MS data confirmed the original data and the lack of dose-dependent exposure is now understood to be due to the multiple and diverse targets and functions and resultant complex biodistribution rather than an assay artifact.
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Bioensayo , Preparaciones Farmacéuticas/química , Preparaciones Farmacéuticas/metabolismo , Espectrometría de Masas en Tándem , Secuencia de Aminoácidos , Animales , Cromatografía Liquida , Humanos , Ligandos , Farmacocinética , Pruebas de ToxicidadRESUMEN
The 2018 12th Workshop on Recent Issues in Bioanalysis took place in Philadelphia, PA, USA on April 9-13, 2018 with an attendance of over 900 representatives from pharmaceutical/biopharmaceutical companies, biotechnology companies, contract research organizations and regulatory agencies worldwide. WRIB was once again a 5-day full immersion in bioanalysis, biomarkers and immunogenicity. As usual, it was specifically designed to facilitate sharing, reviewing, discussing and agreeing on approaches to address the most current issues of interest including both small- and large-molecule bioanalysis involving LCMS, hybrid LBA/LCMS and LBA/cell-based assays approaches. This 2018 White Paper encompasses recommendations emerging from the extensive discussions held during the workshop and is aimed to provide the bioanalytical community with key information and practical solutions on topics and issues addressed, in an effort to enable advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2018 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 3) covers the recommendations for large molecule bioanalysis, biomarkers and immunogenicity using LBA and cell-based assays. Part 1 (LCMS for small molecules, peptides, oligonucleotides and small molecule biomarkers) and Part 2 (hybrid LBA/LCMS for biotherapeutics and regulatory agencies' inputs) are published in volume 10 of Bioanalysis, issues 22 and 23 (2018), respectively.
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Antígenos/análisis , Bioensayo/normas , Citometría de Flujo/normas , Terapia Genética/normas , Farmacocinética , Antígenos/inmunología , Bioensayo/métodos , Biomarcadores/análisis , Biotecnología , Citometría de Flujo/métodos , Agencias Gubernamentales , Humanos , Valores de ReferenciaRESUMEN
Anti-drug antibodies (ADA) pose a potential risk to patient safety and efficacy and are routinely monitored during clinical trials. Pre-existing drug-reactive antibodies are present in patients without prior drug exposure and are defined by their ability to bind to a component of the drug. These pre-existing drug-reactive antibodies are frequently observed and could represent an adaptive immune response of an individual who has been previously exposed to antigens with structural similarities to the biotherapeutic. Clinical consequences of these antibodies can vary from no impact to adverse effects on patient safety, exposure, and efficacy, and are highly dependent on biotherapeutic modality, disease indications, and patient demographics. This paper describes how the immunogenicity risk assessment of a biotherapeutic integrates the existence of pre-existing drug-reactive antibodies, and provides recommendations for risk-based strategies to evaluate treatment-emergent ADA responses.
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Anticuerpos/inmunología , Productos Biológicos/inmunología , Terapia Biológica , Medición de Riesgo , Humanos , Seguridad del PacienteRESUMEN
The bioanalytical strategy for monoclonal antibody therapeutics, intended for multiple oncology indications, includes multiple integrated measurements of pharmacologically relevant therapeutics from discovery through development. Three ligand binding assays were cohesively developed and validated, as applicable, using the Gyrolab microfluidic system for the measurement of a free monoclonal antibody BMS-986207. Accuracy and precision demonstrate %bias from -6.3 to 4.4%, percent coefficient of variation (%CV) from 2.6 to 9.8%, and total error from 4.2 to 13.4% in the nonclinical assay; %bias from -0.3 to 3.3%, %CV from 3.5 to 18.2%, and total error from 6.1 to 19.7% in the clinical assay; and >97% of the sample meeting incurred sample reanalysis criteria. The clinical assay was validated using singlicate wells after gaining significant data in the early phase studies to support this cost-effective and efficient strategy. Each assay met fit-for-purpose and/or regulated bioanalytical method validation criteria including stability, selectivity, dilutional linearity, carryover, and specificity criteria with no interference from co-administered monoclonal antibody.
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Anticuerpos Monoclonales/análisis , Microfluídica/métodos , Humanos , LigandosRESUMEN
Basic fibroblast growth factor (bFGF), stored bound to heparan sulfate proteoglycans in the extracellular matrix (ECM) of the arterial media, may initiate smooth muscle cell (SMC) proliferation after coronary intervention, thus contributing to restenosis. bFGF mobilization from ECM stores after injury may be induced by platelet degranulation products such as heparanase. Therapies aimed at the inhibition of bFGF release and activation may assist in prevention of restenosis. To test this theory, we first examined the mobilization and activation of bFGF in the arterial media by platelet-derived heparanase. Heparanase, locally delivered to the rat carotid artery, was found to release bFGF and induce substantial SMC proliferation in the absence of actual vascular injury. An antibody that neutralizes heparanase was then developed and evaluated in a rat carotid balloon injury model. Local delivery of anti-heparanase IgG was found to inhibit bFGF release by approximately 60% ( p < 0.001) at 4 d; this correlated with the significant reduction in neointima formation observed at 14 d (intimal area/medial area: control 1.3 +/- 0.3, anti-heparanase 0.35 +/- 0.12, p < 0.0001). Platelet-derived heparanase is therefore likely to be important in initiating events leading to restenosis via bFGF mobilization. Furthermore, heparanase neutralization may assist in the prevention of restenosis following vascular injury.
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Anticuerpos/fisiología , Glucuronidasa/antagonistas & inhibidores , Glucuronidasa/inmunología , Miocitos del Músculo Liso/metabolismo , Animales , Arterias Carótidas/inmunología , Arterias Carótidas/metabolismo , Factor 2 de Crecimiento de Fibroblastos/fisiología , Masculino , Miocitos del Músculo Liso/inmunología , Ratas , Ratas Sprague-DawleyRESUMEN
Pre-existing antibodies to biotherapeutic drugs have been detected in drug-naïve subjects for a variety of biotherapeutic modalities. Pre-existing antibodies are immunoglobulins that are either specific or cross-reacting with a protein or glycan epitopes on a biotherapeutic compound. Although the exact cause for pre-existing antibodies is often unknown, environmental exposures to non-human proteins, glycans, and structurally similar products are frequently proposed as factors. Clinical consequences of the pre-existing antibodies vary from an adverse effect on patient safety to no impact at all and remain highly dependent on the biotherapeutic drug modality and therapeutic indication. As such, pre-existing antibodies are viewed as an immunogenicity risk factor requiring a careful evaluation. Herein, the relationships between biotherapeutic modalities to the nature, prevalence, and clinical consequences of pre-existing antibodies are reviewed. Initial evidence for pre-existing antibody is often identified during anti-drug antibody (ADA) assay development. Other interfering factors known to cause false ADA positive signal, including circulating multimeric drug target, rheumatoid factors, and heterophilic antibodies, are discussed.
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Anticuerpos Monoclonales/sangre , Productos Biológicos/sangre , Terapia Biológica/métodos , Animales , Anticuerpos Monoclonales/inmunología , Autoanticuerpos/sangre , Autoanticuerpos/inmunología , Productos Biológicos/inmunología , HumanosRESUMEN
BACKGROUND: The bioanalytical strategy for antibody-drug conjugates (ADC) includes multiple integrated measurements of pharmacologically relevant ADC. METHODS & RESULTS: Three ligand-binding assays were validated for the measurement of total antibody, active ADC and total ADC. Accuracy and precision demonstrate %bias from -8 to 14%, %CV from 3 to 11% and total error from 3 to 21%, with >98% samples meeting incurred sample reanalysis criteria. Each assay met stability, selectivity, dilutional integrity, carry over and specificity criteria with no interference from associated metabolite/impurity. Given the active ADC assay sensitivity to payload, active ADC was used to assess drug to antibody ratio. DISCUSSION & CONCLUSION: Implementation of a microfluidic automated platform enabled high throughput sample analysis of multiple analytes with minimal sample processing.
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Inmunoensayo , Inmunoconjugados/análisis , Anticuerpos Monoclonales/química , Semivida , Inmunoensayo/normas , Inmunoconjugados/farmacocinética , Lignanos , Preparaciones Farmacéuticas/química , Control de CalidadRESUMEN
BACKGROUND: Antibody-drug conjugates (ADCs) are complex drug constructs with multiple species in the heterogeneous mixture that contribute to their efficacy and toxicity. The bioanalysis of ADCs involves multiple assays and analytical platforms. METHODS: A series of ligand binding and LC-MS/MS (LB-LC-MS/MS) hybrid assays, through different combinations of anti-idiotype (anti-Id), anti-payload, or generic capture reagents, and cathepsin-B or trypsin enzyme digestion, were developed and evaluated for the analysis of conjugated-payload as well as for species traditionally measured by ligand-binding assays, total-antibody and conjugated-antibody. RESULTS & CONCLUSION: Hybrid assays are complementary or viable alternatives to ligand-binding assay for ADC bioanalysis and PK/PD modeling. The fit-for-purpose choice of analytes, assays and platforms and an integrated strategy from Discovery to Development for ADC PK and bioanalysis are recommended.
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Inmunoconjugados/sangre , Preparaciones Farmacéuticas/sangre , Espectrometría de Masas en Tándem/métodos , Animales , Cromatografía Liquida/métodos , Haplorrinos , Humanos , Inmunoensayo/métodos , Inmunoconjugados/análisis , Límite de Detección , Preparaciones Farmacéuticas/análisis , RatasRESUMEN
BACKGROUND AND PURPOSE: Peginterferon Lambda was being developed as an alternative to alfa interferon for the treatment of chronic hepatitis C virus (HCV) infection. We compared peginterferon Lambda-1a plus ribavirin (Lambda/RBV) and Lambda/RBV plus daclatasvir (DCV; pangenotypic NS5A inhibitor) with peginterferon alfa-2a plus RBV (alfa/RBV) in treatment-naive patients with HCV genotype 2 or 3 infection. METHODS: In this multicenter, double-blind, phase 3 randomized controlled trial, patients were assigned 2:2:1 to receive 24 weeks of Lambda/RBV, 12 weeks of Lambda/RBV + DCV, or 24 weeks of alfa/RBV. The primary outcome measure was sustained virologic response at post-treatment Week 12 (SVR12). RESULTS: Overall, 874 patients were treated: Lambda/RBV, n = 353; Lambda/RBV + DCV, n = 349; alfa/RBV, n = 172. Patients were 65 % white and 33 % Asian, 57 % male, with a mean age of 47 years; 52 % were infected with genotype 2 (6 % cirrhotic) and 48 % with genotype 3 (9 % cirrhotic). In the Lambda/RBV + DCV group, 83 % (95 % confidence interval [CI] 78.5, 86.5) achieved SVR12 (90 % genotype 2, 75 % genotype 3) whereas SVR12 was achieved by 68 % (95 % CI 63.1, 72.9) with Lambda/RBV (72 % genotype 2, 64 % genotype 3) and 73 % (95 % CI 66.6, 79.9) with peginterferon alfa/RBV (74 % genotype 2, 73 % genotype 3). Lambda/RBV + DCV was associated with lower incidences of flu-like symptoms, hematological abnormalities, and discontinuations due to adverse events compared with alfa/RBV. CONCLUSION: The 12-week regimen of Lambda/RBV + DCV was superior to peginterferon alfa/RBV in the combined population of treatment-naive patients with genotype 2 or 3 infection, with an improved tolerability and safety profile compared with alfa/RBV.
RESUMEN
BACKGROUND: Extensive use of polyethylene glycol (PEG) in consumer products necessitates the assessment of anti-PEG antibodies (APAb). METHODS: In clinical trials comparing PEG-IFN-λ to PEG-IFN-α, conventional bridge and direct assays were assessed. RESULTS & CONCLUSION: The bridge assay detected IgM and IgG APAb reactive with common PEG sizes and derivatives at sufficient sensitivity, 15-500 ng/ml. Of subjects evaluated, 6% of PEG-IFN-λ and 9% of PEG-IFN-α subjects had persistent APAb while 60% of PEG-IFN-λ and 33% of PEG-IFN-α subjects had persistent anti-interferon antibodies (AIAb). Pre-existing APAb and AIAb prevalence was comparable (approximately 10% of subjects). APAb were earlier onset, less frequent, less persistent and lower titer than AIAb. No associated hypersensitivity events were reported.
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Inmunoensayo/métodos , Inmunoglobulina M/análisis , Inmunoglobulinas/análisis , Interferón-alfa/química , Interferón-alfa/inmunología , Polietilenglicoles/química , Reacciones Cruzadas , Hepatitis C/sangre , Humanos , Inmunoglobulina M/sangre , Inmunoglobulina M/inmunología , Inmunoglobulinas/sangre , Inmunoglobulinas/inmunología , Conformación Molecular , Reproducibilidad de los ResultadosRESUMEN
Antibody drug conjugates (ADCs) are complex molecules composed of two pharmacologically distinct components, the cytotoxic payload and the antibody. The measurement of the payload molecules that are attached to the antibody in vivo is important for the evaluation of the safety and efficacy of ADCs, and can also provide distinct information compared to the antibody-related analytes. However, analyzing the antibody-conjugated payload is challenging and in some cases may not be feasible. The in vivo change in drug antibody ratio (DAR), due to deconjugation, biotransformation or other clearance phenomena, generates unique and additional challenges for ADC analysis in biological samples. Here, we report a novel hybrid approach with immuno-capture of the ADC, payload cleavage by specific enzyme, and LC-MS/MS of the cleaved payload to quantitatively measure the concentration of payload molecules still attached to the antibody via linker in plasma. The ADC reference material used for the calibration curve is not likely to be identical to the ADC measured in study samples due to the change in DAR distribution over the PK time course. The assay clearly demonstrated that there was no bias in the measurement of antibody-conjugated payload for ADC with varying DAR, which thus allowed accurate quantification even when the DAR distribution dynamically changes in vivo. This hybrid assay was fully validated based on a combination of requirements for both chromatographic and ligand binding methods, and was successfully applied to support a GLP safety study in monkeys.