Laboratory-developed Tests Research Articles

Analytical validation of tests in laboratories of anatomic pathology: a Belgian population-based study

Laboratories of anatomic pathology have to validate each analytical test before it is implemented in daily routine. However, evidence-based guidelines regarding validation of analytical tests are limited. A 2016 survey on test validation was performed in all 77 licensed Belgian anatomic pathology laboratories in order to evaluate the implementation and to highlight the current issues of test validation in Belgian anatomic pathology laboratories. Therefore, standard operating procedures for test validation and validation reports were evaluated for the presence of predefined items. Separate validation procedures for CE/IVD-labeled, laboratory-modified and laboratory-developed tests and a description of how each performance characteristic was validated were lacking in 51 (66 %) laboratories. Moreover, only 9 (12 %) laboratories reported to have written procedures for when and how analytical tests need to be revalidated. Better results were observed regarding the description of the performance characteristics, the co-workers involved, recording and archiving of results and raw data, the content of the validation report, ongoing validation, release and implementation into daily routine. Contrary to the evaluation results of the procedures for test validation, better results for the content of the validation reports were obtained. A lack of clear and predefined objective acceptance criteria for each determined performance characteristic was the most common shortcoming observed in validation reports in Belgian anatomic pathology laboratories. In conclusion, there appears to be a need for further development of guidelines for validation and revalidation of analytical tests performed in anatomic pathology laboratories.

External quality assessment demonstrates that PD-L1 22C3 and SP263 assays are systematically different.

PD‐L1 inhibitors are part of first line treatment options for patients with advanced non‐small cell lung cancer. PD‐L1 immunohistochemistry (IHC) assays act as either a companion or a complementary diagnostic. The purpose of this study is to describe the experience of external quality assurance (EQA) provider UK NEQAS ICC and ISH with the comparison of different PD‐L1 assays used in daily practice. Three EQA rounds (pilot, run A and run B) were carried out using formalin fixed paraffin embedded samples with sample sets covering a range of epitope concentrations, including ‘critical samples’ near to clinical threshold cut‐offs. An expert panel (n = 4) evaluated all returned slides simultaneously and independently on a multi‐header microscope together with the participants own in‐house control material. The tonsil sample was evaluated as ‘acceptable’ or ‘unacceptable’, and for the other samples the percentage of PD‐L1 stained tumour cells were estimated in predetermined categories (<1%, 1 to <5%, 5 to <10%, 10 to <25%, 25 to <50%, 50 to <80%, 80 to 100%). In the pilot and the two subsequent runs the number of participating laboratories was 43, 69 and 76, respectively. The pass rate for the pilot run was 67%; this increased to 81% at run A and 82% at run B. For two ‘critical samples’, in runs A and B, 22C3 IHC had significantly higher PD‐L1 expression than SP263 IHC (p < 0.001), whilst the PD‐L1 scores for the other six samples were similar for all assays. In run A the laboratory developed tests (LDTs) using 22C3 scored lower than the commercial 22C3 tests (p = 0.01). After the initial testing, improvement in performance of PD‐L1 IHC is shown for approved and LDT PD‐L1 assays. Equivalency of approved PD‐L1 22C3 and SP263 assays cannot be assumed as the scores cross the clinically relevant thresholds of 1% and 50% PD‐L1 expression.

IBS08.01 Harmonization of PD-L1 IHC Including LDT

IBS08.01 Harmonization of PD-L1 IHC Including LDT

Mapping the binding sites of antibodies utilized in programmed cell death ligand-1 predictive immunohistochemical assays for use with immuno-oncology therapies

Programmed cell death ligand-1 (PD-L1) expression levels in patient tumor samples have proven clinical utility across various cancer types. Several independently developed PD-L1 immunohistochemical (IHC) predictive assays are commercially available. Published studies using the VENTANA PD-L1 (SP263) Assay, VENTANA PD-L1 (SP142) Assay, Dako PD-L1 IHC 22C3 pharmDx assay, Dako PD-L1 IHC 28-8 pharmDx assay, and laboratory-developed tests utilizing the E1L3N antibody (Cell Signaling Technology), have demonstrated differing levels of PD-L1 staining between assays, resulting in conjecture as to whether antibody-binding epitopes could be responsible for discordance between assays. Therefore, to understand the performance of different PD-L1 predictive immunohistochemistry assays, we aimed to distinguish the epitopes within the PD-L1 protein responsible for antibody binding. The sites at which antibody clones SP263, SP142, 22C3, 28-8, and E1L3N bind to recombinant PD-L1 were assessed using several methods, including conformational peptide array, surface plasmon resonance, and/or hydrogen/deuterium exchange mass spectrometry. Putative binding sites were confirmed by site-directed mutagenesis of PD-L1, followed by western blotting and immunohistochemical analysis of cell lines expressing mutant constructs. Our results demonstrate that clones SP263 and SP142 bind to an identical epitope in the cytoplasmic domain at the extreme C-terminus of PD-L1, distinct from 22C3 and 28-8. Using mutated PD-L1 constructs, an additional clone, E1L3N, was also found to bind to the cytoplasmic domain of PD-L1. The E1L3N binding epitope overlaps considerably with the SP263/SP142 binding site but is not identical. Clones 22C3 and 28-8 have binding profiles in the extracellular domain of PD-L1, which differ from one another. Despite identifying epitope binding variance among antibodies, evidence indicates that only the SP142 assay generates significantly discordant immunohistochemical staining, which can be resolved by altering the assay protocol. Therefore, inter-assay discordances are more likely attributable to tumor heterogeneity, assay, or platform variables rather than antibody epitope.

False-negative errors in next-generation sequencing contribute substantially to inconsistency of mutation databases.

BackgroundMore than 11,000 laboratories and companies developed their own next-generation sequencing (NGS) for screening and diagnosis of various diseases including cancer. Although inconsistencies of mutation calls as high as 43% in databases such as GDSC (Genomics of Drug Sensitivity in Cancer) and CCLE (Cancer Cell Line Encyclopedia) have been reported, not many studies on the reasons for the inconsistencies have been published. Methods: Targeted-NGS analysis of 151 genes in 35 cell lines common to GDSC and CCLE was performed, and the results were compared with those from GDSC and CCLE wherein whole-exome- or highly-multiplex NGS were employed.ResultsIn the comparison, GDSC and CCLE had a high rate (40–45%) of false-negative (FN) errors which would lead to high rate of inconsistent mutation calls, suggesting that highly-multiplex NGS may have high rate of FN errors. We also posited the possibility that targeted NGS, especially for the detection of low-level cancer cells in cancer tissues might suffer significant FN errors.ConclusionFN errors may be the most important errors in NGS testing for cancer; their evaluation in laboratory-developed NGS tests is needed.

The role of laboratory developed tests in the development of precision medicine and clinical experimental diagnosis

The modern laboratory developed tests (LDTs) plays a very important role in the development of precision medicine and clinical laboratory diagnosis. The perfect LDTs inspection platform not only requires strict quality control system and management standards, but also requires technical support from high-end professional teams. By combing the development process of LDTs, this paper discusses the significance of developing LDTs in the context of precision medicine, the positive role played by the development of laboratory medicine and the cultivation of laboratory talents, and how to effectively develop LDTs. Key words: Medical laboratory science; Clinical laboratory techniques; Precision medicine

Advocacy Journal Club: Teaching Residents and Faculty About Policy and the Importance of Pathology Societies

Abstract Objectives To describe the Advocacy Journal Club, a novel method to expose pathology residents, fellows, and faculty to critical regulatory and policy issues that affect the practice of laboratory medicine and the importance of involvement in advocacy initiatives. Methods Six voluntary conferences were held for UNMC faculty, local pathologists, and residents during a 1-year period. Each featured a unique, 50-minute interactive discussion led by a faculty member on a topic related to systems-based practice, public health, and/or legislative reform in health care. The six topics included Stark Law, Medicare Access and CHIP Reauthorization Act of 2015 (MACRA), Laboratory Developed Tests, Executive Branch Influence on Health Care, Local Coverage Determinants, and Protecting Access to Medicare Act of 2014 (PAMA). In addition, all participants completed an 8- to 10-question pre- and posttest. After the completion, a survey to assess the quality and efficacy of the series was administered. Results Between 5 and 11 residents attended each session. Both residents and faculty demonstrated a marked increase in their posttest scores. In the final survey, 92% stated they gained an understanding of how policy affects their local laboratory and 100% a better appreciation of how involvement in pathology organizations’ advocacy efforts impacts the laws, rules, and regulations that affect laboratory medicine. Most (92.3%) reported that topics of the Advocacy Journal Club are important to pathology training and 100% reported that the format was effective. Conclusion The journal club format is an effective method to teach both residents and faculty about health policy and other issues impacting laboratory medicine and the critical role that participation in the advocacy efforts of pathology societies plays in affecting the future of the specialty.

Evaluation of a laboratory-developed test for simultaneous detection of norovirus and rotavirus by real-time RT-PCR on the Panther Fusion\xae system

The Hologic Panther Fusion® Open Access™ functionality allows implementation of laboratory-developed tests (LDTs), with fully automated sample extraction, real-time PCR, and result interpretation. We report the development and validation of a multiplex LDT for norovirus G1, norovirus G2, and rotavirus from stool samples on this system. The LDT was optimized for primer and probe sequences, salt concentration, and PCR annealing temperature. Reproducibility of the PCR and extraction process was assessed. Performance of the multiplex LDT assay was evaluated with external quality assessment (EQA) samples and compared to a commercial multiplex assay (Allplex™ GI-Virus Assay, Seegene) in clinical samples. Salt concentrations and annealing/extension temperature were optimized to 4 mM MgCl2, 70 mM KCl, 20 mM Tris, and 60 °C, respectively. The user-prepared part of the LDT PCR mix (containing salts, probes, and primers) was stable for ≥ 11 days onboard the instrument. We observed reproducible results of PCR and the extraction process. The LDT had a sensitivity comparable to or greater than the commercial Allplex™ assay and showed excellent linearity. Forty-five EQA samples yielded the expected result with the LDT. There was 100% concordance between LDT and Allplex™ results in 160 clinical samples. Results from the suspension and direct swab stool sample preparation methods were highly concordant in the LDT. We report the successful development and validation of a multiplex PCR LDT for detection of norovirus G1, norovirus G2, and rotavirus from stool samples on the Panther Fusion® system.

Interlaboratory assessment of droplet digital PCR for quantification of BRAF V600E mutation using a novel DNA reference material

Droplet digital PCR (ddPCR) has attracted much attention in the detection of genetic signatures of cancer present at low levels in circulating tumor DNA (ctDNA) in blood. A growing number of laboratory-developed liquid biopsy tests based on such technology have become commercially available for clinical settings. To obtain consistent and comparable results, an international standard is necessary for validation of the analytical performance. In this study, a novel and SI-traceable “ctDNA” reference material (RM) carrying BRAF V600E was prepared by gravimetrically mixing a 152 bp PCR amplicon and sonicated wild-type genomic DNA. The ddPCR performance was evaluated by analyzing serial “ctDNA” dilutions using a competitive MGB assay. The mutant frequency concordance (k) between ddPCR and the gravimetrical value was 1.03 in the range from 53.9% to 0.1%. The limit of blank (LoB), detection (LoD) and quantification (LoQ) of ddPCR assay were determined to be 0.01%, 0.02% and 0.1%, respectively. Results from the interlaboratory study, using challenging low levels of BRAF V600E ctDNA RMs, demonstrated that the participating laboratories had the appropriate technical competency to perform accurate ddPCR-based low level of ratio measurements. However, a systematic error caused by uncorrected droplet volume in Naica Crystal ddPCR platform was found by using the ctDNA RM. Between-laboratory consistency in copy number measurement was greatly improved when a correct droplet volume was applied for the ddPCR measurement by using the ctDNA RM. This confirms that the “ctDNA” RM is fit for the validation of ddPCR systems for ctDNA quantification. This would also support translation of tests for circulating tumor DNA by ddPCR into routine use.

New progress in laboratory monitoring of the rivaroxaban therapy

Rivaroxaban is an oral direct factor FⅩa inhibitor with predictable pharmacokinetics and no routine monitoring, but the laboratory tests can help to assess the safety and effectiveness of rivaroxaban. The laboratory tests for rivaroxaban include liquid chromatography tandem mass spectrometry (LC-MS/MS), prothrombin time(PT), anti factor Ⅹ a activity(anti-Ⅹ a), thromboelastography(TEG) and rotational thromboelastography(ROTEM). LC-MS/MS can be used to quantitatively detect the blood of rivaroxaban with good specificity and sensitivity, but the instrument is expensive, technologically complex, and lack standardization, so it belongs to the laboratory developed tests(LDTs). Because of insufficient data of TEG and ROTEM, their clinical performance still needs to be verified. PT can detect treatment concentration of rivaroxaban, which can be used as a primary screening method to identify the overdose and the risk of severe bleeding, but the sensitivity of different reagents is different; anti-F Ⅹ a test can sensitively reflect the change of blood of rivaroxaban, and its clinical efficacy is similar to LC-MS/MS, and therefore it can be used as an effective method to guide doctors to use drugs rationally. Key words: Rivaroxaban; Chromatography, liquid; Tandem mass spectrometr; Prothrombin time; Factor Ⅹa; Clinical laboratory techniques

Characterization of Reference Materials for Genetic Testing of CYP2D6 Alleles: A GeT-RM Collaborative Project

Pharmacogenetic testing increasingly is available from clinical and research laboratories. However, only a limited number of quality control and other reference materials currently are available for the complex rearrangements and rare variants that occur in the CYP2D6 gene. To address this need, the Division of Laboratory Systems, CDC-based Genetic Testing Reference Material Coordination Program, in collaboration with members of the pharmacogenetic testing and research communities and the Coriell Cell Repositories (Camden, NJ), has characterized 179 DNA samples derived from Coriell cell lines. Testing included the recharacterization of 137 genomic DNAs that were genotyped in previous Genetic Testing Reference Material Coordination Program studies and 42 additional samples that had not been characterized previously. DNA samples were distributed to volunteer testing laboratories for genotyping using a variety of commercially available and laboratory-developed tests. These publicly available samples will support the quality-assurance and quality-control programs of clinical laboratories performing CYP2D6 testing.

Abstract 4936: Development of NTRK reference materials for global assay standardization

Abstract Tropomyosin receptor kinases (TRK) are a family of transmembrane proteins (TRKA, B, and C) encoded by NTRK1, NTRK2 and NTRK3 genes. Fusions involving NTRK genes result in uncontrolled TRK signaling and oncogenesis. Cancers driven by TRK fusions are rare but occur in a broad range of tumor types in both pediatric and adult patients. Accurate testing for NTRK fusions has become critically important because of precision biopharmaceutical treatments, such as Larotrectinib. This drug, which was granted Breakthrough Therapy Designation by the FDA and is currently undergoing review, is a promising treatment option for patients with locally advanced or metastatic solid tumors harboring NTRK fusions. NGS based assays have the potential to accurately detect NTRK fusions; however, the majority of tests currently available are laboratory-developed tests, which vary substantially in their workflow, chemistry, sensitivity, and bioinformatics analyses. In order to achieve precision diagnostics for personalized therapy, testing standardization is needed worldwide. Towards this end, we developed Seraseq® FFPE NTRK Fusion RNA Reference Material for standardization of NTRK fusion testing by targeted NGS panels. The reference material contains 15 clinically-relevant NTRK fusions, selected based on prevalence data, in a single reference sample. The five fusion RNAs each for NTRK1, NTRK2, and NTRK3 are all incorporated in the well characterized GM24385 human reference cell line. The reference material challenges detection across multiple break points for each NTRK gene, as well as 12 different amino terminal fusion partners. Each fusion is quantified by digital PCR with concentrations ranging from 150 - 600 fusion copies per nanogram of total extractable RNA. The reference material was prepared in a formalin fixed paraffin embedded (FFPE) format, which allows evaluation of the full technical workflow. In our laboratory, one 10-micron FFPE curl yields more than 400 ng of extractable RNA when using the Agencourt Formapure® extraction kit. NGS analysis on the RNA-based ArcherDx FusionPlex Solid Tumor assay correctly identified all 15 fusions, demonstrating compatibility with a leading commercial assay. Highly characterized, patient-like reference materials help standardize testing across clinical trial sites and can speed test adoption, training and validation at clinical labs. The Seraseq FFPE NTRK Fusion RNA Reference Material is designed to aid standardization of NTRK fusion testing to identify patients that will benefit from new precision therapeutics. Note: This abstract was not presented at the meeting. Citation Format: Sebastian Bender, Patricia Carrigan, Kara O’Brien, Catherine Huang, Rajeswari Vemula, Praveena Kamineni, Omo Clement, Russell Garlick, Bharathi Anekella. Development of NTRK reference materials for global assay standardization [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4936.

Regulation of Laboratory-Developed Tests.

ObjectivesTo provide a clinical laboratory perspective on the Verifying Accurate Leading-edge IVCT Development Act (VALID) discussion draft. This potential legislative effort, if enacted, would overhaul the regulatory oversight of in vitro diagnostics (IVDs) in the United States and create a single system for regulation of conventional IVDs and laboratory-developed tests (LDTs).MethodsA concise literature-based review of LDT regulation is presented followed by a discussion of key concerns pertinent to clinical laboratories that should be considered in future IVD regulatory reform efforts.ResultsKey issues identified include the importance of fostering innovation, preserving patient safety, protecting the practice of laboratory medicine, and minimizing undue regulatory burden. Clinical laboratories are not equivalent to manufacturing facilities and would therefore encounter challenges in implementing device-centric regulatory oversight models.ConclusionsIt is imperative that a clinical laboratory perspective on LDTs is understood and incorporated prior to advancement of future legislative proposals.

Prevalence and cervical organism burden among Louisiana women with Trichomonas vaginalis infections

Trichomonas vaginalis is the most common curable sexually transmitted infection (STI) worldwide. Although predominately asymptomatic, the disease spectrum of trichomoniasis in women is characterized primarily by signs and symptoms of vaginitis, including purulent discharge and localized vulvar pruritus and erythema. Several FDA-cleared nucleic acid amplification tests (NAATs) are available for the diagnosis of T. vaginalis infections, but laboratory developed tests (LDTs) are widely utilized and cost-effective solutions in both the research and clinical diagnostic settings. LDT diagnosis of T. vaginalis is particularly appealing since it can be performed using remnant specimens collected for other STI testing. Using a LDT implemented as part of this study, T. vaginalis was detected in 7% of participating Louisiana women (14/199). The mean T. vaginalis organism burden was 1.0x106 ± 4.5x105 organisms per mL of ThinPrep PreservCyt. Using DNA eluates obtained after HPV testing on the cobas 4800 system, the T. vaginalis LDT was characterized by excellent intra- and interassay reproducibility (coefficient of variation values all <3.5%). Compared with two commercially available NAATs from TIB MOLBIOL, the sensitivity and specificity of the LDT was 92.9 and 99.5%, respectively. Collectively, this study details the diagnostic and quantitative utility of a LDT for T. vaginalis. When applied in the clinical research setting, we confirmed the high prevalence of T. vaginalis, but also observed extraordinarily high organism burdens in the cervix. These findings highlight the unique host-pathogen relationship of T. vaginalis with lower reproductive tract tissues, and substantiate the need for continued investigation of this highly prevalent STI.

Real-world practice patterns and impact of PD-L1 expression testing in patients with advanced non-small cell lung cancer.

9059 Background: Several tests measuring programmed cell death ligand 1 (PD-L1) expression are available to select patients with advanced non-small cell lung cancer (aNSCLC) for PD-1 axis therapy including FDA approved companion diagnostics (CoDx), as well as complementary (CyDx) and laboratory developed tests (LDTs). However, it is unknown how rapidly PD-L1 expression testing has become adopted, which type of tests are used, or whether testing affects first-line therapy. Methods: We retrospectively reviewed the Flatiron Health electronic health record-derived database, reflecting real-world care at community oncology practices in the U.S. We evaluated trends in the use of PD-L1 expression testing within 12 months of diagnosis. Among patients diagnosed after FDA approval of PD-L1 testing prior to first-line therapy (Oct 2016), and without other identifiable driver mutations, we used multivariable logistic regression to examine the association between PD-L1 testing and receipt of first-line PD-1 axis therapy. We further examined the association between PD-L1 expression result (using overall reported status or % staining) and choice of first-line therapy. Results: We identified 49,546 patients with aNSCLC from 2011 through the third quarter of 2018. The use of PD-L1 expression testing increased from 7.0% in 2015 to 70.6% in 2017 (p &lt; 0.01). Among those receiving testing, the proportion of patients receiving CoDx increased from 29.9% in 2015 to 73.0% in 2017 with corresponding reductions in CyDx and LDTs. PD-L1 expression testing was associated with use of PD1-axis therapy in the first-line (OR = 2.92, 95% CI 2.59-3.30). Among 4,942 treated patients diagnosed after Oct 2016, those with ≥50% staining more frequently received first line PD-1 axis therapy (82.9%) than those with intermediate (35.5%) or low (25.8%) positive staining; conversely, patients with ≥50% were less likely to receive chemotherapy alone or combination with PD-1 axis therapy. Conclusions: PD-L1 expression testing was rapidly adopted following FDA approval of companion diagnostic testing for aNSCLC. Although the results of PD-L1 expression testing inform the choice of first-line therapy, a substantial proportion of patients are not tested prior to first line treatment.

Statistics for Method Verification of Quantitative Assays in Clinical Microbiology

Diagnostic information that describes the actual or relative density of specific microbes in human blood or in other clinical samples is possible because of quantitative molecular methods. Common methods include quantitative polymerase chain reaction (Q-PCR) or quantitative reverse transcription PCR (QRT-PCR). In clinical microbiology, the use of Q-PCR or QRT-PCR is commonly performed for the purpose of viral load testing, which supports the diagnosis, prognosis, therapeutic decisions, clinical strategies, and practices that monitor patients with blood-borne pathogen infections or infections due to organ transplants. For microbial load testing, standardizing results is challenging and evolving with the addition of more quantitative virus standards that support benchmarking of both FDA-cleared methods and laboratory-developed tests. Because there are unique verification requirements for deployment of quantitative molecular methods, this review focuses on the background and biostatistics required to assess the performance of quantitative molecular methods for determination of viral or microbial load testing in the clinical laboratory setting.

The impact of insurance coverage on the prenatal genetic counseling process: An exploration of genetic counselors' experiences with TRICARE.

The prenatal genetic counseling process may be influenced by the patient's insurance coverage for both prenatal testing and termination. Major commercial insurance providers have different policies. TRICARE is the United States Department of Defense health program for uniformed service members. TRICARE provides coverage to approximately 9.4 million beneficiaries, including health plans, special programs, prescriptions, and dental plans. TRICARE's covered medical expenses are outlined in their policies, including those pertaining to genetic testing and termination. This qualitative study aimed to explore the extent to which insurance coverage of prenatal genetic testing and termination of pregnancy affect the genetic counseling process by exploring genetic counselors' experience with TRICARE. The majority of counselors stated that they did not change their overall counseling process for TRICARE patients. However, several counselors expressed that they changed the way they discussed cost with TRICARE patients, specifically in regard to genetic testing. Additionally, counselors provided their perceptions of their patients' emotional experiences. With the recent consolidation of the three TRICARE regions into two TRICARE Regional Office (TRO) regions and the renewal of the Laboratory Developed Tests Demonstration Project, the findings of this study are valuable in the evaluation of TRICARE's coverage of prenatal genetic services.

SAT-022 Improving The Diagnosis, Treatment, And Prevention Of Diseases Through Accurate And Reliable Laboratory Measurements With CDC Clinical Standardization Programs

Laboratory measurements are critical for the correct diagnosis and treatment of patients as well as in the investigation of diseases, such as cardiovascular disease, hypogonadism, bone-related diseases, infertility, and certain cancers. Inaccurate and unreliable measurements can lead to the misclassification of patients and incorrect treatment. In CDC Clinical Standardization Programs (CDC CSP), accuracy, precision, and other analytical parameters are assessed against performance goals defined by clinical and medical organizations. CDC offers two approaches to improve the accuracy and reliability of laboratory measurements. The first approach focuses on calibration and annual certification of commercial assays and laboratory developed tests (LDTs). This approach is used in [1] CDC Hormone Standardization (CDC HoSt) Program for total testosterone (TT) and estradiol (E2), [2] Vitamin D Standardization-Certification Program (CDC VDSCP) and [3] Cardiovascular Disease Biomarker Standardization Programs for total cholesterol (TC), total glycerides (TG), HDL-cholesterol (HDL-C), and LDL-cholesterol (LDL-C). Free thyroxine (fT4) will also be available in late 2019. The second approach monitors the accuracy and imprecision of measurements performed routinely in patient care, public health, and research. This approach is focused on the accuracy and consistency of laboratory tests in the hand of end-users. CDC has implemented this approach in the Lipid Standardization Program (CDC LSP) for TC, TG, HDL-C, apolipoprotein AI and B, and CDC Accuracy-based Monitoring (CDC AMP) Program for TT and 25OHD. CDC AMP for E2 will be available for enrollment in late 2019. CDC CSP have improved the accuracy of participating laboratories. Among-laboratory bias decreased from 16.5% in 2007 to 2.8% in 2017 for TT and 54.8% in 2012 to 13.9% in 2017 for E2. Similar improvements have been observed for 25OHD, with a decrease in among-laboratory bias from 13.9% in 2012 to 5.2% in 2016 at 30 nmol/L (vitamin D deficiency) and 12.3% in 2012 to 3.0% in 2016 at 50 nmol/L (vitamin D insufficiency). CDC CSP efforts have helped maintain analytical performance over time. For example, data collected over the past 10 years from CDC LSP indicate that the majority of TC measurements, performed in research and patient care, are consistently within the recommended bias limits of +3%. CDC continues to address new clinical and public health needs by adding new analytes, such as free testosterone, sex hormone binding globulin (SHBG), fT4, parathyroid hormone (PTH), and glucose. CDC CSP also support projects with establishing reference ranges, creating population data using national surveys, and conducting special research studies. CDC CSP are supported by and collaborate with key stakeholders such as the Partnership for the Accurate Testing of Hormones (PATH) and affiliated organizations, including the Endocrine Society.

31. The PT alphabet soup: LDT, FDA, NGS, non-NGS, @#$!%

The performance of laboratory testing has recently come under increased scrutiny as part of important and ongoing debates on regulation and reimbursement of laboratory developed tests (LDTs), including next generation sequencing (NGS). The College of American Pathologists (CAP) is a well- recognized provider of external proficiency testing (PT) materials that provide a mechanism for laboratories to fulfill Clinical Laboratory Improvement Amendments. The CAP Molecular Oncology Committee has examined the overall performance of laboratories across specific single analytes as well as NGS PT surveys.

The Challenges of Implementing a PD-L1 Proficiency Testing Program in Australia

Background. One important initiative that commenced at the Royal College of Pathologists of Australasia Quality Assurance Program (RCPAQAP) in 2017 was the collaboration with United Kingdom National External Quality Assessment Scheme (UK NEQAS) Immunocytochemistry (ICC) and In-Situ Hybridization (ISH) for the challenging implementation of a PD-L1 immunohistochemistry (IHC) proficiency testing program for non-small cell lung carcinoma (NSCLC). A RCPAQAP participant survey in 2016 showed that only eight laboratories were performing PD-L1 testing. The aim of the collaboration was to increase the sample size of the pilot program to provide meaningful results that could be reported back to RCPAQAP participants with appropriate recommendations. Other challenges of assessment included standardising the clinical cut-offs for positivity for each commercial assay, interpretation of laboratory developed tests (LDTs), using appropriate tissue to cover the critical interpretation points for each assay, interchangeability of clones and interpretation proficiency testing. Methods. The use of a ‘Gold Standard’ for each commercial assay was used as a baseline to compare participant results and tumour proportion score bin categories were implemented to harmonise interpretation across clones. Conclusions. The findings of the pre-pilot test suggest that the use of a clinically validated PD-L1 IHC assay performs better during assessment than adopting a laboratory developed test (LDT). The assessment committee also concluded that tonsil showed a better dynamic range of positivity than placenta. It was acknowledged that participants are limited by the platforms they have available and so it was suggested that validating an optimal method against the clinical assay and continual verification of the test may produce the expected result. The next big challenge is to extend proficiency testing from technical to interpretation. This is being implemented globally via the International Quality Network for Pathology (IQNPath) with participation through local External Quality Assurance programs, including RCPAQAP.