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Background: Based on preclinical data showing addition of CDK4/6 inhibitors to gemcitabine was synergistic, ribociclib was evaluated in combination with gemcitabine to determine the maximum tolerated dose (MTD) and dose limiting toxicities (DLT)., Methods: In this single arm multicohort phase I trial, we evaluated the safety and efficacy of ribociclib plus gemcitabine in patients with advanced solid tumors. Patients received gemcitabine intravenously on days 1 and 8 followed by ribociclib days 8-14, with treatment repeated every 3 weeks., Results: The study enrolled 43 patients between October 2017 and September 2019. The escalation phase (19 patients) determined the MTD and recommended phase II dose (RP2D) to be ribociclib 800 mg daily and gemcitabine 1000 mg/m2 for the expansion phase (24 patients). One patient experienced Grade 4 thrombocytopenia. Eleven patients experienced Grade 3 adverse events (AE), the most common being neutropenia, thrombocytopenia, and anemia. No partial or complete responses were observed. 15/22 (68%) of efficacy evaluable patients who received the MTD achieved best response of stable disease., Conclusions: The addition of ribociclib to gemcitabine was tolerated well and yielded stability of tumors in both cohorts. Biomarkers such as Rb status and activity of CDK2 and CDK4/6 complexes may help to select patients who may respond better to the combination of gemcitabine and ribociclib., Clinical Trial Registration: NCT03237390., Competing Interests: Competing interests: The authors declare no competing interests. Ethics approval and consent to participate: All participants granted written informed consent according to federal and institutional guidelines. The trial was conducted with approval of Mayo Institutional Review Board. The study was performed in accordance with the Declaration of Helsinki. Consent for publication: No individual person’s data is included in this manuscript., (© 2025. The Author(s).)

The ADP-ribosyl hydrolases PARG and ARH3 counteract PARP enzymatic activity by removing ADP-ribosylation. PARG and ARH3 activities have a synthetic lethal effect; however, the specific molecular mechanisms underlying this response remain unknown. Here, we show that the PARG and ARH3 synthetic lethality is enhanced further in the presence of DNA alkylating agents, suggesting that the inability to revert ADP-ribosylation primarily affects the repair of alkylated DNA bases. ARH3 knockout cells, treated with PARG inhibitor and alkylating genotoxins, accumulated single-stranded DNA and DNA damage, resulting in G2/M cell cycle arrest and apoptosis. Furthermore, we reveal a reduction in PARP1/PARP2 levels in ARH3-deficient cells treated with PARG inhibitor due to excessive ADP-ribosylation, which may contribute to alkylating agents' vulnerability. Collectively, these results uncover the potential of targeting ADP-ribosyl hydrolases in combination with alkylating agents for cancer therapy and provide insights into the mechanisms underlying the synthetic lethal effect., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

Objective: In ovarian cancer (OvCa), tumor cell high glucocorticoid receptor (GR) has been associated with poor patient prognosis. In vitro, GR activation inhibits chemotherapy-induced OvCa cell death in association with transcriptional upregulation of genes encoding anti-apoptotic proteins. A recent randomized phase II study demonstrated improvement in progression-free survival (PFS) for heavily pre-treated OvCa patients randomized to receive therapy with a selective GR modulator (SGRM) plus chemotherapy compared to chemotherapy alone. We hypothesized that SGRM therapy would improve carboplatin response in OvCa patient-derived xenograft (PDX)., Methods: Six high-grade serous (HGS) OvCa PDX models expressing GR mRNA ( NR3C1 ) and protein were treated with chemotherapy +/- SGRM. Tumor size was measured longitudinally by peritoneal transcutaneous ultrasonography., Results: One of the 6 GR-positive PDX models showed a significant improvement in PFS with the addition of a SGRM. Interestingly, the single model with an improved PFS was least carboplatin sensitive. Possible explanations for the modest SGRM activity include the high carboplatin sensitivity of 5 of the PDX tumors and the potential that SGRMs activate the tumor invasive immune cells in patients (absent from immunocompromised mice). The level of tumor GR protein expression alone appears insufficient for predicting SGRM response., Conclusion: The significant improvement in PFS shown in 1 of the 6 models after treatment with a SGRM plus chemotherapy underscores the need to determine predictive biomarkers for SGRM therapy in HGS OvCa and to better identify patient subgroups that are most likely to benefit from adding GR modulation to chemotherapy., Competing Interests: JTV is currently an employee of GlaxoKlineSmith. GFF reports honorarium for talk from Curio Science, advisory board for GSK, uncompensated advisory board for TTC, and PI of industry-sponsored study for Corcept, Abbvie, Genentech/Roche, Tesaro/GSK, Syndax, 47 inc, Iovance, Syros, Astex, Merck, Sanofi, Sermonix, Compugen, INcyte, Hoffman LaRoche, Eisai. The authors acknowledge supply of Relacorilant from Corcept Therapeutics. SDC and The University of Chicago have been issued patents on methods of measuring GR expression in triple-negative breast cancer (TNBC) and using GR antagonists in TNBC and prostate cancer., (© 2025. Asian Society of Gynecologic Oncology, Korean Society of Gynecologic Oncology, and Japan Society of Gynecologic Oncology.)

Recent studies indicate that replication checkpoint modulators (RCMs) such as inhibitors of CHK1, ATR, and WEE1 have promising monotherapy activity in solid tumors, including platinum-resistant high grade serous ovarian cancer (HGSOC). However, clinical response rates are generally below 30%. While RCM-induced DNA damage has been extensively examined in preclinical and clinical studies, the link between replication checkpoint interruption and tumor shrinkage remains incompletely understood. Here we utilized HGSOC cell lines and patient-derived xenografts (PDXs) to study events leading from RCM treatment to ovarian cancer cell death. These studies show that RCMs increase CDC25A levels and CDK2 signaling in vitro, leading to dysregulated cell cycle progression and increased replication stress in HGSOC cell lines independent of homologous recombination status. These events lead to sequential activation of JNK and multiple BH3-only proteins, including BCL2L11/BIM, BBC3/PUMA and the BMF, all of which are required to fully initiate RCM-induced apoptosis. Activation of the same signaling pathway occurs in HGSOC PDXs that are resistant to poly(ADP-ribose) polymerase inhibitors but respond to RCMs ex vivo with a decrease in cell number in 3-dimensional culture and in vivo with xenograft shrinkage or a significantly diminished growth rate. These findings identify key cell death-initiating events that link replication checkpoint inhibition to antitumor response in ovarian cancer., (© 2024. The Author(s).)

Purpose: AB160 is a 160-nm nano-immunoconjugate consisting of nab-paclitaxel (ABX) nanoparticles noncovalently coated with bevacizumab (BEV) for targeted delivery into tissues expressing high levels of VEGF. Preclinical data showed that AB160 resulted in greater tumor targeting and tumor inhibition compared with sequential treatment with ABX then BEV. Given individual drug activity, we investigated the safety and toxicity of AB160 in patients with gynecologic cancers., Patients and Methods: A 3+3 phase I trial was conducted with three potential dose levels in patients with previously treated endometrial, cervical, and platinum-resistant ovarian cancer to ascertain the recommended phase II dose (RP2D). AB160 was administered intravenously on days 1, 8, and 15 of a 28-day cycle (ABX 75-175 mg/m2, BEV 30-70 mg/m2). Pharmacokinetic analyses were performed., Results: No dose-limiting toxicities (DLT) were seen among the three dose levels tested. Grade 3/4 toxicities included neutropenia, thromboembolic events, and leukopenia. DL2 (ABX 150 mg/m2, BEV 60 mg/m2) was chosen as the RP2D. Seven of the 19 patients with measurable disease (36.8%) had confirmed partial responses (95% confidence interval, 16.3%-61.6%). Pharmacokinetic analyses demonstrated that AB160 allowed 50% higher paclitaxel dosing and that paclitaxel clearance mirrored that of therapeutic antibodies., Conclusions: The safety profile and clinical activity of AB160 supports further clinical testing in patients with gynecologic cancers; the RP2D is DL2 (ABX 150 mg/m2, BEV 60 mg/m2)., (©2024 The Authors; Published by the American Association for Cancer Research.)

Ovarian cancer is the deadliest gynecological malignancy, owing to its late-stage diagnosis and high rates of recurrence and resistance following standard-of-care treatment, highlighting the need for novel treatment approaches. Through an unbiased drug screen, we identified the kinase inhibitor, lestaurtinib, as a potent antineoplastic agent for chemotherapy- and PARP-inhibitor (PARPi)-sensitive and -resistant ovarian cancer cells and patient derived xenografts (PDXs). RNA-sequencing revealed that lestaurtinib potently suppressed JAK/STAT signaling and lestaurtinib efficacy was shown to be directly related to JAK/STAT pathway activity in cell lines and PDX models. Most ovarian cancer cells exhibited constitutive JAK/STAT pathway activation and genetic loss of STAT1 and STAT3 resulted in growth inhibition. Lestaurtinib also displayed synergy when combined with cisplatin and olaparib, including in a model of PARPi resistance. In contrast, the most well-known JAK/STAT inhibitor, ruxolitinib, lacked antineoplastic activity against all ovarian cancer cell lines and PDX models tested. This divergent behavior was reflected in the ability of lestaurtinib to block both Y701/705 and S727 phosphorylation of STAT1 and STAT3, whereas ruxolitinib failed to block S727. Consistent with these findings, lestaurtinib additionally inhibited JNK and ERK activity, leading to more complete suppression of STAT phosphorylation. Concordantly, combinatorial treatment with ruxolitinib and a JNK or ERK inhibitor resulted in synergistic antineoplastic effects at dose levels where single agents were ineffective. Taken together, these findings indicate that lestaurtinib, and other treatments that converge on JAK/STAT signaling, are worthy of further pre-clinical and clinical exploration for the treatment of highly aggressive and advanced forms of ovarian cancer., Statement of Significance: Lestaurtinib is a novel inhibitor of ovarian cancer, including chemotherapy- and PARPi-resistant models, that acts through robust inhibition of the JAK/STAT pathway and synergizes with standard-of-care agents at clinically relevant concentrations.

Objectives: Our objectives were to determine the incidence, timing, and risk factors for venous thromboembolisms (VTEs) in patients with advanced stage epithelial ovarian cancer (EOC) who received neoadjuvant chemotherapy (NACT). We explored the utilization of direct-acting oral anticoagulants (DOACs) for VTE treatment., Methods: This retrospective cohort study included patients with advanced stage EOC receiving NACT followed by interval cytoreductive surgery (ICS) at a single institution. Risk factors were compared between patients with versus without VTE between EOC diagnosis and 180 days after ICS. Bleeding complications were compared between patient who received a DOAC versus non-DOAC., Results: VTE cases occurred amongst 33 of the 154 (21.4%) patients with 4 (2.6%) concurrent with EOC diagnosis, 9 (5.8%) between EOC diagnosis and NACT start, 13 (8.4%) between NACT start and ICS, and 7 (4.5%) within 180 days after ICS. There were no statistically significant differences in risk factors assessed (age, body mass index, functional status, histology, Khorana score, and smoking history) between patients with versus without VTE. Eleven patients (33.3%) received a DOAC for VTE treatment. There were no significant differences in number of intraoperative blood transfusions (p = 0.38), blood loss (p = 0.95), or bleeding complications (p = 0.53) between patients treated with a DOAC versus a non-DOAC., Conclusion: There is a high incidence of VTE events (21.4%) in patients with advanced stage EOC undergoing NACT. Two-thirds of the VTEs may have been prevented with thromboprophylaxis as they occurred between EOC diagnosis and ICS. These data support consideration of thromboprophylaxis in all patients with advanced stage EOC undergoing NACT., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Pathogenic protein-truncating variants of RAD51C, which plays an integral role in promoting DNA damage repair, increase the risk of breast and ovarian cancer. A large number of RAD51C missense variants of uncertain significance (VUS) have been identified, but the effects of the majority of these variants on RAD51C function and cancer predisposition have not been established. Here, analysis of 173 missense variants by a homology-directed repair (HDR) assay in reconstituted RAD51C-/- cells identified 30 nonfunctional (deleterious) variants, including 18 in a hotspot within the ATP-binding region. The deleterious variants conferred sensitivity to cisplatin and olaparib and disrupted formation of RAD51C/XRCC3 and RAD51B/RAD51C/RAD51D/XRCC2 complexes. Computational analysis indicated the deleterious variant effects were consistent with structural effects on ATP-binding to RAD51C. A subset of the variants displayed similar effects on RAD51C activity in reconstituted human RAD51C-depleted cancer cells. Case-control association studies of deleterious variants in women with breast and ovarian cancer and noncancer controls showed associations with moderate breast cancer risk [OR, 3.92; 95% confidence interval (95% CI), 2.18-7.59] and high ovarian cancer risk (OR, 14.8; 95% CI, 7.71-30.36), similar to protein-truncating variants. This functional data supports the clinical classification of inactivating RAD51C missense variants as pathogenic or likely pathogenic, which may improve the clinical management of variant carriers., Significance: Functional analysis of the impact of a large number of missense variants on RAD51C function provides insight into RAD51C activity and information for classification of the cancer relevance of RAD51C variants., (©2023 The Authors; Published by the American Association for Cancer Research.)

The snATAC + snRNA platform allows epigenomic profiling of open chromatin and gene expression with single-cell resolution. The most critical assay step is to isolate high-quality nuclei to proceed with droplet-base single nuclei isolation and barcoding. With the increasing popularity of multiomic profiling in various fields, there is a need for optimized and reliable nuclei isolation methods, mainly for human tissue samples. Herein we compared different nuclei isolation methods for cell suspensions, such as peripheral blood mononuclear cells (PBMC, n = 18) and a solid tumor type, ovarian cancer (OC, n = 18), derived from debulking surgery. Nuclei morphology and sequencing output parameters were used to evaluate the quality of preparation. Our results show that NP-40 detergent-based nuclei isolation yields better sequencing results than collagenase tissue dissociation for OC, significantly impacting cell type identification and analysis. Given the utility of applying such techniques to frozen samples, we also tested frozen preparation and digestion ( n = 6). A paired comparison between frozen and fresh samples validated the quality of both specimens. Finally, we demonstrate the reproducibility of scRNA and snATAC + snRNA platform, by comparing the gene expression profiling of PBMC. Our results highlight how the choice of nuclei isolation methods is critical for obtaining quality data in multiomic assays. It also shows that the measurement of expression between scRNA and snRNA is comparable and effective for cell type identification.

Objective: To identify high-risk disease in clinicopathologic low-risk endometrial cancer (EC) with high microsatellite instability (MSI-H) or no specific molecular profile (NSMP) and therapeutic insensitivity in clinicopathologic high-risk MSI-H/NSMP EC., Methods: We searched The Cancer Genome Atlas for DNA sequencing, RNA expression, and surveillance data regarding MSI-H/NSMP EC. We used a molecular classification system of E2F1 and CCNA2 expression and sequence variations in POLE , PPP2R1A , or FBXW7 (ECPPF) to prognostically stratify MSI-H/NSMP ECs. Clinical outcomes were annotated after integrating ECPPF and sequence variations in homologous recombination (HR) genes., Results: Data were available for 239 patients with EC, which included 58 MSI-H and 89 NSMP cases. ECPPF effectively stratified MSI-H/NSMP EC into distinct molecular groups with prognostic implications: molecular low risk (MLR), with low CCNA2 and E2F1 expression, and molecular high risk (MHR), with high CCNA2 and E2F1 expression and/or PPP2R1A and/or FBXW7 variants. The 3-year disease-free survival (DFS) rate was 43.8% in the MHR group with clinicopathologic low-risk indicators and 93.9% in the MLR group ( P <.001). In the MHR group, wild-type HR genes were present in 28% of cases but in 81% of documented recurrences. The 3-year DFS rate in patients with MSI-H/NSMP EC with clinicopathologic high-risk indicators was significantly higher in the MLR (94.1%) and MHR/HR variant gene (88.9%) groups than in the MHR/HR wild-type gene group (50.3%, P <.001)., Conclusion: ECPPF may resolve prognostic challenges for MSI-H/NSMP EC by identifying occult high-risk disease in EC with clinicopathologic low-risk indicators and therapeutic insensitivity in EC with clinicopathologic high-risk indicators., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Gonzalez-Bosquet, Weroha, Bakkum-Gamez, Weaver, McGree, Dowdy, Famuyide, Kipp, Halling, Yadav, Couch and Podratz.)

This work examines differences in chromatin accessibility, methylation, and response to DNA hypomethylating agents between mismatch repair-deficient and non-mismatch repair-deficient endometrial cancer. Next-generation sequencing of a stage 1B, grade 2 endometrioid endometrial cancer tumor revealed microsatellite instability and a variant of unknown significance in POLE along with global and MLH1 hypermethylation. Inhibition of viability by decitabine in the study and comparison tumors was minimal, as shown by an inhibitory effect of 0 and 17.9, respectively. Conversely, the inhibitory effect of azacitidine on the study tumor was more pronounced, at 72.8 versus 41.2. In vitro , mismatch repair-deficient endometrial cancer with MLH1 hypermethylation respond better to DNA methyltransferase inhibition by azacytidine (DNA/RNA inhibition), than to decitabine (DNA-only inhibition). Additional large studies are needed to substantiate our findings.

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., (©2022 The Authors; Published by the American Association for Cancer Research.)

Objective: To evaluate recurrence-free survival (RFS) and cause-specific survival (CSS) after observation or vaginal brachytherapy (VB) alone in all subgroups of early-stage high-intermediate (HIR) and high-risk endometrial cancer (EC)., Methods: We identified patients with stage I HIR (GOG-249 criteria) and stage II endometrioid EC, and stage I and II non-endometrioid EC who underwent surgery at Mayo Clinic and Cleveland Clinic between 1999 and 2016. Three-year RFS and CSS after observation or VB only were estimated in 16 subgroups defined by risk factors., Results: Among 4156 ECs, we identified 447 (10.8%) stage I endometrioid HIR, 52 (1.3%) stage II endometrioid, 350 (8.4%) stage I non-endometrioid, and 17 (0.4%) stage II non-endometrioid ECs; observation or VB alone was applied in 349 (78.1%), 24 (46.2%), 187 (53.4%), and 2 (11.8%) patients, respectively. After observation or VB, stage I HIR endometrioid EC subgroups with <2 factors among grade 3, LVSI, or stage IB had a 3-year CSS >95% (lower 95% confidence intervals limit: 89.8%), whereas subgroups with ≥2 factors had poorer outcomes. No EC-related deaths after 3 years were reported in 97 stage IA non-endometrioid ECs without myometrial invasion. Stage II ECs had poor outcomes regardless of histology., Conclusions: Observation or VB only may be sufficient in stage I endometrioid HIR ECs with <2 factors among grade 3, LVSI, or IB and in stage IA non-endometrioid ECs without myometrial invasion. Stratification of early-stage HIR and high-risk ECs into risk subgroups potentially alleviates the overtreatment and undertreatment risk and should be considered in future research., Competing Interests: Declaration of Competing Interest Simone Garzon, Tommaso Grassi, Andrea Mariani, Swapna Kollikonda, Amy L. Weaver, Michaela E. McGree, Ivy A. Petersen, Gretchen E. Glaser, Carrie L. Langstraat, Sudha R. Amarnath, and Mariam AlHilli have nothing to disclose. S. John Weroha declares research funds from Novartis not related to the current project or Endometrial cancer in general., (Copyright © 2022. Published by Elsevier Inc.)

In endometrial cancer, occult high-risk subtypes (rooted in histomorphologically low-risk disease) with insensitivity to adjuvant therapies impede improvements in therapeutic efficacy. Therefore, we aimed to assess the ability of molecular high-risk (MHR) and low-risk (MLR) ECPPF (E2F1, CCNA2, POLE, PPP2R1A, FBXW7) stratification to profile recurrence in early, low-risk endometrioid endometrial cancer (EEC) and insensitivity to platinum-based chemotherapy or radiotherapy (or both) in high-risk EEC. Using The Cancer Genome Atlas endometrial cancer database, we identified 192 EEC cases with available DNA sequencing and RNA expression data. Molecular parameters were integrated with clinicopathologic risk factors and adverse surveillance events. MHR was defined as high (-H) CCNA2 or E2F1 log2 expression (≥2.75), PPP2R1A mutations (-mu), or FBXW7mu; MLR was defined as low (-L) CCNA2 and E2F1 log2 expression (<2.75). We assessed 164 cases, plus another 28 with POLEmu for favorable-outcomes comparisons. MHR and MLR had significantly different progression-free survival (PFS) rates (P < .001), independent of traditional risk factors (eg, TP53mu), except for stage IV disease. PFS of CCNA2-L/E2F1-L paralleled that of POLEmu. ECPPF status stratified responses to adjuvant therapy in stage III-IV EEC (P < .01) and profiled stage I, grade 1-2 cases with risk of recurrence (P < .001). MHR was associated with CTNNB1mu-linked treatment failures (P < .001). Expression of homologous recombination repair (HR) and cell cycle genes was significantly elevated in CCNA2-H/E2F1-H compared with CCNA2-L/E2F1-L (P<1.0E-10), suggesting that HR deficiencies may underlie the favorable PFS in MLR. HRmu were detected in 20.7%. No treatment failures were observed in high-grade or advanced EEC with HRmu (P = .02). Favorable PFS in clinically high-risk EEC was associated with HRmu and MLR ECPPF (P < .001). In summary, MLR ECPPF and HRmu were associated with therapeutic efficacy in EEC. MHR ECPPF was associated with low-risk, early-stage recurrences and insensitivity to adjuvant therapies., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2022 Gonzalez-Bosquet et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Bromodomain and extraterminal (BET) proteins including BRD4 play important roles in oncogenesis and immune inflammation. Here we demonstrate that cancer cells with loss of the retinoblastoma (RB) tumor suppressor became resistant to small molecule bromodomain inhibitors of BET proteins. We find that RB binds to bromodomain-1 (BD1) of BRD4, but binding is impeded by CDK4/6-mediated RB phosphorylation at serine-249/threonine-252 (S249/T252). ChIP-seq analysis shows RB knockdown increases BRD4 occupancy at genomic loci of genes enriched in cancer-related pathways including the GPCR-GNBIL-CREB axis. S249/T252-phosphorylated RB positively correlates with GNBIL protein level in prostate cancer patient samples. BET inhibitor resistance in RB-deficient cells is abolished by co-administration of CREB inhibitor. Our study identifies RB protein as a bona fide intrinsic inhibitor of BRD4 and demonstrates that RB inactivation confers resistance to small molecule BET inhibitors, thereby revealing a regulatory hub that converges RB upstream signaling onto BRD4 functions in diseases such as cancer., (© 2022. The Author(s).)

Targeting glutamine metabolism has emerged as a novel therapeutic strategy for several human cancers, including ovarian cancer. The primary target of this approach is the kidney isoform of glutaminase, glutaminase 1 (GLS1), a key enzyme in glutamine metabolism that is overexpressed in several human cancers. A first-in-class inhibitor of GLS1, called CB839 (Telaglenastat), has been investigated in several clinical trials, with promising results. The first clinical trial of CB839 in platinum-resistant ovarian cancer patients is forthcoming. ARID1A -mutated ovarian clear cell carcinoma (OCCC) is a relatively indolent and chemoresistant ovarian cancer histotype. In OCCC-derived cells ARID1A simultaneously drives GLS1 expression and metabolism reprograming. In ARID1A-mutated OCCC-derived mouse models, loss of ARID1A corresponds to GLS1 upregulation and increases sensitivity to GLS1 inhibition. Thus, targeting of GLS1 with CB839 has been suggested as a targeted approach for OCCC patients with tumors harboring ARID1A -mutations. Here, we investigated whether GLS1 is differentially expressed between OCCC patients whose tumors are ARID1A positive and patients whose tumors are ARID1A negative. In clinical specimens of OCCC, we found that GLS1 overexpression was not correlated with ARID1A loss. In addition, GLS1 overexpression was associated with better clinical outcomes. Our findings have implications for human trials using experimental therapeutics targeting GLS1.

A problematic feature of many human cancers is a lack of understanding of mechanisms controlling organ-specific patterns of metastasis, despite recent progress in identifying many mutations and transcriptional programs shown to confer this potential. To address this gap, we developed a methodology that enables different aspects of the metastatic process to be comprehensively characterized at a clonal resolution. Our approach exploits the application of a computational pipeline to analyze and visualize clonal data obtained from transplant experiments in which a cellular DNA barcoding strategy is used to distinguish the separate clonal contributions of two or more competing cell populations. To illustrate the power of this methodology, we demonstrate its ability to discriminate the metastatic behavior in immunodeficient mice of a well-established human metastatic cancer cell line and its co-transplanted LRRC15 knockdown derivative. We also show how the use of machine learning to quantify clone-initiating cell (CIC) numbers and their subsequent metastatic progeny generated in different sites can reveal previously unknown relationships between different cellular genotypes and their initial sites of implantation with their subsequent respective dissemination patterns. These findings underscore the potential of such combined genomic and computational methodologies to identify new clonally-relevant drivers of site-specific patterns of metastasis., (© The Author(s) 2022. Published by Oxford University Press on behalf of NAR Cancer.)

Long-term treatment outcomes for patients with high grade ovarian cancers have not changed despite innovations in therapies. There is no recommended assay for predicting patient response to second-line therapy, thus clinicians must make treatment decisions based on each individual patient. Patient-derived xenograft (PDX) tumors have been shown to predict drug sensitivity in ovarian cancer patients, but the time frame for intraperitoneal (IP) tumor generation, expansion, and drug screening is beyond that for tumor recurrence and platinum resistance to occur, thus results do not have clinical utility. We describe a drug sensitivity screening assay using a drug delivery microdevice implanted for 24 h in subcutaneous (SQ) ovarian PDX tumors to predict treatment outcomes in matched IP PDX tumors in a clinically relevant time frame. The SQ tumor response to local microdose drug exposure was found to be predictive of the growth of matched IP tumors after multi-week systemic therapy using significantly fewer animals (10 SQ vs 206 IP). Multiplexed immunofluorescence image analysis of phenotypic tumor response combined with a machine learning classifier could predict IP treatment outcomes against three second-line cytotoxic therapies with an average AUC of 0.91., (Copyright © 2022. Published by Elsevier Inc.)

Glucocorticoid receptor can be associated with poor prognosis among a variety of solid tumors in the absence of other nuclear hormone receptors. Our objective was to characterize differences in glucocorticoid receptor (GR), estrogen receptor (ER), progesterone receptor (PR), and androgen receptor expression in the sarcomatous versus carcinomatous components of ovarian and uterine carcinosarcomas. Eighteen patients diagnosed with Mullerian carcinosarcoma between May 2009 and August 2014 were included. Nuclear receptor expression was evaluated by immunohistochemistry using whole tissue specimens. Receptor expression was quantified using the H-score. Mean H-scores were compared between the sarcomatous and carcinomatous components of tumors using Wilcoxon signed-rank tests. We found that GR expression was significantly higher in the sarcomatous components than in the carcinomatous components of the cancers (mean H score 144.4 vs 38.9, p = 0.002). Conversely, ER (3.1 vs 63.1, p = 0.002) and PR (1.7 vs 47.2, p < 0.0001) expression were significantly decreased in the sarcomatous component compared to the carcinomatous component. Androgen receptor expression was low overall (0 versus 2.8, p = 0.04). We hypothesize that GR-high, ER/PR-low expression is associated with epithelial to mesenchymal transition in the sarcomatous cells and may serve as a potential therapeutic target., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 The Authors. Published by Elsevier Inc.)

Dissemination of ovarian cancer cells can lead to inoperable metastatic lesions in the bowel and omentum that cause patient death. Here we show that LRRC15, a type-I 15-leucine-rich repeat-containing membrane protein, highly overexpressed in ovarian cancer bowel metastases compared with matched primary tumors and acts as a potent promoter of omental metastasis. Complementary models of ovarian cancer demonstrated that LRRC15 expression leads to inhibition of anoikis-induced cell death and promotes adhesion and invasion through matrices that mimic omentum. Mechanistically, LRRC15 interacted with β1-integrin to stimulate activation of focal adhesion kinase (FAK) signaling. As a therapeutic proof of concept, targeting LRRC15 with the specific antibody-drug conjugate ABBV-085 in both early and late metastatic ovarian cancer cell line xenograft models prevented metastatic dissemination, and these results were corroborated in metastatic patient-derived ovarian cancer xenograft models. Furthermore, treatment of 3D-spheroid cultures of LRRC15-positive patient-derived ascites with ABBV-085 reduced cell viability. Overall, these data uncover a role for LRRC15 in promoting ovarian cancer metastasis and suggest a novel and promising therapy to target ovarian cancer metastases., Significance: This study identifies that LRRC15 activates β1-integrin/FAK signaling to promote ovarian cancer metastasis and shows that the LRRC15-targeted antibody-drug conjugate ABBV-085 suppresses ovarian cancer metastasis in preclinical models., (©2021 The Authors; Published by the American Association for Cancer Research.)