Impact of Cancer Therapy on Clonal Hematopoiesis Mutations and Subsequent Clinical Outcomes.

Exposure to cancer therapies is associated with an increased risk of clonal hematopoiesis (CH). The objective of our study was to investigate the genesis and evolution of CH following cancer therapy. In this prospective study, we undertook error-corrected duplex DNA sequencing in blood samples collected prior to and at two timepoints following chemoradiation in patients with esophageal or lung cancer recruited from 2013-2018. We applied a customized workflow to identify the earliest changes in CH mutation count and clone size and determine their association with clinical outcomes. Our study included 29 patients (87 samples). Their median age was 67 years, 76% (n = 22) were male; the median follow-up period was 3.9 years. The most mutated genes were DNMT3A, TET2, TP53, and ASXL1. We observed a two-fold increase in the number of mutations from before to after treatment in TP53, which differed from all other genes examined (P < .001). Among mutations detected before and after treatment, we observed an increased clone size in 38% and a decreased clone size in 5% of TP53 mutations (odds ratio = 3.7; 95% CI = 1.75-7.84; P < .001). Changes in mutation count and clone size were not observed in other genes. Individuals with an increase in the number of TP53 mutations following chemoradiation experienced shorter overall survival (hazard ratio = 7.07; 95% CI = 1.50-33.46; P = .014). In summary, we found an increase in the number and size of TP53 CH clones following chemoradiation that were associated with clinical outcomes.

Lidocaine induces apoptosis in head and neck squamous cell carcinoma through activation of bitter taste receptor T2R14.

Head and neck squamous cell carcinomas (HNSCCs) have high mortality and significant treatment-related morbidity. It is vital to discover effective, minimally invasive therapies that improve survival and quality of life. Bitter taste receptors (T2Rs) are expressed in HNSCCs, and T2R activation can induce apoptosis. Lidocaine is a local anesthetic that also activates bitter taste receptor 14 (T2R14). Lidocaine has some anti-cancer effects, but the mechanisms are unclear. Here, we find that lidocaine causes intracellular Ca2+ mobilization through activation of T2R14 in HNSCC cells. T2R14 activation with lidocaine depolarizes mitochondria, inhibits proliferation, and induces apoptosis. Concomitant with mitochondrial Ca2+ influx, ROS production causes T2R14-dependent accumulation of poly-ubiquitinated proteins, suggesting that proteasome inhibition contributes to T2R14-induced apoptosis. Lidocaine may have therapeutic potential in HNSCCs as a topical gel or intratumor injection. In addition, we find that HPV-associated (HPV+) HNSCCs are associated with increased TAS2R14 expression. Lidocaine treatment may benefit these patients, warranting future clinical studies.

Clonal hematopoiesis and risk of prostate cancer in large samples of European ancestry men.

Little is known regarding the potential relationship between clonal hematopoiesis (CH) of indeterminate potential (CHIP), which is the expansion of hematopoietic stem cells with somatic mutations, and risk of prostate cancer, the fifth leading cause of cancer death of men worldwide. We evaluated the association of age-related CHIP with overall and aggressive prostate cancer risk in two large whole-exome sequencing studies of 75 047 European ancestry men, including 7663 prostate cancer cases, 2770 of which had aggressive disease, and 3266 men carrying CHIP variants. We found that CHIP, defined by over 50 CHIP genes individually and in aggregate, was not significantly associated with overall (aggregate HR = 0.93, 95% CI = 0.76-1.13, P = 0.46) or aggressive (aggregate OR = 1.14, 95% CI = 0.92-1.41, P = 0.22) prostate cancer risk. CHIP was weakly associated with genetic risk of overall prostate cancer, measured using a polygenic risk score (OR = 1.05 per unit increase, 95% CI = 1.01-1.10, P = 0.01). CHIP was not significantly associated with carrying pathogenic/likely pathogenic/deleterious variants in DNA repair genes, which have previously been found to be associated with aggressive prostate cancer. While findings from this study suggest that CHIP is likely not a risk factor for prostate cancer, it will be important to investigate other types of CH in association with prostate cancer risk.

Impact of sweet, umami, and bitter taste receptor (TAS1R and TAS2R) genomic and expression alterations in solid tumors on survival.

Originally identified on the tongue for their chemosensory role, the receptors for sweet, umami, and bitter taste are expressed in some cancers where they regulate important cellular processes including apoptosis and proliferation. We examined DNA mutations (n = 5103), structural variation (n = 7545), and expression (n = 6224) of genes encoding sweet or umami receptors (TAS1Rs) and bitter receptors (TAS2Rs) in 45 solid tumors subtypes compared to corresponding normal tissue using The Cancer Genome Atlas and the Genotype Tissue Expression Project databases. Expression of TAS1R and TAS2R genes differed between normal and cancer tissue, and nonsilent mutations occurred in many solid tumor taste receptor genes (~ 1-7%). Expression levels of certain TAS1Rs/TAS2Rs were associated with survival differences in 12 solid tumor subtypes. Increased TAS1R1 expression was associated with improved survival in lung adenocarcinoma (mean survival difference + 1185 days, p = 0.0191). Increased TAS2R14 expression was associated with worse survival in adrenocortical carcinoma (-1757 days, p < 0.001) and esophageal adenocarcinoma (-640 days, p = 0.0041), but improved survival in non-papillary bladder cancer (+ 343 days, p = 0.0436). Certain taste receptor genes may be associated with important oncologic pathways and could serve as biomarkers for disease outcomes.

Clinical and Molecular Characterization of POLE Mutations as Predictive Biomarkers of Response to Immune Checkpoint Inhibitors in Advanced Cancers.

PURPOSE: DNA polymerase epsilon is critical to DNA proofreading and replication. Mutations in POLE have been associated with hypermutated tumors and antitumor response to immune checkpoint inhibitor (ICI) therapy. We present a clinicopathologic analysis of patients with advanced cancers harboring POLE mutations, the pattern of co-occurring mutations, and their response to ICI therapy within the context of mutation pathogenicity. METHODS: We conducted a retrospective analysis of next-generation sequencing data at MD Anderson Cancer Center to identify patient tumors with POLE mutations and their co-occurring mutations. The pathogenicity of each mutation was annotated using InterVar and ClinVar. Differences in therapeutic response to ICI, survival, and co-occurring mutations were reported by POLE pathogenicity status. RESULTS: Four hundred fifty-eight patient tumors with POLE mutations were identified from 14,229 next-generation sequencing reports; 15.0% of POLE mutations were pathogenic, 15.9% benign, and 69.1% variant of unknown significance. Eighty-two patients received either programmed death 1 or programmed death ligand-1 inhibitors as monotherapy or in combination with cytotoxic T-cell lymphocyte-4 inhibitors. Patients with pathogenic POLE mutations had improved clinical benefit rate (82.4% v 30.0%; P = .013), median progression-free survival (15.1 v 2.2 months; P < .001), overall survival (29.5 v 6.8 months; P < .001), and longer treatment duration (median 15.5 v 2.5 months; P < .001) compared to those with benign variants. Progression-free survival and overall survival remained superior when adjusting for number of co-occurring mutations (≥ 10 v < 10) and/or microsatellite instability status (proficient mismatch repair v deficient mismatch repair). The number of comutations was not associated with response to ICI (clinical benefit v progressive disease: median 13 v 11 comutations; P = .18). CONCLUSION: Pathogenic POLE mutations were associated with clinical benefit to ICI therapy. Further studies are warranted to validate POLE mutation as a predictive biomarker of ICI therapy.

Association of clonal hematopoiesis mutations with clinical outcomes: A systematic review and meta-analysis.

Clonal hematopoiesis (CH) mutations are common among individuals without known hematologic disease. CH mutations have been associated with numerous adverse clinical outcomes across many different studies. We systematically reviewed the available literature for clinical outcomes associated with CH mutations in patients without hematologic disease. We searched PubMed, EMBASE, and Scopus for eligible studies. Three investigators independently extracted the data, and each study was verified by a second author. Risk of bias was assessed using the Newcastle-Ottawa Scale. We identified 32 studies with 56 cohorts that examine the association between CH mutations and clinical outcomes. We conducted meta-analyses comparing outcomes among individuals with and without detectable CH mutations. We conducted meta-analyses for cardiovascular diseases (nine studies; HR = 1.61, 95% CI = 1.26-2.07, p = .0002), hematologic malignancies (seven studies; HR = 5.59, 95% CI = 3.31-9.45, p < .0001), therapy-related myeloid neoplasms (four studies; HR = 7.55, 95% CI = 4.3-13.57, p < .001), and death (nine studies; HR = 1.34, 95% CI = 1.2-1.5, p < .0001). The cardiovascular disease analysis was further stratified by variant allele fraction (VAF) and gene, which showed a statistically significant association only with a VAF of ≥ 10% (HR = 1.42, 95% CI = 1.24-1.62, p < .0001), as well as statistically significant associations for each gene examined with the largest magnitude of effect found for CH mutations in JAK2 (HR = 3.5, 95% CI = 1.84-6.68, p < .0001). Analysis of the association of CH mutations with hematologic malignancy demonstrated a numeric stepwise increase in risk with increasing VAF thresholds. This analysis strongly supports the association of CH mutations with a clinically meaningful increased risk of adverse clinical outcomes among individuals without hematologic disease, particularly with increasing VAF thresholds.

T2R bitter taste receptors regulate apoptosis and may be associated with survival in head and neck squamous cell carcinoma.

Better management of head and neck squamous cell carcinomas (HNSCCs) requires a clearer understanding of tumor biology and disease risk. Bitter taste receptors (T2Rs) have been studied in several cancers, including thyroid, salivary, and GI, but their role in HNSCC has not been explored. We found that HNSCC patient samples and cell lines expressed functional T2Rs on both the cell and nuclear membranes. Bitter compounds, including bacterial metabolites, activated T2R-mediated nuclear Ca2+ responses leading to mitochondrial depolarization, caspase activation, and ultimately apoptosis. Buffering nuclear Ca2+ elevation blocked caspase activation. Furthermore, increased expression of T2Rs in HNSCCs from The Cancer Genome Atlas is associated with improved overall survival. This work suggests that T2Rs are potential biomarkers to predict outcomes and guide treatment selection, may be leveraged as therapeutic targets to stimulate tumor apoptosis, and may mediate tumor-microbiome crosstalk in HNSCC.

Phase Ib Dose Expansion and Translational Analyses of Olaparib in Combination with Capivasertib in Recurrent Endometrial, Triple-Negative Breast, and Ovarian Cancer.

PURPOSE: On the basis of strong preclinical rationale, we sought to confirm recommended phase II dose (RP2D) for olaparib, a PARP inhibitor, combined with the AKT inhibitor capivasertib and assess molecular markers of response and resistance. PATIENTS AND METHODS: We performed a safety lead-in followed by expansion in endometrial, triple-negative breast, ovarian, fallopian tube, or peritoneal cancer. Olaparib 300 mg orally twice daily and capivasertib orally twice daily on a 4-day on 3-day off schedule was evaluated. Two dose levels (DL) of capivasertib were planned: 400 mg (DL1) and 320 mg (DL-1). Patients underwent biopsies at baseline and 28 days. RESULTS: A total of 38 patients were enrolled. Seven (18%) had germline BRCA1/2 mutations. The first 2 patients on DL1 experienced dose-limiting toxicities (DLT) of diarrhea and vomiting. No DLTs were observed on DL-1 (n = 6); therefore, DL1 was reexplored (n = 6) with no DLTs, confirming DL1 as RP2D. Most common treatment-related grade 3/4 adverse events were anemia (23.7%) and leukopenia (10.5%). Of 32 evaluable subjects, 6 (19%) had partial response (PR); PR rate was 44.4% in endometrial cancer. Seven (22%) additional patients had stable disease greater than 4 months. Tumor analysis demonstrated strong correlations between response and immune activity, cell-cycle alterations, and DNA damage response. Therapy resistance was associated with receptor tyrosine kinase and RAS-MAPK pathway activity, metabolism, and epigenetics. CONCLUSIONS: The combination of olaparib and capivasertib is associated to no serious adverse events and demonstrates durable activity in ovarian, endometrial, and breast cancers, with promising responses in endometrial cancer. Importantly, tumor samples acquired pre- and on-therapy can help predict patient benefit.

Genomic, Transcriptomic, and Proteomic Profiling of Metastatic Breast Cancer.

PURPOSE: Metastatic breast cancer (MBC) is not curable and there is a growing interest in personalized therapy options. Here we report molecular profiling of MBC focusing on molecular evolution in actionable alterations. EXPERIMENTAL DESIGN: Sixty-two patients with MBC were included. An analysis of DNA, RNA, and functional proteomics was done, and matched primary and metastatic tumors were compared when feasible. RESULTS: Targeted exome sequencing of 41 tumors identified common alterations in TP53 (21; 51%) and PIK3CA (20; 49%), as well as alterations in several emerging biomarkers such as NF1 mutations/deletions (6; 15%), PTEN mutations (4; 10%), and ARID1A mutations/deletions (6; 15%). Among 27 hormone receptor-positive patients, we identified MDM2 amplifications (3; 11%), FGFR1 amplifications (5; 19%), ATM mutations (2; 7%), and ESR1 mutations (4; 15%). In 10 patients with matched primary and metastatic tumors that underwent targeted exome sequencing, discordances in actionable alterations were common, including NF1 loss in 3 patients, loss of PIK3CA mutation in 1 patient, and acquired ESR1 mutations in 3 patients. RNA sequencing in matched samples confirmed loss of NF1 expression with genomic NF1 loss. Among 33 patients with matched primary and metastatic samples that underwent RNA profiling, 14 actionable genes were differentially expressed, including antibody-drug conjugate targets LIV-1 and B7-H3. CONCLUSIONS: Molecular profiling in MBC reveals multiple common as well as less frequent but potentially actionable alterations. Genomic and transcriptional profiling demonstrates intertumoral heterogeneity and potential evolution of actionable targets with tumor progression. Further work is needed to optimize testing and integrated analysis for treatment selection.

A novel patient-derived orthotopic xenograft model of esophageal adenocarcinoma provides a platform for translational discoveries.

Mouse models of gastroesophageal junction (GEJ) cancer strive to recapitulate the intratumoral heterogeneity and cellular crosstalk within patient tumors to improve clinical translation. GEJ cancers remain a therapeutic challenge due to the lack of a reliable mouse model for preclinical drug testing. In this study, a novel patient-derived orthotopic xenograft (PDOX) was established from GEJ cancer via transabdominal surgical implantation. Patient tumor was compared to subcutaneously implanted patient-derived tumor xenograft (PDX) and PDOX by Hematoxylin and Eosin staining, immunohistochemistry and next-generation sequencing. Treatment efficacy studies of radiotherapy were performed. We observed that mechanical abrasion of mouse GEJ prior to surgical implantation of a patient-derived tumor in situ promotes tumor engraftment (100%, n=6). Complete PDOX engraftment was observed with rapid intra- and extraluminal tumor growth, as evidenced by magnetic resonance imaging. PDOXs contain fibroblasts, tumor-associated macrophages, immune and inflammatory cells, vascular and lymphatic vessels. Stromal hallmarks of aggressive GEJ cancers are recapitulated in a GEJ PDOX mouse model. PDOXs demonstrate tumor invasion into vasculature and perineural space. Next-generation sequencing revealed loss of heterozygosity with very high allelic frequency in NOTCH3, TGFB1, EZH2 and KMT2C in the patient tumor, the subcutaneous PDX and the PDOX. Immunohistochemical analysis of Her2/neu (also known as ERBB2), p53 (also known as TP53) and p16 (also known as CDKN2A) in PDX and PDOX revealed maintenance of expression of proteins found in patient tumors, but membranous EGFR overexpression in patient tumor cells was absent in both xenografts. Targeted radiotherapy in this model suggested a decrease in size by 61% according to Response Evaluation Criteria in Solid Tumors (RECIST), indicating a partial response to radiation therapy. Our GEJ PDOX model exhibits remarkable fidelity to human disease and captures the precise tissue microenvironment present within the local GEJ architecture, providing a novel tool for translating findings from studies on human GEJ cancer. This model can be applied to study metastatic progression and to develop novel therapeutic approaches for the treatment of GEJ cancer.This article has an associated First Person interview with the first author of the paper.

Sequential Therapy with PARP and WEE1 Inhibitors Minimizes Toxicity while Maintaining Efficacy.

We demonstrate that concurrent administration of poly(ADP-ribose) polymerase (PARP) and WEE1 inhibitors is effective in inhibiting tumor growth but poorly tolerated. Concurrent treatment with PARP and WEE1 inhibitors induces replication stress, DNA damage, and abrogates the G2 DNA damage checkpoint in both normal and malignant cells. Following cessation of monotherapy with PARP or WEE1 inhibitors, effects of these inhibitors persist suggesting that sequential administration of PARP and WEE1 inhibitors could maintain efficacy while ameliorating toxicity. Strikingly, while sequential administration mirrored concurrent therapy in cancer cells that have high basal replication stress, low basal replication stress in normal cells protected them from DNA damage and toxicity, thus improving tolerability while preserving efficacy in ovarian cancer xenograft and patient-derived xenograft models.

Hybrid oncocytic/chromophobe renal tumors are molecularly distinct from oncocytoma and chromophobe renal cell carcinoma.

Hybrid oncocytic/chromophobe tumor (HOCT) of the kidney represents a poorly understood clinicopathologic entity with pathologic features that overlap between benign renal oncocytoma (RO) and malignant chromophobe renal cell carcinoma (ChRCC). Consequently, characterization of HOCT and its separation from the foregoing entities are clinically important. The aim of this study was to describe the pathologic and molecular features of HOCT and to compare them with those of RO and ChRCC. We retrospectively identified a cohort of 73 cases with renal oncocytic tumors (19 RO, 27 HOCT, and 27 ChRCC) for whom clinical follow-up data were available by 2 tertiary care hospitals. All cases were sporadic except for 2 HOCTs that were associated with Birt-Hogg-Dubé syndrome. Lesional tissues were retrieved for molecular analysis. We performed targeted gene sequencing of all exons of 261 cancer related genes on a subset of HOCT samples (n = 16). Gene expression profiling of a customized codeset was conducted on 19 RO, 24 HOCT, and 27 ChRCC samples. Clinicopathologic characteristics as well as DNA copy number alterations, mutational and transcriptional features of HOCT derived from sequencing and expression profiling data are described and compared to those in RO and ChRCC. HOCTs were more frequently multifocal and did not exhibit mutations in genes that are recurrently mutated in RO or ChRCC but showed copy number alterations primarily involving losses in chromosomes 1 and X/Y. The mRNA transcript data show that HOCT can be separated from RO and ChRCC. Hence, HOCT appears to represent a distinct renal tumor entity with genomic features that are intermediate between those of RO and ChRCC.

Adaptive responses in a PARP inhibitor window of opportunity trial illustrate limited functional interlesional heterogeneity and potential combination therapy options.

Poly (ADP-ribose) polymerase inhibitor (PARPi)-based combination therapies are demonstrating efficacy in patients, however, identifying the right combination for the right patient remains a critical challenge. Thus, it is urgent to develop approaches able to identify patients likely to benefit from specific combination therapies. Several groups, including ours, have demonstrated that targeting adaptive responses induced by PARPi increases depth and duration of response. In this study, we instituted a talazoparib (PARPi) monotherapy window of opportunity trial to identify informative adaptive responses in high grade serous ovarian cancer patients (HGSOC). Patients were treated for 7 to 14 days with PARPi monotherapy prior to surgery with tissue samples from multiple sites being collected pre- and post-treatment in each patient. Analysis of these samples demonstrated that individual patients displayed different adaptive responses with limited interlesional heterogeneity. Ability of combination therapies designed to interdict adaptive responses to decrease viability was validated using model systems. Thus, assessment of adaptive responses to PARPi provides an opportunity for patient-specific selection of combination therapies designed to interdict patient-specific adaptive responses to maximize patient benefit.

Integrated transcriptomic-genomic tool Texomer profiles cancer tissues.

Profiling of both the genome and the transcriptome promises a comprehensive, functional readout of a tissue sample, yet analytical approaches are required to translate the increased data dimensionality, heterogeneity and complexity into patient benefits. We developed a statistical approach called Texomer ( https://github.com/KChen-lab/Texomer ) that performs allele-specific, tumor-deconvoluted transcriptome-exome integration of autologous bulk whole-exome and transcriptome sequencing data. Texomer results in substantially improved accuracy in sample categorization and functional variant prioritization.

Use of Targeted Next-Generation Sequencing to Identify Activating Hot Spot Mutations in Cherry Angiomas.

Importance: Shared gene variants in benign-malignant process pairs, such as BRAF mutations common to benign nevi and melanoma, are associated with differing phenotypic manifestations. Study of gene mechanisms underlying cherry angioma may uncover previously unknown disease relationships. Objective: To identify somatic mutations present in cherry angioma specimens by using targeted next-generation sequencing. Design, Setting, and Participants: In a single-center case series, 10 formalin-fixed, paraffin-embedded cherry angioma specimens from biopsies performed at Massachusetts General Hospital in Boston from July 10, 2016, to January 23, 2018, were obtained and underwent sequencing across a panel of 323 genes most relevant to cancer. Somatic mutations were curated by excluding variants that were presumed to be germline or of low mapping quality. Main Outcomes and Measures: Identification of somatic mutations associated with cherry angiomas. Results: In 10 cherry angioma tissue samples originating from 6 female and 4 male patients with a median (range) age of 54 (26-79) years, 5 samples (50%) revealed somatic missense mutations in GNAQ (Q209H, Q209R, and R183G) and GNA11 (Q209H). Individually, these mutational hot spots are known to be involved in entities that include congenital and anastomosing hemangiomas, hepatic small-vessel neoplasms (Q209), port-wine stains, and Sturge-Weber syndrome (R183). Both hot spots are associated with blue nevi, melanoma associated with blue nevus, and uveal melanoma. Conclusions and Relevance: In this case series study, the high prevalence of 5 known genetic drivers within the benign cherry angioma entity appears to support the context-dependent role of gene alterations in both benign and malignant proliferations from various cellular origins.

Survival Outcomes by TP53 Mutation Status in Metastatic Breast Cancer.

PURPOSE: We sought to determine the significant genomic alterations in patients with metastatic breast cancer (MBC), and survival outcomes in common genotypes. PATIENTS AND METHODS: High-depth next generation sequencing was performed for 202 genes in tumor and normal DNA from 257 patients with MBC, including 165 patients with ER/PR+ HER2- (hormone receptor positive, HR+ positive), 32 patients with HER2+ and 60 patients with triple negative (ER/PR/HER2-) cancer. Kaplan Meier survival analysis was performed in our discovery set, in breast cancer patients analyzed in The Cancer Genome Atlas, and in a separate cohort of 98 patients with MBC who underwent clinical genomic testing. RESULTS: Significantly mutated genes (SMGs) varied by histology and tumor subtype, but TP53 was a SMG in all three subtypes. The most SMGs in HR+ patients included PIK3CA (32%), TP53 (29%), GATA3 (15%), CDH1 (8%), MAP3K1 (8%), PTEN (5%), TGFBR2 (4%), AKT1 (4%), and MAP2K4 (4%). TP53 mutations were associated with shorter recurrence-free survival (P=0.004), progression-free survival (P=0.00057) and overall survival (P=0.003). Further, TP53 status was prognostic among HR+ patients with PIK3CA mutations. TP53 mutations were also associated with poorer overall survival in the 442 HR+ breast cancer patients in the TCGA (P=0.042) and in an independent set of 96 HR+ MBC who underwent clinical sequencing (P=0.0004). CONCLUSIONS: SMGs differ by tumor subtype but TP53 is significantly mutated in all three breast cancer subtypes. TP53 mutations are associated with poor prognosis in HR+ breast cancer. TP53 mutations should be considered in the design and interpretation of precision oncology trials.

Cancer driver mutation prediction through Bayesian integration of multi-omic data.

Identification of cancer driver mutations is critical for advancing cancer research and personalized medicine. Due to inter-tumor genetic heterogeneity, many driver mutations occur at low frequencies, which make it challenging to distinguish them from passenger mutations. Here, we show that a novel Bayesian hierarchical modeling approach, named rDriver can achieve enhanced prediction accuracy by identifying mutations that not only have high functional impact scores but also are associated with systemic variation in gene expression levels. In examining 3,080 tumor samples from 8 cancer types in The Cancer Genome Atlas, rDriver predicted 1,389 driver mutations. Compared with existing tools, rDriver identified more low frequency mutations associated with lineage specific functional properties, timing of occurrence and patient survival. Evaluation of rDriver predictions using engineered cell-line models resulted in a positive predictive value of 0.94 in PIK3CA genes. Our study highlights the importance of integrating multi-omic data in predicting cancer driver mutations and provides a statistically rigorous solution for cancer target discovery and development.

Pathogenic Germline Variants in 10,389 Adult Cancers.

We conducted the largest investigation of predisposition variants in cancer to date, discovering 853 pathogenic or likely pathogenic variants in 8% of 10,389 cases from 33 cancer types. Twenty-one genes showed single or cross-cancer associations, including novel associations of SDHA in melanoma and PALB2 in stomach adenocarcinoma. The 659 predisposition variants and 18 additional large deletions in tumor suppressors, including ATM, BRCA1, and NF1, showed low gene expression and frequent (43%) loss of heterozygosity or biallelic two-hit events. We also discovered 33 such variants in oncogenes, including missenses in MET, RET, and PTPN11 associated with high gene expression. We nominated 47 additional predisposition variants from prioritized VUSs supported by multiple evidences involving case-control frequency, loss of heterozygosity, expression effect, and co-localization with mutations and modified residues. Our integrative approach links rare predisposition variants to functional consequences, informing future guidelines of variant classification and germline genetic testing in cancer.

Comprehensive Genomic Profiling of Metastatic Squamous Cell Carcinoma of the Anal Canal.

Squamous cell carcinoma of the anal canal (SCCA) is a rare gastrointestinal malignancy with an increasing annual incidence globally. The majority of cases are linked to prior infection with the human papillomavirus (HPV). For patients with metastatic SCCA, no consensus standard treatment exists. Identification of relevant targeted agents as novel therapeutic approaches for metastatic SCCA has been limited by a lack of comprehensive molecular profiling. We performed whole-exome sequencing on tumor-normal pairs from 24 patients with metastatic SCCA. Tumor tissue from 17 additional patients was analyzed using a 263-gene panel as a validation cohort. Gene expression profiling was performed on available frozen tissue to assess for differential expression patterns. Based on these findings, patient-derived xenograft (PDX) models of SCCA were generated to test targeted therapies against PI3K and EGFR. Despite a low mutation burden, mutations in PIK3CA, MLL2, and MLL3 were among the most commonly mutated genes. An association between TP53 mutations and HPV-negative SCCA tumors was observed. Gene expression analysis suggested distinct tumor subpopulations harboring PIK3CA mutations and for which HPV had integrated into the host genome. In vivo studies demonstrated improvement with anti-EGFR treatment. Gene mutation frequencies, tumor mutation burden, and gene expression patterns for metastatic SCCA appear similar to other HPV-associated malignancies.Implications: This first comprehensive genomic characterization for patients with metastatic SCCA provides further rationale for the integration of SCCA into the development of novel targeted therapies across HPV-related cancers. Mol Cancer Res; 15(11); 1542-50. ©2017 AACR.

Comprehensive Genomic Characterization of Upper Tract Urothelial Carcinoma.

BACKGROUND: Upper urinary tract urothelial cancer (UTUC) may have unique etiologic and genomic factors compared to bladder cancer. OBJECTIVE: To characterize the genomic landscape of UTUC and provide insights into its biology using comprehensive integrated genomic analyses. DESIGN, SETTING, AND PARTICIPANTS: We collected 31 untreated snap-frozen UTUC samples from two institutions and carried out whole-exome sequencing (WES) of DNA, RNA sequencing (RNAseq), and protein analysis. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Adjusting for batch effects, consensus mutation calls from independent pipelines identified DNA mutations, gene expression clusters using unsupervised consensus hierarchical clustering (UCHC), and protein expression levels that were correlated with relevant clinical variables, The Cancer Genome Atlas, and other published data. RESULTS AND LIMITATIONS: WES identified mutations in FGFR3 (74.1%; 92% low-grade, 60% high-grade), KMT2D (44.4%), PIK3CA (25.9%), and TP53 (22.2%). APOBEC and CpG were the most common mutational signatures. UCHC of RNAseq data segregated samples into four molecular subtypes with the following characteristics. Cluster 1: no PIK3CA mutations, nonsmokers, high-grade