High-Grade, Nonsarcomatoid Chromophobe Renal Cell Carcinoma: A Series of 22 Cases With Novel Molecular Features on a Subset.

Chromophobe renal cell carcinoma (ChRCC) is the third most common subtype of renal cell carcinoma and typically exhibits indolent behavior, though a rare subset can exhibit high-grade morphologic features and is associated with a poor prognosis. Although there are limited data on the molecular characteristics of metastatic and sarcomatoid ChRCC, the molecular features of high-grade, nonsarcomatoid ChRCC remain unexplored. Herein, we characterize 22 cases of ChRCC with high-grade, nonsarcomatoid components. High-grade ChRCC frequently demonstrated advanced stage at diagnosis (64% ≥pT3a or N1), with regions of extrarenal extension, nodal metastases, and vascular invasion consisting solely of high-grade ChRCC morphologically. We performed spatially guided panel-based DNA sequencing on 11 cases comparing high-grade and low-grade regions (n = 22 samples). We identified recurring somatic alterations emblematic of ChRCC, including deletions of chromosomes 1, 2, 6, 10, 13, 17, and 21 in 91% (10/11) of cases and recurring mutations in TP53 (81.8%, n = 9/11) and PTEN (36.4%, n = 4/11). Notably, although PTEN and TP53 alterations were found in both high-grade and low-grade regions, private mutations were identified in 3 cases, indicating convergent evolution. Finally, we identified recurring RB1 mutations in 27% (n = 3) of high-grade regions leading to selective protein loss by immunohistochemistry not observed in adjacent low-grade regions. This finding was confirmed in The Cancer Genome Atlas cohort where 2 of 66 cases contained RB1 mutations and demonstrated unequivocal high-grade, nonsarcomatoid morphology. We also detected multiple chromosomal gains confined to the high-grade regions, consistent with imbalanced chromosome duplication. These findings broaden our understanding of the molecular pathogenesis of ChRCC and suggest that subclonal RB1 mutations can drive the evolution to high-grade, nonsarcomatoid ChRCC.

HER2 amplification by next-generation sequencing to identify HER2-positive invasive breast cancer with negative HER2 immunohistochemistry.

BACKGROUND: Human epidermal growth factor receptor 2 (HER2) positive breast carcinomas due to HER2 amplification are associated with aggressive behavior and a poor prognosis. Anti-HER2-targeted therapies are widely used to treat HER2-positive breast carcinomas with excellent outcomes. Accurate identification of HER2 amplification status in breast carcinomas is of important diagnostic and treatment value. Currently, HER2 amplification status is routinely determined by immunohistochemistry (IHC) and/or fluorescence in situ hybridization (FISH) testing. This study will review our past HER2 data to determine and characterize discordant results between HER2 IHC and FISH. It will also determine a potential impact of HER2 amplification status by next-generation sequencing (NGS) on these patients. METHODS: We reviewed a total of 4884 breast carcinomas with coexisting HER2 IHC and HER2 FISH performed at our institution from 2010 to 2022. 57 cases also had a Next-Generation-Sequencing-based (NGS) gene panel performed. Given the advances in biostatic analysis pipelines, NGS methods were utilized to provide results on HER2 amplification status along with somatic mutations. RESULTS: While the majority (ranging from 98.5% with IHC score of 0 and 93.1% with IHC score of 1 +) of 4884 breast carcinomas had concordant results from HER2 IHC and HER2 FISH testing, a small percentage of patients (ranging from 1.5% in those with IHC score of 0, to 6.9% with IHC score of 1 +) had discordant results, with negative HER2 IHC and positive HER2 FISH results. These patients could be reported as HER2-negative breast carcinomas if only HER2 IHC testing has been performed according to a current cost-effective HER2 test strategy. 57 patients had HER2 amplification status determined by NGS, and all patients had concordant results between HER2 NGS and FISH tests. A HER2-amplified breast carcinoma by NGS had a negative IHC and a positive HER2 FISH result. This case was classified as a HER2-positive breast carcinoma, had anti-HER2-targeted therapy, and achieved a complete clinical response. CONCLUSIONS: A small percentage of HER2-positive breast carcinomas are unidentified because of a negative HER2 IHC based on our current cost-effective HER2 test strategy. It is not feasible and affordable in routine clinical practice to perform HER2 FISH for the cases with negative HER2 IHC (IHC score 0 and 1 +). Therefore, NGS assays capable of simultaneously detecting both somatic mutations and HER2 amplification could provide a more comprehensive genetic profiling for breast carcinomas in a clinical setting. Identification of HER2 amplification by NGS in HER2-positive breast carcinomas with negative HER2 IHC results is important since these cases are concealed by our current cost-effective HER2 test strategy with IHC first (for all cases) and FISH reflex (only for cases with IHC score of 2 +), and would offer the opportunity for potentially beneficial anti-HER2-targeted therapies for these patients.

Clinicopathologic Features and Genetic Alterations of a Primary Osteosarcoma of the Uterine Corpus.

Primary osteosarcoma (OS) of the uterus is distinctly rare. We report a case of primary uterine OS with pulmonary metastasis in a 74-yr-old woman. Histopathologic features of the uterine tumor were in keeping with a pure chondroblastic OS composed of neoplastic cells with osteoblastic/chondroblastic differentiation and neoplastic bone formation. Despite treatment with Doxorubicin and Olaratumab and later with palliative radiation therapy, the patient died 7 mo after hysterectomy due to multiple distant metastases. A targeted next-generation sequencing assay based on a 637-gene panel was performed to analyze genetic alterations in this highly aggressive tumor, but no somatic mutations that are amenable to targeted therapy were detected. Rather, a 51-nucleotide deletion mutation including partial exon 2 of mediator complex subunit 12 (MED12), a gene commonly mutated in leiomyoma, breast fibroadenoma and phyllodes tumor, was identified. Given the MED12 mutation in this uterine OS, we propose possible mechanisms that account for the origin and development of this tumor.

Characterization of functionally active gene fusions in human papillomavirus related oropharyngeal squamous cell carcinoma.

The Cancer Genome Atlas (TCGA) sequencing analysis of head and neck squamous cell carcinoma (HNSCC) recently reported on gene fusions, however, few human papillomavirus (HPV) positive samples were included, and the functional relevance of identified fusions was not explored. We therefore performed an independent analysis of gene fusions in HPV-positive oropharyngeal SCC (OPSCC). RNA sequencing was performed on 47 HPV-positive OPSCC primary tumors and 25 normal mucosal samples from cancer unaffected controls on an Illumina TruSeq platform. MapSplice2 was used for alignment and identification of fusion candidates. Putative fusions with less than five spanning reads, detected in normal tissues, or that mapped to the same gene were filtered out. Selected fusions were validated by RT-PCR and Sanger sequencing. Within 47 HPV-positive OPSCC tumors, 282 gene fusions were identified. Most fusions (85.1%) occurred in a single tumor, and the remaining fusions recurred in 2-16 tumors. Gene fusions were associated with significant up regulation of 16 genes (including EGFR and ERBB4) and down regulation of four genes (PTPRT, ZNF750, DLG2, SLCO5A1). Expression of these genes followed similar patterns of up regulation and down regulation in tumors without these fusions compared to normal tissue. Five of six gene fusions selected for validation were confirmed through RT-PCR and sequencing. This integrative analysis provides a method of prioritizing functionally relevant gene fusions that may be expanded to other tumor types. These results demonstrate that gene fusions may be one mechanism by which functionally relevant genes are altered in HPV-positive OPSCC.

Transflip mutations produce deletions in pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is driven by the inactivation of the tumor suppressor genes (TSGs), CDKN2A (P16) and SMAD4 (DPC4), commonly by homozygous deletions (HDs). Using a combination of high density single-nucleotide polymorphism (SNP) microarray and whole genome sequencing (WGS), we fine-mapped novel breakpoints surrounding deletions of CDKN2A and SMAD4 and characterized them by their underlying structural variants (SVs). Only one third of CDKN2A and SMAD4 deletions (6 of 18) were simple interstitial deletions, rather, the majority of deletions were caused by complex rearrangements, specifically, a translocation on one side of the TSG in combination with an inversion on the other side. We designate these as "TransFlip" mutations. Characteristics of TransFlip mutations are: (1) a propensity to target the TSGs CDKN2A and SMAD4 (P < 0.005), (2) not present in the germline of the examined samples, (3) non-recurrent breakpoints, (4) relatively small (47 bp to 3.4 kb) inversions, (5) inversions can be either telomeric or centromeric to the TSG, and (6) non-reciprocal, and non-recurrent translocations. TransFlip mutations are novel complex genomic rearrangements with unique breakpoint signatures in pancreatic cancer. We hypothesize that they are a common but poorly understood mechanism of TSG inactivation in human cancer. © 2015 Wiley Periodicals, Inc.

Cell-free DNA measurable residual disease as a predictor of postallogeneic hematopoietic cell transplant outcomes.

The measurable residual disease (MRD) assessment provides an attractive predictor of allogeneic hematopoietic cell transplnat (alloHCT) outcomes. Cell-free DNA (cfDNA) has been applied to diagnosis, early detection, and disease burden monitoring in various tumors, but its utility as an MRD test in myeloid malignancies has not been systematically evaluated. We sought to determine the differential sensitivity between bone marrow (BM) and cfDNA MRD and to assess the effect of cfDNA MRD on alloHCT outcomes. The technical and clinical validation cohorts, including 82 patients participating in clinical trials (Bone Marrow Transplant Clinical Trials Network-0201 and 0402), were used. Ultradeep error-corrected targeted sequencing was performed on plasma and BM-derived DNA. We demonstrated that 94.6% (range, 93.9-95.3) of cfDNA was derived from hematopoietic tissue. The mutant allele fraction was congruent between BM and cfDNA (rho = 0.8; P < .0001); however, cfDNA seemed to be more sensitive in detecting clones with a variant allele frequency (VAF) of <0.26%. cfDNA-MRD clearance by day 90 after alloHCT (D90) was associated with improved relapse-free survival (RFS, median survival not reached vs 5.5 months; P < .0001) and overall survival (OS, median survival not reached vs 7.3 months; P < .0001) when compared with patients with persistent MRD. Irrespective of pre-alloHCT MRD, D90 cfDNA MRD was associated with inferior 2-year OS (16.7% vs 84.8%; P < .0001) and RFS (16.7% vs 80.7%; P < .0001). cfDNA seems to be an accurate, minimally invasive alternative to BM aspirates in MRD assessment and confers important prognostic implications in patients with myeloid malignancies undergoing alloHCT.

Optimizing Insertion and Deletion Detection Using Next-Generation Sequencing in the Clinical Laboratory.

Detection of insertions and deletions (InDels) by short-read next-generation sequencing (NGS) technology can be challenging because of frequent misaligned reads. A systematic analysis of short InDels (1 to 30 bases) and fms-related receptor tyrosine kinase 3 (FLT3) internal tandem duplications (ITDs; 6 to 183 bases) from 46 clinical cases of solid or hematologic malignancy processed with a clinical NGS assay identified misaligned reads in every case, ranging from 3% to 100% of reads with the InDel showing mismapped bases. Mismaps also increased with InDel size. As a consequence, the clinical NGS bioinformatics pipeline undercalled the variant allele frequency by 1% to 84%, incorrectly called simultaneous single-base substitutions along with InDels, or did not report an FLT3 ITD that had been detected by capillary electrophoresis. To improve the ability of the pipeline to better detect and quantify InDels, we utilized a software program called Assembly-Based ReAligner (ABRA2) to more accurately remap reads. ABRA2 was able to correct 41% to 100% of the reads with mismapped bases and led to absolute increases in the variant allele frequency from 1% to 61% along with correction of all of the single-base substitutions except for two cases. ABRA2 could also detect multiple FLT3 ITD clones except for one 183-base ITD. Our analysis has found that ABRA2 performs well on short InDels as well as FLT3 ITDs that are <100 bases.

Validation of Long Mononucleotide Repeat Markers for Detection of Microsatellite Instability.

Mismatch repair deficiency (dMMR) predicts response to immune checkpoint inhibitor therapy in solid tumors. Long mononucleotide repeat (LMR) markers may improve the interpretation of microsatellite instability (MSI) assays. Our cohorts included mismatch repair (MMR) proficient and dMMR colorectal cancer (CRC) samples, MMR proficient and dMMR endometrial cancer (EC) samples, dMMR prostate cancer samples, MSI-high (MSI-H) samples of other cancer types, and MSI-low (MSI-L) samples of various cancer types. MMR status was determined by immunohistochemical staining and/or MSI Analysis System Version 1.2 (V1.2). The sensitivity and specificity of the LMR MSI panel for dMMR detection were both 100% in CRC. The sensitivity values of the MSI V1.2 and LMR MSI panels in EC were 88% and 98%, respectively, and the specificity values were both 100%. The sensitivity of the LMR panel was 75% in dMMR prostate cancer detected by immunohistochemistry. The 22 samples of other cancer types that were previously classified as MSI-H were also classified as MSI-H using the LMR MSI panel. For the 12 samples that were previously classified as MSI-L, 1 sample was classified as microsatellite stable using the LMR MSI panel, 8 as MSI-L, and 3 as MSI-H. The LMR MSI panel showed high concordance to the MSI V1.2 panel in CRC and greater sensitivity in EC. The LMR MSI panel improves dMMR detection in noncolorectal cancers.

Utility of targeted next-generation sequencing assay to detect 1p/19q co-deletion in formalin-fixed paraffin-embedded glioma specimens.

Molecular classification of brain neoplasms is important for diagnosis, prognosis, and treatment outcome of histologically similar tumors. Oligodendroglioma is a glioma subtype characterized by 1p/19q co-deletion and IDH1/IDH2 mutations, which predict a good prognosis, responsiveness to therapy, and an improved overall survival compared to other adult gliomas. In a routine clinical setting, 1p/19q co-deletion is detected by interphase-FISH and SNP microarray, and somatic mutations are detected by targeted next-generation sequencing (NGS). The aim of this proof-of-principle study was to investigate the feasibility of using targeted NGS to simultaneously detect both 1p/19q co-deletion and somatic mutations. Among 247 consecutive patients with formalin-fixed paraffin-embedded brain tumors with various subtypes, NGS revealed 1p/19q co-deletion in 26 oligodendrogliomas and an IDH-wildtype astrocytoma, and partial loss across chromosomes 1p and 19q/whole-arm loss of 1p or 19q/copy neutral loss of heterozygosity in 11 nonoligodendrogliomas. For this 247 brain-tumor cohort, the overall sensitivity, specificity, and accuracy of detecting 1p/19q co-deletion by NGS in oligodendrogliomas were 96.2%, 99.6%, and 99.2%, respectively. The oligodendroglioma cohort had more mutations in IDH1/IDH2, CIC, FUBP1, and TERT, and fewer mutations in ATRX and TP53 than the nonoligodendroglioma cohort. This proof-of-concept study demonstrated that targeted NGS can simultaneously detect both 1p/19q co-deletion and somatic mutations, which can provide a more comprehensive genetic profiling for patients with gliomas using a single assay in a clinical setting.

Clonal hematopoiesis in men living with HIV and association with subclinical atherosclerosis.

OBJECTIVES: People with HIV (PWH) are at increased risk for premature cardiovascular disease (CVD). Clonal hematopoiesis is a common age-related condition that may be associated with increased CVD risk. The goal of this study was to determine the prevalence of clonal hematopoiesis and its association with chronic inflammation and CVD in PWH. DESIGN: Cross-sectional study utilizing archived specimens and data from 118 men (86 PWH and 32 HIV-uninfected) from the Baltimore-Washington DC center of the Multicenter AIDS Cohort Study (MACS) who had had coronary computed tomography angiography (CTA) and measurement of 34 serologic inflammatory biomarkers. METHODS: Clonal hematopoiesis was assessed on peripheral blood mononuclear cells utilizing targeted error-corrected next generation sequencing (NGS) focused on 92 genes frequently mutated in hematologic malignancies. Clinical and laboratory data were obtained from the MACS database. RESULTS: Clonal hematopoiesis with a variant allele frequency (VAF) greater than 1% was significantly more common in PWH [20/86 (23.3%)] than in HIV-uninfected men [2/32 (6.3%)] ( P  = 0.035). PWH with clonal hematopoiesis (VAF > 1%) were more likely to have coronary artery stenosis of at least 50% than those without clonal hematopoiesis [6/20 (30%) vs. 6/64 (9%); P  = 0.021]. Presence of clonal hematopoiesis was not significantly associated with serological inflammatory markers, except for significantly lower serum leptin levels; this was not significant after adjustment for abdominal or thigh subcutaneous fat area. CONCLUSION: Clonal hematopoiesis was more common in PWH and among PWH was associated with the extent of coronary artery disease. Larger studies are needed to further examine the biological and clinical consequences of clonal hematopoiesis in PWH.

Artificial Intelligence-Assisted Serial Analysis of Clinical Cancer Genomics Data Identifies Changing Treatment Recommendations and Therapeutic Targets.

PURPOSE: Given the pace of predictive biomarker and targeted therapy development, it is unknown whether repeat annotation of the same next-generation sequencing data can identify additional clinically actionable targets that could be therapeutically leveraged. In this study, we sought to determine the predictive yield of serial reanalysis of clinical tumor sequencing data. EXPERIMENTAL DESIGN: Using artificial intelligence (AI)-assisted variant annotation, we retrospectively reanalyzed sequencing data from 2,219 patients with cancer from a single academic medical center at 3-month intervals totaling 9 months in 2020. The yield of serial reanalysis was assessed by the proportion of patients with improved strength of therapeutic recommendations. RESULTS: A total of 1,775 patients (80%) had ≥1 potentially clinically actionable mutation at baseline, including 243 (11%) patients who had an alteration targeted by an FDA-approved drug for their cancer type. By month 9, the latter increased to 458 (21%) patients mainly due to a single pan-cancer agent directed against tumors with high tumor mutation burden. Within this timeframe, 67 new therapies became available and 45 were no longer available. Variant pathogenicity classifications also changed leading to changes in treatment recommendations for 124 patients (6%). CONCLUSIONS: Serial reannotation of tumor sequencing data improved the strength of treatment recommendations (based on level of evidence) in a mixed cancer cohort and showed substantial changes in available therapies and variant classifications. These results suggest a role for repeat analysis of tumor sequencing data in clinical practice, which can be streamlined with AI support.

Germline ERBB2/HER2 Coding Variants Are Associated with Increased Risk of Myeloproliferative Neoplasms.

Familial cases of myeloproliferative neoplasms (MPN) are relatively common, yet few inherited risk factors have been identified. Exome sequencing of a kindred with a familial cancer syndrome characterized by both MPN and melanoma produced a germline variant in the ERBB2/HER2 gene that co-segregates with disease. To further investigate whether germline ERBB2 variants contribute to MPN predisposition, the frequency of ERBB2 variants was analyzed in 1604 cases that underwent evaluation for hematologic malignancy, including 236 cases of MPN. MPN cases had a higher frequency of rare germline ERBB2 coding variants compared to non-MPN hematologic malignancies (8.9% vs. 4.1%, OR 2.4, 95% CI: 1.4 to 4.0, p = 0.0028) as well as cases without a blood cancer diagnosis that served as an internal control (8.9% vs. 2.7%, OR 3.5, 95% CI: 1.4 to 8.3, p = 0.0053). This finding was validated via comparison to an independent control cohort of 1587 cases without selection for hematologic malignancy (8.9% in MPN cases vs. 5.2% in controls, p = 0.040). The most frequent variant identified, ERBB2 c.1960A > G; p.I654V, was present in MPN cases at more than twice its expected frequency. These data indicate that rare germline coding variants in ERBB2 are associated with an increased risk for development of MPN. The ERBB2 gene is a novel susceptibility locus which likely contributes to cancer risk in combination with additional risk alleles.

Diagnostic Utility of Gene Fusion Panel to Detect Gene Fusions in Fresh and Formalin-Fixed, Paraffin-Embedded Cancer Specimens.

Somatic gene fusions are common in leukemias/lymphomas and solid tumors. The detection of gene fusions is crucial for diagnosis. NanoString fusion technology is a multiplexed hybridization method that interrogates hundreds of gene fusions in a single reaction. This study's objective was to determine the performance characteristics and diagnostic utility of NanoString fusion assays in a clinical diagnostics laboratory. Validation using 100 positive specimens and 15 negative specimens by a combined reference standard of fluorescence in situ hybridization (FISH)/RT-PCR/next-generation sequencing (NGS) assays achieved 100% sensitivity in leukemias/lymphomas and 95.0% sensitivity and 100% specificity in solid tumors. Subsequently, 214 consecutive clinical cases, including 73 leukemia/lymphoma specimens and 141 formalin-fixed, paraffin-embedded solid tumor specimens, were analyzed by gene fusion panels across 638 unique gene fusion transcripts. A variety of comparator tests, including FISH panels, conventional karyotyping, a DNA-based targeted NGS assay, and custom RT-PCR testing, were performed in parallel. The gene fusion assay detected 31 gene fusions, including 16 in leukemia/lymphoma specimens and 15 in solid tumor specimens. The overall sensitivity, specificity, and accuracy of gene fusions detected by the gene fusion panel in all 329 specimens (validation and consecutive clinical specimens) tested in this study were 94.8%, 100%, and 97.9%, respectively, compared with FISH/RT-PCR/NGS assays. The gene fusion panel is a reliable approach that maximizes molecular detection of fusions among both fresh and formalin-fixed, paraffin-embedded cancer specimens.

IDH1 and IDH2 Mutations in Colorectal Cancers.

OBJECTIVES: To elucidate clinicopathologic and molecular characteristics of IDH1 and IDH2 (IDH1/2) mutations in colorectal cancers (CRCs). METHODS: We evaluated IDH1/2 mutations in 1,623 CRCs using a next-generation sequencing assay. RESULTS: IDH1/2 mutations, predominantly IDH1 p.R132C, were detected in 15 (0.9%) CRCs and in 5 (3.0%) of 167 BRAF p.V600E-mutated CRCs. Three IDH1/2-mutated CRCs were associated with inflammatory bowel disease. They were significantly associated with old age, mucinous or signet ring cell adenocarcinoma, and high-grade histomorphology. Concordance of variant allele frequency between IDH1/2 mutants and other trunk drivers in CRCs and presence of IDH1/2 mutation in the adenoma and early adenocarcinoma indicated IDH1/2 mutations could be trunk drivers suitable for targeted therapy. CONCLUSIONS: IDH1/2 mutations in CRCs were uncommon but enriched in BRAF p.V600E-mutated CRCs and perhaps colitis-associated CRCs. Further studies on IDH1/2-mutated CRCs are needed to clarify their clinicopathologic features and implications for targeted therapy.

Clinical Utility of Targeted Next-Generation Sequencing Assay to Detect Copy Number Variants Associated with Myelodysplastic Syndrome in Myeloid Malignancies.

Copy number variants (CNVs) and gene mutations are important for diagnosis and treatment of myeloid malignancies. In a routine clinical setting, somatic gene mutations are detected by targeted next-generation sequencing (NGS) assay, but CNVs are commonly detected by conventional chromosome analysis and fluorescence in situ hybridization (FISH). The aim of this proof-of-principle study was to investigate the feasibility of using targeted NGS to simultaneously detect both somatic mutations and CNVs. Herein, we sequenced 406 consecutive patients with myeloid malignancies by targeted NGS and performed a head-to-head comparison with the results from a myelodysplastic syndrome (MDS) FISH and conventional chromosome analysis to detect CNVs. Among 91 patients with abnormal MDS FISH results, the targeted NGS revealed all 120 CNVs detected by MDS FISH (including -5/5q-, -7/7q-, +8, and 20q-) and 193 extra CNVs detected by conventional chromosome analysis. The targeted NGS achieved 100% concordance with the MDS FISH. The lower limit of detection of MDS CNVs by the targeted NGS was generally 5% variant allele fraction for DNA, based on the lowest percentages of abnormal cells detected by MDS FISH in this study. This proof-of-principle study demonstrated that the targeted NGS assay can simultaneously detect both MDS CNVs and somatic mutations, which can provide a more comprehensive genetic profiling for patients with myeloid malignancies using a single assay in a clinical setting.

CREBBP and STAT6 co-mutation and 16p13 and 1p36 loss define the t(14;18)-negative diffuse variant of follicular lymphoma.

The diffuse variant of follicular lymphoma (dFL) is a rare variant of FL lacking t(14;18) that was first described in 2009. In this study, we use a comprehensive approach to define unifying pathologic and genetic features through gold-standard pathologic review, FISH, SNP-microarray, and next-generation sequencing of 16 cases of dFL. We found unique morphologic features, including interstitial sclerosis, microfollicle formation, and rounded nuclear cytology, confirmed absence of t(14;18) and recurrent deletion of 1p36, and showed a novel association with deletion/CN-LOH of 16p13 (inclusive of CREBBP, CIITA, and SOCS1). Mutational profiling demonstrated near-uniform mutations in CREBBP and STAT6, with clonal dominance of CREBBP, among other mutations typical of germinal-center B-cell lymphomas. Frequent CREBBP and CIITA codeletion/mutation suggested a mechanism for immune evasion, while subclonal STAT6 activating mutations with concurrent SOCS1 loss suggested a mechanism of BCL-xL/BCL2L1 upregulation in the absence of BCL2 rearrangements. A review of the literature showed significant enrichment for 16p13 and 1p36 loss/CN-LOH, STAT6 mutation, and CREBBP and STAT6 comutation in dFL, as compared with conventional FL. With this comprehensive approach, our study demonstrates confirmatory and novel genetic associations that can aid in the diagnosis and subclassification of this rare type of lymphoma.

Granular cell astrocytoma: an aggressive IDH-wildtype diffuse glioma with molecular genetic features of primary glioblastoma.

Granular cell astrocytoma (GCA) is a rare adult infiltrating glioma subtype. We studied a series of 39 GCAs. Median age of presentation was 57.8 years and most cases developed in the frontal or temporal lobes. Tumors included grade II (n = 14), grade III (n = 11), and grade IV (n = 14) by WHO criteria. Granular cell morphology was diffuse in 31 (79%) cases and partial in eight (21%). Immunohistochemistry showed frequent positivity for GFAP (28 of 31), OLIG2 (16 of 16), and CD68 (27 of 30), but HAM56, CD163, and IBA-1 histiocytic markers were all negative (22 of 22). IDH1(R132H) was negative in all the cases tested (16 of 16), while ATRX expression was retained (12 of 12). Cytogenetics demonstrated monosomy 10 (6 of 6) cases, +7 in 4 (of 6), -13q in 4 of 6, and -14 in 4 of 6. Next-generation sequencing demonstrated mutations in PTEN/PIK3 genes in 6/13 (46%), NF1 in 3 of 10 (30%), TP53 in 3 of 13 (23%), PALB2 in 3 of 10 (30%), STAG2 in 3 of 10 (30%), EGFR mutation/amplification in 3 of 13 (23%), and AR in 2 of 10 (20%). CDKN2A/B deletion was identified in 5 of 13 (30%) cases (homozygous deletion in 4). The TERT C228T mutation was identified in 9 of 13 (69%). No mutations were encountered in IDH1, IDH2, CIC, FUBP1, H3F3A, BRAF or ATRX genes. The mean overall survival was 11.3 months. Patients >60 years old at diagnosis had a worse survival than patients <60 years (P = 0.001). There were no statistically significant differences in survival by WHO grade, extent of granular cell change, sex or MIB-1 (P > 0.05). GCA is a variant of IDH-wildtype diffuse glioma with aggressive behavior irrespective of grade and extent of granular cell morphology, and with molecular genetic features corresponding to primary glioblastoma.

Lineage-Specific Alterations in Gynecologic Neoplasms with Choriocarcinomatous Differentiation: Implications for Origin and Therapeutics.

PURPOSE: Choriocarcinoma is most commonly gestational (androgenetic or biparental) but can be of germ cell origin or can develop as a component of a somatic neoplasm (genetically related to the patient). The latter type are aggressive neoplasms for which the underlying genetic alterations are not well characterized. EXPERIMENTAL DESIGN: To investigate the relationship between the different components of somatic neoplasms with choriocarcinomatous elements, the genetic differences between gestational and nongestational tumors, and identify potential targetable alterations, we analyzed 23 samples from 11 tumors, including five gynecologic-type somatic neoplasms with choriocarcinomatous differentiation (two to three different components each) and six pure choriocarcinomas, for somatic mutations, single-nucleotide polymorphisms, and PD-L1 expression. RESULTS: In mixed tumors, gynecologic-type carcinoma components demonstrated lineage-characteristic and lineage-specific alterations, with choriocarcinomatous components sharing some of these as well as demonstrating novel alterations, supporting a clonal relationship with divergent differentiation of the choriocarcinoma from the somatic carcinoma. TP53 mutation only occurred in nongestational tumors. Diffuse PD-L1 expression was characteristic of choriocarcinoma in both pure and mixed tumors but not seen in the gynecologic-type carcinoma components. CONCLUSIONS: Given that the somatic carcinomatous and choriocarcinomatous components of mixed tumors have distinct genetic alterations and biomarker expression, separate analysis of these components is required to guide targeted therapy. High PD-L1 expression suggests a role for checkpoint inhibitor-based immunotherapy in tumors with a choriocarcinoma component. The underlying mechanisms by which cancer stem cells reprogram and initiate trophoblastic retrodifferentiation in some somatic tumors warrant further investigation.

Genetic Alterations Detected in Cell-Free DNA Are Associated With Enzalutamide and Abiraterone Resistance in Castration-Resistant Prostate Cancer.

PURPOSE: Androgen receptor (AR) gene alterations, including ligand-binding domain mutations and copy number (CN) gain, have yet to be fully established as predictive markers of resistance to enzalutamide and abiraterone in men with metastatic castration-resistant prostate cancer (mCRPC). The goal of this study was to validate AR gene alterations detected in cell-free DNA (cfDNA) as markers of enzalutamide and abiraterone resistance in patients with mCRPC. METHODS: Patients with mCRPC (N = 62) were prospectively enrolled between 2014 and 2018. Blood was collected before therapies-enzalutamide (n = 25), abiraterone (n = 35), or enzalutamide and abiraterone (n = 2)-and at disease progression. We used deep next-generation sequencing to analyze cfDNA for sequence variants and CN status in AR and 45 additional cancer-associated genes. Primary end points were prostate-specific antigen response, progression-free survival (PFS), and overall survival (OS). RESULTS: Elevated tumor-specific cfDNA (circulating tumor DNA) was associated with a worse prostate-specific antigen response (hazard ratio [HR], 3.17; 95% CI, 1.11 to 9.05; P = .031), PFS (HR, 1.76; 95% CI, 1.03 to 3.01; P = .039), and OS (HR, 2.92; 95% CI, 1.40 to 6.11; P = .004). AR ligand-binding domain missense mutations (HR, 2.51; 95% CI, 1.15 to 5.72; P = .020) were associated with a shorter PFS in multivariable models. AR CN gain was associated with a shorter PFS; however, significance was lost in multivariable modeling. Genetic alterations in tumor protein p53 (HR, 2.70; 95% CI, 1.27 to 5.72; P = .009) and phosphoinositide 3-kinase pathway defects (HR, 2.62; 95% CI, 1.12 to 6.10; P = .026) were associated with a worse OS in multivariable models. CONCLUSION: These findings support the conclusion that high circulating tumor DNA burden is associated with worse outcomes to enzalutamide and abiraterone in men with mCRPC. Tumor protein p53 loss and phosphoinositide 3-kinase pathway defects were associated with worse OS in men with mCRPC. AR status associations with outcomes were not robust, and additional validation is needed.

Genomic characterization of chromosome translocations in patients with T/myeloid mixed-phenotype acute leukemia.

Mixed-phenotype acute leukemia (MPAL) is a progenitor type of leukemia with ambiguous expression of lineage markers. The diagnosis of MPAL is based on flow cytometric analysis of immunophenotype, which commonly identifies myeloid lineage markers as well as B- or T- lymphoid lineage markers on leukemic blasts. Due to the rare occurrence of this disease, few studies have delineated the molecular bases of MPAL. Combining conventional karyotyping with whole genomic sequencing (WGS) and RNA sequencing (RNA-seq), we report here our identification and characterization of chromosome translocations, gene mutations and gene expression profile in four patients with T/Myeloid MPAL, including two t(6;14)(q25;q32) one t(8;14)(q24.2;q32) and one t(7;8)(p14;q24.2). Notably, seven of the eight translocation breakpoints reside in the non-coding regions and their locations appear to be shared by two or more patients. Gene expression analysis of matched diagnostic vs. remission samples provided evidence of transcriptomes alteration involving nucleosome organization and chromatin assembly.