Copeptin stimulation by combined intravenous arginine and oral LevoDopa/Carbidopa in healthy short children and children with the polyuria-polydipsia syndrome

INTRODUCTION

Stimulated copeptin may provide an alternative to water deprivation testing (WDT) in the evaluation of polyuria-polydipsia syndrome (PPS). Though best studied, arginine stimulation alone produces a modest copeptin response in children. We investigated the effectiveness of the arginine + LevoDopa/Carbidopa stimulation test (ALD-ST) for copeptin.

METHODS

47 healthy short children (controls), 10 children with primary polydipsia and 10 children with AVP deficiency received arginine hydrochloride (500 mg/Kg intravenously over 30 minutes) and Levodopa/carbidopa (10:1 ratio; 175 mg of L-Dopa/m2 BSA) orally. Serum copeptin was measured at 0 60, 90 and 120 minutes.

RESULTS

In controls, ALD-ST increased copeptin from a median of 7.0 pMol/L (IQR 5.0-10.0) to a peak of 44.0 pMol/L (IQR 21.4-181.0) between 60-120 minutes (p<0.001). Copeptin peak was higher in subjects who experienced nausea or vomiting (57%) than in those who did not (131.0 pMol/L [IQR 42.5-193.8] vs 22.7 pMol/L [IQR 16.0-33.7], p<0.001). While subjects with primary polydipsia had similar baseline (8.5 pMol/L [IQR 8.0-11.0]) and stimulated (125.2 pMol/L [IQR 87.6-174.0]) copeptin levels as controls, subjects with AVP deficiency had lower baseline (2.5 pMol/L [IQR 2.0-3.1]) and peak levels (4.6 pMol/L [IQR 2.4-6.0]). A peak copeptin of ≥9.3 pMol/L best predicted absence of complete or partial AVP deficiency with a sensitivity of 100% and specificity of 80%.

CONCLUSIONS

ALD-ST induced a robust peak copeptin in healthy short children and children with primary polydipsia. Nausea/vomiting, a side effect of ALD-ST, amplified the copeptin response. The ALD-ST may be a suitable initial screening test in children with PPS.

Clinical Significance of Uncommon, Non-Clinical, and Novel Autoantibodies

Autoantibodies are a common mark of autoimmune reaction and their identification in the patients' serum, cerebrospinal fluid, or tissues is generally believed to represent diagnostic or prognostic biomarkers of autoimmune diseases or autoinflammatory conditions. Traditionally, autoantibody testing is an important part of the clinical examination of suspected patients, and in the absence of reliable T cell tests, characterization of autoantibody responses might be suitable in finding causes of specific autoimmune responses, their strength, and sometimes commencement of autoimmune disease. Autoantibodies are also useful for prognostic stratification in clinically diverse groups of patients if checked repeatedly. Antibody discoveries are continuing, with important consequences for verifying autoimmune mechanisms, diagnostic feasibility, and clinical management. Adding newly identified autoantibody-autoantigen pairs to common clinical laboratory panels should help upgrade and harmonize the identification of systemic autoimmune rheumatic disorders and other autoimmune conditions. Herein, we aim to summarize our current knowledge of uncommon and novel autoantibodies in the context of discussing their validation, diagnostic practicability, and clinical relevance. The regular updates within the field are important and well justified.

Schwann cells in the normal and pathological lung microenvironment

The lungs are a key organ in the respiratory system. They are regulated by a complex network of nerves that control their development, structure, function, and response to various pathological stimuli. Accumulating evidence suggests the involvement of a neural mechanism in different pathophysiological conditions in the lungs and the development and progression of common respiratory diseases. Lung diseases are the chief source of death globally. For instance, lung cancer is the second most commonly diagnosed malignancy, after prostate cancer in men and breast cancer in women, and is the most lethal cancer worldwide. However, although airway nerves are accepted as a mechanistically and therapeutically important feature that demands appropriate emphasizing in the context of many respiratory diseases, significantly less is known about the role of the neuroglial cells in lung physiology and pathophysiology, including lung cancer. New data have uncovered some cellular and molecular mechanisms of how Schwann cells, as fundamental components of the peripheral nervous system, may regulate lung cancer cells' survival, spreading, and invasiveness in vitro and in vivo. Schwann cells control the formation and maintenance of the lung cancer microenvironment and support metastasis formation. It was also reported that the number of lung cancer-associated Schwann cells correlates with patients' survival. Different factors secreted by Schwann cells, including microRNA, are known to sharpen the lung cancer environment by regulating the tumor-neuro-immune axis. Further clinical and experimental studies are required to elucidate the detailed role of Schwann cells in creating and maintaining pulmonary tumor-neuro-immune axis, which will advance our understanding of the pathogenesis of lung cancer and may inform therapeutic hypotheses aiming neoplasms and metastases in the lung.

Quality standards and internal quality control practices in medical laboratories: an IFCC global survey of member societies

OBJECTIVES

The trueness and precision of clinical laboratory results are ensured through total quality management systems (TQM), which primarily include internal quality control (IQC) practices. However, quality practices vary globally. To understand the current global state of IQC practice and IQC management in relation to TQM the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) Task Force on Global Laboratory Quality (TF-GLQ) conducted a survey of IFCC member countries on IQC practices and management.

METHODS

The survey included 16 questions regarding IQC and laboratory TQM practices and was distributed to IFCC full and affiliate member countries (n=110). A total of 46 (41.8 %) responses were received from all regions except North America.

RESULTS

Of the responding countries, 78.3 % (n=36) had legislative regulations or accreditation requirements governing medical laboratory quality standards. However, implementation was not mandatory in 46.7 % (n=21) of responding countries. IQC practices varied considerably with 57.1 % (n=28) of respondents indicating that they run 2 levels of IQC, 66.7 % (n=24) indicating they run IQC every 24 h and 66.7 % (n=28) using assay manufacturer IQC material sources. Only 29.3 % (n=12) of respondents indicated that every medical laboratory in their country has written IQC policies and procedures. By contrast, 97.6 % (n=40) of responding countries indicated they take corrective action and result remediation in the event of IQC failure.

CONCLUSIONS

The variability in TQM and IQC practices highlights the need for more formal programs and education to standardize and improve TQM in medical laboratories.

Incidence and Transmission of SARS-CoV-2 in US Child Care Centers After COVID-19 Vaccines

Importance

SARS-CoV-2 surveillance studies in US child care centers (CCCs) in the post-COVID-19 vaccine era are needed to provide information on incidence and transmission in this setting.

Objective

To characterize SARS-CoV-2 incidence and transmission in children attending CCCs (students) and their child care providers (CCPs) and household contacts.

Design, Setting, and Participants

This prospective surveillance cohort study was conducted from April 22, 2021, through March 31, 2022, and included 11 CCCs in 2 cities. A subset (surveillance group) of CCPs and students participated in active surveillance (weekly reverse transcription-polymerase chain reaction [RT-PCR] swabs, symptom diaries, and optional baseline and end-of-study SARS-CoV-2 serologic testing), as well as all household contacts of surveillance students. Child care center directors reported weekly deidentified self-reported COVID-19 cases from all CCPs and students (self-report group).

Exposure

SARS-CoV-2 infection in CCC students.

Main Outcomes and Measures

SARS-CoV-2 incidence, secondary attack rates, and transmission patterns were determined from diary entries, self-reports to CCC directors, and case logs. Incidence rate ratios were measured using Poisson regression clustering on centers with a random intercept and unstructured matrix.

Results

From a total population of 1154 students and 402 CCPs who self-reported cases to center directors, 83 students (7.2%; mean [SD] age, 3.86 [1.64] years; 55 male [66%]), their 134 household contacts (118 adults [mean (SD) age, 38.39 (5.07) years; 62 female (53%)], 16 children [mean (SD) age, 4.73 (3.37) years; 8 female (50%)]), and 21 CCPs (5.2%; mean [SD] age, 38.5 [12.9] years; 18 female [86%]) participated in weekly active surveillance. There were 154 student cases (13%) and 87 CCP cases (22%), as defined by positive SARS-CoV-2 RT-PCR or home antigen results. Surveillance students had a higher incidence rate than self-report students (incidence rate ratio, 1.9; 95% CI, 1.1-3.3; P = .01). Students were more likely than CCPs to have asymptomatic infection (34% vs 8%, P < .001). The CCC secondary attack rate was 2.7% to 3.0%, with the upper range representing possible but not definite secondary cases. Whether the index case was a student or CCP, transmission within the CCC was not significantly different. Household cumulative incidence was 20.5%, with no significant difference in incidence rate ratio between adults and children. Household secondary attack rates were 50% for children and 67% for adults. Of 30 household cases, only 5 (17%) represented secondary infections caused by 3 students who acquired SARS-CoV-2 from their CCC. Pre- and poststudy seroprevalence rates were 3% and 22%, respectively, with 90% concordance with antigen or RT-PCR results.

Conclusions and Relevance

In this study of SARS-CoV-2 incidence and transmission in CCCs and students' households, transmission within CCCs and from children infected at CCCs into households was low. These findings suggest that current testing and exclusion recommendations for SARS-CoV-2 in CCCs should be aligned with those for other respiratory viruses with similar morbidity and greater transmission to households.

External quality assessment practices in medical laboratories: an IFCC global survey of member societies

OBJECTIVES

Clinical laboratory results are required for critical medical decisions, underscoring the importance of quality results. As part of total quality management, external quality assessment (EQA) is a vital component to ensure laboratory accuracy. The goal of this survey was to evaluate the current status of global laboratory quality systems and assess the need for implementation, expansion, or harmonization of EQA programs (EQAP) for Clinical Chemistry and Laboratory Medicine.

METHODS

The International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) Task Force on Global Laboratory Quality (TF-GLQ) conducted a survey of IFCC full and affiliate members (n=110) on laboratory quality practice. A total of 41 (37.3%) countries representing all IFCC regions except North America provided responses about EQA availability and practices.

RESULTS

All 41 countries perform EQA, 38 reported that their laboratories had EQA policies and procedures, and 39 further act/evaluate unacceptable EQA results. 39 countries indicated they have international and/or national EQAP and 30 use alternative performance assessments. EQA frequency varied among countries. Generally, an EQAP provided the EQA materials (40/41) with four countries indicating that they did not have an EQAP in their country.

CONCLUSIONS

Globally, most laboratories participate in an EQAP and have defined quality procedures for EQA. There remain gaps in EQA material availability and implementation of EQA as a part of a total laboratory quality system. This survey highlights the need for education, training, and harmonization and will guide efforts of the IFCC TF-GLQ in identifying areas for enhancing global laboratory quality practices.

Performance of High Throughput SARS-CoV-2 Antigen Testing Compared to Nucleic Acid Testing

OBJECTIVE

Independent assessment of SARS-CoV-2 antigen (COV2Ag) tests remains important as varying performance between assays is common. We assessed the performance of a new high-throughput COV2Ag test compared to SARS-CoV-2 nucleic acid amplification tests (NAAT).

METHODS

A total of 347 nasopharyngeal samples collected from January to October 2021 were assessed by NAAT as part of standard-of-care testing (CDC LDT or GeneXpert System, Cepheid) and COV2Ag using the ADVIA Centaur CoV2Ag assay (Siemens Healthineers).

RESULTS

Among NAAT positive specimens we found 82.4% agreement and in NAAT negative specimens we found 97.3% agreement (overall agreement 85.6%). In symptomatic persons, COV2Ag agreed with NAAT 90.0% (n = 291), and in asymptomatic persons, 62.5% (n = 56). Agreement between positive NAAT and COV2Ag increased at lower cycle threshold (Ct) values.

CONCLUSION

The COV2Ag assay exceeded the World Health Organization minimum performance requirements of ≥ 80% sensitivity and ≥ 97% specificity. The COV2Ag assay is helpful for large scale screening efforts due to high-throughput and reduced wait times.

Tixagevimab Plus Cilgavimab Does Not Affect the Interpretation of Electrophoretic and Free Light Chain Assays

OBJECTIVES

There is concern that the anti-severe acute respiratory syndrome coronavirus 2 therapeutic monoclonal antibodies, used as preexposure prophylaxis in patients with multiple myeloma, may appear as a detectable monoclonal protein by electrophoretic methods, resulting in misinterpretation or inability to measure therapeutic responses in some patients. In this pilot study, we characterize the effect of tixagevimab plus cilgavimab (Evusheld; T + C) on interpretation of serum protein electrophoresis (SPE), immunofixation electrophoresis (IFE), and serum free light chain (sFLC) assays.

METHODS

We performed spiking experiments with T + C at serum maximum concentration following a 300-mg dose (1× Cmax) and at 10 times the concentration of Cmax (10× Cmax) with pooled serum samples. SPE and IFE technical procedures were performed on the SPIFE 3000, and sFLC and immunoglobulin G1 (IgG1) subtype quantitation was performed on the Optilite.

RESULTS

T + C-associated interference was not visible as an M-spike in normogammaglobulinemic pooled samples. Hypogammaglobulemic pooled samples at 10× Cmax demonstrated an M-spike in SPE and immunoglobulin Gκ pattern in IFE. No increases were noted in the results of sFLC or IgG1 levels.

CONCLUSIONS

This study indicates that T + C at pharmacologic Cmax is unlikely to interfere with SPE, IFE, sFLC, or IgG1 analyses when spiked into patient serum samples, but further evaluation of recently injected patients may be warranted.

Combined Arginine and Insulin Stimulation Elicits a Robust and Consistent Copeptin Response in Short Children

INTRODUCTION

Copeptin, co-secreted with arginine vasopressin, is regulated by osmotic and volume stimuli but also responds to intravenous arginine and insulin-induced hypoglycemia. The serum copeptin response to the latter agents has been studied in adults but only to a limited extent in children. The objective of this study was to describe the copeptin response to combined arginine and insulin in children with normal posterior pituitary function.

METHODS

We conducted a prospective, single-arm assessment of serum copeptin concentrations in children (age 7-16 years, n = 38) undergoing growth hormone stimulation testing with an arginine-insulin tolerance test (AITT) for short stature or growth deceleration in a tertiary referral center. After overnight fasting, arginine (500 mg/kg) was administered between 0 and 30 min intravenously (IV) followed by insulin (0.1 units/kg IV) at 60 min. Copeptin serum concentrations were measured at baseline (0 min), at the post-arginine peak (60 min), and at the post-insulin peak (90 min; 30 min post-insulin), respectively. The main outcome was the peak copeptin concentration.

RESULTS

Mean ± SD copeptin concentrations increased from 9.9 ± 5.0 pmol/L at 0 min to 13.2 ± 5.8 pmol/L at 60 min (p < 0.0001 vs. 0 min) and 27.7 ± 14.2 pmol/L at 90 min (p < 0.0001 vs. 0 and 60 min). There was no significant correlation between copeptin concentrations and age, BMI, pubertal status, cortisol, growth hormone, or glucose concentrations.

DISCUSSION/CONCLUSION

Arginine and insulin appear to have an additive and consistent effect resulting in significant stimulation of copeptin secretion in children. The AITT may be a useful tool to evaluate for normal posterior pituitary function in this age-group, with potential implications for the evaluation of polyuria-polydipsia syndrome.

Large viral meningoencephalitis CSF serologic panel lacks utility in clinical decisions and outcomes

INTRODUCTION

Accurate diagnosis of viral meningoencephalitis (VMe) and identification of the etiologic agent has clinical importance and large serology panels are available to aid in the detection of several viral pathogens. However, such panels are often send-out testing, with prolonged time to results, thus impacting the actionability of test results. We hypothesized these panels may not contribute to patient care and lack clinical utility.

METHODS

A retrospective review of all VMe CSF serology panels ordered at one pediatric (n = 53; 2017-2019) and two adult (n = 200; 2019-2020) tertiary care hospitals was performed to assess test clinical utility. Panels included serology for: Adenovirus, coxsackie and echoviruses, influenza, measles, lymphocytic choriomeningitis virus, herpes simplex virus, mumps, varicella zoster, encephalitis viruses. Clinical data collected included diagnostic test results, symptoms, comorbidities, and interventions.

RESULTS

In 129/200 (64.5 %) of adult cases and 37/53 (69.8 %) of pediatric cases CSF had a WBC less than 5 cells/mm². In total, 127 (63.5 %, 127/200) adult panels had at least one positive target with 49 panels having more than one positive (38.6 %, 49/127). In 99.5 % of adult and 100 % of pediatric cases there was no change to decisions regarding starting, discontinuing, continuing, or changing antimicrobial therapy based on panel results. In no cases were potentially immunosuppressive therapies like steroid or IVIG administration delayed while awaiting the results of the panel.

CONCLUSIONS

While all patients presented with neurologic symptoms, poor pre-screening for CNS inflammation using CSF WBC analysis likely contributed to poor clinical utility of the VMe panels. Large CSF serologic panels for VMe did not contribute to or add value to clinical decision making in our cohort.

Characterization of Casirivimab Plus Imdevimab, Sotrovimab, and Bamlanivimab Plus Etesevimab-Derived Interference in Serum Protein Electrophoresis and Immunofixation Electrophoresis

Background

Therapeutic monoclonal antibodies can be a source of assay interference in clinical serum protein electrophoresis (SPEP) and immunofixation electrophoresis (IFE), producing monoclonal bands that can be misinterpreted as a monoclonal gammopathy related to a B-cell or plasma cell neoplasm. The extent to which new anti-COVID-19 monoclonal antibodies produce this interference is unknown.

Methods

Casirivimab plus imdevimab, sotrovimab, and bamlanivimab plus etesevimab were spiked into patient serum samples to evaluate for SPEP/IFE interference, to characterize the position of therapy-derived bands relative to a reference band (either combined beta band or beta 1 band, depending on instrument platform), and to confirm heavy and light chain utilization of each medication. Serum samples from patients who had recently received casirivimab plus imdevimab or sotrovimab were also evaluated for comparison.

Results

When spiked into serum samples, all tested anti-COVID-19 monoclonal antibodies generated interference in SPEP/IFE. Importantly, the patterns of interference differed between spiked serum samples and serum from patients who had recently received casirivimab plus imdevimab or sotrovimab.

Conclusions

Imdevimab can be added to the growing list of therapeutic monoclonal antibodies that produce sustained interference in SPEP/IFE. Although casirivimab and sotrovimab also produce assay interference in vitro, these antibodies are not reliably detected in serum from recently infused patients. The value of relative band position in recognizing bands that may represent therapeutic monoclonal antibodies is also emphasized. Clinicians and laboratorians should consider therapeutic monoclonal antibody interference in diagnostic SPEP/IFE and review a patient’s medication list when new or transient monoclonal bands are identified.

Mu heavy chain disease with MYD88 L265P mutation: an unusual manifestation of lymphoplasmacytic lymphoma

Background

Mu heavy chain disease is a rare lymphoid neoplasm characterized by vacuolated bone marrow plasma cells and secretion of defective mu immunoglobulin heavy chains. The biological basis of mu heavy chain disease is poorly understood.

Case presentation

We report a case of mu heavy chain disease with MYD88 L265P mutation and deletion of 6q, genetic aberrations that are both strongly associated with lymphoplasmacytic lymphoma/Waldenström macroglobulinemia. Identification of the truncated mu immunoglobulin was facilitated by mass spectrometric analysis of the patient’s serum.

Conclusions

Mu heavy chain disease has been described as similar to chronic lymphocytic leukemia; however, the frequency of lymphocytosis in mu heavy chain disease has not been previously reported. We reviewed all previously published mu heavy chain disease reports and found that lymphocytosis is uncommon in the entity. This finding, along with the emerging genetic feature of recurrent MYD88 mutation in mu heavy chain disease, argues that at least a significant subset of cases are more similar to lymphoplasmacytic lymphoma than to chronic lymphocytic leukemia.

COVID-19 mRNA Vaccines May Cause False Reactivity in Some Serologic Laboratory Tests, Including Rapid Plasma Reagin Tests

OBJECTIVES

Acute viral infections and some vaccines have been shown to increase false positivity in serologic assays. We assessed if the messenger RNA coronavirus disease 2019 (COVID-19) vaccines could cause false reactivity in common serologic assays in a pilot longitudinal cohort.

METHODS

Thirty-eight participants with sera available prevaccination, 2 weeks after each vaccine dose, and monthly thereafter for up to 5 months were tested for common infectious disease serologies and antiphospholipid syndrome (APS) serology markers on the BioPlex 2200, Sure-Vue rapid plasma reagin (RPR), and Macro-Vue RPR. Twenty-two participants received the Moderna vaccine and 16 received the Pfizer vaccine.

RESULTS

Most assays had no change in reactivity over the course of the sample draws, including APS markers. Epstein-Barr virus immunoglobulin G (IgG), measles IgG, and rubella immunoglobulin M all had possible false reactivity in one to two participants. RPR tests demonstrated false reactivity, with baseline nonreactive participant samples becoming reactive following vaccination. There were more false reactive participants (7/38) in the BioPlex RPR than in the Sure-Vue (2/38) and Macro-Vue (1/38) tests. All falsely reactive RPR tests were in participants who received the Moderna vaccine.

CONCLUSIONS

Serologic assays with results that do not fit the clinical picture following COVID-19 vaccination should be repeated. Effects of false reactivity can last more than 5 months in some assays. In particular, RPR is susceptible to false reactivity, and there is variability among assays. Larger longitudinal studies are needed to determine the incidence and window of false reactivity.

Implementation and challenges of portable blood gas measurements in air medical transport

OBJECTIVES

Ventilator management in prehospital settings using end-tidal CO₂ can lead to inappropriate ventilation in the absence of point of care blood gas (POCBG) measurements. Implementation of POCBG testing in helicopter Emergency Medical Services (HEMS) is limited in part because of concern for preanalytical and analytical errors due to altitude, vibration, and other associated environmental factors and due to insufficient documentation of implementation challenges.

METHODS

We performed accuracy and precision verification studies using standard materials tested pre-, in-, and post-flight (n=10) in a large HEMS agency. Quality assurance error log data were extracted and summarized for common POCBG errors during the first 31 months of use and air medical transport personnel were surveyed regarding POCBG use (n=63).

RESULTS

No clinically significant differences were found between pre-, in-, and post-flight blood gas measurements. Error log data demonstrated a reduction in device errors over time. Survey participants found troubleshooting device errors and learning new clinical processes to be the largest barriers to implementation. Continued challenges for participants coincided with error log data including temperature and sampling difficulties. Survey participants indicated that POCBG testing improved patient management.

CONCLUSIONS

POCBG testing does not appear to be compromised by the HEMS environment. Temperature excursions can be reduced by use of insulated transport bags with heating and cooling packs. Availability of POCBG results in air medical transport appeared to improve ventilator management, increase recognition of ventilation-perfusion mismatch, and improve patient tolerance of ventilation.

Pediatric SARS-CoV-2 seroprevalence during mitigation procedures in Southwestern Pennsylvania

Background

Children infected with SARS-CoV-2 are often asymptomatic or have only mild symptoms, leading to underestimation of disease prevalence in symptom-based testing strategies.

Objectives

This study sought to determine pediatric SARS-CoV-2 disease burden during local mitigation efforts by using antibody testing to compare seroprevalence estimates to cumulative PCR prevalence estimates.

Study design

In this cross-sectional study, we collected 1142 strict phase and 1196 relaxed phase remnant blood specimens from patients less than 19-years-old in southwestern Pennsylvania (SWPA). Patients were excluded if their residential zip code was outside the region of interest, if they were under 6-months-old, or they had recently received antibody-modifying treatments. Demographic, encounter, and laboratory electronic medical record information was extracted. Samples were tested for SARS-CoV-2 spike protein IgG using an EUA ELISA, and PCR results were recorded from county health department data. Seroprevalence and Clopper-Pearson exact 95% confidence intervals were calculated.

Results

The observed seroprevalence of SARS-CoV-2 spike protein antibodies in children during strictest mitigation was 0.53% (95% CI 0.19, 1.14) and 0.92% (95% CI 0.46,1.64) during moderately relaxed. Strict and relaxed phase PCR-based prevalence were significantly higher, 2.87% (95% CI 1.95, 4.08) and 3.64 (95% CI 3.01, 4.38), respectively.

Conclusions

Estimates of pediatric seroprevalence were significantly lower than cumulative PCR prevalence estimates, and less than adult seroprevalence estimates, potentially due to biological, population, or sampling differences. Biological differences in pediatric immune responses to SARS-CoV-2 may make serosurvey interpretation challenging and these differences warrant further study.

Pilot Verification of a Novel Approach to Remove Electrophoretic Interference of the Therapeutic Monoclonal Antibody Daratumumab

Introduction

The advent of therapeutic monoclonal antibodies (tmAbs) in treatment of multiple myeloma poses unique challenges for the clinical laboratory. These tmAbs may appear as a detectable monoclonal protein by electrophoretic methods resulting in misinterpretation or inability to measure therapeutic responses in some patients, and there are currently limited techniques for identifying interference. In this study we performed a preliminary assessment of the SPIFE anti-daratumumab (SPIFE anti-Dara) reagent to determine whether it would be a feasible aid in resolving the interference of tmAbs with serum protein electrophoresis (SPE) and immunofixation electrophoresis (IFE).

Methods

We performed a pilot study with 20 serum samples and clinical correlates. All samples had a characteristic daratumumab electrophoretic pattern (cathodal IgG/κ). A pre-electrophoretic sample treatment was performed with SPIFE anti-Dara. The reagent is a derivatized anti-Dara that forms multiple antibody/daratumumab complexes. SPE and IFE technical procedures were performed on Helena SPIFE 3000 according to the manufacturer instructions.

Results

Of the 20 patients, 14 patients were identified to be on daratumumab therapy. In 14/14 of cases, the daratumumab interference was successfully removed both from SPE and IFE assays. Disease associated M-protein was still visible after pretreatment, and quantification of M-protein may be possible with the use of SPIFE anti-Dara procedure.

Discussion

SPIFE anti-Dara is a promising method to remove the interference of therapeutic monoclonal antibody daratumumab with SPE and IFE results in clinical laboratories and warrants further assessment.

Trends in Use of Granulocyte Colony-Stimulating Factor Following Introduction of Biosimilars Among Adults With Cancer and Commercial or Medicare Insurance From 2014 to 2019

IMPORTANCE

The introduction of biosimilars and novel delivery devices between 2014 and 2019 may have changed the utilization of granulocyte colony-stimulating factors (G-CSF).

OBJECTIVE

To assess utilization trends of G-CSFs for primary prophylaxis of febrile neutropenia (FN) among patients with cancer receiving myelosuppressive chemotherapy with commercial or Medicare insurance.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study assessed G-CSF utilization trends overall and stratified by regimen febrile neutropenia risk level. Associations between patient characteristics and G-CSF use were evaluated. Patients with cancer, including breast, lung, colorectal, esophageal and gastric, pancreatic, prostate, ovarian, and non-Hodgkin lymphomas, initiating myelosuppressive chemotherapy courses were included from the 2014 to 2019 commercial insurance and 2014 to 2018 Medicare fee-for-service claims databases. Data were analyzed from March to June 2021.

EXPOSURES

Year of chemotherapy initiation.

MAIN OUTCOMES AND MEASURES

The main outcomes were use and trends of G-CSFs for primary prophylaxis, from completion to 3 days after in the first chemotherapy cycle.

RESULTS

In total, 86 731 chemotherapy courses (mean [SD] age, 57.7 [11.5] years; 57 838 [66.7%] women and 28 893 [33.3%] men) were identified from 82 410 patients in the commercial insurance database and 32 398 chemotherapy courses (mean [SD] age, 71.8 [8.3] years; 18 468 [57.0%] women and 13 930 [43.0%] men) were identified from 30 279 patients in the Medicare database. Among the commercially insured population, 39 639 patients (45.7%) received G-CSFs, and 12 562 patients (38.8%) received G-CSFs among Medicare insured patients. Overall G-CSF use increased significantly throughout the study period in both populations, from 45.1% (95% CI, 44.4%-45.7%) of patients in 2014 to 47.5% (95% CI, 46.5%-48.5%) of patients in 2019 (P = .001) in the commercially insured population and from 36.0% (95% CI, 34.2%-38.0%) of patients in 2014 to 39.1% (95% CI, 38.1%-40.1%) of patients in 2018 (P < .001) in the Medicare population. The greatest increases in G-CSF use were observed among patients with high FN risk, from 75.0% (95% CI, 74.1%-76.0%) of patients to 83.2% (95% CI, 82.0%-84.2%) of patients (P < .001) among the commercially insured population and 75.3% (95% CI, 71.8%-78.6%) of patients to 86.2% (95% CI, 84.7%-87.6%) of patients (P < .001) among the Medicare population. Use of G-CSFs decreased in the commercially insured population among patients with intermediate FN risk (from 27.5% [95% CI, 26.4%-28.5%] of patients to 20.4% [95% CI, 19.1%-21.7%] of patients; P < .001) or low FN risk (from 19.3% [95% CI, 18.3%-20.4%] of patients to 16.3% [95% CI, 14.7%-18.0%] of patients; P < .001) and remained stable in the Medicare population (intermediate risk: from 26.4% [95% CI, 23.8%-29.2%] of patients to 28.4% [95% CI, 27.0%-29.8%] of patients; P = .35; low risk: from 19.6% [95% CI, 17.0%-22.4%] of patients to 20.9% [95% CI, 19.6%-22.3%] of patients; P = .58). Factors associated with increased odds of G-CSF use included older age (commercial insurance: adjusted odds ratio [aOR], 1.50 [95% CI, 1.41-1.59]; Medicare: aOR, 1.36 [95% CI, 1.08-1.71]), receiving a regimen with high FN risk (commercial insurance: aOR, 16.01 [95% CI, 15.17-16.90]; Medicare: aOR, 17.17 [95% CI, 15.76-18.71]), and history of neutropenia (commercial insurance: 3.90 (3.67-4.15); Medicare: 3.82 (3.50-4.18).

CONCLUSIONS AND RELEVANCE

This cross-sectional study found that utilization of G-CSFs increased among patients with cancer with high FN risk in both a commercially and Medicare-insured population, but 14% to 17% of patients still did not receive preventive treatment.

Differential Antibody Response to mRNA COVID-19 Vaccines in Healthy Subjects

Knowledge about development and duration of virus-specific antibodies after COVID-19 vaccination is important for understanding how to limit the pandemic via vaccination in different populations and societies. However, the clinical utility of postvaccination testing of antibody response and selection of targeted SARS-CoV-2 antigen(s) has not been established. The results of such testing from clinical teams independent from vaccine manufacturers are also limited. Here, we report the initial results of an ongoing clinical study on evaluation of antibody response to four different SARS-CoV-2 antigens after first and second dose of Pfizer and Moderna mRNA vaccines and at later time points. We revealed a peak of antibody induction after the vaccine boosting dose with a gradual decline of antibody levels at later time. Anti-nucleocapsid antibody was not induced by spike protein-encoding vaccines and this may continue to serve as a marker of previous SARS-CoV-2 infection. No differences between the two vaccines in terms of antibody response were revealed. Age and gender dependencies were determined to be minimal within the healthy adult (but not aged) population. Our results suggest that postvaccination testing of antibody response is an important and feasible tool for following people after vaccination and selecting individuals who might require a third dose of vaccine at an earlier time point or persons who may not need a second dose due to previous SARS-CoV-2 infection. IMPORTANCE Now that authorized vaccines for COVID-19 have been widely used, it is important to understand how they induce antivirus antibodies, which antigens are targeted, how long antibodies circulate, and how personal health conditions and age may affect this humoral immunity. Here, we report induction and time course of multiple anti-SARS-CoV-2 antibody responses in healthy individuals immunized with Pfizer and Moderna mRNA vaccines. We also determined the age and gender dependence of the antibody response and compared antibody levels to responses seen in those who have recovered from COVID-19. Our results suggest the importance of screening for antibody response to multiple antigens after vaccination in order to reveal individuals who require early and late additional boosting and those who may not need second dose due to prior SARS-CoV-2 infection.

Multiplex assessment of SARS-CoV-2 antibodies improves assay sensitivity and correlation with neutralizing antibodies

OBJECTIVES

Detection of antibodies to multiple SARS-CoV-2 antigens in a single assay could increase diagnostic accuracy, differentiate vaccination from natural disease, and aid in retrospective exposure determination. Correlation of binding antibody assessment in clinical assays with neutralizing antibodies is needed to better understand the humoral response to SARS-CoV-2 infection and establish of correlates of protection.

METHODS

A cohort of 752 samples was used to assess specificity, sensitivity, and comparison to 6 other Conformitè Europëenne serologic assays for the BioRad SARS-CoV-2 IgG multiplex assay which measures receptor binding domain IgG (RBD), spike-S1 IgG (S1), spike-S2 IgG (S2), and nucleocapsid IgG (N). A subset of serial specimens from 14 patients was also tested for neutralizing antibodies (n = 61).

RESULTS

Specificity for RBD and S1 IgG was 99.4% (n = 170) and 100% for S2 and N IgG (n = 170) in a cohort selected for probable interference. Overall assay concordance with other assays was >93% for IgG and total antibody assays and reached 100% sensitivity for clinical concordance at >14 days as a multiplex assay. RBD and S1 binding antibody positivity demonstrated 79-95% agreement with the presence of neutralizing antibodies.

CONCLUSIONS

The BioRad SARS-CoV-2 IgG assay is comparable to existing assays, and achieved 100% sensitivity when all markers were included. The ability to measure antibodies against spike and nucleocapsid proteins simultaneously may be advantageous for complex clinical presentations, epidemiologic research, and in decisions regarding infection prevention strategies. Additional independent validations are needed to further determine binding antibody and neutralizing antibody correlations.

Unexpected False-Positive Rates in Pediatric SARS-CoV-2 Serology Using the EUROIMMUN Anti-SARS-CoV-2 ELISA IgG Assay

OBJECTIVES

Serologic assay performance studies for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-​2) in pediatric populations are lacking, and few seroprevalence studies have routinely incorporated orthogonal testing to improve accuracy.

METHODS

Remnant serum samples for routine bloodwork from 2,338 pediatric patients at UPMC Children's Hospital of Pittsburgh were assessed using the EUROIMMUN Anti-SARS-CoV-2 ELISA IgG (EuroIGG) assay. Reactive cases with sufficient volume were also tested using 3 additional commercial assays.

RESULTS

Eighty-five specimens were reactive according to the EuroIGG, yielding 3.64% (95% confidence interval [CI], 2.91%-4.48%) seropositivity, of which 73 specimens had sufficient remaining volume for confirmation by orthogonal testing. Overall, 19.18% (95% CI, 10.18%-28.18%) of samples were positive on a second and/or third orthogonal assay. This 80.82% false positivity rate is disproportionate to the expected false positivity rate of 50% given our pediatric population prevalence and assay performance.

CONCLUSIONS

In pediatric populations, false-positive SARS-CoV-2 serology may be more common than assay and prevalence parameters would predict, and further studies are needed to establish the performance of SARS-CoV-2 serology in children.

Incidence and Management of Therapeutic Monoclonal Antibody Interference in Monoclonal Gammopathy Monitoring

BACKGROUND

The treatment of multiple myeloma (MM) has been revolutionized by the introduction of therapeutic monoclonal antibodies (tmAbs). Daratumumab, a human IgG1/κ tmAb against CD38 on plasma cells, has improved overall survival in refractory MM and was recently approved as a frontline therapy for MM. Work on tmAb interference with serum protein electrophoresis (SPE) during MM monitoring has failed to provide information for laboratories on incidence of interference and effective methods of managing the interference at a practicable level. We aimed to evaluate daratumumab and elotuzumab interference in a large academic hospital setting and implement immediate solutions.

METHODS

We identified and chart reviewed all cases of possible daratumumab interference by electrophoretic pattern (120 of 1317 total cases over 3 months). We retrospectively reviewed SPE cases in our laboratory to assess clinical implications of tmAb interference before the laboratory was aware of tmAb treatment. We supplemented samples with daratumumab and elotuzumab to determine the limits of detection and run free light chain analysis.

RESULTS

Approximately 9% (120 of 1317) of tested cases have an SPE and/or immunofixation electrophoresis (IFE) pattern consistent with daratumumab, but only approximately 47% (56) of these cases were associated with daratumumab therapy. Presence of daratumumab led to physician misinterpretation of SPE/IFE results. Limits of daratumumab detection varied with total serum gammaglobulin concentrations, but serum free light chain analysis was unaffected.

CONCLUSIONS

Clinical laboratories currently rely on interference identification by electrophoretic pattern, which may be insufficient and is inefficient. Critical tools in preventing misinterpretation efficiently include physician education, pharmacy notifications, separate order codes, and interpretive comments.

SARS-CoV-2 Serologic Immune Response in Exogenously Immunosuppressed Patients

Background

While it is presumed that immunosuppressed patients, such as solid organ transplant recipients on immunosuppression, are at greater risk from SARS-CoV-2 infection than the general population, the antibody response to infection in this patient population has not been studied.

Methods

In this report, we follow the anti-SARS-CoV-2 antibody levels in patients with COVID-19 who are undergoing exogenous immunosuppression. Specifically, we studied the antibody response of three solid organ transplant recipient patients, three patients who take daily inhaled fluticasone, and a patient on etanercept and daily inhaled fluticasone, and compared them to five patients not on exogenous immunosuppression.

Results

We found that the solid organ transplant patients on full immunosuppression are at risk of having a delayed antibody response and poor outcome. We did not find evidence that inhaled steroids nor etanercept predispose patients to delayed immune response to SARS-CoV-2.

Conclusion

The data presented here suggest that solid organ transplant recipients may be good candidates for early targeted intervention against SARS-CoV-2.

Rapid Detection of SARS-CoV-2 Antigens Using High-Purity Semiconducting Single-Walled Carbon Nanotube-Based Field-Effect Transistors

Early diagnosis of SARS-CoV-2 infection is critical for facilitating proper containment procedures, and a rapid, sensitive antigen assay is a critical step in curbing the pandemic. In this work, we report the use of a high-purity semiconducting (sc) single-walled carbon nanotube (SWCNT)-based field-effect transistor (FET) decorated with specific binding chemistry to assess the presence of SARS-CoV-2 antigens in clinical nasopharyngeal samples. Our SWCNT FET sensors, with functionalization of the anti-SARS-CoV-2 spike protein antibody (SAb) and anti-nucleocapsid protein antibody, detected the S antigen (SAg) and N antigen (NAg), reaching a limit of detection of 0.55 fg/mL for SAg and 0.016 fg/mL for NAg in calibration samples. SAb-functionalized FET sensors also exhibited good sensing performance in discriminating positive and negative clinical samples, indicating a proof of principle for use as a rapid COVID-19 antigen diagnostic tool with high analytical sensitivity and specificity at low cost.

Variable Performance in 6 Commercial SARS-CoV-2 Antibody Assays May Affect Convalescent Plasma and Seroprevalence Screening

Objectives

Serologic detection of prior severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is needed for definition of convalescent plasma donors, for confounding SARS-CoV-2 presentation, and for seroprevalence studies. Reliable serologic assays with independent validation are required.

Methods

Six SARS-CoV-2 antibody assays from Beckman Coulter, Euroimmun (IgG, IgA), Roche, and Siemens (Centaur, Vista) were assessed for specificity (n = 184), sensitivity (n = 154), and seroconversion in a defined cohort with clinical correlates and molecular SARS-CoV-2 results.

Results

Assay specificity was 99% or greater for all assays except the Euroimmun IgA (95%). Sensitivity at more than 21 days from symptom onset was 84%, 95%, 72%, 98%, 67%, and 96% for Beckman Coulter, Centaur, Vista, Roche, Euroimmun IgA, and Euroimmun IgG, respectively. Average day of seroconversion was similar between assays (8-10 d), with 2 patients not producing nucleocapsid antibodies during hospitalization.

Conclusions

SARS-CoV-2 nucleocapsid antibodies may be less reliably produced early in disease than spike protein antibodies. Assessment of convalescent plasma donors at more than 30 days from symptom onset and seroprevalence studies should use assays with defined sensitivity at time points of interest because not all assays detected antibodies reliably at more than 30 days.

Evaluating the incidence of engraftment syndrome with different melphalan formulations in adult multiple myeloma and immunoglobulin light chain amyloidosis patients undergoing autologous hematopoietic cell transplantation

BACKGROUND

Engraftment syndrome (ES) is a common complication of autologous hematopoietic cell transplantation (HCT). The difference in incidence of ES between melphalan formulations has not been widely reported throughout the literature and would allow for a more comprehensive understanding of the advantages and disadvantages of both melphalan formulations.

PATIENTS AND METHODS

This retrospective, single-center, observational study evaluated 83 adult multiple myeloma and immunoglobulin light chain amyloidosis patients who received either propylene glycol-containing (PG) or propylene glycol-free (PG-free) melphalan 140 mg/m² as single-agent conditioning chemotherapy for autologous HCT from May 31, 2015 to May 31, 2019. The primary outcome was to assess the incidence of ES, as defined using the Maiolino criteria, with both melphalan formulations. Secondary outcomes included an analysis of potential risk factors for the development of ES, as well as an evaluation of overall length of stay (LOS).

RESULTS

The incidence of ES for PG and PG-free melphalan did not differ significantly, 14/39 (35.9%) and 12/44 (27.3%) (P = 0.4), respectively. No potential risk factors for ES were identified on multivariate logistic regression analysis. A statistically significant difference in number of days to engraftment was identified for PG and PG-free melphalan, 15.56 vs. 13.82 days (P = 0.01), respectively; although, this did not translate to a decrease in LOS, 19.9 vs. 18.59 days (P = 0.14).

CONCLUSIONS

The incidence of ES did not differ significantly between melphalan formulations. Future research is needed to determine whether the faster time to engraftment seen with PG-free melphalan may translate to a decrease in LOS.

Evaluation of SARS-CoV-2 prototype serologic test in hospitalized patients

OBJECTIVES

Humoral immune response to SARS-CoV-2 infection has been reported in several patient cohorts with results that vary by method and population studied due to the lack of reliable commercial assays available as the pandemic initially spread. We sought to clinically assess commercial prototype SARS-CoV-2 IgG and IgA assays for use in screening for prior infection and convalescent plasma donation.

DESIGN AND METHODS

Prototype SARS-CoV-2 IgG and IgA assays from Euroimmun were assessed utilizing remnant specimens. Specificity testing used specimens in their convalescent window for the common coronaviruses and other infectious diseases known to be associated with increased non-specificity in serologic assays. Sensitivity testing utilized serial specimens from molecularly confirmed SARS-CoV-2 critically ill patients to assess seroconversion. Utilizing recombinant spike protein we also developed a competitive confirmation procedure to increase assay specificity.

RESULTS

We determined specificity to be 97% and 81%, respectively, when indeterminate samples were considered positive and 99% and 86% when indeterminate samples were considered negative. We developed a new confirmation methodology to enhance the specificity of the assays with an anticipated specificity of 98% for IgA. Valuation of hospitalized COVID-19 patients determined median IgA seroconversion to be 8 days and IgG 10 days. Neither level nor timing of antibody response correlated with days on ventilation. End titer measurements indicate that validated improved assays may be capable of semi-quantitative measurement.

CONCLUSIONS

We found these assays to be clinically acceptable for the high prevalence population tested, for instance, for convalescent plasma donation.

Recognizing Laboratory Medicine's Collaborative Role in Identifying and Eliminating Health Disparities

BACKGROUND

A health disparity is a health outcome that presents in a lesser or greater extent between populations. Health disparities in diseases are products of complex interactions between social, economic, and to a lesser extent, biological factors and can be mediated by structural racism and discriminatory policies. The objective of this review is to understand how both laboratorians and nonlaboratorians think about the relationship between laboratory medicine and health disparities and to highlight ways in which laboratory medicine can play a role in eliminating health disparities.

CONTENT

We developed an electronic survey from which we selected the top responses reported by the 215 participants to frame a discussion around why laboratorians perceive health disparities exists, and how they can reduce health disparities.

SUMMARY

We found that both laboratorians and nonlaboratorians feel that laboratory medicine can and should play a role in reducing health disparities using many tools already in use in the clinical laboratory. The skills of laboratory workers in data generation, the establishment of reference ranges, control over the presentation of laboratory results, generation of test menus, and the development of novel diagnostics may impact health disparities. Laboratorians' responses in our survey indicated that they felt that they could reduce health disparities by using laboratory data to proactively track in cooperation with healthcare providers individuals with chronic conditions to prevent acute events, ensuring gender and ethnic diversity in new clinical trials, including appropriate curriculum in laboratory medicine training, using equations and reference intervals based on physiological differences and participating in unconscious bias training.

SARS-CoV-2 growth, furin-cleavage-site adaptation and neutralization using serum from acutely infected hospitalized COVID-19 patients

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), emerged at the end of 2019 and by mid-June 2020 the virus had spread to at least 215 countries, caused more than 8 000 000 confirmed infections and over 450 000 deaths, and overwhelmed healthcare systems worldwide. Like severe acute respiratory syndrome coronavirus (SARS-CoV), which emerged in 2002 and caused a similar disease, SARS-CoV-2 is a betacoronavirus. Both viruses use human angiotensin-converting enzyme 2 (hACE2) as a receptor to enter cells. However, the SARS-CoV-2 spike (S) glycoprotein has a novel insertion that generates a putative furin cleavage signal and this has been postulated to expand the host range. Two low-passage (P) strains of SARS-CoV-2 (Wash1 : P4 and Munich : P1) were cultured twice in Vero E6 cells and characterized virologically. Sanger and MinION sequencing demonstrated significant deletions in the furin cleavage signal of Wash1 : P6 and minor variants in the Munich : P3 strain. Cleavage of the S glycoprotein in SARS-CoV-2-infected Vero E6 cell lysates was inefficient even when an intact furin cleavage signal was present. Indirect immunofluorescence demonstrated that the S glycoprotein reached the cell surface. Since the S protein is a major antigenic target for the development of neutralizing antibodies, we investigated the development of neutralizing antibody titres in serial serum samples obtained from COVID-19 human patients. These were comparable regardless of the presence of an intact or deleted furin cleavage signal. These studies illustrate the need to characterize virus stocks meticulously prior to performing either in vitro or in vivo pathogenesis studies.

Immunocompromised Seroprevalence and Course of Illness of SARS-CoV-2 in One Pediatric Quaternary Care Center

BACKGROUND

The burden of coronavirus disease 2019 (COVID-19) is poorly understood in pediatric patients due to frequent asymptomatic and mild presentations. Additionally, the disease prevalence in pediatric immunocompromised patients remains unknown.

METHODS

This cross-sectional study tested convenience samples from pediatric patients who had clinically indicated lab work collected and an immunocompromising condition, including oncologic diagnoses, solid organ transplant (SOT), bone marrow transplant, primary immunodeficiency, and rheumatologic conditions or inflammatory bowel disease on systemic immunosuppression, for the presence of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

RESULTS

We tested sera from 485 children and observed SARS-CoV-2 seroprevalence of 1.0% (Confidence Interval [CI] 95%: 0.3%-2.4%). Two patients were positive by nasopharyngeal (NP) swab Reverse transcriptase polymerase chain reaction (RT-PCR), but only 1 seroconverted. Patients with oncologic diagnoses or SOT were most likely to be tested for COVID-19 when presenting with respiratory illness as compared with other groups.

CONCLUSIONS

Seroprevalence of antibodies to SARS-CoV-2 in immunocompromised children was similar to that of an immunocompetent pediatric population (0.6%, CI 95%: 0.3%-1.1%), suggesting an adequate antibody response. However, none of the patients who tested positive for antibodies or via NP RT-PCR had more than a mild illness course and 2 patients did not have any reported illness, suggesting that SARS-CoV-2 may not cause a worse clinical outcome in immunosuppressed children, in contrast to immunocompromised adults.

SARS-CoV-2 growth, furin-cleavage-site adaptation and neutralization using serum from acutely infected, hospitalized COVID-19 patients

SARS-CoV-2, the causative agent of COVID-19, emerged at the end of 2019 and by mid-June 2020, the virus has spread to at least 215 countries, caused more than 8,000,000 confirmed infections and over 450,000 deaths, and overwhelmed healthcare systems worldwide. Like SARS-CoV, which emerged in 2002 and caused a similar disease, SARS-CoV-2 is a betacoronavirus. Both viruses use human angiotensin-converting enzyme 2 (hACE2) as a receptor to enter cells. However, the SARS-CoV-2 spike (S) glycoprotein has a novel insertion that generates a putative furin cleavage signal and this has been postulated to expand the host range. Two low passage (P) strains of SARS-CoV-2 (Wash1: P4 and Munich: P1) were cultured twice in Vero-E6 cells and characterized virologically. Sanger and MinION sequencing demonstrated significant deletions in the furin cleavage signal of Wash1: P6 and minor variants in the Munich: P3 strain. Cleavage of the S glycoprotein in SARS-CoV-2-infected Vero-E6 cell lysates was inefficient even when an intact furin cleavage signal was present. Indirect immunofluorescence demonstrated the S glycoprotein reached the cell surface. Since the S protein is a major antigenic target for the development of neutralizing antibodies we investigated the development of neutralizing antibody titers in serial serum samples obtained from COVID-19 human patients. These were comparable regardless of the presence of an intact or deleted furin cleavage signal. These studies illustrate the need to characterize virus stocks meticulously prior to performing either in vitro or in vivo pathogenesis studies.

A novel approach to remove interference of therapeutic monoclonal antibody with serum protein electrophoresis

OBJECTIVES

Multiple myeloma (MM) is characterized by malignant growth of plasma cells, usually producing a monoclonal antibody (mAb). New treatments for MM include therapeutic monoclonal antibodies (tmAbs), but patients treated with tmAb demonstrate interference on serum electrophoresis (SPE) and immunoprecipitation electrophoresis (IEP). Evaluation of treatment efficacy and determination of MM remission include SPE and IEP which identifies mAb, but cannot differentiate between disease associated mAb and tmAb. We hypothesized that tmAb could be removed from patient sera before testing by SPE and IEP to provide accurate diagnoses for clinicians.

DESIGN AND METHODS

We developed the Antigen Specific therapeutic monoclonal Antibody Depletion Assay (ASADA), that utilizes magnetic beads coated with the cognate antigen of the tmAbs, to deplete two different tmAb (daratumumab, elotuzumab) from saline and patient sera and assessed for complete removal of tmAb by SPE and IEP.

RESULTS

We found that tmAb could be efficiently removed from saline and patient sera. ASADA demonstrated acceptable analytical specificity and sensitivity in IEP. Recovery of appropriate quantitative values by SPE was demonstrated with clinically acceptable precision. A single bead cocktail could be used to treat both daratumumab and elotuzumab.

CONCLUSIONS

This demonstrates proof of principle that ASADA can be used to remove current and future tmAb from patient sera, regardless of platform. This research provides for accurate diagnosis, disease monitoring, and remission status in MM patients being treated with tmAb.

Newly Emerging Drugs of Abuse and Their Detection Methods: An ACLPS Critical Review

Objectives

Illicit drug abuse has reached an epidemic level in the United States. Drug overdose has become the leading cause of injury-related deaths since 2008 due to the recent surge of opioid overdose by heroin, controlled prescription drugs, and nonmethadone synthetic opioids. Synthetic designer drugs such as synthetic cathinones ("bath salts") and synthetic cannabinoids ("Spice" and "K2") continue to emerge and attract recreational users.

Methods

The emergence of new drugs of abuse poses a steep challenge for clinical toxicology laboratories. Limited information about the emerging drugs and their metabolism, "rebranding" of the illicit drugs, and a lack of Food and Drug Administration-approved screening methods for these drugs contribute to this difficulty. Here we review detection methods that can aid in identifying emerging drugs of abuse.

Results

One promising approach is the utilization of untargeted drug screening by mass spectrometry. Historically, gas chromatography-mass spectrometry has been the gold standard.

Conclusions

Liquid chromatography-tandem mass spectrometry and liquid chromatography-high-resolution mass spectrometry offer improved detection capability of new drugs with simplified sample preparation, making it the new standard.

Pharmacokinetic and clinical outcomes when ideal body weight is used to dose busulfan in obese hematopoietic stem cell transplant recipients

Weight-based dosing of intravenous busulfan is widely used in hematopoietic cell transplantation. However, a variety of dosing weights have been described. The objective of this retrospective study was to determine the pharmacokinetic impact of using ideal body weight as the initial dosing weight in obese as compared to non-obese transplant recipients. The secondary objectives were to describe the use of alternative dosing weights, the impact on survival, and the rates of toxicities. The mean steady-state concentration was 779.3 ng/mL (n = 82) in the non-obese cohort and 673.7 ng/mL (n = 63) in the obese cohort (p < 0.001). A smaller proportion of concentrations were below goal in the non-obese cohort (10% vs. 41%, p < 0.001). Ideal body weight and adjusted body weights with a 25 and 40% correction factor are appropriate in non-obese patients; adjusted body weights with a 25 and 40% correction factor are appropriate in obese patients. There was no difference in overall survival (p = 0.18); there was a difference in median progression-free survival (1078 vs. 500 days, p = 0.045) in the non-obese compared to obese cohorts. The use of ideal body weight to dose busulfan resulted in lower steady-state concentrations, a larger proportion of subtherapeutic concentrations, and worse progression-free survival in obese patients.

Suppression of circadian secretion of glucagon-like peptide-1 by the saturated fatty acid, palmitate

AIM

Glucagon-like peptide-1 is an incretin hormone secreted by the intestinal L-cell with a circadian rhythm that parallels expression of the core clock gene, Bmal1. Although feeding rats a high-fat/high-sucrose Western diet impairs rhythmic glucagon-like peptide-1 release, the mechanisms underlying this effect remain unclear. Therefore, the aim of this study was to determine the pathway(s) by which the saturated fat, palmitate, a major component of the Western diet, impairs circadian glucagon-like peptide-1 secretion.

METHODS

Murine mGLUTag L-cells were synchronized, and the effects of palmitate pre-treatment on gene expression and glucagon-like peptide-1 secretion were determined, in addition to metabolite quantification, mitochondrial function analysis and enzyme inhibition and activation assays. Glucagon-like peptide-1 secretion was also analysed in ileal crypt cultures from control and Bmal1 knockout mice.

RESULTS

Pre-treatment with palmitate dampened Bmal1 mRNA and protein expression and glucagon-like peptide-1 secretion at 8 but not 20 hours after cell synchronization (P < .05-.001). Glucagon-like peptide-1 release was also impaired in Bmal1 knockout cultures as compared to wild-type controls (P < .001). Palmitate pre-treatment reduced expression of the Bmal1 downstream target, nicotinamide phosphoribosyltransferase, the rate-limiting enzyme in the synthesis of NAD+ . This was paralleled by dampening of total NAD+ levels, as well as impaired mitochondrial function and ATP production (P < .05-.001). Whereas direct inhibition of nicotinamide phosphoribosyltransferase also decreased glucagon-like peptide-1 release, activation of this enzyme restored glucagon-like peptide-1 secretion in the presence of palmitate.

CONCLUSION

Palmitate impairs L-cell clock function at the peak of Bmal1 gene expression, thereby impairing mitochondrial function and ultimately rhythmic glucagon-like peptide-1 secretion.

A Model of Dormant-Emergent Metastatic Breast Cancer Progression Enabling Exploration of Biomarker Signatures

Breast cancer mortality predominantly results from dormant micrometastases that emerge as fatal outgrowths years after initial diagnosis. In order to gain insights concerning factors associated with emergence of liver metastases, we recreated spontaneous dormancy in an all-human ex vivo hepatic microphysiological system (MPS). Seeding this MPS with small numbers (<0.05% by cell count) of the aggressive MDA-MB-231 breast cancer cell line, two populations formed: actively proliferating ("growing"; EdU+), and spontaneously quiescent ("dormant"; EdU-). Following treatment with a clinically standard chemotherapeutic, the proliferating cells were eliminated and only quiescent cells remained; this residual dormant population could then be induced to a proliferative state ("emergent"; EdU+) by physiologically-relevant inflammatory stimuli, lipopolysaccharide (LPS) and epidermal growth factor (EGF). Multiplexed proteomic analysis of the MPS effluent enabled elucidation of key factors and processes that correlated with the various tumor cell states, and candidate biomarkers for actively proliferating (either primary or secondary emergence) versus dormant metastatic cells in liver tissue. Dormancy was found to be associated with signaling reflective of cellular quiescence even more strongly than the original tumor-free liver tissue, whereas proliferative nodules presented inflammatory signatures. Given the minimal tumor burden, these markers likely represent changes in the tumor microenvironment rather than in the tumor cells. A computational decision tree algorithm applied to these signatures indicated the potential of this MPS for clinical discernment of each metastatic stage from blood protein analysis.

Clinical laboratory verification of thyroglobulin concentrations in the presence of autoantibodies to thyroglobulin: comparison of EIA, radioimmunoassay and LC MS/MS measurements in an Urban Hospital

OBJECTIVE

Thyroglobulin (Tg) measurements assess recurrence in post-thyroidectomy thyroid cancer patients. Tg measurements by enzyme immunoassays (EIA) can be falsely elevated by interference from Tg autoantibodies (TgAb). Radioimmunoassay (RIA) is less susceptible to TgAb interference and has been the standard-of-care test for TgAb positive patients. Recently developed liquid chromatography tandem mass spectrometry (LC-MS/MS) methods may eliminate TgAb interference. We assessed the performance of Tg measurements by EIA, RIA and LC-MS/MS to evaluate TgAb interference differences.

RESULTS

We measured TgAb and Tg in 50 plasma samples from 40 patients in whom Tg measurement was part of their routine follow-up and 10 healthy volunteers. Discrepancy between EIA and both LC-MS/MS and RIA was observed at low Tg concentrations (≤ 7.55 ng/mL) in TgAb positive specimens (LC-MS/MS = 1.9 * EIA - 0.03, r = 0.68). RIA and LC-MS/MS Tg measurements in TgAb positive specimens with low Tg concentrations had improved correlation but demonstrated bias (LC MS/MS = 0.6 * RIA - 1.4, r = 0.90). Disagreement between methods may be attributed to LC-MS/MS reported Tg concentrations as undetectable compared to RIA. It seems likely that most discrepant cases are falsely elevated in RIA due to TgAb interference, however, some cases appear below the detection limit of LC-MS/MS; implementation of LC-MS/MS by clinicians will require lower detection limits.