Development and Validation of StrataNGS, a Multiplex PCR, Semiconductor Sequencing-Based Comprehensive Genomic Profiling Test

A Case of CDKN2C/CIC Null Epithelioid Leiomyosarcoma With a Low-grade Component Indistinguishable From Leiomyoma

Numerous emerging molecularly defined subtypes of uterine leiomyosarcoma (LMS) have been described in recent years. Here we report our experience with a challenging case of the recently described CDKN2C/CIC null subtype of LMS - a LMS subtype that is frequently epithelioid in appearance, is wild-type for both TP53 and RB1 and may exhibit low-grade histology that falls short of LMS. The 48-year-old patient was initially diagnosed with an epithelioid leiomyoma with a component of intravenous leiomyomatosis. Recurrence occurred 5 years later with an extensive disease burden in the abdomen and pelvis. Upon review, the lesion in the hysterectomy specimen and the recurrent tumor had similar morphology. This included (1) focal epithelioid morphology meeting current diagnostic criteria for epithelioid LMS and (2) other areas with morphology indistinguishable from leiomyoma (LM), including conventional spindle cell LM, cellular LM, and LM with bizarre nuclei. Targeted next-generation molecular analysis performed on both the original tumor in the hysterectomy specimen and the tumor from the recurrence showed the same CDKN2C/CIC null profile. This case highlights the striking intratumoral heterogeneity that is possible in CDKN2C/CIC null LMS, including areas morphologically indistinguishable from LM. Clinicopathological findings in this case, including features that may assist in recognizing this challenging LMS subtype, are discussed. We underscore the importance of early diagnosis, which can facilitate appropriate adjuvant and/or maintenance therapy that may decrease the morbidity associated with extensive debulking surgery.

Hepatic adenomas in males: Is molecular characterization helpful in guiding its management?

BACKGROUND AND AIMS

Hepatocellular adenomas (HCAs) in males are very rare. We performed detailed clinicopathologic, immunohistochemical and molecular characterization of HCAs in males, to understand their pathogenesis and malignant potential.

METHODS

Seven cases of HCA in males formed our study cohort. The histologic slides, clinical and follow-up information were reviewed and immunohistochemical stains were performed. DNA was extracted and targeted sequencing was performed using Ion Torrent chemistry. Filtered variants were annotated to identify pathogenic mutations.

RESULTS

Six (86 %) patients were morbidly obese. All showed at least focal cytologic atypia. Three lesions were markedly steatotic and 2 were hemorrhagic. One lesion showed focal reticulin loss, diffuse glutamine synthetase (GS) positivity and beta-catenin (β-catenin) nuclear staining, suggestive of atypical hepatocellular neoplasm. Three (42.8 %) cases were inflammatory-type, showing diffuse serum amyloid-associated protein/C-reactive protein. One other inflammatory-type HCA showed peripheral accentuation with GS and another non-inflammatory HCA showed patchy staining with GS; both revealed CTNBB1 mutations but no β-catenin nuclear staining. None showed TP53, TERT promotor mutations, or significant copy number alterations.

CONCLUSION

A significant proportion of HCAs in males occurred in obese patients and were inflammatory-type. While some are beta-catenin mutated and need to be resected, a subset of HCAs in males appears to be low-risk by molecular features and may be treated conservatively.

Genomic and Immune Landscape of Non-Small Cell Lung Cancer Brain Metastases

PURPOSE

Metastatic spread of non-small cell lung cancer (NSCLC) to the brain is a commonly occurring and challenging clinical problem, often resulting in patient mortality. Systemic therapies including immunotherapy have modest efficacy in treating brain metastases. Moreover, the local immune environment of brain metastases remains poorly described. This study aims to understand the genomic and immune landscape of NSCLC brain metastases.

METHODS

A total of 3,060 patients with NSCLC sequenced with the Strata Select assay on the Strata Oncology Platform were analyzed. Genomic alterations, tumor mutation burden (TMB), PD-L1 expression, and immune gene expression were compared across different tissue sites and histologies and within brain metastases.

RESULTS

A significant increase in TMB was observed in the brain metastasis samples compared with nonbrain metastasis samples. Mutations in TP53, KRAS, and CDKNA2A were more prevalent within the brain metastasis cohort compared with other tissue locations. In addition, PD-L1 expression was significantly decreased within brain metastasis samples compared with other sites. The overall immune landscape within the brain metastasis samples was largely reduced compared with primary lung samples. However, an immune-enriched brain metastasis cohort was identified with higher expressions of PD-L1 and other immune-related genes.

CONCLUSION

The overall TMB is increased within brain metastases compared with primary lung and other metastasis sites and is associated with a markedly diminished overall immune landscape. The identification of an immune-enriched brain metastasis subgroup suggests potential heterogeneity within the brain metastasis patient cohort, which might have implications for the development of targeted therapies.

Half of oncologists fail to use ordered NGS results to guide their first-line treatment decision in advanced NSCLC: A retrospective study in a community-based integrated healthcare system

Purpose

Next generation sequencing (NGS) testing is used to identify driver mutation(s) in non-small cell lung cancer (NSCLC) that are amenable to targeted therapy, resulting in superior outcomes and improved tolerability. We characterized how clinicians in a large integrated healthcare system utilized NGS testing to inform first line treatment decisions in patients with stage IV NSCLC shortly after diagnosis.

Methods

We conducted a cross-sectional study of 964 patients within an integrated healthcare system, Kaiser Permanente Southern California (KPSC), who were diagnosed with stage IV NSCLC and completed NGS testing (Strata Oncology) between May 2019 to June 2021. Treatment start dates were used to divide patients into those who started treatment before or after NGS results, or those who did not receive treatment after NGS results. Patients harboring alterations in seven genes (EGFR, ALK, ROS-1, BRAF, KRAS, RET, and MET) were considered candidates for targeted first line therapy.

Results

First line treatment was initiated in half (52 %; n = 284) of all treated patients prior to NGS results. Just under half (48 %; n = 137) of these patients were found to have a targetable mutation by NGS, of whom 59 % received first line chemotherapy and/or immunotherapy, rather than targeted therapy. Nearly 27 % of the sample never received treatment, of which 31 % had a targetable mutation, and may have been candidates for targeted therapy. Not undergoing first line treatment was correlated with older age, higher comorbidity index, smoking history, and the lack of an identifiable driver mutation.

Conclusion

NGS tests results were not exclusively used to inform first line treatment decisions in most patients with stage IV NSCLC, and most patients with a targetable mutation were not treated with targeted therapy. Possible explanations include lengthy turnaround times for NGS testing and the availability of timelier but less accurate single gene testing.

Recommendations for Tumor Mutational Burden Assay Validation and Reporting: A Joint Consensus Recommendation of the Association for Molecular Pathology, College of American Pathologists, and Society for Immunotherapy of Cancer

Tumor mutational burden (TMB) has been recognized as a predictive biomarker for immunotherapy response in several tumor types. Several laboratories offer TMB testing, but there is significant variation in how TMB is calculated, reported, and interpreted among laboratories. TMB standardization efforts are underway, but no published guidance for TMB validation and reporting is currently available. Recognizing the current challenges of clinical TMB testing, the Association for Molecular Pathology convened a multidisciplinary collaborative working group with representation from the American Society of Clinical Oncology, the College of American Pathologists, and the Society for the Immunotherapy of Cancer to review the laboratory practices surrounding TMB and develop recommendations for the analytical validation and reporting of TMB testing based on survey data, literature review, and expert consensus. These recommendations encompass pre-analytical, analytical, and postanalytical factors of TMB analysis, and they emphasize the relevance of comprehensive methodological descriptions to allow comparability between assays.

PTEN pathogenic variants are associated with poor prognosis in patients with advanced soft tissue sarcoma

BACKGROUND

We aimed to examine whether PTEN pathogenic variants (mutPTEN) were associated with overall survival (OS) in patients with advanced soft tissue sarcoma (STS) with the presence of one or more of the most common genomic alterations including p53, CDKN2A, RB1, and ATRX pathogenic variants.

METHODS

This study included patients from Kaiser Permanente Northern California and Stanford Cancer Center with grade 2 or higher locally advanced and metastatic STS.

RESULTS

A total of 174 patients had leiomyosarcoma (LMS), 136 had undifferentiated pleomorphic sarcoma (UPS), 78 had Liposarcoma (LPS), and 214 had other histology subtypes (Others). Among all patients with STS, OS was worse for those with mutPTEN versus wild-type PTEN (wtPTEN, adjusted HR [aHR] = 1.58 [95% CI, 1.11-2.23]), mutCDKN2A vs wtCDKN2A (aHR = 1.33 [95% CI .99-1.80]), and mutRB1 vs wtRB1 (aHR = 1.26 [95% CI 0.93-1.70[), while OS was similar for mutp53 vs wtp53 and mutATRX vs wtATRX. MutPTEN versus wtPTEN was consistently associated with worse OS in histologic subtypes including LMS and UPS and molecular subgroups.

CONCLUSION

MutPTEN vs wtPTEN was associated with worse OS in advanced STS. If confirmed, our findings could be helpful for prognostic stratification in clinical practice and for further understanding the molecular mechanisms of STS.

Sex-dependent Prognosis of Patients with Advanced Soft Tissue Sarcoma

PURPOSE

To examine whether overall survival (OS) differs for male and female patients with advanced soft-tissue sarcoma (STS).

EXPERIMENTAL DESIGN

The study included patients from Kaiser Permanente Northern California and Stanford Cancer Center with grade 2 and 3 locally advanced or metastatic STS whose tumor underwent next-generation sequencing. We used Cox regression modeling to examine association of sex and OS adjusting for other important factors.

RESULTS

Among 388 eligible patients, 174 had leiomyosarcoma (LMS), 136 had undifferentiated pleomorphic sarcoma (UPS), and 78 had liposarcoma. OS for male versus female patients appeared to be slightly better among the full cohort [HR = 0.89; 95% confidence interval (CI), 0.66-1.20]; this association appeared to be stronger among the subsets of patients with LMS (HR = 0.76; 95% CI, 0.39-1.49) or liposarcoma (HR = 0.74; 95% CI, 0.32-1.70). Better OS for male versus female patients was also observed among all molecular subgroups except mutRB1 and mutATRX, especially among patients whose tumor retained wtTP53 (HR = 0.73; 95% CI, 0.44-1.18), wtCDKN2A (HR = 0.85; 95% CI, 0.59-1.23), wtRB1 (HR = 0.73; 95% CI, 0.51-1.04), and among patients whose tumor had mutPTEN (HR = 0.37; 95% CI, 0.09-1.62). OS also appeared to be better for males in the MSK-IMPACT and TCGA datasets.

CONCLUSIONS

A fairly consistent pattern of apparent better OS for males across histologic and molecular subgroups of STS was observed. If confirmed, our results could have implications for clinical practice for prognostic stratification and possibly treatment tailoring as well as for future clinical trials design.

Stress Keratin 17 Is a Predictive Biomarker Inversely Associated with Response to Immune Check-Point Blockade in Head and Neck Squamous Cell Carcinomas and Beyond

Low response rates in immune check-point blockade (ICB)-treated head and neck squamous cell carcinoma (HNSCC) drive a critical need for robust, clinically validated predictive biomarkers. Our group previously showed that stress keratin 17 (CK17) suppresses macrophage-mediated CXCL9/CXCL10 chemokine signaling involved in attracting activated CD8+ T cells into tumors, correlating with decreased response rate to pembrolizumab-based therapy in a pilot cohort of ICB-treated HNSCC (n = 26). Here, we performed an expanded analysis of the predictive value of CK17 in ICB-treated HNSCC according to the REMARK criteria and investigated the gene expression profiles associated with high CK17 expression. Pretreatment samples from pembrolizumab-treated HNSCC patients were stained via immunohistochemistry using a CK17 monoclonal antibody (n = 48) and subjected to spatial transcriptomic profiling (n = 8). Our findings were validated in an independent retrospective cohort (n = 22). CK17 RNA expression in pembrolizumab-treated patients with various cancer types was investigated for predictive significance. Of the 48 patients (60% male, median age of 61.5 years), 21 (44%) were CK17 high, and 27 (56%) were CK17 low. A total of 17 patients (35%, 77% CK17 low) had disease control, while 31 patients (65%, 45% CK17 low) had progressive disease. High CK17 expression was associated with a lack of disease control (p = 0.037), shorter time to treatment failure (p = 0.025), and progression-free survival (PFS, p = 0.004), but not overall survival (OS, p = 0.06). A high CK17 expression was associated with lack of disease control in an independent validation cohort (p = 0.011). PD-L1 expression did not correlate with CK17 expression or clinical outcome. CK17 RNA expression was predictive of PFS and OS in 552 pembrolizumab-treated cancer patients. Our findings indicate that high CK17 expression may predict resistance to ICB in HNSCC patients and beyond.

Clinical, molecular, and immune correlates of the Immunotherapy Response Score in patients with advanced urothelial carcinoma under atezolizumab monotherapy: analysis of the phase II IMvigor210 trial

BACKGROUND

In the advanced urothelial carcinoma (aUC) scenario there are no consistent immune checkpoint blockade predictive biomarkers. Recently a novel pan-tumor molecular tissue-based biomarker, the Immunotherapy Response Score (IRS), has been proposed. We conducted a retrospective study to validate the prognostic/predictive utility of the IRS in patients with aUC under atezolizumab monotherapy and to characterize its underlying molecular/immune features in the context of the IMvigor210 phase II trial.

PATIENTS AND METHODS

This is a post hoc pooled analysis of 261 patients with available clinical, molecular, and immune tumor data treated with atezolizumab monotherapy in the IMvigor210 phase II clinical trial. Efficacy endpoints were overall survival (OS), disease control rate (DCR), and overall response rate (ORR). Survival estimates were calculated by the Kaplan-Meier method, and groups were compared with the log-rank test. The Cox proportional hazards regression model was used to evaluate factors independently associated with OS. Factors associated with disease control (DC) and response were tested with logistic regression in univariable and multivariable analyses. Comparisons between patient and disease characteristics were carried out using chi-square or Fisher's exact tests. All P values were two-sided, and those <0.05 were considered statistically significant.

RESULTS

High IRS was significantly associated with a better OS in univariable [hazard ratio (HR) = 0.49, P < 0.001] and multivariable (HR = 0.60, P = 0.018) analyses. DCR and ORR were significantly higher among high IRS patients (DCR for high IRS versus low IRS patients: 57% versus 32%, P < 0.001; ORR: 42% versus 10%, P < 0.001). High IRS patients presented a higher probability of DC and response in univariable [DC: odds ratio (OR) = 2.72, P < 0.001; response: OR = 3.92, P < 0.001] and multivariable (DC: OR = 2.72, P < 0.001; response: OR = 3.92, P < 0.001) analyses.

CONCLUSIONS

This study validates IRS as a strong independent prognostic and predictive biomarker for OS and DC/response in patients with aUC treated with atezolizumab monotherapy in the IMvigor210 phase II clinical trial.

Validation of Immunotherapy Response Score as Predictive of Pan-solid Tumor Anti-PD-1/PD-L1 Benefit

Immunotherapy response score (IRS) integrates tumor mutation burden (TMB) and quantitative expression biomarkers to predict anti-PD-1/PD-L1 [PD-(L)1] monotherapy benefit. Here, we evaluated IRS in additional cohorts. Patients from an observational trial (NCT03061305) treated with anti-PD-(L)1 monotherapy were included and assigned to IRS-High (-H) versus -Low (-L) groups. Associations with real-world progression-free survival (rwPFS) and overall survival (OS) were determined by Cox proportional hazards (CPH) modeling. Those with available PD-L1 IHC treated with anti-PD-(L)1 with or without chemotherapy were separately assessed. Patients treated with PD-(L)1 and/or chemotherapy (five relevant tumor types) were assigned to three IRS groups [IRS-L divided into IRS-Ultra-Low (-UL) and Intermediate-Low (-IL), and similarly assessed]. In the 352 patient anti-PD-(L)1 monotherapy validation cohort (31 tumor types), IRS-H versus IRS-L patients had significantly longer rwPFS and OS. IRS significantly improved CPH associations with rwPFS and OS beyond microsatellite instability (MSI)/TMB alone. In a 189 patient (10 tumor types) PD-L1 IHC comparison cohort, IRS, but not PD-L1 IHC nor TMB, was significantly associated with anti-PD-L1 rwPFS. In a 1,103-patient cohort (from five relevant tumor types), rwPFS did not significantly differ in IRS-UL patients treated with chemotherapy versus chemotherapy plus anti-PD-(L)1, nor in IRS-H patients treated with anti-PD-(L)1 versus anti-PD-(L)1 + chemotherapy. IRS associations were consistent across subgroups, including both Europeans and non-Europeans. These results confirm the utility of IRS utility for predicting pan-solid tumor PD-(L)1 monotherapy benefit beyond available biomarkers and demonstrate utility for informing on anti-PD-(L)1 and/or chemotherapy treatment.

Significance

This study confirms the utility of the integrative IRS biomarker for predicting anti-PD-L1/PD-1 benefit. IRS significantly improved upon currently available biomarkers, including PD-L1 IHC, TMB, and MSI status. Additional utility for informing on chemotherapy, anti-PD-L1/PD-1, and anti-PD-L1/PD-1 plus chemotherapy treatments decisions is shown.

Sex- and Co-Mutation-Dependent Prognosis in Patients with SMARCA4-Mutated Malignancies

BACKGROUND

Whether sex and co-mutations impact prognosis of patients with SMARCA4-mutated (mutSMARCA4) malignancies is not clear.

METHODS

This cohort included patients from Northern California Kaiser Permanente with next-generation sequencing (NGS) performed from August 2020 to October 2022. We used Cox regression modeling to examine the association between sex and overall survival (OS), adjusting for demographics, performance status, Charlson comorbidity index, receipt of treatment, tumor mutation burden (TMB), and TP53, KRAS, CDKN2A, STK11, and Keap1 co-mutations.

RESULTS

Out of 9221 cases with NGS performed, 125 cases (1.4%) had a mutSMARCA4. The most common malignancies with a mutSMARCA4 were non-small cell lung cancer (NSCLC, 35.2%), esophageal and stomach adenocarcinoma (12.8%), and cancer of unknown primary (11.2%). The most common co-mutations were p53 (mutp53, 59.2%), KRAS (mutKRAS, 28.8%), CDKN2A (mutCDKN2A, 31.2%), STK11 (mutSTK11, 12.8%), and Keap1 (mutKeap1, 8.8%) mutations. Male patients had substantially worse OS than female patients both among the entire mutSMARCA4 cohort (HR = 1.71, [95% CI 0.92-3.18]) with a median OS of 3.0 versus 43.3 months (p < 0.001), and among the NSCLC subgroup (HR = 14.2, [95% CI 2.76-73.4]) with a median OS of 2.75 months versus un-estimable (p = 0.02). Among all patients with mutSMARCA4, mutp53 versus wtp53 (HR = 2.12, [95% CI 1.04-4.29]) and mutSTK11 versus wtSTK11 (HR = 2.59, [95% CI 0.87-7.73]) were associated with worse OS. Among the NSCLC subgroup, mutp53 versus wtp53 (HR = 0.35, [0.06-1.97]) and mutKRAS versus wtKRAS (HR = 0.04, [0.003-.45]) were associated with better OS, while mutCDKN2A versus wtCDKN2A (HR = 5.04, [1.12-22.32]), mutSTK11 versus wtSTK11 (HR = 13.10, [95% CI 1.16-148.26]), and mutKeap1 versus wtKeap1 (HR = 5.06, [95% CI 0.89-26.61}) were associated with worse OS.

CONCLUSION

In our cohort of patients with mutSMARCA4, males had substantially worse prognosis than females, while mutTP53, mutKRAS, mutCDKN2A, mutSTK11 and mutKeap1were differentially associated with prognosis among all patients and among the NSCLC subgroup. Our results, if confirmed, could suggest potentially unidentified mechanisms that underly this sex and co-mutation-dependent prognostic disparity among patients whose tumor bears a mutSMARCA4.

Next-generation universal hereditary cancer screening: implementation of an automated hereditary cancer screening program for patients with advanced cancer undergoing tumor sequencing in a large HMO

Variants in hereditary cancer risk genes are frequently identified following tumor-based DNA sequencing and represent an opportunity to diagnose hereditary cancer. We implemented an automated hereditary cancer screening program in a large HMO for all patients who underwent tumor-based DNA sequencing to identify patients with hereditary cancer and determine if this approach augmented existing genetic counseling approaches driven by personal/family history criteria. Regular automated searches of a centralized tumor DNA variant database were performed for ATM, BRCA1, BRCA2, MLH1, MSH2, MSH6, PALB2, and/or PMS2 variants, and germline hereditary cancer gene panel testing was offered to patients with tumor variants who had never undergone germline testing. Patients completing germline testing due to their tumor DNA test results were considered part of the tumor DNA safety net. Patients previously completing germline testing via traditional genetic counseling and tumor DNA safety net were compared for demographics, tumor type, presence of germline pathogenic/likely pathogenic (P/LP) variant, and whether NCCN criteria were met for hereditary cancer genetic testing. Germline P/LP variants were common in both groups. Patients who received germline testing through traditional genetic counseling were more likely to have cardinal hereditary tumors than the tumor DNA safety net group. Patients identified with hereditary cancer through traditional genetic counseling were more likely to meet NCCN personal/family history criteria for germline testing than the tumor DNA safety net group (99% versus 34%). A universal tumor DNA safety net screen is an important diagnostic strategy which augments traditional genetic counseling approaches based on personal/family history.

Development and validation of an integrative pan-solid tumor predictor of PD-1/PD-L1 blockade benefit

BACKGROUND

Anti-PD-1 and PD-L1 (collectively PD-[L]1) therapies are approved for many advanced solid tumors. Biomarkers beyond PD-L1 immunohistochemistry, microsatellite instability, and tumor mutation burden (TMB) may improve benefit prediction.

METHODS

Using treatment data and genomic and transcriptomic tumor tissue profiling from an observational trial (NCT03061305), we developed Immunotherapy Response Score (IRS), a pan-tumor predictive model of PD-(L)1 benefit. IRS real-world progression free survival (rwPFS) and overall survival (OS) prediction was validated in an independent cohort of trial patients.

RESULTS

Here, by Cox modeling, we develop IRS-which combines TMB with CD274, PDCD1, ADAM12 and TOP2A quantitative expression-to predict pembrolizumab rwPFS (648 patients; 26 tumor types; IRS-High or -Low groups). In the 248 patient validation cohort (248 patients; 24 tumor types; non-pembrolizumab PD-[L]1 monotherapy treatment), median rwPFS and OS are significantly longer in IRS-High vs. IRS-Low patients (rwPFS adjusted hazard ratio [aHR] 0.52, p = 0.003; OS aHR 0.49, p = 0.005); TMB alone does not significantly predict PD-(L)1 rwPFS nor OS. In 146 patients treated with systemic therapy prior to pembrolizumab monotherapy, pembrolizumab rwPFS is only significantly longer than immediately preceding therapy rwPFS in IRS-High patients (interaction test p = 0.001). In propensity matched lung cancer patients treated with first-line pembrolizumab monotherapy or pembrolizumab+chemotherapy, monotherapy rwPFS is significantly shorter in IRS-Low patients, but is not significantly different in IRS-High patients. Across 24,463 molecularly-evaluable trial patients, 7.6% of patients outside of monotherapy PD-(L)1 approved tumor types are IRS-High/TMB-Low.

CONCLUSIONS

The validated, predictive, pan-tumor IRS model can expand PD-(L)1 monotherapy benefit outside currently approved indications.

Consistency and reproducibility of large panel next-generation sequencing: Multi-laboratory assessment of somatic mutation detection on reference materials with mismatch repair and proofreading deficiency

INTRODUCTION

Clinical precision oncology increasingly relies on accurate genome-wide profiling using large panel next generation sequencing; however, difficulties in accurate and consistent detection of somatic mutation from individual platforms and pipelines remain an open question.

OBJECTIVES

To obtain paired tumor-normal reference materials that can be effectively constructed and interchangeable with clinical samples, and evaluate the performance of 56 panels under routine testing conditions based on the reference samples.

METHODS

Genes involved in mismatch repair and DNA proofreading were knocked down using the CRISPR-Cas9 technology to accumulate somatic mutations in a defined GM12878 cell line. They were used as reference materials to comprehensively evaluate the reproducibility and accuracy of detection results of oncopanels and explore the potential influencing factors.

RESULTS

In total, 14 paired tumor-normal reference DNA samples from engineered cell lines were prepared, and a reference dataset comprising 168 somatic mutations in a high-confidence region of 1.8 Mb were generated. For mutations with an allele frequency (AF) of more than 5% in reference samples, 56 panels collectively reported 1306 errors, including 729 false negatives (FNs), 179 false positives (FPs) and 398 reproducibility errors. The performance metric varied among panels with precision and recall ranging from 0.773 to 1 and 0.683 to 1, respectively. Incorrect and inadequate filtering accounted for a large proportion of false discovery (including FNs and FPs), while low-quality detection, cross-contamination and other sequencing errors during the wet bench process were other sources of FNs and FPs. In addition, low AF (<5%) considerably influenced the reproducibility and comparability among panels.

CONCLUSIONS

This study provided an integrated practice for developing reference standard to assess oncopanels in detecting somatic mutations and quantitatively revealed the source of detection errors. It will promote optimization, validation, and quality control among laboratories with potential applicability in clinical use.