Darren P Ennis

Identification of actionable targets using DEPArray ‐based sorting of pure carcinoma and stromal populations from formalin‐fixed paraffin‐embedded tissues followed by shallow whole‐genome sequencing

Abstract Formalin‐fixed paraffin‐embedded (FFPE) tissue specimens represent precious resources for clinical genomic profiling studies, especially when coupled with comprehensive medical records. Even though next‐generation sequencing (NGS) is an effective tool to detect somatic mutations and somatic copy number alterations (sCNA), the biggest challenges in unlocking clinically translatable genomic information from FFPE tissue are low DNA yields and degraded DNA, affected by variable formalin fixation. Another issue is that the proportion of carcinoma and other noncarcinoma cells is variable and can be confounded by intratumoral heterogeneity. To explore these challenges, we isolated pure carcinoma and stromal cells using the DEPArray™ NxT system, a microchip‐based digital sorter that allows isolation of pure, homogeneous subpopulations of cells from FFPE samples. We isolated pure carcinoma and stromal cell populations from 12 FFPE tissues, including tissues from nine primary and metastatic breast cancer and three primary ovarian high‐grade serous carcinomas. This was followed by downstream shallow whole‐genome sequencing (WGS) for copy number landscape profiling (10 samples) and/or a targeted panel for somatic mutation and sCNA analysis (seven samples), subject to cell availability. Seven out of 10 samples (even some with low tumour content or of old age) produced good‐quality genomic data, detecting sCNA in all carcinoma population samples but not in the stromal populations. Mutation analysis was performed successfully in 6/7 samples and somatic mutations were detected in all of them. Our workflow enabled the identification of clinically actionable targets, including PIK3CA, ERBB2, FGFR1/2, CDK6, CCNE1, KRAS amplifications and RB, BRCA1/2 losses in patients that would direct therapy. © 2025 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

The genomic trajectory of ovarian high‐grade serous carcinoma can be observed in STIC lesions

AbstractOvarian high‐grade serous carcinoma (HGSC) originates in the fallopian tube, with secretory cells carrying a TP53 mutation, known as p53 signatures, identified as potential precursors. p53 signatures evolve into serous tubal intraepithelial carcinoma (STIC) lesions, which in turn progress into invasive HGSC, which readily spreads to the ovary and disseminates around the peritoneal cavity. We recently investigated the genomic landscape of early‐ and late‐stage HGSC and found higher ploidy in late‐stage (median 3.1) than early‐stage (median 2.0) samples. Here, to explore whether the high ploidy and possible whole‐genome duplication (WGD) observed in late‐stage disease were determined early in the evolution of HGSC, we analysed archival formalin‐fixed paraffin‐embedded (FFPE) samples from five HGSC patients. p53 signatures and STIC lesions were laser‐capture microdissected and sequenced using shallow whole‐genome sequencing (sWGS), while invasive ovarian/fallopian tube and metastatic carcinoma samples underwent macrodissection and were profiled using both sWGS and targeted next‐generation sequencing. Results showed highly similar patterns of global copy number change between STIC lesions and invasive carcinoma samples within each patient. Ploidy changes were evident in STIC lesions, but not p53 signatures, and there was a strong correlation between ploidy in STIC lesions and invasive ovarian/fallopian tube and metastatic samples in each patient. The reconstruction of sample phylogeny for each patient from relative copy number indicated that high ploidy, when present, occurred early in the evolution of HGSC, which was further validated by copy number signatures in ovarian and metastatic tumours. These findings suggest that aberrant ploidy, suggestive of WGD, arises early in HGSC and is detected in STIC lesions, implying that the trajectory of HGSC may be determined at the earliest stages of tumour development. © 2024 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Epithelial-to-Mesenchymal Transition Supports Ovarian Carcinosarcoma Tumorigenesis and Confers Sensitivity to Microtubule Targeting with Eribulin

Abstract Ovarian carcinosarcoma (OCS) is an aggressive and rare tumor type with limited treatment options. OCS is hypothesized to develop via the combination theory, with a single progenitor resulting in carcinomatous and sarcomatous components, or alternatively via the conversion theory, with the sarcomatous component developing from the carcinomatous component through epithelial-to-mesenchymal transition (EMT). In this study, we analyzed DNA variants from isolated carcinoma and sarcoma components to show that OCS from 18 women is monoclonal. RNA sequencing indicated that the carcinoma components were more mesenchymal when compared with pure epithelial ovarian carcinomas, supporting the conversion theory and suggesting that EMT is important in the formation of these tumors. Preclinical OCS models were used to test the efficacy of microtubule-targeting drugs, including eribulin, which has previously been shown to reverse EMT characteristics in breast cancers and induce differentiation in sarcomas. Vinorelbine and eribulin more effectively inhibited OCS growth than standard-of-care platinum-based chemotherapy, and treatment with eribulin reduced mesenchymal characteristics and N-MYC expression in OCS patient-derived xenografts. Eribulin treatment resulted in an accumulation of intracellular cholesterol in OCS cells, which triggered a downregulation of the mevalonate pathway and prevented further cholesterol biosynthesis. Finally, eribulin increased expression of genes related to immune activation and increased the intratumoral accumulation of CD8+ T cells, supporting exploration of immunotherapy combinations in the clinic. Together, these data indicate that EMT plays a key role in OCS tumorigenesis and support the conversion theory for OCS histogenesis. Targeting EMT using eribulin could help improve OCS patient outcomes. Significance: Genomic analyses and preclinical models of ovarian carcinosarcoma support the conversion theory for disease development and indicate that microtubule inhibitors could be used to suppress EMT and stimulate antitumor immunity.

Divergent trajectories to structural diversity impact patient survival in high grade serous ovarian cancer

Abstract Deciphering the structural variation across tumour genomes is crucial to determine the events driving tumour progression and better understand tumour adaptation and evolution. High grade serous ovarian cancer (HGSOC) is an exemplar tumour type showing extreme, but poorly characterised structural diversity. Here, we comprehensively describe the mutational landscape driving HGSOC, exploiting a large (N = 324), deeply whole genome sequenced dataset. We reveal two divergent evolutionary trajectories, affecting patient survival and involving differing genomic environments. One involves homologous recombination repair deficiency (HRD) while the other is dominated by whole genome duplication (WGD) with frequent chromothripsis, breakage-fusion-bridges and extra-chromosomal DNA. These trajectories contribute to structural variation hotspots, containing candidate driver genes with significantly altered expression. While structural variation predominantly drives tumorigenesis, we find high mtDNA mutation loads associated with shorter patient survival. We show that a combination of mutations in the mitochondrial and nuclear genomes impact prognosis, suggesting strategies for patient stratification.