APOBEC3B stratifies ovarian clear cell carcinoma with distinct immunophenotype and prognosis.

BACKGROUND: Ovarian clear cell carcinoma (OCCC) is a challenging disease due to its intrinsic chemoresistance. Immunotherapy is an emerging treatment option but currently impeded by insufficient understanding of OCCC immunophenotypes and their molecular determinants. METHODS: Whole-genome sequencing on 23 pathologically confirmed patients was employed to depict the genomic profile of primary OCCCs. APOBEC3B expression and digital pathology-based Immunoscore were assessed by performing immunohistochemistry and correlated with clinical outcomes. RESULTS: An APOBEC-positive (APOBEC+) subtype was identified based on the characteristic mutational signature and prevalent kataegis events. APOBEC + OCCC displayed favourable prognosis across one internal and two external patient cohorts. The improved outcome was ascribable to increased lymphocytic infiltration. Similar phenomena of APOBEC3B expression and T-cell accumulation were observed in endometriotic tissues, suggesting that APOBEC-induced mutagenesis and immunogenicity could occur early during OCCC pathogenesis. Corroborating these results, a case report was presented for an APOBEC + patient demonstrating inflamed tumour microenvironment and clinical response to immune checkpoint blockade. CONCLUSIONS: Our findings implicate APOBEC3B as a novel mechanism of OCCC stratification with prognostic value and as a potential predictive biomarker that may inform immunotherapeutic opportunities.

Baseline immunity and impact of chemotherapy on immune microenvironment in cervical cancer.

BACKGROUND: We aimed to comprehensively evaluate the immunologic landscape at baseline and upon chemotherapy in cervical cancer. The information should aid ongoing clinical investigations of checkpoint blockade immunotherapies in this disease setting. METHODS: A series of 109 cervical carcinoma patients was retrospectively assayed before and after neoadjuvant chemotherapy. Tumour-infiltrating immune markers (CD3, CD4, CD8, CD20, CD56, CD68, PD-1, PD-L1) were assessed by immunohistochemistry. RNA sequencing analysis was performed on matched pre- and post-treatment fresh-frozen tissues. RESULTS: At diagnosis, diverse immune cell types including CD20+ B cells, CD3+ T cells, CD56+ natural killer (NK) cells, and CD68+ macrophages were detected in different proportions of cervical carcinoma. Unsupervised hierarchical clustering evidently showed that CD4+ and CD8+ T cell abundance correlated with PD-L1 expression. Based on the immune infiltration patterns, the patients could be stratified into four groups with prognostic relevance, namely, 'immuno-active', 'immuno-medial', 'immuno-NK', and 'immuno-deficient'. Neoadjuvant chemotherapy was associated with increased CD4, CD8, CD20, and CD56 signals, most prominently in good responders. Transcriptomic data corroborated the improved anticancer immunity and identified immunosuppressive CD200 upregulation following chemotherapeutic intervention. CONCLUSIONS: A subset of cervical cancer harbours active immune microenvironment, and chemotherapy treatment may further exert locoregional immunostimulation. Immune checkpoint inhibitors as combination or maintenance therapies warrant future exploration in clinic.

Urinary Molecular Pathology for Patients with Newly Diagnosed Urothelial Bladder Cancer.

PURPOSE: Next-generation sequencing (NGS)-based profiling of both urinary tumor DNA (utDNA) and circulating tumor DNA (ctDNA) shows promise for noninvasive detection and surveillance of urothelial bladder cancer (UBC). However, the analytical performance of these assays remains undefined in the real-world setting. Here, we sought to evaluate the concordance between tumor DNA (tDNA) profiling and utDNA or ctDNA assays using a UBC patient cohort from the intended-use population. MATERIALS AND METHODS: Fifty-nine cases with pathologically confirmed disease and matching tissue/urine pairs were prospectively enrolled. Baseline peripheral blood mononuclear cell and plasma specimens were collected during clinic visits. The PredicineCARETM NGS assay was applied for ultra-deep targeted sequencing and somatic alteration identification in tDNA, utDNA and ctDNA. RESULTS: Diverse quantitative metrics including cancer cell fraction, variant allele frequency and tumor mutation burden were invariably concordant between tDNA and utDNA, but not ctDNA. The mutational landscapes captured by tDNA or utDNA were highly similar, whereas a considerable proportion of ctDNA aberrations stemmed from clonal hematopoiesis. Using tDNA-informed somatic events as reference, utDNA assays achieved a specificity of 99.3%, a sensitivity of 86.7%, a positive predictive value of 67.2%, a negative predictive value of 99.8% and a diagnostic accuracy of 99.1%. Higher preoperative utDNA or tDNA abundance correlated with worse relapse-free survival. Actionable variants including FGFR3 alteration and ERBB2 amplification were identified in utDNA. CONCLUSIONS: Urine-based molecular pathology provides a valid and complete genetic profile of bladder cancer, and represents a faithful surrogate for genotyping and monitoring newly diagnosed UBC.

T-cell exhaustion interrelates with immune cytolytic activity to shape the inflamed tumor microenvironment.

Direct quantification of exhausted T cells in human cancer is lacking, and its predictive value for checkpoint-based treatment remains poorly investigated. We sought to systematically characterize the pan-cancer landscape and molecular hallmarks of T-cell dysfunction for the purpose of precision immunotherapy. Here, we defined a transcriptional signature for T-cell exhaustion through analyzing differential gene expression between PD-1-high and PD-1-negative CD8+ T lymphocytes from primary non-small cell lung cancer (NSCLC), followed by positive correlation tests with PDCD1 in TCGA lung carcinomas. A 78-gene signature for exhausted CD8+ T cells (GET) was identified and validated to reflect dysfunctional immune state spanning different species and disease models. We discovered that GET estimation significantly correlated with intratumoral immune cytolytic activity (CYT) and T-cell-inflamed gene expression profile (GEP) across 30 solid tumor types. Miscellaneous tumor-intrinsic and -extrinsic properties, in particular leukocyte proportions, genomic abnormalities, specific mutational signatures, and signaling pathways, were notably associated with GET levels. Furthermore, higher GET expression predicted an increased likelihood of clinical response to immune checkpoint inhibitors. These findings highlight the interrelation between T-cell exhaustion and immune cytolytic activity at the pan-cancer scale. The resulting inflamed tumor microenvironment may further crosstalk with other molecular and clinicopathological factors, which should be properly considered during immunotherapy biomarker development. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Multiregion whole-genome sequencing depicts intratumour heterogeneity and punctuated evolution in ovarian clear cell carcinoma.

BACKGROUND: Ovarian clear cell carcinoma (OCCC) arises from endometriosis and represents a difficult-to-treat gynaecological malignancy, in part, because its spatial intratumour heterogeneity and temporal evolutionary trajectories have not been explicitly defined. METHODS: We performed whole-genome sequencing on six pathologically confirmed patients with OCCC. An R package named KataegisPortal was developed to identify and annotate loci of localised hypermutations. Immunohistochemical staining was conducted on a tissue microarray containing 143 OCCC specimens. RESULTS: Multiregion analysis demonstrated considerable degrees of subclonal diversification, ascribable to dynamic mutagenic processes, as well as macroevolutionary events including the acquisition of aneuploidy and chromoplexy. KataegisPortal unveiled APOBEC-mediated kataegis in the early phases of OCCC pathogenesis. We further showed evidence that APOBEC3A and APOBEC3B were frequently expressed in OCCC and possibly regulated by the MAPK pathway. Notably, APOBEC3B-expressing OCCC displayed favourable prognosis and appreciable immunogenicity manifested by marked cytotoxic T-cell infiltration. CONCLUSIONS: These results point to an appealing model of punctuated tumour evolution underlying OCCC neoplastic transformation and progression, which may pose formidable challenges of early detection and intervention, and indicate the intratumour heterogeneity of cancer-driving alterations, yielding important implications for molecular diagnosis and targeted treatment of this lethal disease.

Clinicopathological, microenvironmental and genetic determinants of molecular subtypes in KEAP1/NRF2-mutant lung cancer.

Somatic KEAP1-NRF2 pathway alterations are frequently detected in both lung adenocarcinomas and squamous cell carcinomas. However, the biological characteristics and molecular subtypes of KEAP1/NRF2-mutant lung cancer remain largely undefined. Here, we performed a stepwise, integrative analytic and experimental interrogation of primary tumors and cancer cell lines harboring KEAP1 or NFE2L2 (encoding NRF2) gene mutations. First, we discovered that KEAP1/NRF2-mutant lung cancer presented APOBEC-mediated mutational signatures, impaired tumor angiogenesis, elevated hypoxic stress and deficient immune-cell infiltrates. Second, gene expression-based subtyping revealed three molecular subsets of KEAP1/NRF2-mutant lung adenocarcinomas and two molecular subsets of KEAP1/NRF2-mutant lung squamous cell carcinomas, each associated with distinguishing genetic, differentiation, immunological and clinicopathological properties. Third, single-sample prediction allowed for de novo identification of KEAP1/NRF2-active tumors within KEAP1/NRF2-wild-type samples. Our data demonstrate that KEAP1/NRF2-mutant lung cancer is a microenvironmentally distinct, biologically heterogeneous, and clinically underestimated disease. These new pathological and molecular insights may accelerate the development of efficacious therapeutic strategies against human malignancies featured by KEAP1-NRF2 pathway activation.

Prevalence and clonality of synchronous primary carcinomas in the bladder and prostate.

Incidental prostate adenocarcinoma (IPCa) has been frequently discovered during postoperative histopathological evaluation of radical cystoprostatectomy specimens in patients with bladder cancer (BCa). However, there is currently no conclusive study addressing the clinical significance of IPCa and the clonal relatedness of IPCa and BCa. Here, we performed a retrospective single-center review of 919 BCa cases and an additional meta-analysis including a total of 19 868 individuals who underwent radical cystectomy for bladder cancer. IPCa, mostly clinically insignificant, was detected in 67 of 919 BCa patients (7.3%) and was significantly associated with greater age. In the meta-analysis, a lower prevalence was observed in Asian than in non-Asian countries (19% versus 32%), presumably due to their different rates of prostate cancer occurrence. Whole-exome sequencing on matched BCa and IPCa samples unambiguously revealed independent clonal origins of the synchronous tumors. BCa and IPCa lesions from each patient displayed distinctive genomic abnormalities and largely unrelated mutational signatures of single nucleotide variations, indicating disparate mutational processes underlying bladder and prostate oncogenesis. These findings provide important insights into the incidental nature of prostate adenocarcinoma in patients with bladder cancer, and suggest that the two concurrent diseases can be managed separately. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

ADReCS: an ontology database for aiding standardization and hierarchical classification of adverse drug reaction terms.

Adverse drug reactions (ADRs) are noxious and unexpected effects during normal drug therapy. They have caused significant clinical burden and been responsible for a large portion of new drug development failure. Molecular understanding and in silico evaluation of drug (or candidate) safety in laboratory is thus so desired, and unfortunately has been largely hindered by misuse of ADR terms. The growing impact of bioinformatics and systems biology in toxicological research also requires a specialized ADR term system that works beyond a simple glossary. Adverse Drug Reaction Classification System (ADReCS; http://bioinf.xmu.edu.cn/ADReCS) is a comprehensive ADR ontology database that provides not only ADR standardization but also hierarchical classification of ADR terms. The ADR terms were pre-assigned with unique digital IDs and at the same time were well organized into a four-level ADR hierarchy tree for building an ADR-ADR relation. Currently, the database covers 6544 standard ADR terms and 34,796 synonyms. It also incorporates information of 1355 single active ingredient drugs and 134,022 drug-ADR pairs. In summary, ADReCS offers an opportunity for direct computation on ADR terms and also provides clues to mining common features underlying ADRs.

Chiral selection and frequency response of spiral waves in reaction-diffusion systems under a chiral electric field.

Chirality is one of the most fundamental properties of many physical, chemical, and biological systems. However, the mechanisms underlying the onset and control of chiral symmetry are largely understudied. We investigate possibility of chirality control in a chemical excitable system (the Belousov-Zhabotinsky reaction) by application of a chiral (rotating) electric field using the Oregonator model. We find that unlike previous findings, we can achieve the chirality control not only in the field rotation direction, but also opposite to it, depending on the field rotation frequency. To unravel the mechanism, we further develop a comprehensive theory of frequency synchronization based on the response function approach. We find that this problem can be described by the Adler equation and show phase-locking phenomena, known as the Arnold tongue. Our theoretical predictions are in good quantitative agreement with the numerical simulations and provide a solid basis for chirality control in excitable media.

Transient targeting of BIM-dependent adaptive MCL1 preservation enhances tumor response to molecular therapeutics in non-small cell lung cancer.

Despite remarkable efficacy, targeted treatments often yield a subpopulation of residual tumor cells in part due to non-genetic adaptions. Previous mechanistic understanding on the emergence of these drug-tolerant persisters (DTPs) has been limited to epigenetic and transcriptional reprogramming. Here, by comprehensively interrogating therapy-induced early dynamic protein changes in diverse oncogene-addicted non-small cell lung cancer models, we identified adaptive MCL1 increase as a new and universal mechanism to confer apoptotic evasion and DTP formation. In detail, acute MAPK signaling disruption in the presence of genotype-based tyrosine kinase inhibitors (TKIs) prompted mitochondrial accumulation of pro-apoptotic BH3-only protein BIM, which sequestered MCL1 away from MULE-mediated degradation. A small-molecule combination screen uncovered that PI3K-mTOR pathway blockade prohibited MCL1 upregulation. Biochemical and immunocytochemical evidence indicated that mTOR complex 2 (mTORC2) bound and phosphorylated MCL1, facilitating its interaction with BIM. As a result, short-term polytherapy combining antineoplastic TKIs with PI3K, mTOR or MCL1 inhibitors sufficed to prevent DTP development and promote cancer eradication. Collectively, these findings support that upfront and transient targeting of BIM-dependent, mTORC2-regulated adaptive MCL1 preservation holds enormous promise to improve the therapeutic index of molecular targeted agents.

Therapeutic targeting of CPSF3-dependent transcriptional termination in ovarian cancer.

Transcriptional dysregulation is a recurring pathogenic hallmark and an emerging therapeutic vulnerability in ovarian cancer. Here, we demonstrated that ovarian cancer exhibited a unique dependency on the regulatory machinery of transcriptional termination, particularly, cleavage and polyadenylation specificity factor (CPSF) complex. Genetic abrogation of multiple CPSF subunits substantially hampered neoplastic cell viability, and we presented evidence that their indispensable roles converged on the endonuclease CPSF3. Mechanistically, CPSF perturbation resulted in lengthened 3'-untranslated regions, diminished intronic polyadenylation and widespread transcriptional readthrough, and consequently suppressed oncogenic pathways. Furthermore, we reported the development of specific CPSF3 inhibitors building upon the benzoxaborole scaffold, which exerted potent antitumor activity. Notably, CPSF3 blockade effectively exacerbated genomic instability by down-regulating DNA damage repair genes and thus acted in synergy with poly(adenosine 5'-diphosphate-ribose) polymerase inhibition. These findings establish CPSF3-dependent transcriptional termination as an exploitable driving mechanism of ovarian cancer and provide a promising class of boron-containing compounds for targeting transcription-addicted human malignancies.

Dual Inhibition of CDK12/CDK13 Targets Both Tumor and Immune Cells in Ovarian Cancer.

Therapeutic perturbation of cyclin-dependent kinase 12 (CDK12) is proposed to have pleiotropic effects in ovarian cancer, including direct cytotoxicity against tumor cells and indirect induction of immunogenicity that confer synthetic sensitivity to immune-based treatment. However, formal testing of this hypothesis has been hindered by an insufficient mechanistic understanding of CDK12 and its close homolog CDK13, as well as generally unfavorable pharmacokinetics of available CDK12/CDK13 covalent inhibitors. In this study, we used an innovative arsenous warhead modality to develop an orally bioavailable CDK12/CDK13 covalent compound. The dual CDK12/CDK13 inhibitors ZSQ836 exerted potent anticancer activity in cell culture and mouse models and induced transcriptional reprogramming, including downregulation of DNA damage response genes. CDK12 and CDK13 were both ubiquitously expressed in primary and metastatic ovarian cancer, and the two kinases performed independent and synergistic functions to promote tumorigenicity. Unexpectedly, although ZSQ836 triggered genomic instability in malignant cells, it counterintuitively impaired lymphocytic infiltration in neoplastic lesions by interfering with T-cell proliferation and activation. These findings highlight the Janus-faced effects of dual CDK12/CDK13 inhibitors by simultaneously suppressing tumor and immune cells, offering valuable insights into the future direction of drug discovery to pharmacologically target CDK12. SIGNIFICANCE: This study dissects the specific roles of CDK12 and CDK13 in ovarian cancer and develops a CDK12/CDK13 inhibitor that impairs both tumor and immune cells, which could guide future CDK12 inhibitor development.

SOX17 and PAX8 constitute an actionable lineage-survival transcriptional complex in ovarian cancer.

Müllerian tissue-specific oncogenes, prototyped by PAX8, underlie ovarian tumorigenesis and represent unique molecular vulnerabilities. Further delineating such lineage-dependency factors and associated therapeutic implications would provide valuable insights into ovarian cancer biology and treatment. In this study, we identified SOX17 as a new lineage-survival master transcription factor, which shared co-expression pattern with PAX8 in epithelial ovarian carcinoma. Genetic disruption of SOX17 or PAX8 analogously inhibited neoplastic cell viability and downregulated a spectrum of lineage-related transcripts. Mechanistically, we showed that SOX17 physically interacted with PAX8 in cultured cell lines and clinical tumor specimens. The two nuclear proteins bound to overlapping genomic regions and regulated a common set of downstream genes, including those involved in cell cycle and tissue morphogenesis. In addition, we revealed that small-molecule inhibitors of transcriptional cyclin-dependent kinases (CDKs) effectively reduced SOX17 and PAX8 expression. ZSQ1722, a novel orally bioavailable CDK12/13 covalent antagonist, exerted potent anti-tumor activity in xenograft models. These findings shed light on an actionable lineage-survival transcriptional complex in ovarian cancer, and facilitated drug discovery by generating a serial of candidate compounds to pharmacologically target this difficult-to-treat malignancy.

Epithelial-Mesenchymal Transition Induces GSDME Transcriptional Activation for Inflammatory Pyroptosis.

GSDME is a newly recognized executor of cellular pyroptosis, and has been recently implicated in tumor growth and immunity. However, knowledge about the molecular regulators underlying GSDME abundance remains limited. Here, we performed integrative bioinformatics analyses and identified that epithelial-mesenchymal transition (EMT) gene signatures exhibited positive correlation with GSDME levels across human cancers. A causal role was supported by the observation that EMT dictated GSDME reversible upregulation in multiple experimental models. Mechanistically, transcriptional activation of GSDME was directly driven by core EMT-activating transcription factors ZEB1/2, which bound to the GSDME promoter region. Of functional importance, elevated GSDME in mesenchymally transdifferentiated derivatives underwent proteolytic cleavage upon antineoplastic drug exposure, leading to pyroptotic cell death and consequent cytokine release. Taken together, our findings pinpointed a key transcriptional machinery controlling GSDME expression and indicated potential therapeutic avenues to exploit GSDME-mediated inflammatory pyroptosis for the treatment of mesenchymal malignancies.

PAX8 regulon in human ovarian cancer links lineage dependency with epigenetic vulnerability to HDAC inhibitors.

PAX8 is a prototype lineage-survival oncogene in epithelial ovarian cancer. However, neither its underlying pro-tumorigenic mechanisms nor potential therapeutic implications have been adequately elucidated. Here, we identified an ovarian lineage-specific PAX8 regulon using modified cancer outlier profile analysis, in which PAX8-FGF18 axis was responsible for promoting cell migration in an autocrine fashion. An image-based drug screen pinpointed that PAX8 expression was potently inhibited by small-molecules against histone deacetylases (HDACs). Mechanistically, HDAC blockade altered histone H3K27 acetylation occupancies and perturbed the super-enhancer topology associated with PAX8 gene locus, resulting in epigenetic downregulation of PAX8 transcripts and related targets. HDAC antagonists efficaciously suppressed ovarian tumor growth and spreading as single agents, and exerted synergistic effects in combination with standard chemotherapy. These findings provide mechanistic and therapeutic insights for PAX8-addicted ovarian cancer. More generally, our analytic and experimental approach represents an expandible paradigm for identifying and targeting lineage-survival oncogenes in diverse human malignancies.

Hybrid sequencing-based personal full-length transcriptomic analysis implicates proteostatic stress in metastatic ovarian cancer.

Comprehensive molecular characterization of myriad somatic alterations and aberrant gene expressions at personal level is key to precision cancer therapy, yet limited by current short-read sequencing technology, individualized catalog of complete genomic and transcriptomic features is thus far elusive. Here, we integrated second- and third-generation sequencing platforms to generate a multidimensional dataset on a patient affected by metastatic epithelial ovarian cancer. Whole-genome and hybrid transcriptome dissection captured global genetic and transcriptional variants at previously unparalleled resolution. Particularly, single-molecule mRNA sequencing identified a vast array of unannotated transcripts, novel long noncoding RNAs and gene chimeras, permitting accurate determination of transcription start, splice, polyadenylation and fusion sites. Phylogenetic and enrichment inference of isoform-level measurements implicated early functional divergence and cytosolic proteostatic stress in shaping ovarian tumorigenesis. A complementary imaging-based high-throughput drug screen was performed and subsequently validated, which consistently pinpointed proteasome inhibitors as an effective therapeutic regime by inducing protein aggregates in ovarian cancer cells. Therefore, our study suggests that clinical application of the emerging long-read full-length analysis for improving molecular diagnostics is feasible and informative. An in-depth understanding of the tumor transcriptome complexity allowed by leveraging the hybrid sequencing approach lays the basis to reveal novel and valid therapeutic vulnerabilities in advanced ovarian malignancies.

Comprehensive genomic profiling of neuroendocrine bladder cancer pinpoints molecular origin and potential therapeutics.

Neuroendocrine bladder cancer is a relatively rare but often lethal malignancy, with cell of origin, oncogenomic architecture and standard treatment poorly defined. Here we performed comprehensive whole-genome and transcriptome sequencing on a unique cohort of genitourinary neuroendocrine neoplasms, mainly small cell carcinomas of the urinary bladder. The mutational landscape and signatures of neuroendocrine bladder cancer strikingly resembled those in conventional urothelial carcinoma, along with typically mixed histologies, supporting a common cellular origin. We identified pervasive age-related and APOBEC-mediated mutagenesis patterns, and one patient displayed a somatic fingerprint attributable to aristolochic acid exposure, an established etiology of urothelial cell carcinoma. Deep RNA sequencing revealed dysregulated tumorigenic pathways and novel fusion transcripts, including a targetable in-frame PVT1-ERBB2 variant associated with aberrant expression of ERBB2 gene (encoding HER2 receptor). Furthermore, we provided preliminary evidence that combined TP53 and RB1 depletion favored lineage switching from oncogene-addicted urothelial cancer cells to neuroendocrine-like tumor cells, and resulted in decreased response to targeted agents. Together, these data present the first high-resolution genomic portrait of neuroendocrine bladder cancer, which holds important implications for the biological understanding and rational treatment of this deadly disease.

Molecular Targeted Therapies Elicit Concurrent Apoptotic and GSDME-Dependent Pyroptotic Tumor Cell Death.

PURPOSE: The induced death signals following oncogene inhibition underlie clinical efficacy of molecular targeted therapies against human cancer, and defects of intact cell apoptosis machinery often lead to therapeutic failure. Despite potential importance, other forms of regulated cell death triggered by pharmacologic intervention have not been systematically characterized. EXPERIMENTAL DESIGN: Pyroptotic cell death was assessed by immunoblot analysis, phase-contrast imaging, scanning electron microscopy, and flow cytometry. Tumor tissues of patients with lung cancer were analyzed using IHC. Functional impact of pyroptosis on drug response was investigated in cell lines and xenograft models. RESULTS: We showed that diverse small-molecule inhibitors specifically targeting KRAS-, EGFR-, or ALK-driven lung cancer uniformly elicited robust pyroptotic cell death, in addition to simultaneously invoking cellular apoptosis. Upon drug treatment, the mitochondrial intrinsic apoptotic pathway was engaged and the mobilized caspase-3 protease cleaved and activated gasdermin E (GSDME, encoded by DFNA5), which permeabilized cytoplasmic membrane and executed cell-lytic pyroptosis. GSDME displayed ubiquitous expression in various lung cancer cell lines and clinical specimens, including KRAS-mutant, EGFR-altered, and ALK-rearranged adenocarcinomas. As a result, cooccurrence and interplay of apoptosis and pyroptosis were widespread in lung cancer cells, succumbing to genotype-matched regimens. We further demonstrated that pyroptotic cell death partially contributed to the drug response in a subset of cancer models. CONCLUSIONS: These results pinpoint GSDME-dependent pyroptosis as a previously unrecognized mechanism of action for molecular targeted agents to eradicate oncogene-addicted neoplastic cells, which may have important implications for the clinical development and optimal application of anticancer therapeutics.

Clonality, Heterogeneity, and Evolution of Synchronous Bilateral Ovarian Cancer.

Synchronous bilateral ovarian cancer (SBOC) represents a relatively frequent occurrence and clinically relevant diagnostic dilemma. Delineation of its clonal architecture, genetic heterogeneity, and evolutionary trajectories may have important implications for prognosis and management of patients with SBOC. Here, we describe the results of next-generation whole-exome or whole-genome sequencing of specimens from 12 SBOC cases and report that bilateral tumors from each individual display a comparable number of genomic abnormalities and similar mutational signatures of single-nucleotide variations. Clonality indices based on tumor-specific alterations supported monoclonal origins of SBOC. Each of the ovarian lesions was nevertheless oligoclonal, with inferred metastatic tumors harboring more subclones than their primary counterparts. The phylogenetic structure of SBOC indicated that most cancer cell dissemination occurred early, when the primary carcinoma was still relatively small (<100 million cells). Accordingly, the mutation spectra and mutational signatures of somatic variants exhibited pronounced spatiotemporal differences in each patient. Overall, these findings suggest that SBOCs are clonally related and form through pelvic spread rather than independent multifocal oncogenesis. Metastatic dissemination is often an early event, with dynamic mutational processes leading to divergent evolution and intratumor and intertumor heterogeneity, ultimately contributing substantially to phenotypic plasticity and diverse clinical course in SBOC. Cancer Res; 77(23); 6551-61. ©2017 AACR.

Preclinical Efficacy and Molecular Mechanism of Targeting CDK7-Dependent Transcriptional Addiction in Ovarian Cancer.

Ovarian cancer remains a significant cause of gynecologic cancer mortality, and novel therapeutic strategies are urgently needed in clinic as new treatment options. We previously showed that BET bromodomain inhibitors displayed promising efficacy for the treatment of epithelial ovarian cancer by downregulating pivot transcription factors. However, the potential antitumor activities and molecular mechanisms of other epigenetic or transcriptional therapies have not been systematically determined. Here, by performing an unbiased high-throughput drug screen to identify candidate compounds with antineoplastic effects, we identified THZ1, a recently developed covalent CDK7 inhibitor, as a new transcription-targeting compound that exerted broad cytotoxicity against ovarian tumors. Mechanistically, CDK7 represented a previously unappreciated actionable vulnerability in ovarian cancer, and CDK7 inhibition led to a pronounced dysregulation of gene transcription, with a preferential repression of E2F-regulated genes and transcripts associated with super-enhancers. Our findings revealed the molecular underpinnings of THZ1 potency and established pharmaceutically targeting transcriptional addiction as a promising therapeutic strategy in aggressive ovarian cancer. Mol Cancer Ther; 16(9); 1739-50. ©2017 AACR.