Deep oncopanel sequencing reveals within block position-dependent quality degradation in FFPE processed samples.

BACKGROUND: Clinical laboratories routinely use formalin-fixed paraffin-embedded (FFPE) tissue or cell block cytology samples in oncology panel sequencing to identify mutations that can predict patient response to targeted therapy. To understand the technical error due to FFPE processing, a robustly characterized diploid cell line was used to create FFPE samples with four different pre-tissue processing formalin fixation times. A total of 96 FFPE sections were then distributed to different laboratories for targeted sequencing analysis by four oncopanels, and variants resulting from technical error were identified. RESULTS: Tissue sections that fail more frequently show low cellularity, lower than recommended library preparation DNA input, or target sequencing depth. Importantly, sections from block surfaces are more likely to show FFPE-specific errors, akin to "edge effects" seen in histology, while the inner samples display no quality degradation related to fixation time. CONCLUSIONS: To assure reliable results, we recommend avoiding the block surface portion and restricting mutation detection to genomic regions of high confidence.

Cross-oncopanel study reveals high sensitivity and accuracy with overall analytical performance depending on genomic regions.

BACKGROUND: Targeted sequencing using oncopanels requires comprehensive assessments of accuracy and detection sensitivity to ensure analytical validity. By employing reference materials characterized by the U.S. Food and Drug Administration-led SEquence Quality Control project phase2 (SEQC2) effort, we perform a cross-platform multi-lab evaluation of eight Pan-Cancer panels to assess best practices for oncopanel sequencing. RESULTS: All panels demonstrate high sensitivity across targeted high-confidence coding regions and variant types for the variants previously verified to have variant allele frequency (VAF) in the 5-20% range. Sensitivity is reduced by utilizing VAF thresholds due to inherent variability in VAF measurements. Enforcing a VAF threshold for reporting has a positive impact on reducing false positive calls. Importantly, the false positive rate is found to be significantly higher outside the high-confidence coding regions, resulting in lower reproducibility. Thus, region restriction and VAF thresholds lead to low relative technical variability in estimating promising biomarkers and tumor mutational burden. CONCLUSION: This comprehensive study provides actionable guidelines for oncopanel sequencing and clear evidence that supports a simplified approach to assess the analytical performance of oncopanels. It will facilitate the rapid implementation, validation, and quality control of oncopanels in clinical use.

Evaluating the analytical validity of circulating tumor DNA sequencing assays for precision oncology.

Circulating tumor DNA (ctDNA) sequencing is being rapidly adopted in precision oncology, but the accuracy, sensitivity and reproducibility of ctDNA assays is poorly understood. Here we report the findings of a multi-site, cross-platform evaluation of the analytical performance of five industry-leading ctDNA assays. We evaluated each stage of the ctDNA sequencing workflow with simulations, synthetic DNA spike-in experiments and proficiency testing on standardized, cell-line-derived reference samples. Above 0.5% variant allele frequency, ctDNA mutations were detected with high sensitivity, precision and reproducibility by all five assays, whereas, below this limit, detection became unreliable and varied widely between assays, especially when input material was limited. Missed mutations (false negatives) were more common than erroneous candidates (false positives), indicating that the reliable sampling of rare ctDNA fragments is the key challenge for ctDNA assays. This comprehensive evaluation of the analytical performance of ctDNA assays serves to inform best practice guidelines and provides a resource for precision oncology.

SWI/SNF chromatin remodeling complex alterations in meningioma.

PURPOSE: While SWI/SNF chromatin remodeling complex alterations occur in approximately 20% of cancer, the frequency and potential impact on clinical outcomes in meningiomas remains to be comprehensively elucidated. METHODS: A large series of 255 meningiomas from a single institution that was enriched for high grade and recurrent lesions was identified. We performed next-generation targeted sequencing of known meningioma driver genes, including NF2, AKT1, PIK3CA, PIK3R1, and SMO and SWI/SNF chromatin remodeling complex genes, including ARID1A, SMARCA4, and SMARCB1 in all samples. Clinical correlates focused on clinical presentation and patient outcomes are presented. RESULTS: The series included 63 grade I meningiomas and 192 high-grade meningiomas, including 173 WHO grade II and 19 WHO grade III. Samples from recurrent surgeries comprised 37.3% of the series. A total of 41.6% meningiomas were from the skull base. NF2, AKT1, PIK3CA, PIK3R1, and SMO were mutated in 40.8, 7.1, 3.5, 3.9, and 2.4% of samples, respectively. ARID1A, SMARCA4, and SMARCB1 mutations were observed in 17.3, 3.5, and 5.1% of samples, respectively. A total of 68.2% of ARID1A-mutant meningiomas harbored a p.Gln1327del in-frame deletion. ARID1A mutations were seen in 19.1% of Grade I, 16.8% of Grade II, and 15.8% of Grade III meningiomas (P = 0.9, Fisher's exact). Median overall survival was 16.3 years (95% CI 10.9, 16.8). With multivariable analysis, the presence of an ARID1A mutation was significantly associated with a 7.421-fold increased hazard of death (P = 0.04). CONCLUSION: ARID1A mutations occur with similar frequency between low and high-grade meningiomas, but ARID1A mutations are independently prognostic of worse prognosis beyond clinical and histopathologic features.

NF2 mutation status and tumor mutational burden correlate with immune cell infiltration in meningiomas.

BACKGROUND: The tumor microenvironment is an emerging biomarker of underlying genomic heterogeneity and response to immunotherapy-based treatment regimens in solid malignancies. How tumor mutational burden influences the density, distribution, and presence of a localized immune response in meningiomas is unknown. METHODS: Representative hematoxylin and eosin slides were reviewed at 40X to assess for the density of inflammatory cells. Lymphocytes and macrophages were quantified in the following ordinal manner: 0 = not present, 1 = 1-25 cells present, and 2 = greater than 26 cells present. Immune cell infiltrate grade was scored for both scattered and aggregated distributions. Next generation targeted sequencing was performed on all meningiomas included in this study. RESULTS: One hundred and forty-five meningiomas were evaluated in this study. Lymphocytes were observed in both scattered (95.9%) and aggregated (21.4%) distributions. A total of 115 (79.3%) meningiomas had 1-25 scattered lymphocytes, and 24 (16.6%) had > 25 scattered lymphocytes, and 6 (4.1%) had no scattered lymphocytes. Twenty (13.8%) meningiomas had 1-25 aggregated lymphocytes. Eleven (7.6%) had > 25 aggregated lymphocytes and 114 (78.6%) had no aggregated lymphocytes. Six (4.1%) meningiomas had 1-25 aggregated macrophages, 5 (3.4%) had > 25 aggregated macrophages, and 134 (92.4%) had no aggregated macrophages. Density of aggregated lymphocytes and aggregated macrophages were associated with higher tumor grade, P = 0.0071 and P = 0.0068, respectively. Scattered lymphocyte density was not associated with meningioma grade. The presence of scattered lymphocytes was associated with increased tumor mutational burden. Meningiomas that did not have scattered lymphocytes had a mean number of single mutations of 2.3 ± 2.9, compared with meningiomas that had scattered lymphocytes, 6.9 ± 20.3, P = 0.03. NF2 mutations were identified in 59 (40.7%) meningiomas and were associated with increased density of scattered lymphocytes. NF2 mutations were seen in 0 (0%) meningiomas that did not have scattered lymphocytes, 46 (40.0%) meningiomas that had 1-25 scattered lymphocytes, and 13 (54.2%) meningiomas that had > 25 scattered lymphocytes, P = 0.046. CONCLUSIONS: Our findings suggest that distribution of immune cell infiltration in meningiomas is associated with tumor mutational burden. NF2 mutational status was associated with an increasing density of scattered lymphocytes. As the role of immunotherapy in meningiomas continues to be elucidated with clinical trials that are currently underway, these results may serve as a novel biomarker of tumor mutational burden in meningiomas.

Peritumoral edema correlates with mutational burden in meningiomas.

PURPOSE: Meningiomas are the most common primary central nervous system tumor. Emerging data supports that higher mutational burden portends worse clinical outcomes in meningiomas. However, there is a lack of imaging biomarkers that are associated with tumor genomics in meningiomas. METHODS: We performed next-generation targeted sequencing in a cohort of 75 primary meningiomas and assessed preoperative imaging for tumor volume and peritumoral brain edema (PTBE). An Edema Index was calculated. RESULTS: Meningiomas that were high grade (WHO grade II or grade III) had significantly larger tumor volume and were more likely to present with PTBE. Moreover, PTBE was associated with brain invasion on histopathology and reduced overall survival. There was a direct association between Edema Index and mutational burden. For every one increase in Edema Index, the number of single nucleotide variants increased by 1.09-fold (95% CI: 1.02, 1.2) (P = 0.01). CONCLUSION: These data support that Edema Index may serve as a novel imaging biomarker that can inform underlying mutational burden in patients with meningiomas.

Retro-inverso D-peptides as a novel targeted immunotherapy for Type 1 diabetes.

Over the past four decades, the number of people with Type 1 Diabetes (T1D) has increased by 4% per year, making it an important public health challenge. Currently, no curative therapy exists for T1D and the only available treatment is insulin replacement. HLA-DQ8 has been shown to present antigenic islet peptides driving the activation of CD4+ T-cells in T1D patients. Specifically, the insulin peptide InsB:9-23 activates self-reactive CD4+ T-cells, causing pancreatic beta cell destruction. The aim of the current study was to identify retro-inverso-d-amino acid based peptides (RI-D-peptides) that can suppress T-cell activation by blocking the presentation of InsB:9-23 peptide within HLA-DQ8 pocket. We identified a RI-D-peptide (RI-EXT) that inhibited InsB:9-23 binding to recombinant HLA-DQ8 molecule, as well as its binding to DQ8 expressed on human B-cells. RI-EXT prevented T-cell activation in a cellular antigen presentation assay containing human DQ8 cells loaded with InsB:9-23 peptide and murine T-cells expressing a human T-cell receptor specific for the InsB:9-23-DQ8 complex. Moreover, RI-EXT blocked T-cell activation by InsB:9-23 in a humanized DQ8 mice both ex vivo and in vivo, as shown by decreased production of IL-2 and IFN-γ and reduced lymphocyte proliferation. Interestingly, RI-EXT also blocked lymphocyte activation and proliferation by InsB:9-23 in PBMCs isolated from recent onset DQ8-T1D patients. In summary, we discovered a RI-D-peptide that blocks InsB:9-23 binding to HLA-DQ8 and its presentation to T-cells in T1D. These findings set the stage for using our approach as a novel therapy for patients with T1D and potentially other autoimmune diseases.

STK11 mutation status is associated with decreased survival in meningiomas.

BACKGROUND: Emerging evidence suggests that STK11 mutations may influence clinical outcome and response to immunotherapy in cancer. MATERIALS AND METHODS: Next-generation targeted sequencing of STK11 mutation status in a large cohort of 188 meningiomas. RESULTS: STK11 loss-of-function mutations were identified in 3.7% of meningiomas. STK11 mutations were found in both low- and high-grade lesions and samples from primary and recurrent disease. There was a 2.8-fold increased risk of death for patients whose meningioma harbored an STK11 mutation, after controlling for lesion grade and occurrence status. The median overall survival for patients with STK11-mutated meningiomas was 4.4 years compared with 16.8 years. CONCLUSION: These data identify recurrent STK11 mutations in a subset of meningiomas. Genotyping of STK11 is encouraged for meningioma patients undergoing immunotherapy-based therapy.

Comparative genomic analysis of driver mutations in matched primary and recurrent meningiomas.

A significant proportion of low-grade WHO grade I and higher-grade WHO grade II or III meningiomas are at risk to develop post-resection recurrence. Though recent studies investigated genomic alterations within histological subtypes of meningiomas, few have compared genomic profiles of primary meningiomas matched to their recurrences. The present study aimed to identify oncogenic driver mutations that may indicate risk of meningioma recurrence and aggressive clinical course. Seventeen patients treated for low-grade (n = 8) or high-grade (n = 9) meningioma and underwent both primary and recurrent resection between 2007-2017 were reviewed. Tumor specimens (n = 38) underwent genomic sequencing of known oncogenic driver mutations. Primary and recurrent tumors were compared using matched-pair analyses for mutational associations with clinical outcomes including functional status, progression-free survival (PFS) and overall survival (OS). Most common driver mutations included POLE and NF2. There was no enrichment for any driver mutation from primary to recurrent tumor specimen. NF2 mutant meningiomas were associated with larger tumor size (8-fold increase), presence of vasogenic edema, and higher mitotic proliferation on univariate and independently on multivariate regression (p's < 0.05) after controlling for preoperative and tumor features. Tumors with POLE driver mutations were associated with decreased functional status at last postoperative follow-up (p = 0.022) relative to presentation. Mutation status was not associated with PFS or OS on multivariate Cox regression, but rather with grade of resection (p = 0.046) for PFS. While primary and recurrent tumors exhibited similar driver mutations within patients, the identification of driver mutations associated with clinical outcomes is crucial for guiding potential targeted treatments in recurrent meningiomas.