Recommendations for Cell-Free DNA Assay Validations: A Joint Consensus Recommendation of the Association for Molecular Pathology and College of American Pathologists.

Diagnosing, selecting therapy for, and monitoring cancer in patients using a minimally invasive blood test represents a significant advance in precision medicine. Wide variability exists in how circulating tumor DNA (ctDNA) assays are developed, validated, and reported in the literature, which hinders clinical adoption and may negatively impact patient care. Standardization is needed for factors affecting ctDNA assay performance and reporting, including pre-analytical variables, analytical considerations, and elements of laboratory assay reporting. The Association for Molecular Pathology Clinical Practice Committee's Liquid Biopsy Working Group (LBxWG), including organizational representation from the American Society of Clinical Oncology and the College of American Pathologists, has undertaken a full-text data extraction of 1228 ctDNA publications that describe assays performed in patients with lymphoma and solid tumor malignancies. With an emphasis on clinical assay validation, the LBxWG has developed a set of 13 best practice consensus recommendations for validating, reporting, and publishing clinical ctDNA assays. Recommendations include reporting key pre-analytical considerations and assay performance metrics; this analysis demonstrates these elements are inconsistently included in publications. The LBxWG recommendations are intended to assist clinical laboratories with validating and reporting ctDNA assays and to ensure high-quality data are included in publications. It is expected that these recommendations will need to be updated as the body of literature continues to mature.

An Unexpected Diagnosis Uncovered by Quantitative Molecular Findings: A Case Report.

A 74-year-old male presented with rectal pain; workup uncovered an anal mass, and a diagnosis of melanoma was rendered via histologic examination and immunohistochemical (IHC) studies. Droplet digital PCR (ddPCR)-based BRAF testing was performed and revealed the presence of BRAF V600E, which is a common targetable genetic alteration in melanoma. Interestingly, the ratio of mutant to wild-type copy number was low (0.3%), whereas tumor cell percentage on tissue slides was 90%. With additional workup, BRAF V600E IHC confirmed a very small subset of BRAF V600E-positive cells, and a next-generation sequencing (NGS) panel revealed a pathogenic KIT variant, p.L576P, with an allele frequency of 63%. It was initially hypothesized that the main driver of the melanoma was the KIT alteration, whereas a small subclone (not detected by NGS, which has a 5% limit of detection) was driven by the BRAF V600E detected by ddPCR. To determine whether there were morphologic differences between the 2 clones, a careful review of the histology was performed and revealed distinct morphology of the BRAF V600E-positive cells, including pale cytoplasm, nuclear grooves, and infiltrating eosinophils. Additional IHC workup of the BRAF V600E-positive cells showed coexpression of CD1a, Langerin, and S100, diagnostic of Langerhans cell histiocytosis (LCH). This diagnosis was unexpected and would have been missed without highly sensitive molecular testing; yet it is of clinical importance for the patient. This case raises interesting biology questions regarding the relationship between melanoma and LCH; moreover, it highlights the importance of integrating quantitative information in molecular data interpretation.

Transcriptomic and immunophenotypic characterization of two cases of adamantinoma-like Ewing sarcoma of the thyroid gland.

INTRODUCTION: Adamantinoma-like Ewing sarcoma (ALES) is a rare aggressive malignancy occasionally diagnosed in the thyroid gland. ALES shows basaloid cytomorphology, expresses keratins, p63, p40, frequently CD99, and harbours the t(11;22) EWSR1::FLI1 translocation. There is debate on whether ALES resembles more sarcoma or carcinoma. METHODS: We performed RNA sequencing from two ALES cases and compared findings with skeletal Ewing's sarcomas and nonneoplastic thyroid tissue. ALES was investigated by in situ hybridization (ISH) for high-risk human papillomavirus (HPV) DNA and immunohistochemistry for the following antigens: keratin 7, keratin 20, keratin 5, keratins (AE1/AE3 and CAM5.2), CD45, CD20, CD5, CD99, chromogranin, synaptophysin, calcitonin, thyroglobulin, PAX8, TTF1, S100, p40, p63, p16, NUT, desmin, ER, FLI1, INI1, and myogenin. RESULTS: An uncommon EWSR1::FLI transcript with retained EWSR1 exon 8 was detected in both ALES cases. Regulators of EWSR1::FLI1 splicing (HNRNPH1, SUPT6H, SF3B1) necessary for production of a functional fusion oncoprotein, as well as 53 genes (including TNNT1, NKX2.2) activated downstream to the EWSR1::FLI1 cascade, were overexpressed. Eighty-six genes were uniquely overexpressed in ALES, most of which were related to squamous differentiation. Immunohistochemically, ALES strongly expressed keratins 5, AE1/AE3 and CAM5.2, p63, p40, p16, and focally CD99. INI1 was retained. The remaining immunostains and HPV DNA ISH were negative. CONCLUSION: Comparative transcriptomic profiling reveals overlapping features of ALES with skeletal Ewing's sarcoma and an epithelial carcinoma, as evidenced by immunohistochemical expression of keratin 5, p63, p40, CD99, the transcriptome profile, and detection of EWSR1::FLI1 fusion transcript by RNA sequencing.

BRAF V600 Mutation Detection in Plasma Cell-Free DNA: NCCTG N0879 (Alliance).

OBJECTIVE: To evaluate the prognostic significance of detectable circulating cell-free DNA (cfDNA) BRAF V600E/K mutations in patients with advanced melanoma enrolled in a clinical trial without BRAF-targeted therapy. PATIENTS AND METHODS: BRAF V600E/K mutation status was determined on archived tissue and pretreatment stored plasma from 149 patients with unresectable stage IV melanoma who were enrolled between May 5, 2010 and May 2, 2014 in the North Central Cancer Treatment Group/Alliance N0879 randomized phase 2 clinical trial. Results were reported as presence or absence of cfDNA BRAF V600E/K detection of assay vs tissue. Progression-free survival (PFS) and overall survival (OS) were assessed for patients with and without detectable BRAF mutation. RESULTS: In total, 63 of 149 (42.3%) patients had BRAF V600E/K results for tissue and blood, and 20 of 63 (31.7%) patients had tissue-diagnosed mutant BRAF. Of these, 11 of 20 (55.0%) patients had detectable plasma cfDNA BRAF. Among patients with tissue-mutant BRAF V600E/K, PFS and OS were shorter for those with corresponding cfDNA mutations (PFS, 5.8 vs 12.0 months; P=.051; OS, 9.2 vs 27.1 months; P=.054). Our assay demonstrated sensitivity of 55% (95% CI, 0.322 to 0.768), specificity of 97.7% (95% CI, 0.932 to 1.000), positive predictive value of 91.7% (95% CI, 0.760 to 1.000), and negative predictive value of 82.4% (95% CI, 0.719 to 0.928). CONCLUSION: In advanced melanoma, detectable cfDNA BRAF V600E/K mutation is present in about half the patients with stage IV with BRAF-mutant melanoma tumor tissue and appears to confer a poorer prognosis when detectable. Given the poorer prognosis, cfDNA can be used to risk-stratify patients with metastatic melanoma in practice or clinical trials.Trial Registration: clinicaltrials.gov Identifier: NCT00976573.

RNA-Seq Reveals Differences in Expressed Tumor Mutation Burden in Colorectal and Endometrial Cancers with and without Defective DNA-Mismatch Repair.

Tumor mutation burden (TMB) is an emerging biomarker of immunotherapy response. RNA sequencing in FFPE tissue samples was used for determining TMB in microsatellite-stable (MSS) and microsatellite instability-high (MSI-H) tumors in patients with colorectal or endometrial cancer. Tissue from tumors and paired normal tissue from 46 MSI-H and 12 MSS cases were included. Of the MSI-H tumors, 29 had defective DNA mismatch-repair mutations, and 17 had MLH1 promoter hypermethylation. TMB was measured using the expressed somatic nucleotide variants (eTMB). A method of accurate measurement of eTMB was developed that removes FFPE-derived artifacts by leveraging mutation signatures. There was a significant difference in the median eTMB values observed between MSI-H and MSS cases: 27.3 versus 6.7 mutations/megabase (mut/Mb) (P = 3.5 × 10-9). Among tumors with defective DNA-mismatch repair, those with mismatch-repair mutations had a significantly higher median eTMB than those with hypermethylation: 28.1 versus 17.5 mut/Mb (P = 0.037). Multivariate analysis showed that MSI status, tumor type (endometrial or colorectal), and age were significantly associated with eTMB. Additionally, using whole-exome sequencing in a subset of these patients, it was determined that DNA TMB correlated well with eTMB (Spearman correlation coefficient, 0.83). These results demonstrate that RNA sequencing can be used for measuring eTMB in FFPE tumor specimens.

Assessment of RAS Dependency for BRAF Alterations Using Cancer Genomic Databases.

Importance: Understanding RAS dependency and mechanisms of RAS activation in non-V600 BRAF variant cancers has important clinical implications. This is the first study to date to systematically assess RAS dependency of BRAF alterations with real-world cancer genomic databases. Objective: To evaluate RAS dependency of individual BRAF alterations through alteration coexistence analysis using cancer genomic databases. Design and Setting: A cross-sectional data analysis of 119 538 nonredundant cancer samples using cancer genomics databases including GENIE (Genomics Evidence Neoplasia Information Exchange) and databases in cBioPortal including TCGA (The Cancer Genome Atlas) (accessed March 24, 2020), in addition to 2745 cancer samples from Mayo Clinic Genomics Laboratory (January 1, 2015, to July 1, 2020). Frequencies and odds ratios of coexisting alterations of RAS (KRAS, NRAS and HRAS) and RAS regulatory genes (NF1, PTPN11 and CBL) were calculated for individual BRAF alterations, and compared according to the current BRAF alteration classification; cancer type specificity of coexisting alterations of RAS or RAS regulatory genes was also evaluated. Main Outcomes and Measures: Primary outcome measurement is enrichment of RAS (KRAS, NRAS and HRAS) alterations in BRAF variant cancers. Secondary outcome measurement is enrichment of RAS regulatory gene (NF1, PTPN11, and CBL) in BRAF variant cancers. Results: A total of 2745 cancer samples from 2708 patients (female/male ratio: 1.0) tested by Mayo Clinic Genomics Laboratory and 119 538 patients (female/male ratio: 1.1) from GENIE and cBioPortal database were included in the study. In 119 538 nonredundant cancer samples, class 1 BRAF alterations and BRAF fusions were found to be mutually exclusive to alterations of RAS or RAS regulatory genes (odds ratio range 0.03-0.13 and 0.03-0.73 respectively), confirming their RAS independency. Both class 2 and class 3 BRAF alterations show variable and overlapping levels of enriched RAS alterations (odds ratio range: 0.03-5.9 and 0.63-2.52 respectively), suggesting heterogeneity in RAS dependency and a need to revisit BRAF alteration classification. For RAS-dependent BRAF alterations, the coexisting alterations also involve RAS regulatory genes by enrichment analysis (for example, S467L shows an odds ratio of 8.26 for NF1, 9.87 for PTPN11, and 15.23 for CBL) and occur in a variety of cancer types with some coalterations showing cancer type specificity (for example, HRAS variations account for 46.7% of all coexisting RAS alterations in BRAF variant bladder cancers, but 0% in non-small cell lung cancers). Variant-level assessment shows that BRAF alterations involving the same codon may differ in RAS dependency. In addition, RAS dependency of previously unclassified BRAF alterations could be assessed. Conclusions and Relevance: Current BRAF alteration classification based on in vitro assays does not accurately predict RAS dependency in vivo for non-V600 BRAF alterations. RAS-dependent BRAF variant cancers with different mechanisms of RAS activation suggest the need for different treatment strategies.

Assessment of clinical outcomes with immune checkpoint inhibitor therapy in melanoma patients with CDKN2A and TP53 pathogenic mutations.

BACKGROUND: CDKN2A and TP53 mutations are recurrent events in melanoma, occurring in 13.3% and 15.1% of cases respectively and are associated with poorer outcomes. It is unclear what effect CDKN2A and TP53 mutations have on the clinical outcomes of patients treated with checkpoint inhibitors. METHODS: All patients with cutaneous melanoma or melanoma of unknown primary who received checkpoint inhibitor therapy and underwent genomic profiling with the 50-gene Mayo Clinic solid tumor targeted cancer gene panel were included. Patients were stratified according to the presence or absence of mutations in BRAF, NRAS, CDKN2A, and TP53. Patients without mutations in any of these genes were termed quadruple wild type (QuadWT). Clinical outcomes including median time to progression (TTP), median overall survival (OS), 6-month and 12-month OS, 6-month and 12-month without progression, ORR and disease control rate (DCR) were analyzed according to the mutational status of CDKN2A, TP53 and QuadWT. RESULTS: A total of 102 patients were included in this study of which 14 had mutations of CDKN2A (CDKN2Amut), 21 had TP53 mutations (TP53mut), and 12 were QuadWT. TP53mut, CDKN2Amut and QuadWT mutational status did not impact clinical outcomes including median TTP, median OS, 6-month and 12-month OS, 6-month and 12-month without progression, ORR and DCR. There was a trend towards improved median TTP and DCR in CDKN2Amut cohort and a trend towards worsened median TTP in the QuadWT cohort. CONCLUSION: Cell cycle regulators such as TP53 and CDKN2A do not appear to significantly alter clinical outcomes when immune checkpoint inhibitors are used.

Incidence of major hemorrhage after aggressive image-guided liver mass biopsy in the era of individualized medicine.

PURPOSE: To analyze a large volume of image-guided liver mass biopsies to assess for an increased incidence of major hemorrhage after aggressive liver mass sampling, and to determine if coaxial technique reduces major hemorrhage rate. METHODS: Patients who underwent image-guided liver mass biopsy over a 15-year period (December 7, 2001-September 22, 2016) were retrospectively identified. An aggressive biopsy was defined as a biopsy event in which ≥ 4 core needle passes were performed. Association of major hemorrhage after aggressive liver mass biopsy and other potential risk factors of interest were assessed using logistic regression analysis. For the subset of aggressive biopsies, Fisher's exact test was used to compare the incidence of major hemorrhage using coaxial versus noncoaxial techniques. RESULTS: Aggressive biopsies constituted 11.6% of biopsy events (N =579/5011). The incidence of major hemorrhage with <4 passes was 0.4% (N =18/4432) and with ≥4 passes 1.2% (N =6/579). In univariable models, aggressive biopsy was significantly associated with major hemorrhage (OR 3.0, 95% CI 1.16-6.92, p =0.025). After adjusting for gender and platelet count, the association was not significant at the p =0.05 level (OR 2.58, 95% CI 0.927-6.24, p =0.067). The rate of major hemorrhage in the coaxial biopsy technique group was 1.4% (N =3/209) compared to 1.1% (N =4/370) in the noncoaxial biopsy technique group, which was not a significant difference (p =0.707). CONCLUSIONS: Although aggressive image-guided liver mass biopsies had an increased incidence of major hemorrhage, the overall risk of bleeding remained low. The benefit of such biopsies will almost certainly outweigh the risk in most patients.

Development and Verification of an RNA Sequencing (RNA-Seq) Assay for the Detection of Gene Fusions in Tumors.

We assessed the performance characteristics of an RNA sequencing (RNA-Seq) assay designed to detect gene fusions in 571 genes to help manage patients with cancer. Polyadenylated RNA was converted to cDNA, which was then used to prepare next-generation sequencing libraries that were sequenced on an Illumina HiSeq 2500 instrument and analyzed with an in-house developed bioinformatic pipeline. The assay identified 38 of 41 gene fusions detected by another method, such as fluorescence in situ hybridization or RT-PCR, for a sensitivity of 93%. No false-positive gene fusions were identified in 15 normal tissue specimens and 10 tumor specimens that were negative for fusions by RNA sequencing or Mate Pair NGS (100% specificity). The assay also identified 22 fusions in 17 tumor specimens that had not been detected by other methods. Eighteen of the 22 fusions had not previously been described. Good intra-assay and interassay reproducibility was observed with complete concordance for the presence or absence of gene fusions in replicates. The analytical sensitivity of the assay was tested by diluting RNA isolated from gene fusion-positive cases with fusion-negative RNA. Gene fusions were generally detectable down to 12.5% dilutions for most fusions and as little as 3% for some fusions. This assay can help identify fusions in patients with cancer; these patients may in turn benefit from both US Food and Drug Administration-approved and investigational targeted therapies.

NCCTG N0879 (Alliance): A randomized phase 2 cooperative group trial of carboplatin, paclitaxel, and bevacizumab ± everolimus for metastatic melanoma.

BACKGROUND: Despite the success of immune checkpoint and targeted therapy, many patients with melanoma ultimately require further treatment. The combination of carboplatin, paclitaxel, and bevacizumab (CPB) has demonstrated promising activity in a single-arm study. In the current study, the authors performed a randomized phase 2 study to confirm efficacy and to determine whether adding everolimus would increase the activity of the combination. METHODS: Through the North Central Cancer Treatment Group, a total of 149 patients with unresectable AJCC 6th edition stage IV melanoma were randomized from May 2010 to May 2014 to either CPB or CPB with everolimus (CPBE). The primary endpoint was progression-free survival (PFS), with secondary endpoints of overall survival (OS), response rate, and tolerability. RESULTS: The CPB and CPBE treatment arms were balanced with regard to age (median age: 59 years vs 58 years) and high lactate dehydrogenase (48% vs 51%), but were unbalanced with regard to sex (male sex: 72% vs 55%; P = .03). Overall, there was no difference noted with regard to PFS, with a median PFS of 5.6 months for CPB versus 5.1 months for CPBE (hazard ratio [HR], 1.14; 95% confidence interval [95% CI], 0.81-1.62 [P = .44]), or for OS, with a median OS of 14.5 months for CPB versus 10.8 months for CPBE (HR, 1.16; 95% CI, 0.84-1.84). The confirmed response rate was 13% for CPB and 23% for CPBE (P = .13). Toxicity was higher for CPBE compared with CPB (83% for grade 3 + and 14% for grade 4 + vs 63% for grade 3 + and 11% for grade 4+, respectively) (toxicities were graded using the Cancer Therapy Evaluation Program of the National Cancer Institute Common Terminology Criteria for Adverse Events [version 4.0]). Common grade 3 + toxicities were neutropenia, leukopenia, and fatigue, which occurred in both treatment arms with comparable frequency. CONCLUSIONS: Both experimental arms demonstrated activity, with a PFS of >5 months. However, the addition of everolimus to CPB failed to improve outcomes, with increased toxicity noted. These findings replicate the moderate antitumor activity of CPB, with future development possibly in combination with targeted or immunotherapy. Cancer 2018;124:537-45. © 2017 American Cancer Society.

Autosomal dominant distal myopathy due to a novel ACTA1 mutation.

Mutations in skeletal muscle α-actin 1-encoding gene (ACTA1) cause autosomal dominant or recessive myopathies with marked clinical and pathological heterogeneity. Patients typically develop generalized or limb-girdle pattern of weakness, but recently a family with scapuloperoneal myopathy was reported. We describe a father and 2 children with childhood-to-juvenile onset distal myopathy, carrying a novel dominant ACTA1 variant, c.757G>C (p.Gly253Arg). Father had delayed motor development and developed significant proximal weakness later in life; he was initially misdiagnosed as having spinal muscular atrophy based on electromyographic findings. His children had predominant anterior distal leg and finger extensor involvement. Nemaline rods were abundant on the daughter's biopsy, absent on the father's initial biopsy, and extremely rare on the father's subsequent biopsy a decade later. The father's second biopsy also showed myofibrillar pathology and rare fibers with actin filament aggregates. The present family expands the spectrum of actinopathy to include a distal myopathy.

Experience with precision genomics and tumor board, indicates frequent target identification, but barriers to delivery.

BACKGROUND: The ability to analyze the genomics of malignancies has opened up new possibilities for off-label targeted therapy in cancers that are refractory to standard therapy. At Mayo Clinic these efforts are organized through the Center for Individualized Medicine (CIM). RESULTS: Prior to GTB, datasets were analyzed and integrated by a team of bioinformaticians and cancer biologists. Therapeutically actionable mutations were identified in 65% (92/141) of the patients tested with 32% (29/92) receiving genomically targeted therapy with FDA approved drugs or in an independent clinical trial with 45% (13/29) responding. Standard of care (SOC) options were continued by 15% (14/92) of patients tested before exhausting SOC options, with 71% (10/14) responding to treatment. Over 35% (34/92) of patients with actionable targets were not treated with 65% (22/34) choosing comfort measures or passing away. MATERIALS AND METHODS: Patients (N = 165) were referred to the CIM Clinic between October 2012 and December 2015. All patients received clinical genomic panel testing with selected subsets receiving array comparative genomic hybridization and clinical whole exome sequencing to complement and validate panel findings. A genomic tumor board (GTB) reviewed results and, when possible, developed treatment recommendations. CONCLUSIONS: Treatment decisions driven by tumor genomic analysis can lead to significant clinical benefit in a minority of patients. The success of genomically driven therapy depends both on access to drugs and robustness of bioinformatics analysis. While novel clinical trial designs are increasing the utility of genomic testing, robust data sharing of outcomes is needed to optimize clinical benefit for all patients.

Expression of PD-1 and PD-L1 in Anaplastic Thyroid Cancer Patients Treated With Multimodal Therapy: Results From a Retrospective Study.

Context: Anaplastic thyroid cancer (ATC) is rare and a highly fatal malignancy. The role of programmed death-1 (PD-1) and programmed death ligand-1 (PD-L1) as prognostic and/or predictive markers in ATC is unknown. Objective: Multimodal therapy offers the best chance at tumor control. The objective of this study was to detect potential associations of PD-1/PD-L1 axis variables with outcome data in ATC. Design: Retrospective study of a uniformly treated cohort. Setting: Single institution retrospective cohort study. Patients or Other Participants: Sixteen patients who received intensity-modulated radiation therapy (15 had preceding surgery) were studied. Main Outcome Measure: Patients treated with multimodal therapy were followed and assessed for overall survival (OS) and progression-free survival (PFS). Results: All samples demonstrated PD-1 expression in inflammatory cells whereas tumor cells were primarily negative. PD-L1 was expressed on ATC tumor cells in most samples and showed mainly membranous staining. High PD-1 expression (>40% staining) in inflammatory cells was associated with worse overall survival (OS; hazard ratio, 3.36; 95% confidence interval, 1.00 to 12.96; P < 0.05) and trended toward worse PFS, whereas high PD-L1 expression in tumor cells (>33% staining) trended toward worse PFS and OS. Conclusion: PD-1/PD-L1 pathway proteins are highly expressed in ATC tumor samples and appear to represent predictive markers of PFS and OS in multimodality-treated ATC patients.

Impact of RNA degradation on fusion detection by RNA-seq.

BACKGROUND: RNA-seq is a well-established method for studying the transcriptome. Popular methods for library preparation in RNA-seq such as Illumina TruSeq® RNA v2 kit use a poly-A pulldown strategy. Such methods can cause loss of coverage at the 5' end of genes, impacting the ability to detect fusions when used on degraded samples. The goal of this study was to quantify the effects RNA degradation has on fusion detection when using poly-A selected mRNA and to identify the variables involved in this process. RESULTS: Using both artificially and naturally degraded samples, we found that there is a reduced ability to detect fusions as the distance of the breakpoint from the 3' end of the gene increases. The median transcript coverage decreases exponentially as a function of the distance from the 3' end and there is a linear relationship between the coverage decay rate and the RNA integrity number (RIN). Based on these findings we developed plots that show the probability of detecting a gene fusion ("sensitivity") as a function of the distance of the fusion breakpoint from the 3' end. CONCLUSIONS: This study developed a strategy to assess the impact that RNA degradation has on the ability to detect gene fusions by RNA-seq.

S768I Mutation in EGFR in Patients with Lung Cancer.

INTRODUCTION: Epidermal growth factor receptor gene (EGFR) mutations are relatively common oncogenic drivers in non-small cell lung cancer (NSCLC). The outcomes of patients who present with less common EGFR mutations or more than one EGFR mutation are uncertain. We reviewed our experience with the S768I mutation of exon 20 of EGFR to provide insight into the clinical significance of this mutation. METHODS: We used a natural language search program to search our electronic medical record system and every EGFR mutation analysis of patients with NSCLC treated at Mayo Clinic that was performed in our Department of Molecular Genetics to identify patients with EGFR S768I mutation. Relevant clinical and laboratory data were abstracted for selected cases, including evaluation of response after treatment with tyrosine kinase inhibitors. RESULTS: A total of 1527 patients with NSCLC who underwent EGFR testing were reviewed. The S768I mutation was present in nine patients (0.59%), four of whom were female. Only three had an isolated S768I mutation, four had a concurrent G719 mutation, and two had a concurrent L858R mutation. Among patients with stage IV disease treated with erlotinib (n = 4), one had an isolated S768I mutation and three had additional mutations (two patients with G719 and one patient with L858R). The tumor response to erlotinib of patients with stage IV disease was highly variable (progression-free survival ranged from 3 to 30 months and overall survival ranged from 5 to more than 51 months). CONCLUSIONS: S768I mutations in exon 20 of the EGFR gene are rare and are typically seen in conjunction with sensitizing EGFR mutations. Because of this mutation's rarity and the variability of responses of treated cases, its exact prognostic and predictive role is not fully understood. In our experience, S768I mutations in isolation do not necessarily confer sensitivity to erlotinib, but in conjunction with sensitizing EGFR mutations, S768I mutations do not restrict efficacy.

SERPINA1 Full-Gene Sequencing Identifies Rare Mutations Not Detected in Targeted Mutation Analysis.

Genetic α-1 antitrypsin (AAT) deficiency is characterized by low serum AAT levels and the identification of causal mutations or an abnormal protein. It needs to be distinguished from deficiency because of nongenetic causes, and diagnostic delay may contribute to worse patient outcome. Current routine clinical testing assesses for only the most common mutations. We wanted to determine the proportion of unexplained cases of AAT deficiency that harbor causal mutations not identified through current standard allele-specific genotyping and isoelectric focusing (IEF). All prospective cases from December 1, 2013, to October 1, 2014, with a low serum AAT level not explained by allele-specific genotyping and IEF were assessed through full-gene sequencing with a direct sequencing method for pathogenic mutations. We reviewed the results using American Council of Medical Genetics criteria. Of 3523 cases, 42 (1.2%) met study inclusion criteria. Pathogenic or likely pathogenic mutations not identified through clinical testing were detected through full-gene sequencing in 16 (38%) of the 42 cases. Rare mutations not detected with current allele-specific testing and IEF underlie a substantial proportion of genetic AAT deficiency. Full-gene sequencing, therefore, has the ability to improve accuracy in the diagnosis of AAT deficiency.

Selective Arterial Calcium Stimulation With Hepatic Venous Sampling Differentiates Insulinoma From Nesidioblastosis.

CONTEXT: In adult patients with endogenous hyperinsulinemic hypoglycemia and negative or inconclusive noninvasive imaging, insulinoma and non-insulinoma pancreatogenous hypoglycemic syndrome (NIPHS) resulting from diffuse nesidioblastosis must be considered in the differential diagnosis. It is not known whether the biochemical results of selective arterial calcium stimulation (SACST) with hepatic venous sampling can differentiate insulinoma from diffuse nesidioblastosis. OBJECTIVE: To determine the specificity of SACST with hepatic venous sampling in differentiating insulinoma from diffuse nesidioblastosis. DESIGN: Retrospective review (January 1996 to March 2014). SETTING: Tertiary referral center. PATIENTS OR OTHER PARTICIPANTS: A total of 116 patients with biochemical evidence of endogenous hyperinsulinemic hypoglycemia and negative or inconclusive noninvasive imaging who were subsequently shown at surgery to have insulinoma (n = 42) or nesidioblastosis (n = 74) after undergoing SACST with hepatic venous sampling. INTERVENTION(S): SACST with hepatic venous sampling before pancreatic exploration. MAIN OUTCOME MEASURE(S): Receiver operating characteristic curves were generated from the biochemical results of SACST to determine the specificity of the maximum hepatic venous insulin concentration (mHVI) and the relative-fold increase in hepatic venous insulin concentration (rHVI) over baseline after calcium injection from the dominant artery in differentiating insulinoma from nesidioblastosis. RESULTS: The mHVI (21.5-fold; P < .001) and rHVI (3.9-fold; P < .001) were significantly higher in the insulinoma group compared to the nesidioblastosis group. The areas under the receiver operating characteristic curve for mHVI and rHVI were excellent (0.94; P < .0001) and good (0.83; P < .0001), respectively, for differentiating insulinoma from nesidioblastosis. mHVI cutoffs of > 91.5 and > 263.5 µIU/mL were 95 and 100% specific for insulinoma, respectively. A 19-fold increase in rHVI over baseline was 99% specific for insulinoma. CONCLUSIONS: These data suggest that the mHVI and rHVI at SACST may be useful in differentiating insulinoma from nesidioblastosis with high specificity in patients with hyperinsulinemic hypoglycemia and negative or inconclusive noninvasive imaging.

Heterogenous MSH6 loss is a result of microsatellite instability within MSH6 and occurs in sporadic and hereditary colorectal and endometrial carcinomas.

Mismatch-repair (MMR) immunohistochemistry is used to detect tumor MMR deficiency associated with high-level microsatellite instability (MSI). Rare tumors show heterogenous loss of mutS homolog 6 (MSH6) with immunohistochemistry, defined by areas of retained staining and separate areas of complete loss of staining. To investigate the clinical interpretation of this phenomenon, we identified 22 cases of heterogenous MSH6 loss interpreted at Mayo Clinic from January 2001 through December 2012 and reviewed histologic features, MSH6 and other MMR immunohistochemistry, and accompanying MSI testing results (n=20). Heterogenous MSH6 loss was seen in colorectal carcinoma (n=18), endometrial carcinoma (n=3), and sebaceous neoplasm (n=1). In the 18 colorectal carcinoma cases, it accompanied complete loss of mutL homolog 1 (MLH1) or PMS2, or both. Heterogenous MSH6 loss was characterized by MSI and MSH6 C8 tract instability in treatment-naive cases and showed mucinous or signet-ring zones in one quarter of cases. Two cases status post neoadjuvant chemoradiation showed heterogenous MSH6 loss but were microsatellite and C8 tract stable. C8 tracts were unstable in 2 of 4 MSH6-associated Lynch syndrome (LS) tumors, but all 4 showed complete MSH6 loss on immunohistochemistry. Further, 12 such MSH6-associated LS cases showed complete MSH6 loss. In conclusion, heterogenous MSH6 loss is uncommon, usually caused by instability in MSH6 exon 5 polycytosine tract, and not associated with germline MSH6 mutation. Although heterogenous MSH6 loss provides evidence against germline MSH6 mutation, patients whose tumors exhibit this immunolabeling pattern may have LS due to a defect in a different MMR gene.

The diagnostic utility of combination of HMGA2 and IMP3 qRT-PCR testing in thyroid neoplasms.

The diagnosis of malignant thyroid tumors in some cytologic and histologic specimens remains challenging. High-mobility group A2 (HMGA2) expression and insulin-like growth factor II mRNA-binding protein-3 (IMP3) expression were evaluated by relative quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The aim of this study was to evaluate whether the combination of HMGA2 and IMP3 qRT-PCR was diagnostically useful in differentiating benign from malignant thyroid neoplasms. Fine-needle aspiration (FNA) specimens from 120 patients including 56 benign lesions and 64 carcinomas were used. The available 80 corresponding formalin-fixed paraffin-embedded (FFPE) thyroid tissues from 66 patients were also included in this study. HMGA2 and IMP3 expression levels were detected by qRT-PCR and reported as relative fold change after normalizing with a calibrator. The diagnostic utilities of HMGA2 and IMP3 qRT-PCR tests were evaluated individually and in combination. In FNA specimens, HMGA2 and IMP3 expression was consistently higher in thyroid malignancies compared with benign lesions in all subgroups except in Hürthle cell tumors. After exclusion of Hürthle cell tumors, the sensitivity was 90.2% for HMGA2, 88.2% for IMP3, and 98% for HMGA2+IMP3; the specificity was 97.1% for HMGA2, 79.4% for IMP3, and 79.4% for HMGA+IMP3. qRT-PCR data showed similar results in FFPE tissues: the sensitivity was 84.2% for HMGA2, 85.7% for IMP3, and 94.7% for HMGA2+IMP3; the specificity was 96.9% for HMGA2, 91.2% for IMP3, and 90.6% for HMGA2+IMP3. qRT-PCR data were concordant between FNA and FFPE samples for HMGA2 (97.4%) and IMP3 (96.9%). The results indicate that HMGA2 qRT-PCR with high specificity may be a useful ancillary technique to assist in the classification of difficult thyroid specimens, excluding Hürthle cell tumors. The HMGA2 and IMP3 qRT-PCR combination model with increased sensitivity and negative predictive value (96.4%) may be useful in screening thyroid cytology specimens.

Preappointment testing for BRAF/KIT mutation in advanced melanoma: a model in molecular data delivery for individualized medicine.

The emergence of individualized medicine is driven by developments in precision diagnostics, epitomized by molecular testing. Because treatment decisions are being made based on such molecular data, data management is gaining major importance. Among data management challenges, creating workflow solutions for timely delivery of molecular data has become pivotal. This study aims to design and implement a scalable process that permits preappointment BRAF/KIT mutation analysis in melanoma patients, allowing molecular results necessary for treatment plans to be available before the patient's appointment. Process implementation aims to provide a model for efficient molecular data delivery for individualized medicine. We examined the existing process of BRAF/KIT testing in melanoma patients visiting our institution for oncology consultation. We created 5 working groups, each designing a specific segment of an alternative process that would allow preappointment BRAF/KIT testing and delivery of results. Data were captured and analyzed to evaluate the success of the alternative process. For 1 year, 35 (59%) of 55 patients had prior BRAF/KIT testing. The remaining 20 patients went through the new process of preappointment testing; results were available at the time of appointment for 12 patients (overall preappointment results availability, 85.5%). The overall process averaged 13.4 ± 4.7 days. In conclusion, we describe the successful implementation of a scalable workflow solution that permits preappointment BRAF/KIT mutation analysis and result delivery in melanoma patients. This sets the stage for further applications of this model to other conditions, answering an increasing demand for robust delivery of molecular data for individualized medicine.