Pooled Human Serum Research Articles

Proteomic Analysis of Human Serum Proteins Adsorbed onto Collagen Barrier Membranes.

Collagen barrier membranes are frequently used in guided tissue and bone regeneration. The aim of this study was to analyze the signature of human serum proteins adsorbed onto collagen membranes using a novel protein extraction method combined with mass spectrometry. Native porcine-derived collagen membranes (Geistlich Bio-Gide®, Wolhusen, Switzerland) were exposed to pooled human serum in vitro and, after thorough washing, subjected to protein extraction either in conjunction with protein enrichment or via a conventional surfactant-based method. The extracted proteins were analyzed via liquid chromatography with tandem mass spectrometry. Bioinformatic analysis of global profiling, gene ontology, and functional enrichment of the identified proteins was performed. Overall, a total of 326 adsorbed serum proteins were identified. The enrichment and conventional methods yielded similar numbers of total (315 vs. 309), exclusive (17 vs. 11), and major bone-related proteins (18 vs. 14). Most of the adsorbed proteins (n = 298) were common to both extraction groups and included several growth factors, extracellular matrix (ECM) proteins, cell adhesion molecules, and angiogenesis mediators involved in bone regeneration. Functional analyses revealed significant enrichment of ECM, exosomes, immune response, and cell growth components. Key proteins [transforming growth factor-beta 1 (TGFβ1), insulin-like growth factor binding proteins (IGFBP-5, -6, -7)] were exclusively detected with the enrichment-based method. In summary, native collagen membranes exhibited a high protein adsorption capacity in vitro. While both extraction methods were effective, the enrichment-based method showed distinct advantages in detecting specific bone-related proteins. Therefore, the use of multiple extraction methods is advisable in studies investigating protein adsorption on biomaterials.

B-347 Analytical Performance Evaluation of the High Sensitivity PSA Assay and the Free PSAII Assay on the Atellica IM Analyzer

Abstract Background Measurement of serum prostate specific antigen (PSA) levels may be used in prostate cancer (PC) screening, but elevated PSA levels also are observed in patients with other etiologies such as benign prostatic hypertrophy. Studies suggest that measuring PSA with or before digital rectal examination (DRE) provides a better method of detecting PC than DRE alone. The free prostate specific antigen (fPSA) assay is an aid for distinguishing PC from benign prostate conditions in men 50 years or older with PSA values 4.0-10.0 ng/mL (µg/L) and DRE findings nonsuspicious for PC. The goal of this study was to evaluate the analytical performance of the high sensitivity PSA (hsPSA)* and free PSA (fPSAII)* assays on the Atellica® IM Analyzer. Methods Detection capability studies were performed per CLSI EP17-A2. Precision testing was performed per CLSI EP05-A3 with native human serum and QC samples, 3 reagent lots, 1 analyzer, 2 runs/day, 2 replicates/run for 20 days. For Atellica® hsPSA and fPSAII assays a multi-site reproducibility study was conducted per CLSI EP-05 A3 using native and contrived serum samples, 3 reagent lots, and 3 different sites and analyzers; samples were assayed in triplicate for five days, two runs/day ∼2 hours apart. Linearity testing was performed per CLSI EP06-A on a dilution series made from a high PSA sample (native human male serum pool) and a low sample (native human female serum), 4 replicates, 3 reagent lots, and 1 analyzer. Specimen equivalency was determined by Weighted Deming regression model per CLSI EP09c-ed3. Results Results are presented in the table. Conclusions The Atellica IM hsPSA assay and fPSAII assays detection capability, precision, linearity, and specimen equivalency were acceptable. *CAUTION: Investigational Device. Not available for sale. Future availability cannot be guaranteed. The results are preliminary and were achieved in unique setting with no expected timeline for completion.

B-051 Clinical Validation of Vectra® DA: A Multi-Biomarker Based Test for the Objective Measurement of Disease Activity in Patients with Rheumatoid Arthritis

Abstract Background The Vectra® DA test measures serum levels of 12 protein biomarkers associated with rheumatoid arthritis (RA) and uses these levels in an algorithmic calculation to generate a numeric score that represents RA disease activity where established categories are low for scores 1 to 29, moderate for 30 to 44, and high for 45 to 100. LabCorp Specialty Lab in Calabasas, CA completed the quantitative analytical validations of 12 Vectra biomarkers (SAA, CRP, VCAM-1, IL-6, TNF-RI, EGF, VEGF-A, Leptin, Resistin, MMP-1, MMP-3, and YKL-40) and the clinical verification of the Vectra score algorithm. Methods The Vectra test consists of the quantitative measurements of EGF, Leptin, MMP-1, TNF-R1, VEGF, MMP-3, Resistin, VCAM, YKL-40, CRP, SAA and IL-6 using multiplex immunoassay platforms. The data acquired from each biomarker assay is processed through an algorithm where a composite Vectra score adjusted based on age, gender, and adiposity of the patient is computed. Analytical parameters validated for each biomarkers include sensitivity, precision, accuracy, specificity and stability. Precision was validated using pooled human serum controls at low, moderate, and high Vectra score levels. Method comparison was performed using 584 clinically defined serum samples. Quantitatively measured analyte values and computed Vectra scores by the Labcorp Vectra assay were compared with Vectra data produced by Myriad laboratory. Results Intra- and inter-assay sample precision of the final Vectra score was <13% and <18%, respectively. Sample stability using freshly collected serum subject to ambient and refrigerated temperature up to 14 days and frozen up to 364 days and up to 6 freeze-thaw cycles were acceptable. Of 584 clinical Vectra data compared, Labcorp vs Myriad, 96% of data were comparable within the acceptable criteria. Correlation of Vectra score from Labcorp and Myriad was excellent. A linear least square model resulted in a correlation coefficient (R) of 0.981 and a Deming slope of 1.009. Qualitative method comparison of Vectra scores resulted in excellent agreement of risk of radiographic progression and rheumatoid arthritis disease activity. A 91% agreement of risk category match between Labcorp and Myriad and 100% agreement of Vectra scores within 1 risk category was achieved. Conclusions We validated the Vectra® DA multiplex assay for measuring serum levels of 12 protein biomarkers associated with RA. Vectra combines biomarker levels into a personalized disease score that represents a patient’s RA inflammation and predict their risk of radiographic progression. High Vectra® DA scores (> 44) have been associated with a 20% 1-year risk of radiographic progression while low scores (< 30) carry only a 1% risk. Thus, the Vectra score provides an objective measurement of RA disease activity that can be used in combination with existing assessment tools to aid physicians to manage patients with RA.

Dual electrochemical detection of leucovorin and its metabolite 5-methyltetrahydrofolic acid

Current healthcare trends focus on personalised precision medicine, which customises treatment based on individual responses to both diseases and therapeutic interventions. This marks a departure from a “one size fits all” approach towards a more sophisticated strategy. However, notwithstanding progress in the theoretical knowledge for personalised precision approaches, resource constraints impede their implementation. Monitoring drug therapies is vital for the advancement of precision medicine, alongside drug development and targeted treatment strategies. This study presents the potential of electrochemical approaches including square wave voltammetry (SWV) as a proof-of-concept for the simultaneous monitoring of circulating concentrations of 5-methyltetrahydrofolate (5-MTHF) and leucovorin calcium (LV) within biological matrices. An easy-to-use and portable sensor has been developed for the detection of 5-MTHF and LV at therapeutically relevant concentrations without prior sample preparation. The sensor was successfully tested in artificial urine and human pooled serum, demonstrating its efficacy in diverse biological matrices. This approach successfully illustrated the dual detection of LV and 5-MTHF over the linear range 0 to 10 µM which is within the therapeutically relevant range for both within urine. The developed sensor exemplifies the potential of electrochemical sensors as point-of-care devices. Its rapid time to result and elimination of time-consuming sample preparation improve usability for clinicians, broadening the application of electrochemical sensors in clinical settings. This dual monitoring approach offers significant contributions to the evolution of precision medicine by providing real-time, accurate drug monitoring capabilities.

Nanoparticle-Supported, Rapid, and Electronic Detection of SARS-CoV-2 Antibodies and Antigens at Attomolar Level.

A gold nanoparticle (AuNP)-supported rapid, electronic detection (NasRED) platform is demonstrated with high specificity to differentiate SARS-CoV-2 from human coronaviruses while achieving high sensitivity. Uniquely, active fluidic force is exerted on AuNPs in a microcentrifuge tube, through engineered centrifugation and vortex agitation, to accelerate signal transduction from biochemical protein binding to physical AuNP aggregation and precipitation and finally to electronic signals in a customized, stabilized circuitry. The limits of detection are found <80 aM (12 fg/mL) and ∼700 aM (105 fg/mL) to detect antibodies in human pooled serum and 20% diluted whole blood, and <900 aM (45 fg/mL) and 4.1 fM (200 fg/mL) to detect nucleocapsid proteins in human saliva and nasal fluid, respectively. With a small test volume (6 µL), a rapid turnaround time (as fast as <15 min), low reagent cost (estimated ∼$2), and a small system footprint, this novel digital platform can be utilized for accurate diagnosis and screening of a wide range of infectious and chronic diseases.

A Critical Role of Culture Medium Selection in Maximizing the Purity and Expansion of Natural Killer Cells.

Natural killer (NK) cells hold promise in cancer treatment due to their ability to spontaneously lyse cancer cells. For clinical use, high quantities of pure, functional NK cells are necessary. Combining adherence-based isolation with specialized media showed the unreliability of the isolation method, but demonstrated the superiority of the NK MACS® medium, particularly in suboptimal conditions. Neither human pooled serum, fetal calf serum (FCS), human platelet lysate, nor chemically defined serum replacement could substitute human AB serum. Interleukin (IL-)2, IL-15, IL-21, and combined CD2/NKp46 stimulation were assessed. IL-21 and CD2/NKp46 stimulation increased cytotoxicity, but reduced NK cell proliferation. IL-15 stimulation alone achieved the highest proliferation, but the more affordable IL-2 performed similarly. The RosetteSep™ human NK cell enrichment kit was effective for isolation, but the presence of peripheral blood mononuclear cells (PBMCs) in the culture enhanced NK cell proliferation, despite similar expression levels of CD16, NKp46, NKG2D, and ICAM-1. In line with this, purified NK cells cultured in NK MACS® medium with human AB serum and IL-2 demonstrated high cytotoxicity against primary glioblastoma stem cells.

Development of a visual Adhesion/Invasion Inhibition Assay to assess the functionality of Shigella-specific antibodies.

Shigella is the etiologic agent of a bacillary dysentery known as shigellosis, which causes millions of infections and thousands of deaths worldwide each year due to Shigella's unique lifestyle within intestinal epithelial cells. Cell adhesion/invasion assays have been extensively used not only to identify targets mediating host-pathogen interaction, but also to evaluate the ability of Shigella-specific antibodies to reduce virulence. However, these assays are time-consuming and labor-intensive and fail to assess differences at the single-cell level. Here, we developed a simple, fast and high-content method named visual Adhesion/Invasion Inhibition Assay (vAIA) to measure the ability of anti-Shigellaantibodies to inhibit bacterial adhesion to and invasion of epithelial cells by using the confocal microscope Opera Phenix. We showed that vAIA performed well with a pooled human serum from subjects challenged with S. sonnei and that a specific anti-IpaD monoclonal antibody effectively reduced bacterial virulence in a dose-dependent manner. vAIA can therefore inform on the functionality of polyclonal and monoclonal responses thereby supporting the discovery of pathogenicity mechanisms and the development of candidate vaccines and immunotherapies. Lastly, this assay is very versatile and may be easily applied to other Shigella species or serotypes and to different pathogens.

A flow cytometry-based assay to determine the ability of anti-Streptococcus pyogenes antibodies to mediate monocytic phagocytosis in human sera

Streptococcus pyogenes, commonly referred to as Group A Streptococcus (Strep A), causes a spectrum of diseases, with the potential to progress into life-threatening illnesses and autoimmune complications. The escalating threat of antimicrobial resistance, stemming from the prevalent reliance on antibiotic therapies to manage Strep A infections, underscores the critical need for the development of disease control strategies centred around vaccination. Phagocytes play a critical role in controlling Strep A infections, and phagocytosis-replicating assays are essential for vaccine development. Traditionally, such assays have employed whole-blood killing or opsonophagocytic methods using HL-60 cells as neutrophil surrogates. However, assays mimicking Fcγ receptors- phagocytosis in clinical contexts are lacking. Therefore, here we introduce a flow cytometry-based method employing undifferentiated THP-1 cells as monocytic/macrophage model to swiftly evaluate the ability of human sera to induce phagocytosis of Strep A. We extensively characterize the assay's precision, linearity, and quantification limit, ensuring robustness. By testing human pooled serum, the assay proved to be suitable for the comparison of human sera's phagocytic capability against Strep A. This method offers a valuable complementary assay for clinical studies, addressing the gap in assessing FcγR-mediated phagocytosis. By facilitating efficient evaluation of Strep A -phagocyte interactions, it may contribute to elucidating the mechanisms required for the prevention of infections and inform the development of future vaccines and therapeutic advancements against Strep A infections.

Suspect Screening Analysis of Pooled Human Serum Samples Using GC × GC/TOF-MS.

Humans interact with thousands of chemicals. This study aims to identify substances of emerging concern and in need of human health risk evaluations. Sixteen pooled human serum samples were constructed from 25 individual samples each from the National Institute of Environmental Health Sciences' Clinical Research Unit. Samples were analyzed using gas chromatography (GC) × GC/time-of-flight (TOF)-mass spectrometry (MS) in a suspect screening analysis, with follow-up confirmation analysis of 19 substances. A standard reference material blood sample was also analyzed through the confirmation process for comparison. The pools were stratified by sex (female and male) and by age (≤45 and >45). Publicly available information on potential exposure sources was aggregated to annotate presence in serum as either endogenous, food/nutrient, drug, commerce, or contaminant. Of the 544 unique substances tentatively identified by spectral matching, 472 were identified in females, while only 271 were identified in males. Surprisingly, 273 of the identified substances were found only in females. It is known that behavior and near-field environments can drive exposures, and this work demonstrates the existence of exposure sources uniquely relevant to females.

PH Quantification in Human Dermal Interstitial Fluid Using Ultra-Thin SOI Silicon Nanowire ISFETs and a High-Sensitivity Constant-Current Approach.

In this paper, we propose a novel approach to utilize silicon nanowires as high-sensitivity pH sensors. Our approach works based on fixing the current bias of silicon nanowires Ion Sensitive Field Effect Transistors (ISFETs) and monitor the resulting drain voltage as the sensing signal. By fine tuning the injected current levels, we can optimize the sensing conditions according to different sensor requirements. This method proves to be highly suitable for real-time and continuous measurements of biomarkers in human biofluids. To validate our approach, we conducted experiments, with real human sera samples to simulate the composition of human interstitial fluid (ISF), using both the conventional top-gate approach and the optimized constant current method. We successfully demonstrated pH sensing within the physiopathological range of 6.5 to 8, achieving an exceptional level of accuracy in this complex matrix. Specifically, we obtained a maximum error as low as 0.92% (equivalent to 0.07 pH unit) using the constant-current method at the optimal current levels (1.71% for top-gate). Moreover, by utilizing different pools of human sera with varying total protein content, we demonstrated that the protein content among patients does not impact the sensors' performance in pH sensing. Furthermore, we tested real-human ISF samples collected from volunteers. The obtained accuracy in this scenario was also outstanding, with an error as low as 0.015 pH unit using the constant-current method and 0.178 pH unit in traditional top-gate configuration.

Development and optimization of an in-house heterologous ELISA for detection of prednisolone drug in enzyme conjugates using spacers.

The introduction of spacers in coating steroid protein complexes and/or enzyme conjugates or immunogens is known to exert an influence on the sensitivity of steroid enzyme immunoassays. We investigated the impact of different homobifunctional spacers, ranging in atomic length from 3 to 10, on the sensitivity and specificity of prednisolone (PSL) enzyme immunoassays. In this study, four homo-bifunctional spacers, namely, carbohydrazide (CH), adipic acid dihydrazide (ADH), ethylene diamine (EDA), and urea (U), were incorporated between PSL and horseradish peroxidase (HRP) for preparing the enzyme conjugate with an aim to improve the sensitivity of the assay without compromising assay specificity. The assays were developed using these enzymes conjugated with antibodies raised against the PSL-21-HS-BSA immunogen. The sensitivity of the PSL assays after insertion of a bridge in the enzyme conjugate was 1.22 ng/mL, 0.59 ng/mL, 0.48 ng/mL, and 0.018 ng/mL with ADH, CH, EDA, and urea as a spacer, respectively. Among the four combinations, the PSL-21-HS-BSA-antibody with PSL-21-HS-U-HRP-enzyme conjugate gave better sensitivity and less cross-reaction. The percent recovery of PSL from the exogenously spiked human serum pools was in the range of 88.32%-102.50%. The intra and inter-assay CV% was< 8.46%. The PSL concentration was estimated in the serum samples of patients on PSL treatment. The serum PSL values obtained by this method correlated well with the commercially available kit (r2 = 0.98). The present study suggests that the nature of the spacer is related to assay sensitivity and not the spacer length.

Novel recombinant proteins and peptides from Clonorchis sinensis and Opisthorchis viverrini for liver fluke exposure ELISA

Human serum samples from individuals living in Vietnam and Taiwan suspected of past Clonorchis sinensis or Opisthorchis viverrini infection were screened using several novel peptides and recombinant liver fluke proteins to determine if any consistent patterns could be discerned and used as the basis for future liver fluke ELISA development. Absorbance values at 405 nm were compared to those of pooled unexposed normal human serum and analyzed for statistical significance. The data exhibited some interesting patterns consistent with egg antigen sequestration in the gut possibly leading to lower serum antibody levels and potential regional exposure differences between Vietnamese and Taiwanese subjects. In particular, antibodies against Cathepsin B and B2 peptides, as well as a partial Cahedrin Domain peptide may be elevated in some Taiwanese serum samples while antibodies against recombinant Clonorchis egg protein and Hepatocellular Carcinoma Peptide Antigen 59 may be elevated in some samples from both Taiwan and Vietnam. The data appear to suggest that some of the novel recombinant protein and peptide antigens selected and tested herein warrant further study with larger sample sizes as possible targets for detecting anti-liver fluke antibodies by ELISA from humans suspected of liver fluke infections.

Deep Characterization of Serum Metabolome Based on the Segment-Optimized Spectral-Stitching Direct-Infusion Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Approach.

Direct-infusion Fourier transform ion cyclotron resonance mass spectrometry (DI-FTICR MS) shows great promise for metabolomic analysis due to ultrahigh mass accuracy and resolution. However, most of the DI-FTICR MS approaches focused on high-throughput metabolomics analysis at the expense of sensitivity and resolution and the potential for metabolome characterization has not been fully explored. Here, we proposed a novel deep characterization approach of serum metabolome using a segment-optimized spectral-stitching DI-FTICR MS method integrated with high-confidence and database-independent formula assignments. With varied acquisition parameters for each segment, a highly efficient acquisition was achieved for the whole mass range with sub-ppm mass accuracy. In a pooled human serum sample, thousands of features were assigned with unambiguous formulas and possible candidates based on highly accurate mass measurements. Furthermore, a reaction network was used to select confidently unique formulas from possible candidates, which was constructed by unambiguous formulas and possible candidates connected by the formula differences resulting from biochemical and MS transformation. Compared with full-range and conventional segment acquisition, 8- and 1.2-fold increases in observed features were achieved, respectively. Assignment accuracy was 93-94% for both a standard mixture containing 190 metabolites and a spiked serum sample with the root mean square mass error of 0.15-0.16 ppm. In total, 3534 unequivocal neutral molecular formulas were assigned in the pooled serum sample, 35% of which are contained in the HMDB. This method offers great enhancement in the deep characterization of serum metabolome by DI-FTICR MS.

Commutability evaluation of candidate reference materials and ERM-DA470k/IFCC for immunoglobulin M using two international approaches.

This study aimed to assess the commutability of frozen pooled human serum (PHS), high concentration of Immunoglobulin M (IgM) pure diluted materials (HPDM), commercialized pure materials (CPM), and dilutions of ERM-DA470k/IFCC in IgM detection using the CLSI and IFCC approaches, to support standardization or harmonization of IgM measurement. Twenty-four serum samples, relevant reference materials (PHS, HPDM, CPM), and different ERM-DA470k/IFCC dilutions were analyzed in triplicate using six routine methods. The commutability of the relevant reference materials was carried out following CLSI EP30-A and IFCC bias analysis. According to the CLSI approach, low, medium, and high concentrations of PHS, HPDM, and CPM were commutable on 10, 13, 15, 13, and 8 of 15 assay combinations, respectively. Using the IFCC approach, low, medium, and high concentrations of PHS, HPDM, and CPM were commutable on 10, 11, 9, 15, and 10 of 15 assay combinations, respectively. The ERM-DA470k/IFCC dilutions with D-PBS and RPMI-1640 Medium were commutable on 13 of 15 assay combinations according to CLSI and were commutable on all 15 assay combinations using IFCC approach. High concentration of PHS were commutable on all six detection systems using the CLSI approach. Low and medium concentration of PHS showed unsatisfied commutability. HPDM, not CPM have good commutability, has the potential to become reference materials. ERM-DA470k/IFCC diluted with different medium showed different commutability.

Solid-phase immunoextraction followed by liquid chromatography-tandem mass spectrometry for the selective determination of thyroxine in human serum

In this work, an analytical method based on solid-phase extraction (SPE) followed by liquid chromatography-tandem mass spectrometry analysis (LC-MS/MS) has been developed for the selective determination of thyroxine (T4) in human serum. For this purpose, two immunosorbents (ISs) specific to T4 were synthesized by grafting two different T4-specific monoclonal antibodies on a cyanogen bromide (CNBr)-activated-Sepharose® 4B solid support. The grafting yields obtained from the immobilization of each antibody on the CNBr-activated-Sepharose® 4B were over 90%, demonstrating that most of the antibodies were covalently bound to the solid support. The SPE procedure was optimized by studying the retention capability and selectivity of the two ISs in pure media fortified with T4. Under the optimized conditions, high elution efficiencies were achieved in the elution fraction for both specific ISs (i.e., 85%), whereas low ones were obtained in the control ISs (ca. 2%), showing the selectivity of the specific ISs. The ISs were also characterized by studying extraction and synthesis repeatability (RSD <8%), and capacity (104 ng of T4 per 35 mg of ISs, i.e., 3 μg g−1). Finally, the methodology was applied to a pooled human serum sample in order to study its analytical utility and accuracy. Relative recovery (RR) values between 81 and 107% were obtained, showing no matrix effects during the global methodology. Furthermore, the need to perform the immunoextraction was evidenced by comparing the LC-MS scan chromatograms and RR values with and without applying the immunoextraction procedure on a serum sample submitted to protein precipitation. This works exploits, for the first time, the use of an IS on the selective determination of T4 in human serum samples.

Evaluation of THEO-260 as a novel oncolytic virus therapy for treating stromal rich tumours.

e14573 Background: Stromal rich tumours pose a significant challenge to the effectiveness of systemic anticancer therapies, including immunotherapies and oncolytic viruses. This is due to the abundance of cancer associated fibroblasts (CAFs) that suppress immune cells and limit drug penetration. THEO-260 is a potent, mechanistically novel oncolytic virus therapy intrinsically capable of lysing both cancer cells and CAFs, and is currently in development for late stage relapsed refractory ovarian cancer. Methods: The efficacy and safety of THEO-260 was assessed in multicellular spheroids, in patient-derived ex vivo fresh ovarian samples and in mouse models of human stromal tumours. Results: Unpassaged ascites and tumour samples collected from cytoreductive surgeries for advanced ovarian cancer (n=24 independent patients) were treated with a clinically-relevant dose of THEO-260. THEO-260 effectively killed the cancer cell (EpCAM+ EGFR+PDL1+ CA125+) and CAF (FAP+) populations, being efficacious in treatment-naive and platinum-resistant patient samples. Importantly, the T cell population in these patients, in addition to primary normal fibroblasts (including intestinal, pulmonary, dermal, cardiac, uterine fibroblasts) from healthy donors, were not damaged. Ex vivo studies show THEO-260 stimulates effector T cell responses upon tumour lysis as indicated by IFNγ release. Demonstrating suitability as an IV delivered agent, THEO-260 was active in pooled human serum and whole human blood (n = 10 donors). THEO-260 excels in low nutrient, low proliferative environments, typical of human solid tumours and has been developed with a view to persist in the tumour microenvironment without the need for repeated cycles of delivery. THEO-260 is well tolerated in vivo following a clinically relevant intravenous dosing regimen. In PARP inhibitor and platinum resistant ovarian cancer murine models containing human CAFs and cancer cells, THEO-260 shows antitumor efficacy, with a complete reduction in tumour volume in subcutaneous and intraperitoneal systems, and superiority to SOC. Virus activity is not restricted to ovarian cancer, with cell line data demonstrating killing in additional solid tumour types, including pancreatic, colorectal, lung, and breast cancer. THEO-260 exhibits genetic and temperature based stability, and GMP manufacturing to high yields is underway. Conclusions: Taken together, we present a preclinical data package for THEO-260 supporting progression to Phase I clinical trials.

Sedimentation velocity FDS studies of antibodies in pooled human serum.

The biotech industry has great interest in investigating therapeutic proteins in high concentration environments like human serum. The fluorescence detection system (Aviv-FDS) allows the performance of analytical ultracentrifuge (AUC) sedimentation velocity (SV) experiments in tracer or BOLTS protocols. Here, we compare six pooled human serum samples by AUC SV techniques and demonstrate the potential of this technology for characterizing therapeutic antibodies in serum. Control FDS SV experiments on serum alone reveal a bilirubin-HSA complex whose sedimentation is slowed by solution nonideality and exhibits a Johnston-Ogston (JO) effect due to the presence of high concentrations of IgG. Absorbance SV experiments on diluted serum samples verify the HSA-IgG composition as well as a significant IgM pentamer boundary at 19s. Alexa-488 labeled Simponi (Golimumab) is used as a tracer to investigate the behavior of a therapeutic monoclonal antibody (mAb) in serum, and the sedimentation behavior of total IgG in serum. Serum dilution experiments allow extrapolation to zero concentration to extract so, while global direct boundary fitting with SEDANAL verifies the utility of a matrix of self- and cross-term phenomenological nonideality coefficients (ks and BM1) and the source of the JO effect. The best fits include weak reversible association (~ 4 × 103M-1) between Simponi and total human IgG. Secondary mAbs to human IgG and IgM verify the formation of a 10.2s 1:1 complex with human IgG and a 19s complex with human IgM pentamers. These results demonstrate that FDS AUC allows a range of approaches for investigating therapeutic antibodies in human serum.

Exploration of suitable external quality assessment materials for serum C-peptide measurement.

To find suitable external quality assessment (EQA) materials for serum C-peptide, we evaluated the commutability of five types of processed materials. Seventy-four individual serum samples and 12 processed samples including three EQA samples currently in use, frozen human serum pools (FHSP), and three other kinds of processed samples were prepared by dissolving WHO International Standard Reagent for C-peptide (WHO ISR 13/146) in three different matrixes: 0.05 % bovine serum albumin, fetal bovine serum and human serum pools. Samples were analyzed using the isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) method and six widely used immunoassays. The commutabilities of processed materials were assessed according to the difference in bias approach recommended by the IFCC. And the short- and long-term stability of FHSP samples at different temperatures were also evaluated. Out of the five kinds of processed materials, FHSP samples were commutable on most assays. In contrast, the EQA materials currently in use were only commutable on a few immunoassays. Additionally, processed materials derived from WHO ISR 13/146 were found to be un-commutable on over half of immunoassays. The FHSP samples could be stably stored at 4 and-20 °C for at least 16days, and at-80 °C for at least 1 year, but at room temperature only for 12 h. With clarified commutability and stability information, the human serum pool samples along with the developed ID-LC-MS/MS method could be used in the EQA program to promote the comparability among laboratories for C-peptide measurement in China.

Development of an in vitro pharmacokinetic/pharmacodynamic model in the presence of serum for studying micafungin activity against Candida albicans: a need for revision of CLSI susceptibility breakpoints.

The CLSI breakpoint for micafungin and Candida albicans is 0.25 mg/L, higher than the CLSI epidemiological cut-off value (0.03 mg/L) whereas the EUCAST values are identical (0.016 mg/L). We developed a novel in vitro dialysis-diffusion pharmacokinetic/pharmacodynamic (PK/PD) model, confirmed correlation to in vivo outcome and studied micafungin pharmacodynamics against Canida albicans. Four C. albicans isolates, including a weak (F641L) and a strong (R647G) fks1 mutants, were studied using a 104 cfu/mL inoculum and RPMI medium with and without 10% pooled human serum. The exposure-effect relationship fAUC0-24/MIC was described for CLSI and EUCAST methodology. Monte Carlo simulation analysis included standard (100 mg i.v.) and higher (150-300 mg) doses q24h to determine the corresponding probability of target attainment (PTA). The in vitro PK/PD targets for stasis/1-log kill were 36/57 fAUC0-24/MIC in absence and 2.8/9.2 fAUC0-24/MIC in the presence of serum, and similar for wild-type and fks mutant isolates. The PTAs for both PK/PD targets were high (>95%) for EUCAST susceptible isolates but not for CLSI susceptible non-wild-type isolates (CLSI MICs 0.06-0.25 mg/L). 300 mg q24h was needed to attain PK/PD targets for non-wild-type isolates with CLSI MICs 0.06-0.125 mg/L and EUCAST MICs 0.03-0.06 mg/L. The in vitro 1-log kill effect corresponded to stasis in animal model and mycological response in patients with invasive candidiasis, thereby validating the model for studying pharmacodynamics of echinocandins in vitro. EUCAST breakpoints were well supported by our findings but our data questions whether the current CLSI breakpoint, which is higher than the epidemiological cut-off values, is appropriate.

Assessment of WHO 07/202 reference material and human serum pools for commutability and for the potential to reduce variability among soluble transferrin receptor assays.

The clinical use of soluble transferrin receptor (sTfR) as an iron status indicator is hindered by a lack of assay standardization and common reference ranges and decision thresholds. In 2009, the WHO and National Institute for Biological Standards and Controls (NIBSC) released a sTfR reference material (RM), 07/202, for assay standardization; however, a comprehensive, formal commutability study was not conducted. This study evaluated the commutability of WHO 07/202 sTfR RM and human serum pools and the impacts of their use as common calibrators. Commutability was assessed for six different measurement procedures (MPs). Serum pools were prepared according to updated CLSI C37-A procedures (C37) or non-C37 procedures. The study design and analyses were based on Parts 2 and 3 of the 2018 IFCC Commutability in Metrological Traceability Working Group's Recommendations for Commutability Assessment. WHO 07/202 and serum pools were used for instrument/assay and mathematical recalibration, respectively, to determine if their use decreases inter-assay measurement variability for clinical samples. The WHO 07/202 RM dilutions were commutable for all 6MPs assessed and, when used for instrument calibration, decreased inter-assay variability from 208 to 55.7 %. Non-C37 and C37 serum pools were commutable for all 6MPs assessed and decreased inter-assay variability from 208 to 13.8 % and 4.6 %, respectively, when used for mathematical recalibration. All materials evaluated, when used as common calibrators, substantially decreased inter-assay sTfR measurement variability. MP calibration to non-C37 and C37 serum pools may reduce the sTfR IMPBR to a greater extent than WHO 07/202 RM.