Risk Of False-negative Results Research Articles

Advancing Endocrine Disruptors via In Vitro Evaluation: Recognizing the Significance of the Organization for Economic Co-Operation and Development and United States Environmental Protection Agency Guidelines, Embracing New Assessment Methods, and the Urgent Need for a Comprehensive Battery of Tests.

Efforts are being made globally to improve the evaluation and understanding of endocrine-disrupting chemicals. Recognition of their impact on human health and the environment has stimulated attention and research in this field. Various stakeholders, including scientists, regulatory agencies, policymakers, and industry representatives, are collaborating to develop robust methodologies and guidelines for assessing these disruptors. A key aspect of these efforts is the development of standardized testing protocols and guidelines that aim to provide consistent and reliable methods for identifying and characterizing endocrine disruptors. When evaluating the potential endocrine-disrupting activity of chemicals, no single test is capable of detecting all relevant endocrine-disrupting agents. The test battery approach is designed to reduce the risk of false negative results for compounds with toxic potential. A weight-of-evidence approach is therefore necessary for endocrine disruptor evaluation. This approach considers various types of data from multiple sources, assessing the overall strength, consistency, and reliability of the evidence. OECD guidelines are highly regarded for their scientific rigor, transparency, and consensus-based development process. It is crucial to explore and develop new methodologies that can effectively evaluate the risks associated with potential endocrine disruptors. Integrating these methods into a comprehensive weight-of-evidence framework will enhance risk assessments and facilitate informed decisions regarding the regulation and management of these substances, ensuring the protection of human health and the environment from their adverse effects.

Detection of latent tuberculosis by tuberculin booster in patients with immunosuppressive treatment

Introduction and objectiveOne-third of the world's population has latent tuberculosis. Because it can be reactivated by immunosuppressive treatments, screening is suggested. In Colombia, the tuberculin test with the booster is recommended in this population because of the risk of false negative results and anergy caused by treatments. Currently, the number of patients detected with this second test is unknown, so the primary objective is to determine the percentage of additional positive detections. Materials and methodsFrom 2017 to 2022, a cross-sectional, analytical study was conducted on a group of patients from a rheumatology service who had a tuberculin test and a booster within a year to check for latent tuberculosis. Over the course of a year and three weeks, we looked at the number of patients whose booster tests showed new findings. A study was conducted to see if there were any differences in treatment based on the first tuberculin result. ResultsA tuberculin test was performed on 674 subjects, of whom 496 were immunosuppressed. From the 382 whose test was negative, 191 and 74 booster tests were performed within a year and three weeks; 8 (4.1%) and 3 (3.6%) were positive, respectively. When evaluating the differences in treatments between the groups with a positive and negative first tuberculin test, significant differences were found. Use of prednisolone at 5mg or more per day (p=.02) and three immunosuppressants (p=.005) was more frequent in negative tuberculin tests. ConclusionsIt can be said that the booster test raises the number of people with latent tuberculosis by 4%. More use of prednisolone at 5mg/day or three immunosuppressants in the group with the negative tuberculin test was found to be statistically significant.

Isolation and characterization of an atypical Mycoplasma gallisepticum strain showing a new mgc2 variant

Mycoplasma gallisepticum (MG) is an important pathogen of the poultry industry able to cause chronic respiratory disease in chickens and infectious sinusitis in turkeys. Despite the application of biosecurity measures and the availability of vaccines for chickens, monitoring systems routinely applied for MG detection are still essential for infection control. Pathogen isolation is time-consuming and not suitable for rapid detection, albeit it is a compulsory step for genetic typing and antimicrobial susceptibility evaluation of single strains. The mgc2 gene is a species-specific molecular target adopted by most of the PCR protocols available for MG diagnosis, which are also included in the WOAH Terrestrial Manual. We describe the case of an atypical MG strain, isolated in 2019 from Italian turkeys, characterized by an mgc2 sequence not detectable by common endpoint PCR primers. Considering the potential risk of false negative results during diagnostic screenings with the endpoint protocol, the authors propose an alternative mgc2 PCR endpoint protocol, named MG600, which should be considered as a further diagnostic tool.

Liquid Biopsies in Lung Cancer.

As lung cancer has the highest cancer-specific mortality rates worldwide, there is an urgent need for new therapeutic and diagnostic approaches to detect early-stage tumors and to monitor their response to the therapy. In addition to the well-established tissue biopsy analysis, liquid-biopsy-based assays may evolve as an important diagnostic tool. The analysis of circulating tumor DNA (ctDNA) is the most established method, followed by other methods such as the analysis of circulating tumor cells (CTCs), microRNAs (miRNAs), and extracellular vesicles (EVs). Both PCR- and NGS-based assays are used for the mutational assessment of lung cancer, including the most frequent driver mutations. However, ctDNA analysis might also play a role in monitoring the efficacy of immunotherapy and its recent accomplishments in the landscape of state-of-the-art lung cancer therapy. Despite the promising aspects of liquid-biopsy-based assays, there are some limitations regarding their sensitivity (risk of false-negative results) and specificity (interpretation of false-positive results). Hence, further studies are needed to evaluate the usefulness of liquid biopsies for lung cancer. Liquid-biopsy-based assays might be integrated into the diagnostic guidelines for lung cancer as a tool to complement conventional tissue sampling.

Cystathionine Beta-Synthase Deficiency: Three Consecutive Cases Detected in 40 Days by Newborn Screening in Emilia Romagna (Italy) and a Comprehensive Review of the Literature.

Cysthiatonine beta-synthase (CBS) deficiency (CBSD) is an autosomal recessive rare disorder caused by variations on CBS that leads to impaired conversion of homocysteine (Hcy) to cystathionine. Marked hyperhomocysteinemia is the hallmark of the disease. The administration of pyridoxine, the natural cofactor of CBS, may reduce total plasma Hcy. Patient phenotype is classified on pyridoxine responsivity in two groups: pyridoxine-responsive and non-responsive patients. Ectopia lentis, bone deformities, developmental delay, and thromboembolism are the classic signs and symptoms of the disease. Early diagnosis and treatment impact patients' natural history. Therapy aims to lower promptly and maintain Hcy concentrations below 100 μmol/L. Depending on the patient's phenotype, the treatment goals could be obtained by the administration of pyridoxine and/or betaine associated with a methionine-restricted diet. CBSD could be diagnosed in the early days of life by expanded newborn screening (ENS), however, the risk of false negative results is not negligible. In Emilia-Romagna (Italy), during the first 10 years of screening experience, only three cases of CBSD identified have been diagnosed, all in the last two years (incidence 1:118,000 live births). We present the cases and a comprehensive review of the literature to emphasize the role of ENS for early diagnosis of CBSD and its potential pitfalls, reiterating the need for a more effective method to screen for CBSD.

Evaluation of a MALDI-TOF MS cephalosporinase assay for blood culture isolates

Objectives: Rapid detection of beta-lactamases has the potential to improve antimicrobial stewardship and sepsis outcomes. The aim of this study was to evaluate a recently TGA-approved cephalosporinase detection method utilising matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) on blood culture isolates. This was compared to standard antimicrobial susceptibility testing and phenotypic cephalosporinase detection. Methods: A total of 114 gram negative blood culture isolates were retrospectively analysed. Isolates were selected to either be ceftriaxone non-susceptible by Vitek 2 semi-automated system (version 08.01; bioMerieux, USA, AST-N246 card) (n=31) and/or demonstrate an inducible cephalosporinase or ESBL on disc approximation testing (n=32). This cohort was compared to an equal number of ceftriaxone-susceptible isolates by Vitek 2 (n=57). The range of organisms included Escherichia coli (n=62), followed by Serratia marcescens (n=12), Pseudomonas aeruginosa (n=11), Enterobacter cloacae complex (n=10), Klebsiella aerogenes (n=5), Klebsiella pneumoniae (n=3), Klebsiella oxytoca (n=3), Morganella morganii (n=3), Acinetobacter calcoaceticus-A. baumannii complex (n=3), and Citrobacter freundii (n=2). Sub-cultured colonies were prepared with the MBT STAR-Cepha IVD Kit and third-generation cephalosporin hydrolysis was detected using the MBT STAR-BL IVD Module (Bruker Daltronics) on MALDI-TOF MS after 30 min incubation time. Results: The MALDI-TOF MS assay sensitivity and specificity for third-generation cephalosporinase activity was 61.3% and 77.1% respectively. The assay detected 11/11 (100%) ESBL producers and 5/6 (83.3%) AmpC type third-generation cephalosporinase producers. Additionally, third generation cephalosporinase activity was detected by the MALDI-TOF MS assay in 17 of 26 inducible cephalosporinase positive isolates (65.4%) that tested susceptible to ceftriaxone by Vitek 2. Of all species included, Pseudomonas aeruginosa had the lowest concordance of MALDI-TOF MS and Vitek 2 results, with only 1/11 isolates (9%) positive by MALDI-TOF MS. Conclusions: Overall the MALDI-TOF MS cephalosporinase assay lacked sensitivity in detection of third generation cephalosporinases compared to antimicrobial susceptibility testing by Vitek 2. The risk for false negative results in screening for resistance in blood culture isolates is too high to consider its implementation in the standard workflow, although there may be possible benefit in detecting ESBL and ampC type cephalosporinase activity following species identification as an alternative to standard disc approximation testing.

Pooling samples to increase testing capacity with Xpert Xpress SARS-CoV-2 during the Covid-19 pandemic in Lao People's Democratic Republic.

The COVID-19 pandemic created the need for large-scale testing of populations. However, most laboratories do not have sufficient testing capacity for mass screening. We evaluated pooled testing of samples, as a strategy to increase testing capacity in Lao PDR. Samples of consecutive patients were tested in pools of four using the Xpert Xpress SARS CoV-2 assay. Positive pools were confirmed by individual testing, and we describe the performance of the test and savings achieved. We also diluted selected positive samples to describe its effect on the assays CT values. 1,568 patients were tested in 392 pools of four. 361 (92.1%) pools were negative and 31 (7.9%) positive. 29/31 (93.5% (95%CI 77-99%) positive pools were confirmed by individual testing of the samples but, in 2/31 (6.5%) the four individual samples were negative, suggesting contamination. Pools with only one positive sample had higher CT values (lower RNA concentrations) than the respective individual samples, indicating a dilution effect, which suggested an increased risk of false negative results with dilutions >1:10. However, this risk may be low if the prevalence of infection is high, when pools are more likely to contain more than one positive sample. Pooling saved 67% of cartridges and substantially increased testing capacity. Pooling samples increased SARS-CoV-2 testing capacity and resulted in considerable cartridge savings. Given the need for high-volume testing, countries may consider implementation of pooling for SARS-CoV-2 screening.

Clinical characteristics and comparison of longitudinal qPCR results from different specimen types in a cohort of ambulatory and hospitalized patients infected with monkeypox virus.

BackgroundThe ongoing monkeypox virus outbreak includes at least 7553 confirmed cases in previously non-endemic countries worldwide as of July 2022. Clinical presentation has been reported as highly variable, sometimes lacking classically described systemic symptoms, and only small numbers of cutaneous lesions in most patients. The aim of this study was to compare clinical data with longitudinal qPCR results from lesion swabs, oropharyngeal swabs and blood in a well characterized patient cohort.Methods16 male patients (5 hospitalized, 11 outpatients) were included in the study cohort and serial testing for monkeypox virus-DNA carried out in various materials throughout the course of disease. Laboratory analysis included quantitative PCR, next-generation sequencing, immunofluorescence tests and virus isolation in cell culture.ResultsAll patients were male, between age 20 and 60, and self-identified as men having sex with men. Two had a known HIV infection, coinciding with an increased number of lesions and viral DNA detectable in blood. In initial- and serial testing, lesion swabs yielded viral DNA-loads at, or above 106 cp/ml and only declined during the third week. Oropharyngeal swabs featured lower viral loads and returned repeatedly negative in some cases. Viral culture was successful only from lesion swabs but not from oropharyngeal swabs or plasma.DiscussionThe data presented underscore the reliability of lesion swabs for monkeypox virus-detection, even in later stages of the disease. Oropharyngeal swabs and blood samples alone carry the risk of false negative results, but may hold value in pre-/asymptomatic cases or viral load monitoring, respectively.

Usage of FTA® Classic Cards for Safe Storage, Shipment, and Detection of Arboviruses.

Infections caused by arthropod-borne RNA viruses are overrepresented among emerging infectious diseases. Effective methods for collecting, storing, and transporting clinical or biological specimens are needed worldwide for disease surveillance. However, many tropical regions where these diseases are endemic lack analytical facilities and possibility of continuous cold chains, which presents challenges from both a biosafety and material preservation perspective. Whatman® FTA® Classic Cards may serve as an effective and safe option for transporting hazardous samples at room temperature, particularly for RNA viruses classified as biosafety level (BSL) 2 and 3 pathogens, from sampling sites to laboratories. In this study, we investigated the biosafety and perseverance of representative alpha- and flaviviruses stored on FTA® cards. To evaluate the virus inactivation capacity of FTA® cards, we used Sindbis virus (SINV), chikungunya virus (CHIKV), and Japanese encephalitis virus (JEV). We inoculated susceptible cells with dilution series of eluates from viral samples stored on the FTA® cards and observed for cytopathic effect to evaluate the ability of the cards to inactivate viruses. All tested viruses were inactivated after storage on FTA® cards. In addition, we quantified viral RNA of JEV, SINV, and tick-borne encephalitis virus (TBEV) stored on FTA® cards at 4 °C, 25 °C, and 37 °C for 30 days using two reverse transcriptase quantitative PCR assays. Viral RNA of SINV stored on FTA® cards was not reduced at either 4 °C or 25 °C over a 30-day period, but degraded rapidly at 37 °C. For JEV and TBEV, degradation was observed at all temperatures, with the most rapid degradation occurring at 37 °C. Therefore, the use of FTA® cards provides a safe and effective workflow for the collection, storage, and analysis of BSL 2- and 3-virus RNA samples, but there is a risk of false negative results if the cards are stored at higher temperatures for long periods of time. Conscious usage of the cards can be useful in disease surveillance and research, especially in tropical areas where transportation and cold chains are problematic.

Systematic Retesting for Helicobacter pylori: The Potential Overestimation of Suppressive Conditions.

Background and Aims In contrast to guideline recommendations, endoscopic testing for Helicobacter pylori is frequently performed under Helicobacter pylori suppressive conditions, e.g., intake of proton-pump inhibitors (PPI), preceded antibiotic treatment, or recent gastrointestinal bleeding. Our study's aim was to retest patients with—under suppressive conditions—negative test results. This was carried out in order to examine the rate of false negative tests previously gathered under suppressive conditions. Methods The trial was conducted in a large patient collective in a university hospital. Every elective esophagogastroduodenoscopy from in- and outpatients was included. Prior to endoscopy, suppressive conditions were collected via standardized questionnaire. If Helicobacter pylori testing was indicated, both helicobacter urease test and histology were performed in analogy to the Sydney classification. In case of a negative result under suppressive conditions, the patient was reinvited after, if possible, withdrawal of suppressive condition in order to perform a urea breath test (UBT). Results 1,216 patients were included (median 59 years, 72.0% inpatients, 28.0% outpatients). Overall, 60.6% (737) were under Helicobacter pylori suppressive conditions. The main suppressive condition was intake of PPIs (54.5%). In 53.7% (653) of all included cases, Helicobacter pylori testing was performed. Of those, 14.1% (92) had a positive test, and 85.9% (561) were negative. Out of the patients with negative result, 50.8% (285) were tested under suppressive conditions and consequently invited for retesting via UBT. In 20.4% (45), suppressive conditions could not be ceased. In 22.8% (65), retesting was conducted. Of those, 98.5% (64) congruently presented a negative result again, and only 1.5% (1) was positive for Helicobacter pylori. Conclusion Many patients undergoing esophagogastroduodenoscopy in everyday clinical practice are tested for Helicobacter pylori under suppressive conditions leading to a potentially higher risk of false negative results. However, our research shows that this issue might be overestimated.

HIV Self-testing Among Previously Diagnosed HIV-Positive People in Khayelitsha, South Africa: No Evidence of Harm but may Facilitate Re-engagement in ART Care

In South Africa, where an estimated 34% of nearly 7-million HIV-positive people were not on antiretroviral therapy (ART) in 2019, innovative strategies to diagnose and link people to care are needed. HIV self-testing (HIVST) is one such strategy. However, there is concern that access to HIVST might result in re-testing among people on ART, with a risk of false negative results and disengagement from care. Between November 2017 and December 2018, HIVST kits were distributed at a private pharmacy and at HIV testing outreach events. Each participant was instructed to report their result via SMS and those who did not were followed-up telephonically 10 days later. Electronic medical records of participants were searched for evidence of HIV services 6 months before and after enrollment. Of 1482 participants, 163 (11%) were previously diagnosed HIV-positive prior to taking the test. Of these, 123 reported a result, however 87% reported a negative result. Of the 163 previously diagnosed, 84 were not in ART care prior to the test, with 15 (18%) linking to care post-test. Of 79 who were in ART care prior to the test, 76 (96%) remained in care, even though 51 (67%) had reported a negative result. Overall, 29% of participants reported their result via SMS, and 48% when telephoned. Despite efforts to dissuade them, some previously diagnosed HIV-positive utilised HIVST. For those disengaged from care this may facilitate re-engagement. Self-testing among those already in care, regardless of the reported result, did not disrupt their treatment, and their reasons for doing the test remain unclear.

Malaria prevalence and performance of diagnostic tests among patients hospitalized with acute undifferentiated fever in Zanzibar

BackgroundControl efforts in Zanzibar reduced the burden of malaria substantially from 2000 to 2015, but re-emergence of falciparum malaria has been observed lately. This study evaluated the prevalence of malaria and performance of routine diagnostic tests among hospitalized fever patients in a 1.5 years period in 2015 and 2016.MethodsFrom March 2015 to October 2016, paediatric and adult patients hospitalized with acute undifferentiated fever at Mnazi Mmoja Hospital, Zanzibar were included. The malaria prevalence, and performance of rapid diagnostic test (RDT) and microscopy, were assessed using polymerase chain reaction (PCR) as gold standard.ResultsThe malaria prevalence was 9% (63/731). Children under 5 years old had lower malaria prevalence (5%, 14/260) than older children (15%, 20/131, p = 0.001) and persons aged 16 to 30 years (13%, 15/119, p = 0.02), but not different from persons over 30 years old (6%, 14/217, p = 0.7). All cases had Plasmodium falciparum infection, except for one case of Plasmodium ovale. Ten malaria patients had no history of visiting mainland Tanzania. The RDT had a sensitivity of 64% (36/56) and a specificity of 98% (561/575), and microscopy had a sensitivity of 50% (18/36) and  a specificity of 99% (251/254), compared to PCR. The malaria parasitaemia was lower in patients with false negative results on RDT (median 7 × 103 copies/µL, interquartile range [IQR] 2 × 103 – 8 × 104, p = 0.002) and microscopy (median 9 × 103 copies/µL, IQR 8 × 102 – 7 × 104, p = 0.006) compared to those with true positive RDT (median 2 × 105 copies/µL, IQR 3 × 104 – 5 × 105) and microscopy (median 2 × 105 copies/µL, IQR 6 × 104 – 5 × 105).ConclusionsThe study emphasizes that malaria was a frequent cause of febrile illness in hospitalized patients in Zanzibar in the years 2015-2016, particularly among school age children and young adults. We found evidence of autochthonous malaria transmission in Zanzibar. Compared to PCR, both RDT and microscopy had low sensitivity, and false negative results were associated with low parasitaemia. While low parasitaemia identified only by PCR in a semi-immune individual could be coincidental and without clinical relevance, clinicians should be aware of the risk of false negative results on routine tests.

Isothermal gene amplification coupled MALDI-TOF MS for SARS-CoV-2 detection.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been spreading worldwide for more than a year and has undergone several mutations and evolutions. Due to the lack of effective therapeutics and long-active vaccines, accurate and large-scale screening and early diagnosis of infected individuals are crucial to control the pandemic. Nevertheless, the current widely used RT-qPCR-based methods suffer from complicated temperature control, long processing time and the risk of false-negative results. Herein, we present a three-way junction induced exponential rolling circle amplification (3WJ-eRCA) combined MALDI-TOF MS assay for SARS-CoV-2 detection. The assay can detect simultaneously the target nucleocapsid (N) and open reading frame 1 ab (orf1ab) genes of SARS-CoV-2 in a single test within 30 min, with an isothermal process (55 °C). High specificity to discriminate SARS-CoV-2 from other coronaviruses, like SARS-CoV, MERS-CoV and bat SARS-like coronavirus (bat-SL-CoVZC45), was observed. We have further used the method to detect pseudovirus of SARS-CoV-2 in various matrices, e.g. water, saliva and urine. The results demonstrated a great potential of the method for large scale screening of COVID-19, which is an important part of the pandemic control.

Factors determining non-attendance in breast cancer screening among women in the Netherlands: a national study.

Breast cancer is one of the most common types of cancer among women. National mammography screening programs can detect breast cancer early, but attendance rates have been decreasing in the Netherlands over the past decade. Non-attendees reported that overdiagnosis, the risk of false-negative results, x-ray exposure and mammography pain could be barriers to attendance, but it is not clear whether these disadvantages explain non-attendance and in which situations they are considered barriers. We conducted a national survey among 1227 Dutch women who did not attend mammography screening appointments in 2016. Logistic regression models were used to identify factors that influenced the likelihood of the abovementioned disadvantages leading to non-attendance. The results showed that the doctor's opinion increased the likelihood of the risk of false-negative being perceived as a reason for non-attendance. Moreover, opportunistic screening increased the likelihood that the risk of false-negative, overdiagnosis and x-ray exposure would lead to non-attendance. Women with lower education levels were less likely to consider overdiagnosis and x-ray exposure as reasons for non-attendance, while women who had not undergone mammography screening before were more likely to reject the screening invitation because of concerns about x-ray exposure and mammography pain. These findings indicate how we can address the specific concerns of different groups of women in the Netherlands to encourage them to attend potentially life-saving breast-screening appointments. Screening organizations could provide accurate and unbiased information on the effectiveness of mammography screening to GPs, putting them in a better position to advise their patients.

LuNER: Multiplexed SARS-CoV-2 detection in clinical swab and wastewater samples.

Clinical and surveillance testing for the SARS-CoV-2 virus relies overwhelmingly on RT-qPCR-based diagnostics, yet several popular assays require 2–3 separate reactions or rely on detection of a single viral target, which adds significant time, cost, and risk of false-negative results. Furthermore, multiplexed RT-qPCR tests that detect at least two SARS-CoV-2 genes in a single reaction are typically not affordable for large scale clinical surveillance or adaptable to multiple PCR machines and plate layouts. We developed a RT-qPCR assay using the Luna Probe Universal One-Step RT-qPCR master mix with publicly available primers and probes to detect SARS-CoV-2 N gene, E gene, and human RNase P (LuNER) to address these shortcomings and meet the testing demands of a university campus and the local community. This cost-effective test is compatible with BioRad or Applied Biosystems qPCR machines, in 96 and 384-well formats, with or without sample pooling, and has a detection sensitivity suitable for both clinical reporting and wastewater surveillance efforts.

Treatment of Relapsed/Refractory Waldenström Macroglobulinemia Patients: Final Clinical and Molecular Results of the Phase II Brb (Bendamustine, Rituximab and Bortezomib) Trial of the Fondazione Italiana Linfomi (FIL)

IntroductionSymptomatic patients with relapsed/refractory Waldenström Macroglobulinemia (RR-WM) treated with standard rituximab plus chemotherapy as second-line salvage therapy, generally show a 18-months progression free survival (PFS) of about 50%. On behalf of the Fondazione Italiana Linfomi, a multicenter phase II study was designed to assess whether a combination of bendamustine, rituximab and bortezomib (BRB) (EudraCT Number:2013-005129-22) could be considered a promising new treatment in this setting.Patients and MethodsThis single-arm phase II study tested the hypothesis that 18-months PFS is at least 65%. The required sample size was 38 patients (alpha=0.10; beta=0.25; minimum follow up=24 months). Treatment plan provided: rituximab 375 mg/m2 intravenously on day 1 followed by intravenously bendamustine 90 mg/m2 on day 1 and 2 and subcutaneous bortezomib 1.3 mg/m2 on day 1, 8, 15 and 22, every 28 days for 6 months (6 cycles).MYD88 L265P and CXCR4 S338X mutations were tested by ddPCR in bone marrow (BM), plasma and peripheral blood (PB) samples, both at baseline (as mutational screening) and at the end of treatment (for minimal residual disease purposes, MRD).ResultsMedian age was 66.8 years (8 patients were older than 75 years). Many patients had features of advanced disease such as cytopenia (anemia 71%, thrombocytopenia 20%), systemic symptoms (40%) and symptomatic splenomegaly (24%). Sixteen (42%) patients had at least one comorbidity, mostly cardiovascular disease (21%) or metabolic disorders (16%), such as diabetes mellitus.Thirty patients completed six cycles, 7 patients stopped therapy for toxicity and 1 for progressive disease. Overall response rate at the end of therapy was 82%, including 4 (11%) complete, 15 (39%) very good partial, 12 (32%) partial responses according to IWM response criteria.At 18, 24, and 30 months PFS was 84% (95% CI 68-92%), 81% (95%CI 65-91) and 79% (95%CI 62-89) respectively. At 18 months OS was 92% (95%CI 77-97%) and no deaths were observed between 18 and 30 months. Nineteen patients (50%) experienced grade ≥3 hematological toxicity, mainly thrombocytopenia, 12 patients (31.5%) developed grade ≥3 extra-hematological toxicity of which only one cutaneous toxicity related to bendamustine. Bortezomib-related nervous system disorders were observed in 6 patients (5 of grade 1-2 and 1 of grade 3), with no discontinuations.Mutational data were available for 21 patients: all patients scored MYD88 L265P in BM, 18/19 (95%) in plasma and only 18/21 (86%) in PB, prospectively confirming the risk of false negative results when only PB of rituximab pre-treated patients is analyzed. CXCR4 S338X was detected only in one patient at baseline. MRD negativization rates after treatment differed across investigated tissues: in detail, 5/17 (29%) in BM, 6/14 (43%) in plasma and 12/16 (75%) in PB. Overall, a good concordance was observed between BM and plasma (Cohen's kappa= 0.714), suggesting the possibility of avoiding BM aspiration for mutational screening and MRD analysis.ConclusionThe final results of FIL BRB phase II trial showed that BRB regimen, used as second-line therapy, is an effective and well-tolerated salvage treatment for RR-WM patients. The deep anti-tumor activity of the novel combination is highlighted by an absolute increase of PFS rate in comparison to historical controls (30-months PFS of 79%), as well as by high rates of clinical response, with an ORR (CR+VGPR+PR) of 82% (95%CI 66-92). Moreover, MRD monitoring showed promising efficacy of BRB regimen in clearing the residual disease. DisclosuresBenevolo: Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Amgen: Speakers Bureau. Ferrero: Morphosys: Research Funding; Servier: Speakers Bureau; EUSA Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Gilead: Research Funding, Speakers Bureau; Incyte: Membership on an entity's Board of Directors or advisory committees; Clinigen: Membership on an entity's Board of Directors or advisory committees. Cavallo: ROCHE: Membership on an entity's Board of Directors or advisory committees; Servier: Speakers Bureau; Gilead: Speakers Bureau. Gaidano: Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astrazeneca: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Beigene: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Musuraca: janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; incyte: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Varettoni: AstraZeneca: Membership on an entity's Board of Directors or advisory committees; beigene: Membership on an entity's Board of Directors or advisory committees; janssen: Membership on an entity's Board of Directors or advisory committees; roche: Membership on an entity's Board of Directors or advisory committees. Vitolo: Gilead: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Kite: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

667. Next Generation Sequencing of Microbial Cell Free DNA in the Diagnosis and Treatment of Infectious Disease in Children: When Does the Result Justify the Cost?

BackgroundPathogen testing using next-generation sequencing of microbial cell-free DNA (NGS cfDNA) is a promising diagnostic tool to identify pathogens that might not be detected using conventional lab evaluation. Considering the cost of this test, it is important to determine when it is most useful to the plan of care (POC). Figure 1. Unit of admission among cases Figure 2. Patient characteristics in cases determined to be valuable and not valuable to the plan of care (POC) MethodsIn this retrospective study, we collected data from the medical charts of 50 consecutive NGS cfDNA tests in a free-standing children’s hospital. We evaluated patients for demographics, underlying conditions, diagnosis at time of testing, conventional laboratory testing and timing, medical treatment, and NGS cfDNA test results for clinical relevance or false negative results compared to conventional testing. The primary goal was to identify patients for whom the NGS cfDNA testing affected the POC. Charts were reviewed, and determinations regarding whether the result influenced the POC were confirmed by a provider.ResultsWe were unable to differentiate patients with clinically valuable NGS cfDNA results (Fig 1 & 2). Among those with NGS cfDNA results valuable to the POC (n=22), both negative and positive testing guided POC (13 valuable negative vs. 9 diagnostic cases). In the total sample, 5 cases (10%) had a clinically relevant pathogen identified through conventional testing, but not through NGS cfDNA and 2 cases had antimicrobial resistance on culture, which is not detected by NGS cfDNA. ConclusionWhile we did not find a specific clinical profile for NGS cfDNA use, positive results were essential to the diagnosis in 18% of cases with otherwise negative laboratory evaluation for the pathogen identified in NGS cfDNA. Negative tests affected the POC in 26% of cases by avoiding unnecessary antimicrobials in high risk immunocompromised patients and patients that presented with low-risk of infection, but unclear disease process. Caution must be exercised with reliance on this test with respect to antimicrobial resistance and risk of false negative results. Disclosures All Authors: No reported disclosures

The Role of Skin Tests in the Prevention and Diagnosis of Hypersensitivity Reactions to Platinum Agents in Gynecological Cancer: A Single-Center Italian Retrospective Study.

Simple SummaryThe development of hypersensitivity reactions to platinum agents in patients with gynecological cancers limits the use of platinum re-treatment for recurrent disease. In those patients who developed a hypersensitivity reactions during treatment with platinum agents it could be safer to undergo allergy diagnosis. This approach includes the in-vivo skin tests before re-exposure to the platinum agent, especially in those patients who have to undergo a 2nd or 3rd line therapy. In our experience, skin test for platinum agents resulted in a simple and sensitive tool for the diagnosis and prevention of hypersensitivity reactions to platinum agents. In addition, this approach identified a sub-group of patients that became sensitized to the platinum agent during the previous platinum-based therapy. Background: Hypersensitivity reactions (HSR)s to platinum agents are increasing in frequency, due to their extensive use and repeated exposures in patients with increased life expectancy. The aims of our study are to analyze the frequency of both type I and type IV HSRs in patients with gynecological cancer treated with (CBDCA) carboplatin and/or (CDDP) cisplatin, to evaluate the role of skin tests in the diagnosis and prevention of HSRs. Methods: From 2011 to 2018, we evaluated 124 consecutive female patients previously treated with CBDCA and/or CDDP for gynecological cancer. All patients, including those with and without HSR to previous platinum-based therapy, underwent in-vivo skin tests for platinum agents before starting the second or more therapeutic lines. To reduce the risk of false negative results, patients with a negative skin test at the first evaluation were re-tested after 3 weeks from the platinum re-exposure. Results: Among the 124 patients evaluated, 58 (47%) experienced HSRs to at least one platinum agent: 35% were to CBDCA, 5% to CDDP, 7% to both. Fifty-six of the 58 HSRs were classified as immediate and two delayed. Skin tests confirmed an IgE-dependent mechanism in 67% of patients with immediate-HSRs to CBDCA and identified a cross-reactivity between platinum agents in 18% of patients. Moreover, among those who had never developed an HSRs during platinum-based therapy, in-vivo skin tests identified 12% of sensitized patients. Conclusions: On the basis of our findings, skin test for platinum agents is a simple and sensitive tool for the diagnosis and prevention of HSRs to CBDCA and/or CDDP and can be useful for detecting possible cross-reactivity among platinum agents.

Computed tomography angiography scoring systems and the role of skull defects in the confirmation of brain death

To assess and compare all current computed tomography angiography (CTA) scoring systems for the diagnostic workup of brain death (BD) to digital subtraction angiography (DSA) and clinical tests. Fifty-two patients with a clinical suspicion of BD underwent CTA and subsequently DSA. The diagnostic performance of all current CTA scoring systems was compared to that of DSA, in all patients with a suspicion of BD. A comparison to clinical tests was made only in DSA-positive for BD patients (n = 49), since in DSA-negative BD patients (n = 3) clinical tests were not performed. Further subgroup analysis was performed in relation to skull defects (SDs) stratification. Statistical analysis was conducted by applying statistics-contingency tables, Cochran’s-Q test and McNemar’s test. The CTA -10, and -7- and all 4-point scoring systems, showed overall sensitivities of 81,6%, 87.8% and 95.9% respectively and 100% specificity, when compared to DSA. In patients with a clinical verification of BD, the CTA -10 and -7-point scoring systems were significantly inferior to clinical tests (p = 0.004 and p = 0.031), while the 4-point scoring systems showed no such difference (p = 0.5). All 4-point scoring systems showed 100% sensitivity in patients with a minor SD or no SD. In patients with a major SD, all CTA scoring systems (− 10, − 7- and all 4-point) were less sensitive (62.5%, 62.5% and 75% respectively). The presence of a major SD was associated with an 8 × relative risk for false negative results in all 4-point scoring systems. CTA showed excellent diagnostic performance in patients with a suspicion of BD. The 4-point CTA scoring systems are the most sensitive for the diagnosis of BD, although in patients with a major SD patient, the role of CTA is ambiguous.

Spatiotemporal imaging and pharmacokinetics of fluorescent compounds in zebrafish eleuthero-embryos after different routes of administration

Zebrafish (Danio rerio) is increasingly used to assess the pharmacological activity and toxicity of compounds. The spatiotemporal distribution of seven fluorescent alkyne compounds was examined during 48 h after immersion (10 µM) or microinjection (2 mg/kg) in the pericardial cavity (PC), intraperitoneally (IP) and yolk sac (IY) of 3 dpf zebrafish eleuthero-embryos. By modelling the fluorescence of whole-body contours present in fluorescence images, the main pharmacokinetic (PK) parameter values of the compounds were determined. It was demonstrated that especially in case of short incubations (1–3 h) immersion can result in limited intrabody exposure to compounds. In this case, PC and IP microinjections represent excellent alternatives. Significantly, IY microinjections did not result in a suitable intrabody distribution of the compounds. Performing a QSPkR (quantitative structure-pharmacokinetic relationship) analysis, LogD was identified as the only molecular descriptor that explains the final uptake of the selected compounds. It was also shown that combined administration of compounds (immersion and microinjection) provides a more stable intrabody exposure, at least in case of a prolonged immersion and compounds with LogD value > 1. These results will help reduce the risk of false negative results and can offer an invaluable input for future translational research and safety assessment applications.