Performance Comparison of Different Analytic Methods in Proficiency Testing for Mutations in the BRAF, EGFR, and KRAS Genes: A Study of the College of American Pathologists Molecular Oncology Committee

The Significance of External Quality Assessment Schemes for Molecular Testing in Clinical Laboratories

Simple Summary

Patients and clinicians often rely on the outcome of laboratory tests, but can we really trust these test results? Good quality management is key for laboratories to guarantee reliable test results. This review focusses on external quality assessment (EQA) schemes which are a tool for laboratories to examine and improve the quality of their testing routines. In this review, an overview of the role and importance of EQA schemes for clinical laboratories is given, and different types of EQA schemes and EQA providers available on the market are discussed, as well as recent developments in the EQA landscape.

Abstract

External quality assessment (EQA) schemes are a tool for clinical laboratories to evaluate and manage the quality of laboratory practice with the support of an independent party (i.e., an EQA provider). Depending on the context, there are different types of EQA schemes available, as well as various EQA providers, each with its own field of expertise. In this review, an overview of the general requirements for EQA schemes and EQA providers based on international guidelines is provided. The clinical and scientific value of these kinds of schemes for clinical laboratories, clinicians and patients are highlighted, in addition to the support EQA can provide to other types of laboratories, e.g., laboratories affiliated to biotech companies. Finally, recent developments and challenges in laboratory medicine and quality management, for example, the introduction of artificial intelligence in the laboratory and the shift to a more individual-approach instead of a laboratory-focused approach, are discussed. EQA schemes should represent current laboratory practice as much as possible, which poses the need for EQA providers to introduce latest laboratory innovations in their schemes and to apply up-to-date guidelines. By incorporating these state-of-the-art techniques, EQA aims to contribute to continuous learning.

Genomic alterations in cholangiocarcinoma: clinical significance and relevance to therapy

Improving the survival of patients with cholangiocarcinoma (CCA) has long proved challenging, although the treatment of this disease nowadays is on advancement. The historical invariability of survival outcomes and the limited number of agents known to be effective in the treatment of this disease has increased the number of studies designed to identify genetic targetable hits that can be efficacious for novel therapies. In this respect, the increasing feasibility of molecular profiling starting either from tumor tissue or circulating cell-free DNA (cfDNA) has led to an increased understanding of CCA biology. Intrahepatic CCA (iCCA) and extrahepatic CCA (eCCA) display different and typical patterns of actionable genomic alterations, which offer opportunity for therapeutic intervention. This review article will summarize the current knowledge on the genomic alterations of iCCA and eCCA, provide information on the main technologies for genomic profiling using either tumor tissue or cfDNA, and briefly discuss the main clinical trials with targeted agents in this disease.

Somatic Genomic Testing in Patients With Metastatic or Advanced Cancer: ASCO Provisional Clinical Opinion

PURPOSE

An ASCO provisional clinical opinion offers timely clinical direction to ASCO's membership following publication or presentation of potentially practice-changing data from major studies. This provisional clinical opinion addresses the appropriate use of tumor genomic testing in patients with metastatic or advanced solid tumors.

CLINICAL CONTEXT

An increasing number of therapies are approved to treat cancers harboring specific genomic biomarkers. However, there is a lack of clarity as to when tumor genomic sequencing should be ordered, what type of assays should be performed, and how to interpret the results for treatment selection.

PROVISIONAL CLINICAL OPINION

Patients with metastatic or advanced cancer should undergo genomic sequencing in a certified laboratory if the presence of one or more specific genomic alterations has regulatory approval as biomarkers to guide the use of or exclusion from certain treatments for their disease. Multigene panel-based assays should be used if more than one biomarker-linked therapy is approved for the patient's disease. Site-agnostic approvals for any cancer with a high tumor mutation burden, mismatch repair deficiency, or neurotrophic tyrosine receptor kinase (NTRK) fusions provide a rationale for genomic testing for all solid tumors. Multigene testing may also assist in treatment selection by identifying additional targets when there are few or no genotype-based therapy approvals for the patient's disease. For treatment planning, the clinician should consider the functional impact of the targeted alteration and expected efficacy of genomic biomarker-linked options relative to other approved or investigational treatments.Additional information is available at www.asco.org/assays-and-predictive-markers-guidelines.

Reference Samples to Compare Next-Generation Sequencing Test Performance for Oncology Therapeutics and Diagnostics

OBJECTIVES

Diversity of laboratory-developed tests (LDTs) using next-generation sequencing (NGS) raises concerns about their accuracy for selection of targeted therapies. A working group developed a pilot study of traceable reference samples to measure NGS LDT performance among a cohort of clinical laboratories.

METHODS

Human cell lines were engineered via CRISPR/Cas9 and prepared as formalin-fixed, paraffin-embedded cell pellets ("wet" samples) to assess the entire NGS test cycle. In silico mutagenized NGS sequence files ("dry" samples) were used to assess the bioinformatics component of the NGS test cycle. Single and multinucleotide variants (n = 36) of KRAS and NRAS were tested at 5% or 15% variant allele fraction to determine eligibility for therapy with the EGFR inhibitor panitumumab in the setting of metastatic colorectal cancer.

RESULTS

Twenty-one (21/21) laboratories tested wet samples; 19 of 21 analyzed dry samples. Of the laboratories that tested both the wet and dry samples, 7 (37%) of 19 laboratories correctly reported all variants, 3 (16%) of 19 had fewer than five errors, and 9 (47%) of 19 had five or more errors. Most errors were false negatives.

CONCLUSIONS

Genetically engineered cell lines and mutagenized sequence files are complementary reference samples for evaluating NGS test performance among clinical laboratories using LDTs. Variable accuracy in detection of genetic variants among some LDTs may identify different patient populations for targeted therapy.

Tiered Somatic Variant Classification Adoption Has Increased Worldwide With Some Practice Differences Based on Location and Institutional Setting

CONTEXT.—

The 2017 Association for Molecular Pathology/American Society of Clinical Oncology/College of American Pathologists (CAP) tier classification guideline provides a framework to standardize interpretation and reporting of somatic variants.

OBJECTIVE.—

To evaluate the adoption and performance of the 2017 guideline among laboratories performing somatic next-generation sequencing (NGS).

DESIGN.—

A survey was distributed to laboratories participating in NGS CAP proficiency testing for solid tumors (NGSST) and hematologic malignancies (NGSHM).

RESULTS.—

Worldwide, 64.4% (152 of 236) of NGSST and 66.4% (87 of 131) of NGSHM participants used tier classification systems, of which the 2017 guideline was used by 84.9% (129 of 152) of NGSST and 73.6% (64 of 87) of NGSHM participants. The 2017 guideline was modified by 24.4% (30 of 123) of NGSST and 21.7% (13 of 60) of NGSHM laboratories. Laboratories implementing the 2017 guideline were satisfied or very satisfied (74.2% [89 of 120] NGSST and 69.5% [41 of 59] NGSHM), and the impression of tier classification reproducibility was high (mean of 3.9 [NGSST] and 3.6 [NGSHM] on a 5-point scale). Of nonusers, 35.2% (38 of 108) of NGSST and 39.4% (26 of 66) of NGSHM laboratories were planning implementation. For future guideline revisions, respondents favored including variants to monitor disease (63.9% [78 of 122] NGSST, 80.0% [48 of 60] NGSHM) and germline variants (55.3% [63 of 114] NGSST, 75.0% [45 of 60] NGSHM). Additional subtiers were not favored by academic laboratories compared to nonacademic laboratories (P < .001 NGSST and P = .02 NGSHM).

CONCLUSIONS.—

The 2017 guideline has been implemented by more than 50.0% of CAP laboratories. While most laboratories using the 2017 guideline report satisfaction, thoughtful guideline modifications may further enhance the quality, reproducibility, and clinical utility of the 2017 guideline for tiered somatic variant classification.

Practical considerations in screening for genetic alterations in cholangiocarcinoma

Cholangiocarcinoma (CCA) encompasses diverse epithelial tumors historically associated with poor outcomes due to an aggressive disease course, late diagnosis, and limited benefit of standard chemotherapy for advanced disease. Comprehensive molecular profiling has revealed a diverse landscape of genomic alterations as oncogenic drivers in CCA. TP53 mutations, CDKN2A/B loss, and KRAS mutations are the most common genetic alterations in CCA. However, intrahepatic CCA (iCCA) and extrahepatic CCA (eCCA) differ substantially in the frequency of many alterations. This includes actionable alterations, such as isocitrate dehydrogenase 1 (IDH1) mutations and a large variety of FGFR2 rearrangements, which are found in up to 29% and ∼10% of patients with iCCA, respectively, but are rare in eCCA. FGFR2 rearrangements are currently the only genetic alteration in CCA for which a targeted therapy, the fibroblast growth factor receptor 1-3 inhibitor pemigatinib, has been approved. However, favorable phase III results for IDH1-targeted therapy with ivosidenib in iCCA have been published, and numerous other alterations are actionable by targeted therapies approved in other indications. Recent advances in next-generation sequencing (NGS) have led to the development of assays that allow comprehensive genomic profiling of large gene panels within 2-3 weeks, including in vitro diagnostic tests approved in the United States. These assays vary regarding acceptable source material (tumor tissue or peripheral whole blood), genetic source for library construction (DNA or RNA), target selection technology, gene panel size, and type of detectable genomic alterations. While some large commercial laboratories offer rapid and comprehensive genomic profiling services based on proprietary assay platforms, clinical centers may use commercial genomic profiling kits designed for clinical research to develop their own customized laboratory-developed tests. Large-scale genomic profiling based on NGS allows for a detailed and precise molecular diagnosis of CCA and provides an important opportunity for improved targeted treatment plans tailored to the individual patient's genetic signature.

The Science and Art of Clinical Genetic Variant Classification and Its Impact on Test Accuracy

Clinical genetic variant classification science is a growing subspecialty of clinical genetics and genomics. The field's continued improvement is essential for the success of precision medicine in both germline (hereditary) and somatic (oncology) contexts. This review focuses on variant classification for DNA next-generation sequencing tests. We first summarize current limitations in variant discovery and definition, and then describe the current five- and four-tier classification systems outlined in dominant standards and guideline publications for germline and somatic tests, respectively. We then discuss measures of variant classification discordance and the field's bias for positive results, as well as considerations for panel size and population screening in the context of estimates of positive predictive value thatincorporate estimated variant classification imperfections. Finally, we share opinions on the current state of variant classification from some of the authors of the most widely used standards and guideline publications and from other domain experts.

An Overview of Characteristics of Clinical Next-Generation Sequencing-Based Testing for Hematologic Malignancies

CONTEXT.—

With the increasing integration of molecular alterations into the evaluation of hematologic malignancies (HM), somatic mutation profiling by next-generation sequencing (NGS) has become a common clinical testing strategy. Limited data are available about the characteristics of these assays.

OBJECTIVE.—

To describe assay characteristics, specimen requirements, and reporting practices for NGS-based HM testing using College of American Pathologists proficiency testing survey data.

DESIGN.—

The College of American Pathologists NGS Hematologic Malignancies Survey (NGSHM) results from 78 laboratories were used to determine laboratory practices in NGS-based HM testing.

RESULTS.—

The majority of laboratories performed tumor-only (88.5% [69 of 78]), targeted sequencing of cancer genes or mutation hotspots (98.7% [77 of 78]); greater than 90% performed testing on fresh bone marrow and peripheral blood. The majority of laboratories reported a 5% lower limit of detection for single-nucleotide variants (73.1% [57 of 78]) and small insertions and deletions (50.6% [39 of 77]). A majority of laboratories used benchtop sequencers and custom enrichment approaches.

CONCLUSIONS.—

This manuscript summarizes the characteristics of clinical NGS-based testing for the detection of somatic variants in HM. These data may be broadly useful to inform laboratory practice and quality management systems, regulation, and oversight of NGS testing, and precision medicine efforts using a data-driven approach.

Clinical Utilization, Utility, and Reimbursement for Expanded Genomic Panel Testing in Adult Oncology

PURPOSE

The routine use of large next-generation sequencing (NGS) pan-cancer panels is required to identify the increasing number of, but often uncommon, actionable alterations to guide therapy. Inconsistent coverage and variable payment is hindering NGS adoption into clinical practice. A review of test utilization, clinical utility, coverage, and reimbursement was conducted in a cohort of patients diagnosed with high-risk cancer who received pan-cancer panel testing as part of their clinical care.

MATERIALS AND METHODS

The Columbia Combined Cancer Panel (CCCP), a 467-gene panel designed to detect DNA variations in solid and liquid tumors, was performed in the Laboratory of Personalized Genomic Medicine at Columbia University Irving Medical Center. Utilization was characterized at test order. Results were reviewed by a molecular pathologist, followed by a multidisciplinary molecular tumor board where clinical utility was classified by consensus. Reimbursement was reviewed after payers provided final coverage decisions.

RESULTS

NGS was performed on 359 high-risk tumors from 349 patients. Reimbursement data were available for 246 cases. The most common reason providers ordered CCCP testing was for patients diagnosed with a treatment-resistant or recurrent tumor (n = 214; 61%). Findings were clinically impactful for 229 cases (64%). Molecular alterations that may inform future therapy in the event of progression or relapse were found in 42% of cases, and a targeted therapy was initiated in 23 cases (6.6%). The majority of tests were denied coverage by payers (n = 190; 77%). On average, insurers reimbursed 10.75% of the total NGS service charge.

CONCLUSION

CCCP testing identified clinically impactful alterations in 64% of cases. Limited coverage and low reimbursement remain barriers, and broader reimbursement policies are needed to adopt pan-cancer NGS testing that benefits patients into clinical practice.

The regulatory landscape of precision oncology laboratory medicine in the United States - Perspective on the past 5 years and considerations for future regulation

The regulatory landscape for precision oncology in the United States is complicated, with multiple governmental regulatory agencies with different scopes of jurisdiction. Several regulatory proposals have been introduced since the Food and Drug Administration released a draft guidance to regulate laboratory-developed tests in 2014. Key aspects of the most recent proposals and discussion of central arguments related to the regulation of precision oncology laboratory tests provides insight to stakeholders for future discussions related to regulation of laboratory tests.

Proficiency Testing of Standardized Samples Shows High Interlaboratory Agreement for Clinical Next Generation Sequencing-Based Hematologic Malignancy Assays With Survey Material-Specific Differences in Variant Frequencies

CONTEXT.—

As laboratories increasingly turn from single-analyte testing in hematologic malignancies to next-generation sequencing-based panel testing, there is a corresponding need for proficiency testing to ensure adequate performance of these next-generation sequencing assays for optimal patient care.

OBJECTIVE.—

To report the performance of laboratories on proficiency testing from the first 4 College of American Pathologists Next-Generation Sequencing Hematologic Malignancy surveys.

DESIGN.—

College of American Pathologists proficiency testing results for 36 different engineered variants and/or allele fractions as well as a sample with no pathogenic variants were analyzed for accuracy and associated assay performance characteristics.

RESULTS.—

The overall sensitivity observed for all variants was 93.5% (2190 of 2341) with 99.8% specificity (22 800 of 22 840). The false-negative rate was 6.5% (151 of 2341), and the largest single cause of these errors was difficulty in identifying variants in the sequence of CEBPA that is rich in cytosines and guanines. False-positive results (0.18%; 40 of 22 840) were most likely the result of preanalytic or postanalytic errors. Interestingly, the variant allele fractions were almost uniformly lower than the engineered fraction (as measured by digital polymerase chain reaction). Extensive troubleshooting identified a multifactorial cause for the low variant allele fractions, a result of an interaction between the linearized nature of the plasmid and the Illumina TruSeq chemistry.

CONCLUSIONS.—

Laboratories demonstrated an overall accuracy of 99.2% (24 990 of 25 181) with 99.8% specificity and 93.5% sensitivity when examining 36 clinically relevant somatic single-nucleotide variants with a variant allele fraction of 10% or greater. The data also highlight an issue with artificial linearized plasmids as survey material for next-generation sequencing.