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Clonal hematopoiesis (CH) represents clonal expansion of mutated hematopoietic stem cells detectable in the peripheral blood or bone marrow through next generation sequencing. The current prevailing model posits that CH mutations detected in the peripheral blood mirror bone marrow mutations with clones widely disseminated across hematopoietic compartments. We sought to test the hypothesis that all clones are disseminated throughout hematopoietic tissues by comparing CH in hip vs peripheral blood specimens collected at the time of hip replacement surgery. Here, we show that patients with osteoarthritis have a high prevalence of CH, which involve genes encoding epigenetic modifiers and DNA damage repair pathway proteins. Importantly, we illustrate that CH, including clones with variant allele frequencies >10%, can be confined to specific bone marrow spaces and may be eliminated through surgical excision. Future work will define whether clones with somatic mutations in particular genes or clonal fractions of certain sizes are either more likely to be localized or are slower to disseminate into the peripheral blood and other bony sites.

GLI1 encodes a transcription factor that targets cell cycle regulators affecting stem cell proliferation. GLI1 gene fusions were initially described in pericytomas with a t[7;12] translocation and more recently in gastric plexiform fibromyxomas and gastroblastomas. This study describes the clinicopathologic, immunohistochemical, and molecular features of three intestinal-based neoplasms harboring GLI1 gene fusions. We studied three unique mesenchymal small bowel tumors. Paraffin embedded tumor tissues from these cases and 62 additional tumor samples that included a plexiform fibromyxoma were sequenced using a targeted RNAseq method to detect fusion events. The study patients included two women and one man who were 52, 80, and 22 years of age at the time of diagnosis. The tumors involved the submucosa and muscularis propria of the duodenum, jejunum, and ileum. All 3 tumors contained a proliferation of monotonous oval or spindle cells with scattered, somewhat dilated vessels. Two cases showed epithelioid structures such as glands, tubules, or nests. Immunohistochemical analysis revealed cytokeratin expression in the epithelioid components of both tumors displaying these features, and variable numbers of mesenchymal cells. Diffuse CD56 positivity was seen in the mesenchymal component of 2 tumors and desmin and smooth muscle actin staining in the other tumor. Immunostains for S-100 protein, DOG-1, and CD117 were negative in all cases. GLI1 fusions with different partner genes were detected in all tumors, and in the plexiform fibromyxoma, used as a control. Validation by fluorescence in situ hybridization was performed. None of the tumors have recurred or metastasize after surgery. We describe novel GLI1 fusions in 3 mesenchymal neoplasms of the small intestine, including 2 with biphenotypic features. Thus far, all cases have pursued indolent clinical courses. We propose the term " GLI1 -rearranged enteric tumor" to encompass this group of unique neoplasms of the small intestine that harbor GLI1 gene fusions and expand the spectrum of gastrointestinal neoplasms with these alterations.

Advanced urothelial cancer is a frequently lethal disease characterized by marked genetic heterogeneity. In this study, we investigate the evolution of the genomic signatures caused by endogenous and external mutagenic stimuli and their interplay with complex structural variants. We superimposed mutational signatures and phylogenetic analyses of matched serial tumors from patients with urothelial cancer to define the evolutionary patterns of these processes. We show that APOBEC3-induced mutations are clonal and early, whereas mutational bursts comprising hundreds of late subclonal mutations are induced by chemotherapy. Using a novel genome graph computational paradigm, we observed frequent circular high copy-number amplicons characteristic of extrachromosomal DNA (ecDNA) involving double-minutes, breakage-fusion-bridge, and tyfonas events. We characterized the distinct temporal patterns of APOBEC3 mutations and chemotherapy-induced mutations within ecDNA, gaining new insights into the timing of these events relative to ecDNA biogenesis. Finally, we discovered that mostCCND1amplifications in urothelial cancer arise within circular ecDNA amplicons. TheseCCND1ecDNA amplification events persisted and increased in complexity incorporating additional DNA segments potentially contributing selective fitness advantage to the evolution of treatment resistance. Our findings define fundamental mechanisms driving urothelial cancer evolution and have therapeutic implications for treating this disease.

Women of sub-Saharan African descent have disproportionately higher incidence of triple-negative breast cancer (TNBC) and TNBC-specific mortality across all populations. Population studies show racial differences in TNBC biology, including higher prevalence of basal-like and quadruple-negative subtypes in African Americans (AA). However, previous investigations relied on self-reported race (SRR) of primarily U.S. populations. Due to heterogeneous genetic admixture and biological consequences of social determinants, the true association of African ancestry with TNBC biology is unclear. To address this, we conducted RNA sequencing on an international cohort of AAs, as well as West and East Africans with TNBC. Using comprehensive genetic ancestry estimation in this African-enriched cohort, we found expression of 613 genes associated with African ancestry and 2,000+ associated with regional African ancestry. A subset of African-associated genes also showed differences in normal breast tissue. Pathway enrichment and deconvolution of tumor cellular composition revealed that tumor-associated immunologic profiles are distinct in patients of African descent.Significance:Our comprehensive ancestry quantification process revealed that ancestry-associated gene expression profiles in TNBC include population-level distinctions in immunologic landscapes. These differences may explain some differences in race–group clinical outcomes. This study shows the first definitive link between African ancestry and the TNBC immunologic landscape, from an African-enriched international multiethnic cohort.See related commentary by Hamilton et al., p. 2496.This article is highlighted in the In This Issue feature, p. 2483

Supplementary Table from African Ancestry–Associated Gene Expression Profiles in Triple-Negative Breast Cancer Underlie Altered Tumor Biology and Clinical Outcome in Women of African Descent

Supplementary Data from African Ancestry–Associated Gene Expression Profiles in Triple-Negative Breast Cancer Underlie Altered Tumor Biology and Clinical Outcome in Women of African Descent

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Supplementary Table 5. Patient B Single and buparlisib Combination High Throughput Drug Screen.

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Supplementary Figures 1 - 6

Supplementary Table 2. Drug Library Concentrations.

Supplementary Table 3. Patient A single and duparlisib combination high throughout drug screen.

Supplementary Information includes: Supplementary Methods, Supplementary Table 1 which shows pathologic and clinical characteristics of patient WCM1388; Supplementary Figure 1 which shows SLFN11 expression across different cancer types; Supplementary Figure 2 which shows CK vs SLFN11 expression in CTCs; Supplementary Figure 3 which shows the discordant case between CTCs and tissue mRNA; Supplementary Figure 4 which is SLFN11 knockout of organoids and response to olaparib

Supplementary Table 1. Genomic analysis of 15 patients.

Expression of the DNA/RNA helicase schlafen family member 11 (SLFN11) has been identified as a sensitizer of tumor cells to DNA-damaging agents including platinum chemotherapy. We assessed the impact of SLFN11 expression on response to platinum chemotherapy and outcomes in patients with metastatic castration-resistant prostate cancer (CRPC). Tumor expression of SLFN11 was assessed in 41 patients with CRPC treated with platinum chemotherapy by RNA sequencing (RNA-seq) of metastatic biopsy tissue (n = 27) and/or immunofluorescence in circulating tumor cells (CTC; n = 20). Cox regression and Kaplan–Meier methods were used to evaluate the association of SLFN11 expression with radiographic progression-free survival (rPFS) and overall survival (OS). Multivariate analysis included tumor histology (i.e., adenocarcinoma or neuroendocrine) and the presence or absence of DNA repair aberrations. Patient-derived organoids with SLFN11 expression and after knockout by CRISPR-Cas9 were treated with platinum and assessed for changes in dose response. Patients were treated with platinum combination (N = 38) or platinum monotherapy (N = 3). Median lines of prior therapy for CRPC was two. Median OS was 8.7 months. Overexpression of SLFN11 in metastatic tumors by RNA-seq was associated with longer rPFS compared with those without overexpression (6.9 vs. 2.8 months, HR = 3.72; 95% confidence interval (CI), 1.56–8.87; P < 0.001); similar results were observed for patients with SLFN11-positive versus SLFN11-negative CTCs (rPFS 6.0 vs. 2.2 months, HR = 4.02; 95% CI, 0.77–20.86; P = 0.002). A prostate-specific antigen (PSA) decline of ≥50% was observed in all patients with SLFN11 overexpression. No association was observed between SLFN11 expression and OS. On multivariable analysis, SLFN11 was an independent factor associated with rPFS on platinum therapy. Platinum response of organoids expressing SLFN11 was reduced after SLFN11 knockout. Our data suggest that SLFN11 expression might identify patients with CRPC with a better response to platinum chemotherapy independent of histology or other genomic alterations. Additional studies, also in the context of PARP inhibitors, are warranted.

Supplementary Table Legends

Supplementary Table 7. Patient D SINGLE and afatinib COMBINATION High Throughput Drug Screen.

Supplementary Table 4. Patient A Single and vorinostat COMBINATION High Throughput Drug Screen.

Supplementary Materials and Methods

Supplementary Tables

Purpose:Neuroendocrine prostate cancer (NEPC) is an aggressive variant of prostate cancer that may develop de novo or as a mechanism of treatment resistance. N-myc is capable of driving NEPC progression. Alisertib inhibits the interaction between N-myc and its stabilizing factor Aurora-A, inhibiting N-myc signaling, and suppressing tumor growth.Patients and Methods:Sixty men were treated with alisertib 50 mg twice daily for 7 days every 21 days. Eligibility included metastatic prostate cancer and at least one: small-cell neuroendocrine morphology; ≥50% neuroendocrine marker expression; new liver metastases without PSA progression; or elevated serum neuroendocrine markers. The primary endpoint was 6-month radiographic progression-free survival (rPFS). Pretreatment biopsies were evaluated by whole exome and RNA-seq and patient-derived organoids were developed.Results:Median PSA was 1.13 ng/mL (0.01–514.2), number of prior therapies was 3, and 68% had visceral metastases. Genomic alterations involved RB1 (55%), TP53 (46%), PTEN (29%), BRCA2 (29%), and AR (27%), and there was a range of androgen receptor signaling and NEPC marker expression. Six-month rPFS was 13.4% and median overall survival was 9.5 months (7.3–13). Exceptional responders were identified, including complete resolution of liver metastases and prolonged stable disease, with tumors suggestive of N-myc and Aurora-A overactivity. Patient organoids exhibited concordant responses to alisertib and allowed for the dynamic testing of Aurora–N-myc complex disruption.Conclusions:Although the study did not meet its primary endpoint, a subset of patients with advanced prostate cancer and molecular features supporting Aurora-A and N-myc activation achieved significant clinical benefit from single-agent alisertib.

Supplementary Video

Purpose:In this study, we addressed the underlying mechanisms for the association between enzalutamide (ENZ) treatment and neuroendocrine prostate cancer (NEPC), and the critical involvement of MYCN, and loss of RB1 function in neuroendocrine differentiation (NED) of prostatic epithelial cells, and the development of NEPC. We further sought to determine whether PARP inhibition could suppress NEPC, and to identify molecular determinants of this therapeutic activity.Experimental Design:We used a novel prostate cancer patient–derived xenograft (PDX) treatment model, prostatic adenocarcinoma and NEPC cell lines, an NEPC organoid line, and NEPC xenograft models to address the mechanistic basis of ENZ-induced NED, and to analyze suppression of NED and NEPC growth by PARP inhibition.Results:We identified an ENZ treatment–associated glucocorticoid receptor (GR)–MYCN–CDK5–RB1–E2F1 signaling pathway that drives NED in prostatic adenocarcinoma PDX and cell line models. Mechanistically, long-term ENZ treatment transcriptionally upregulates signaling of the GR–MYCN axis, leading to CDK5R1 and CDK5R2 upregulation, Rb1 phosphorylation, and N-Myc–mediated and E2F1-mediated NED gene expression. Importantly, olaparib (OLA) or talazoparib (TALA) suppressed these activities, and the combination of OLA and dinaciclib (DINA), an inhibitor of CDK2 and CDK5, which also inhibits Rb1 phosphorylation, suppressed NED and significantly improved therapeutic efficiency in NEPC cells in vitro and in NEPC tumors in vivo.Conclusions:The results of our study indicate an important role of GR–MYCN–CDK5R1/2–RB1–NED signaling in ENZ-induced and PARP inhibitor–suppressed NEPC. We also demonstrated efficacy for OLA+DINA combination therapy in NEPC xenograft models.

Supplementary Methods, Figures, Table Legends Supplementary Figure 1: Representative Hematoxylin and Eosin stained photomicrographs of prostatectomy specimens demonstrating the effects of neoadjuvant chemohormonal therapy. Supplementary Figure 2: Quality metrics for targeted DNA sequencing of FFPE biopsy and RP specimens. Supplementary Figure 3: Somatic mutations detected pre- and post-treatment through targeted DNA sequencing. Supplementary Figure 4: Differences in the number and allelic frequency of somatic mutations between treated and untreated specimens. Supplementary Figure 5: Persistence of TP53 mutations in post-treated radical prostatectomy (RP) specimens. Supplementary Figure 6: Representative copy number plots from targeted sequencing of diagnostic biopsies and RP specimens from the untreated arm. Supplementary Figure 7: Pearson's correlation comparing the Nanostring platform (x axis) and RNA-seq (y axis) performed in 13 matched cases. Supplementary Figure 8: Scatterplots showing Pearson correlation between Nanostring data obtained from matched FFPE and fresh/frozen tissue in 7 patients. Supplementary Figure 9: Gene expression of PTEN (y axis) relative to genomic status (PTEN deletion or wild type (WT). Supplementary Figure 10: Left: Correlation of TMPRSS2-ERG fusion transcript expression (x axis) and ERG gene expression (y axis). Right: ERG expression vs. TMPRSS2-ERG fusion status with positive defined as normalized count> 50. Supplementary Figure 11: Principal component analysis plotted using the Biological Coefficient of Variation (BCV) distance as part of the edgeR package. Supplementary Figure 12: Unsupervised analysis of expression of all genes within the panel in radical prostatectomies from treated (green) and untreated (yellow) arms. Red= high expression; blue= low expression.

Supplementary Data

Supplemental Table S5

Table S1: Targeted gene panel for DNA sequencing Table S2: List of genes in the custom Nanostring gene panel Table S3: Clinical characteristics of the patient cohort. Table S4: Predicted minimum tumor cellularity estimated by targeted DNA sequencing. Table S5: Somatic mutation calls from targeted DNA-sequencing. Table S6: Germline mutation calls from targeted DNA sequencing. Table S7: Comparison of non-silent mutations detected by targeted sequencing and whole exome sequencing (WES). Table S8: Differential gene expression between treated and untreated specimens Table S9: Gene expression values (normalized counts) of radical prostatectomy specimens Table S10: Gene expression values (normalized counts) of tumor biopsies Table S11: Gene expression values (normalized counts) of benign prostate specimens

Supplemental Tables S2, S3, and S4

Supplementary Figures

Supplemental Table S1

Purpose: The combination of docetaxel chemotherapy and androgen deprivation therapy (ADT) has become a standard treatment for patients with metastatic prostate cancer. The recently accrued phase III CALGB 90203 trial was designed to investigate the clinical effectiveness of this treatment approach earlier in the disease. Specimens from this trial offer a unique opportunity to interrogate the acute molecular response to docetaxel and ADT and identify potential biomarkers.Experimental Design: We evaluated baseline clinical data, needle biopsies, and radical prostatectomy (RP) specimens from 52 (of 788) patients enrolled on CALGB 90203 at one high volume center. Pathology review, tumor and germline-targeted DNA sequencing (n = 72 genes), and expression profiling using NanoString platform (n = 163 genes) were performed to explore changes in critical prostate cancer pathways linked to aggression and resistance.Results: Three of 52 patients had only microfocal residual cancer at prostatectomy. The most common alterations included TMPRSS2-ERG fusion (n = 32), TP53 mutation or deletion (n = 11), PTEN deletion (n = 6), FOXA1 (n = 6), and SPOP (n = 4) mutation, with no significant enrichment in posttreated specimens. We did not observe AR amplification or mutations. The degree of AR signaling suppression varied among treated tumors and there was upregulation of both AR and AR-V7 expression as well as a subset of neuroendocrine and plasticity genes.Conclusions: These data support the feasibility of targeted and temporal genomic and transcriptome profiling of neoadjuvant-treated prostate cancer with limited formalin-fixed paraffin embedded tissue requirement. Characterization of the heterogeneity of treatment response and molecular outliers that arise posttreatment provides new insight into potential early markers of resistance. Clin Cancer Res; 23(22); 6802–11. ©2017 AACR.

Supplementary Table 1, Figure Legends 1-5 from Integrative Microarray Analysis of Pathways Dysregulated in Metastatic Prostate Cancer

Supplementary Figure 4 from Integrative Microarray Analysis of Pathways Dysregulated in Metastatic Prostate Cancer

Supplementary Figure 5 from Integrative Microarray Analysis of Pathways Dysregulated in Metastatic Prostate Cancer

Supplementary Figure 3 from Integrative Microarray Analysis of Pathways Dysregulated in Metastatic Prostate Cancer

Supplementary Figure 1 from Integrative Microarray Analysis of Pathways Dysregulated in Metastatic Prostate Cancer

Supplementary Figure 2 from Integrative Microarray Analysis of Pathways Dysregulated in Metastatic Prostate Cancer

Primary prostate cancer (PCa) can show marked molecular heterogeneity. However, systematic analyses comparing primary PCa and matched metastases in individual patients are lacking. We aimed to address the molecular aspects of metastatic progression while accounting for the heterogeneity of primary PCa. In this pilot study, we collected 12 radical prostatectomy (RP) specimens from men who subsequently developed metastatic castration-resistant prostate cancer (mCRPC). We used histomorphology (Gleason grade, focus size, stage) and immunohistochemistry (IHC) (ERG and p53) to identify independent tumors and/or distinct subclones of primary PCa. We then compared molecular profiles of these primary PCa areas to matched metastatic samples using whole-exome sequencing (WES) and amplicon-based DNA and RNA sequencing. Based on combined pathology and molecular analysis, seven (58%) RP specimens harbored monoclonal and topographically continuous disease, albeit with some degree of intratumor heterogeneity; four (33%) specimens showed true multifocal disease; and one displayed monoclonal disease with discontinuous topography. Early (truncal) events in primary PCa included SPOP p.F133V (one patient), BRAF p.K601E (one patient), and TMPRSS2:ETS rearrangements (eight patients). Activating AR alterations were seen in nine (75%) mCRPC patients, but not in matched primary PCa. Hotspot TP53 mutations, found in metastases from three patients, were readily present in matched primary disease. Alterations in genes encoding epigenetic modifiers were observed in several patients (either shared between primary foci and metastases or in metastatic samples only). WES-based phylogenetic reconstruction and/or clonality scores were consistent with the index focus designated by pathology review in six out of nine (67%) cases. The three instances of discordance pertained to monoclonal, topographically continuous tumors, which would have been considered as unique disease in routine practice. Overall, our results emphasize pathologic and molecular heterogeneity of primary PCa, and suggest that comprehensive IHC-assisted pathology review and genomic analysis are highly concordant in nominating the 'index' primary PCa area. © 2022 The Authors. The Journal of Pathology published by John WileySons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Objective To describe the use of artificial intelligence (AI) in medical literature and trial data extraction, and its applications in uro-oncology. This bridging review, which consolidates information from the diverse applications of AI, highlights how AI users can investigate more sophisticated queries than with traditional methods, leading to synthesis of raw data and complex outputs into more actionable and personalized results, particularly in the field of uro-oncology. Methods Literature and clinical trial searches were performed in PubMed, Dimensions, Embase and Google (1999-2020). The searches focused on the use of AI and its various forms to facilitate literature searches, clinical guidelines development, and clinical trial data extraction in uro-oncology. To illustrate how AI can be applied toaddress questions about optimizing therapeutic decision making and individualizing treatment regimens, the Dimensions-linked information platform was searched for "prostate cancer" keywords (76 publications were identified; 48 were included). Results AI offers the promise of transforming raw data and complex outputs into actionable insights. Literature and clinical trial searches can be automated, enabling clinicians to develop and analyze publications expeditiously on complex issues such as therapeutic sequencing and to obtain updates on documents that evolve at the pace and scope of the landscape. An AI-based platform inclusive of 12 trial databases and >100 scientific literature sources enabled the creation of an interactive visualization. Conclusion As the literature and clinical trial landscape continues to grow in complexity and with increasing speed, the ability to pull the right information at the right time from different search engines and resources while excluding social media bias becomes more challenging. This review demonstrates that by applying natural language processing and machine learning algorithms, validated and optimized AI leads to a speedier, more personalized, efficient and focused search compared with traditional methods.

PTCL with T-follicular helper phenotype (PTCL-TFH) has recurrent mutations affecting epigenetic regulators, which may contribute to aberrant DNA methylation and chemoresistance. This phase 2 study evaluated oral azacitidine (CC-486), a DNA methyltransferase inhibitor, plus CHOP as initial treatment for PTCL (ClinicalTrials.gov - NCT03542266). CC-486 at 300 mg daily was administered for 7 days prior to C1 of CHOP, and for 14 days before CHOP C2-6. The primary endpoint was end-of-treatment CR. Secondary endpoints included ORR, safety and survival. Correlative studies assessed mutations, gene expression and methylation in tumor samples. Grade 3-4 hematologic toxicities were mostly neutropenia (71%), with febrile neutropenia uncommon (14%). Non-hematologic toxicities included fatigue (14%) and GI symptoms (5%). In 20 evaluable patients, CR was 75%, including 88.2% for PTCL-TFH (n=17). At a median follow-up of 21 months, 2-yr PFS was 65.8% for all and 69.2% for PTCL-TFH, while 2-yr OS was 68.4% for all and 76.1% for PTCL-TFH. The frequencies of the TET2, RHOA, DNMT3A, and IDH2 mutations were 76.5%, 41.1%, 23.5% and 23.5%, respectively, with TET2 mutations significantly associated with CR (p=0.007), favorable PFS (p=0.004) and OS (p=0.015), and DNMT3A mutations associated with adverse PFS (p=0.016). CC-486 priming contributed to the reprograming of the tumor microenvironment by upregulation of genes related to apoptosis (p

Purpose: Patients with neuroendocrine prostate cancer (NEPC) are often managed with immunotherapy regimens extrapolated from small cell lung cancer (SCLC). We sought to evaluate the tumor immune landscape of NEPC compared to other prostate cancer types and SCLC. Experimental Design: In this retrospective study, a cohort of 170 patients with 230 RNA sequencing and 104 matched whole exome sequencing data were analyzed. Differences in immune and stromal constituents, frequency of genomic alterations, and associations with outcomes were evaluated. Results: In our cohort, 36% of the prostate tumors were identified as CD8+ T-cell inflamed, while the remaining 64% were T-cell depleted. T-cell inflamed tumors were enriched in anti-inflammatory M2 macrophages and exhausted T-cells and associated with shorter overall survival relative to T-cell depleted tumors (HR=2.62, p

Mutagenic processes leave distinct signatures in cancer genomes. The mutational signatures attributed to APOBEC3 cytidine deaminases are pervasive in human cancers. However, data linking individual APOBEC3 proteins to cancer mutagenesis in vivo are limited. Here, we showed that transgenic expression of human APOBEC3G promotes mutagenesis, genomic instability, and kataegis, leading to shorter survival in a murine bladder cancer model. Acting as mutagenic fuel, APOBEC3G increased the clonal diversity of bladder cancer, driving divergent cancer evolution. Characterization of the single-base substitution signature induced by APOBEC3G in vivo established the induction of a mutational signature distinct from those caused by APOBEC3A and APOBEC3B. Analysis of thousands of human cancers revealed the contribution of APOBEC3G to the mutational profiles of multiple cancer types, including bladder cancer. Overall, this study dissects the mutagenic impact of APOBEC3G on the bladder cancer genome, identifying that it contributes to genomic instability, tumor mutational burden, copy-number loss events, and clonal diversity.Significance:APOBEC3G plays a role in cancer mutagenesis and clonal heterogeneity, which can potentially inform future therapeutic efforts that restrict tumor evolution.See related commentary by Caswell and Swanton, p. 487

Low-grade, low-stage endometrioid carcinomas (LGLS EC) demonstrate 5-yr survival rates up to 95%. However, a small subset of these tumors recur, and little is known about prognostic markers or established mutation profiles associated with recurrence. The goal of the current study was to identify the molecular profiles of the primary carcinomas and the genomic differences between primary tumors and subsequent recurrences. Four cases of LGLS EC with recurrence and 8 cases without recurrence were evaluated via whole-exome sequencing. Three of the 4 recurrent tumors were evaluated via Oncomine Comprehensive Assay. The resulting molecular profiles of the primary and recurrent tumors were compared. Two of the 3 recurrent cases showed additional mutations in the recurrence. One recurrent tumor included an additional TP53 mutation and the other recurrent tumor showed POLE and DDR2 kinase gene mutation. The POLE mutation occurred outside the exonuclease domain. PIK3CA mutations were detected in 4 of 4 primary LGLS EC with recurrence and in 3 of 8 disease-free cases. LGLS EC with recurrence showed higher MSIsensor scores compared with LGLS without recurrence. The level of copy number gains in LGLS EC with recurrence was larger than LGLS EC without recurrence. This pilot study showed 1 of 3 recurrent cases gained a mutation associated with genetic instability (TP53) and 1 of them also acquired a mutation in the DDR2 kinase, a potential therapeutic target. We also noted a higher level of copy number gains, MSIsensor scores and PIK3CA mutations in the primary tumors that later recurred.

Mutagenic processes leave distinct signatures in cancer genomes. The mutational signatures attributed to APOBEC3 cytidine deaminases are pervasive in human cancers. However, data linking individual APOBEC3 proteins to cancer mutagenesis in vivo are limited. Here, we show that transgenic expression of human APOBEC3G promotes mutagenesis, genomic instability, and kataegis, leading to shorter survival in a murine bladder cancer model. Acting as mutagenic fuel, APOBEC3G increases the clonal diversity of bladder cancers, driving divergent cancer evolution. We characterize the single base substitution signature induced by APOBEC3G in vivo, showing the induction of a mutational signature different from that caused by APOBEC3A and APOBEC3B. Analysis of thousands of human cancers reveals the contribution of APOBEC3G to the mutational profiles of multiple cancer types, including bladder cancer. Our findings define the role of APOBEC3G in cancer mutagenesis and clonal heterogeneity. These results potentially inform future therapeutic efforts that restrict tumor evolution.

Background Characterization of circulating tumor DNA (ctDNA) has been integrated into clinical practice. Although labs have standardized validation procedures to develop single locus tests, the efficacy of on‐site plasma‐based next‐generation sequencing (NGS) assays still needs to be proved. Materials and Methods In this retrospective study, we profiled DNA from matched tissue and plasma samples from 75 patients with cancer. We applied an NGS test that detects clinically relevant alterations in 33 genes and microsatellite instability (MSI) to analyze plasma cell‐free DNA (cfDNA). Results The concordance between alterations detected in both tissue and plasma samples was higher in patients with metastatic disease. The NGS test detected 77% of sequence alterations, amplifications, and fusions that were found in metastatic samples compared with 45% of those alterations found in the primary tumor samples (p = .00005). There was 87% agreement on MSI status between the NGS test and tumor tissue results. In three patients, MSI‐high ctDNA correlated with response to immunotherapy. In addition, the NGS test revealed an FGFR2 amplification that was not detected in tumor tissue from a patient with metastatic gastric cancer, emphasizing the importance of profiling plasma samples in patients with advanced cancer. Conclusion Our validation experience of a plasma‐based NGS assay advances current knowledge about translating cfDNA testing into clinical practice and supports the application of plasma assays in the management of oncology patients with metastatic disease. With an in‐house method that minimizes the need for invasive procedures, on‐site cfDNA testing supplements tissue biopsy to guide precision therapy and is entitled to become a routine practice. Implications for Practice This study proposes a solution for decentralized liquid biopsy testing based on validation of a next‐generation sequencing (NGS) test that detects four classes of genomic alterations in blood: sequence mutations (single nucleotide substitutions or insertions and deletions), fusions, amplifications, and microsatellite instability (MSI). Although there are reference labs that perform single‐site comprehensive liquid biopsy testing, the targeted assay this study validated can be established locally in any lab with capacity to offer clinical molecular pathology assays. To the authors' knowledge, this is the first report that validates evaluating an on‐site plasma‐based NGS test that detects the MSI status along with common sequence alterations encountered in solid tumors., This report describes the concordance between circulating tumor DNA and matched tumor tissue molecular profiles, discusses interpretation of observed discordant data, and illustrates applications through clinical cases. It is the first known report to evaluate the performance of an on‐site plasma‐based next‐generation sequencing test to detect microsatellite instability status along with common sequence alterations in the context of its clinical utility and therapeutic applications in precision oncology.

Myoepithelial carcinomas (MECs) of soft tissue are rare and aggressive tumors affecting young adults and children, but their molecular landscape has not been comprehensively explored through genome sequencing. Here, we present the whole-exome sequencing (WES), whole-genome sequencing (WGS), and RNA sequencing findings of two MECs. Patients 1 and 2 (P1, P2), both male, were diagnosed at 27 and 37 yr of age, respectively, with shoulder (P1) and inguinal (P2) soft tissue tumors. Both patients developed metastatic disease, and P2 died of disease. P1 tumor showed a rhabdoid cytomorphology and a complete loss of INI1 (SMARCB1) expression, associated with a homozygousSMARCB1deletion. The tumor from P2 showed a clear cell/small cell morphology, retained INI1 expression and strong S100 positivity. By WES and WGS, tumors from both patients displayed low tumor mutation burdens, and no targetable alterations in cancer genes were detected. P2's tumor harbored anEWSR1::KLF15rearrangement, whereas the tumor from P1 showed a novelASCC2::GGNBP2fusion. WGS evidenced a complex genomic event involving mainly Chromosomes 17 and 22 in the tumor from P1, which was consistent with chromoplexy. These findings are consistent with previous reports ofEWSR1rearrangements (50% of cases) in MECs and provide a genetic basis for the loss of SMARCB1 protein expression observed through immunohistochemistry in 10% of 40% of MEC cases. The lack of additional driver mutations in these tumors supports the hypothesis that these alterations are the key molecular events in MEC evolution. Furthermore, the presence of complex structural variant patterns, invisible to WES, highlights the novel biological insights that can be gained through the application of WGS to rare cancers.

Untreated prostate cancers rely on androgen receptor (AR) signaling for growth and survival, forming the basis for the initial efficacy of androgen deprivation therapy (ADT). Yet the disease can relapse and progress to a lethal stage termed castration-resistant prostate cancer (CRPC). Reactivation of AR signaling represents the most common driver of CRPC growth, and next-generation AR signaling inhibitors (ARSIs) are now used in combination with ADT as first-line therapy. However, ARSIs can result in selective pressure, thereby generating AR-independent tumors. The transition from AR dependence frequently accompanies a change in a phenotype resembling developmental transdifferentiation or “lineage plasticity”. Neuroendocrine prostate cancer, which lacks a defined pathologic classification, is the most studied type of lineage plasticity. However, most AR-null tumors do not exhibit neuroendocrine features and are classified as “double-negative prostate cancer”, the drivers of which are poorly defined. Lineage plasticity studies in CRPC are limited by the lack of genetically defined patient-derived models that recapitulate the disease spectrum. To address this, we developed a biobank of organoids generated from patient biopsies to study the landscape of metastatic CRPC and allow for functional validation assays. Proteins called transcription factors (TFs) are drivers of tumor lineage plasticity. To identify the key TFs that drive the growth of AR-independent tumors, we integrated epigenetic and transcriptomic data generated from CRPC models. We generated ATAC-seq (assay for transposase-accessible chromatin sequencing) and RNA-seq data from 22 metastatic human prostate cancer organoids, six patient-derived xenografts (PDXs), and 12 derived or traditional cell lines. We classified the 40 models into four subtypes and predicted key TFs of each subtype. Besides the well-characterized AR-dependent (CRPC-AR) and neuroendocrine subtypes (CRPC-NE), we identified two novel AR-negative/low groups, including a Wnt-dependent subtype (CRPC-WNT), driven by TCF/LEF TFs, and a stem cell-like (SCL) subtype (CRPC-SCL), driven by the AP-1 family of TFs. To apply the subtype classification to patient samples, we derived RNA-seq signatures from the organoids and applied them to 366 patient samples from two independent CRPC cohorts. The generated signatures recapitulated the four-subtype classification and revealed that CRPC-SCL is the second most prevalent group. Patients from CRPC-SCL are also associated with shorter time under ARSI treatment compared to CRPC-AR, indicating that the ARSI treatments were less effective for CRPC-SCL patients. Additional chromatin immunoprecipitation sequencing (ChIP-seq) analysis indicated that AP-1 (FOSL1) collaboratively binds with TEAD and transcription coactivators, YAP and TAZ. Knocking down of AP-1 (FOSL1), YAP/TAZ decreased cell growth of CRPC-SCL and showed a decrease of chromatin accessibility at CRPC-SCL-specific open chromatin sites and down-regulation of YAP/TAZ target gene expression. In addition, the expression of AP-1 (FOSL1) decreased upon YAP/TAZ knockdown suggesting a positive feedback loop as well as YAP/TAZ as actional targets in CRPC-SCL. We used two small-molecule inhibitors, verteporfin and T-5224, that act on the YAP/TAZ/AP-1 pathway for their potential use as therapeutics for CRPC-SCL tumors, both inhibited the growth of samples from CRPC-SCL but not CRPC-AR. By overexpressing an AP-1 family gene (FOSL1) in AR-high cells, we observed an increase in chromatin accessibility at CRPC-SCL-specific open chromatin sites as well as significant up-regulation of CRPC-SCL signature genes, suggesting that AP-1 functions as a pioneering factor and master regulator for CRPC-SCL. All this work was recently published in Science (Tang, Xu et al. Science, 2022) where I am the co-first author. In summary, by using a diverse biobank of organoids, PDXs, and cell lines that recapitulate the heterogeneity of metastatic prostate cancer, we created a map of the chromatin accessibility and transcriptomic landscape of CRPC. We validated the CRPC-AR and CRPC-NE subtypes and report two novel subtypes of AR-negative/low samples, CRPC-SCL and CRPC-WNT, as well as their respective key TFs. Additional analysis revealed a model in which YAP, TAZ, TEAD, and AP-1 function together and drive oncogenic growth in CRPC-SCL samples. In addition, we proposed small inhibitors of YAP and TAZ that can potentially be used to treat CRPC-SCL patients. Overall, our results show how the stratification of CRPC patients into four subtypes using their transcriptomes can potentially inform appropriate clinical decisions. Citation Format: Fanying Tang, Duo Xu, Shangqian Wang, Chen Khuan Wong, Alexander Martinez-Fundichely, Cindy J. Lee, Sandra Cohen, Jane Park, Corinne E. Hill, Kenneth Eng, Rohan Bareja, Teng Han, Eric Minwei Liu, Ann Palladino, Wei Di, Dong Gao, Wassim Abida, Shaham Beg, Loredana Puca, Maximiliano Meneses, Elisa de Stanchina, Michael F. Berger, Anuradha Gopalan, Lukas E. Dow, Juan Miguel Mosquera, Himisha Beltran, Cora N. Sternberg, Ping Chi, Howard I. Scher, Andrea Sboner, Yu Chen, Ekta Khurana. Chromatin profiles classify castration-resistant prostate cancers suggesting therapeutic targets. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr NG10.

Whole genome sequencing (WGS) has emerged as a tool to characterize the entire genomic landscape of cancer and capture potential new targets and predictive biomarkers. Using state-of-the-art whole-genome and transcriptome sequencing (WGTS) analysis we interrogated a pan cancer cohort to nominate new treatment options. WGS was performed on 414 tumor/germline pairs from our pan cancer cohort of 355 patients, of which 103 had results of other commercial NGS assays. RNAseq data was available in 96 samples. We employed the Isabl GxT analytic platform and manually curated single base substitution (COSMIC v3) mutational signatures and structural variants (SVs). WGTS results were correlated with available clinico-pathologic data. High throughput drug screening that included PARP inhibitors and functional validation were performed in 61 matched patient-derived tumor organoids (PDTO). We found 5,129 SVs affecting at least one cancer gene in 88% of cases. High-confidence homologous recombination deficiency (HRD), determined by curation of mutational signatures and mutations/SVs affecting oncogenes and tumor suppressor genes, was detected in 8.3% of solid tumors (e.g., prostate, pancreas, ovarian, uterine, breast, gallbladder, and stomach carcinomas). HRD status included tumors with BRCA1/2 wildtype and SVs impacting BRCA1/2, RAD51, ATM and other HRD genes. CDK12-loss associated genomic instability was detected in 7 cases including 3 cases of prostate adenocarcinoma. 93 gene fusions involving cancer genes were detected including known and novel fusions of potential significance (e.g., SLC45A3::ALK in metastatic prostate adenocarcinoma, TMEM106A::BRCA1 in serious ovarian carcinoma, ESR1::EP300 in metastatic breast cancer). Some tumor cohorts demonstrated enrichment of drivers e.g., FGFR1 amplification in male breast cancer, rearrangements at the TERT locus in adrenocortical carcinoma, enrichment for repeat-mediated deletion attributed to mismatch repair (MMR) in gynecological carcinosarcoma, and SVs affecting FHIT in gastric adenocarcinoma. Drug screening of PDTO and functional testing with RAD51 immunofluorescence assay validated high-confidence HRD annotation. One example is a BRCA1/2 wildtype pancreatic adenocarcinoma with increased tandem duplications and SV (inversion) impacting BRCA2, and high-confidence HRD by our novel WGS classifier. Drug screening of the corresponding PDTO showed an enhanced response to Olaparib, in contrast to cases without HRD that did not. We have used state-of-the-art analysis of WGTS to improve the detection of targets and significant biomarkers in a pan cancer cohort, including HRD, CDK12-type genomic instability, pathogenic germline mutations and potential targetable novel fusions. A robust and clinically relevant ex vivo preclinical model allowed us to validate a WGS-based classifier that detects HRD even in cancers with wildtype BRCA1/2. Citation Format: Majd Al Assaad, Hui-Hsuan Kuo, Jones Nauseef, Max F. Levine, Gunes Gundem, Juan S. Medina-Martínez, Jyothi Manohar, Michael Sigouros, Ahmed Elsaeed, David Wilkes, Elli Papaemmanuil, Eloise Chapman, Scott T. Tagawa, Allyson Ocean, Cora N. Sternberg, Eleni Andreopoulou, Manish Shah, Andrea Sboner, Kevin Holcomb, David Nanus, Laura Martin, Olivier Elemento, Juan Miguel Mosquera. Whole genome and transcriptome sequencing of a pan cancer cohort unearths novel therapeutic avenues [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3437.

Background: Triple-negative breast cancer (TNBC) remains the most aggressive molecular subtype of breast cancer, with worse survival outcomes compared to other breast cancer subtypes. TNBC prevalence is highest among women of African descent worldwide, and through our previous work we have established a connection between West African ancestry (WAa) and higher rates of TNBC. Specifically, we have shown that prevalence rates of TNBC among West African and African American women are similar and higher than that of East African and White American women. We have also shown that quantified African ancestry is higher among TNBC cases compared to non-TNBC cases. To determine the influence African ancestry on the TNBC tumor environment, we sought to determine any differences in gene expression profiles of Ghanaian (West African) compared to Ethiopian (East African) women. Methods: RNA was extracted and sequenced from a pilot cohort of archival FFPE tumor tissue among Ghanaian (n = 19) and Ethiopian (n = 20) women. RNAseq reads were aligned, and quality of alignments were assessed, where de-duplicated samples with counts above 10M reads were included in the final analysis. Genetic ancestry was quantified by obtaining SNVs called from the RNAseq alignments, using GATK best practices. Differentially expressed genes lists were determined comparing Ghanaian vs. Ethiopian TNBC tumors, and also by identifying genes that were associated with increasing African ancestry. These gene lists, and log-fold change between comparison groups, were used as input for Ingenuity Pathway Analysis (IPA), to identify canonical pathways and de novo networks that are specific to Ghanaian or Ethiopian TNBC tumors. Results: Using 1KG populations as our reference to quantify genetic ancestry, we show that Ghanaian samples have >94% AFR ancestry, specifically matching population groups representative of WAa. The Ethiopian samples showed between 37-48% AFR ancestry, primarily represented by East African groups. Interestingly, there seems to be a significant proportion of EUR ancestry among the Ethiopians samples (30-49%), primarily represented by Italian ancestry. We have conducted the differential gene expression analysis in two ways. First, we have compared gene expression profiles between Ghanaian and Ethiopian tumors. In our preliminary analysis, we identified >600 genes (p < 0.01) that were differentially expressed between Ghanaian and Ethiopian TNBC tumors. Second, we used AFR ancestry as a continuous variable, where we conducted a linear regression analysis to identify genes associated with AFR ancestry. We identified >900 genes associated with AFR ancestry (p < 0.01), and this gene signature distinguished Ghanaian from Ethiopian tumors in an unsupervised hierarchical clustering. In comparing the differentially expressed gene lists from these two approaches, approximately 200 genes were shared, indicating the distinct value of both analyses. Using these gene lists as input for IPA analysis, we have begun to identify canonical pathways that have been altered by our differentially expressed genes, alongside de novo networks that differ between our Ghanaian and Ethiopian tumors. In our overlapping gene list, we see predicted differences in functions such as quantity of T lymphocytes, where genes downregulated in Ethiopian tumors may indicated reduced presence of these immune cells. Using CIBERSORT and xCell deconvolution methods, validation of these findings are ongoing. Conclusions and Ongoing work: This work highlights how ancestry-specific gene regulation can delineate differences in the tumor microenvironment among a cohort of African tumors. We are currently evaluating distribution of TNBC subtypes and estimation of immune cell populations in these tumors, to determine ancestry-specific differences in tumor heterogeneity and immune response. Citation Format: Rachel Martini, Endale Gebregzabher, Princesca Dorsaint, Timothy Chu, Kanika Arora, Lee Gibbs, Zarko Manojlovic, Nicolas Robine, Andrea Sboner, Olivier Elemento, John Carpten, Lisa Newman, Melissa Davis. Gene expression profiles of Ghanaian and Ethiopian triple-negative breast tumors [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr SS1-07.