Edward Tanner

Preclinical Evaluation of NTX-301, a Novel DNA Hypomethylating Agent in Ovarian Cancer

Abstract Purpose: DNA methylation causes silencing of tumor-suppressor and differentiation-associated genes, being linked to chemoresistance. Previous studies demonstrated that hypomethylating agents (HMA) resensitize ovarian cancer to chemotherapy. NTX-301 is a highly potent and orally bioavailable HMA, in early clinical development. Experimental Design: The antitumor effects of NTX-301 were studied in ovarian cancer models by using cell viability, stemness and ferroptosis assays, RNA sequencing, lipidomic analyses, and stimulated Raman spectroscopy. Results: Ovarian cancer cells (SKOV3, IC50 = 5.08 nmol/L; OVCAR5 IC50 = 3.66 nmol/L) were highly sensitive to NTX-301 compared with fallopian tube epithelial cells. NTX-301 downregulated expression of DNA methyltransferases 1–3 and induced transcriptomic reprogramming with 15,000 differentially expressed genes (DEG, P < 0.05). Among them, Gene Ontology enrichment analysis identified regulation of fatty acid biosynthesis and molecular functions related to aldehyde dehydrogenase (ALDH) and oxidoreductase, known features of cancer stem cells. Low-dose NTX-301 reduced the ALDH(+) cell population and expression of stemness-associated transcription factors. Stearoyl-coenzyme A desaturase 1 (SCD), which regulates production of unsaturated fatty acids (UFA), was among the top DEG downregulated by NTX-301. NTX-301 treatment decreased levels of UFA and increased oxidized lipids, and this was blunted by deferoxamine, indicating cell death via ferroptosis. NTX-301–induced ferroptosis was rescued by oleic acid. In vivo, monotherapy with NTX-301 significantly inhibited ovarian cancer and patient-derived xenograft growth (P < 0.05). Decreased SCD levels and increased oxidized lipids were detected in NTX-301–treated xenografts. Conclusions: NTX-301 is active in ovarian cancer models. Our findings point to a new mechanism by which epigenetic blockade disrupts lipid homeostasis and promotes cancer cell death.

Laparoscopic surgical access in morbidly obese women undergoing endometrial cancer surgery: Repurposing the left upper quadrant approach

The study purpose was to report the outcomes of patients undergoing endometrial cancer surgical staging with laparoscopic abdominal access entry using a left upper quadrant (LUQ) access technique. This was a retrospective cohort study conducted from 1 January 2013 to 1 January 2018. The setting was an academic, single institution gynecologic oncology service with a high volume of minimally invasive surgery (MIS). The patient cohort included obese (defined as BMI > 30 kg/m In total, 317 patients were included with a median age of 54 years (range, 24-79) and median BMI 42.5 kg/m A LUQ abdominal technique is a safe and reliable method of laparoscopic access in morbidly obese women undergoing MIS for endometrial cancer staging. This may be the preferred method of laparoscopic access for women with a panniculus or central adiposity, given the caudal displacement of the umbilicus and poor correlation with intraperitoneal anatomic landmarks in this setting.

Minimally Invasive Surgery Rate as a Quality Metric for Endometrial Cancer

To determine the frequency with which Commission on Cancer-accredited hospitals met a metric of ≥80% minimally invasively performed hysterectomies for endometrial cancer and to compare the clinical outcomes of hospitals meeting this metric with those that did not. Retrospective cohort study. Hospitals caring for ≥20 endometrial cancer patients per year recorded in the National Cancer Database in 2015 were included. Women who had undergone hysterectomy for endometrial cancer and had an epithelial histology, a Charlson comorbidity score of 0, and stage I to III disease. Patient characteristics, patterns of care, and outcomes were compared between hospitals performing ≥80% minimally invasive hysterectomies and hospitals not meeting this metric. The hospitals (n = 510) treated 20 670 women with endometrial cancer. In 283 (55%) hospitals ≥80% of hysterectomies were minimally invasively performed (high-minimally invasive surgery [MIS] hospitals, overall MIS rate 89%). In the 227 hospitals that did not meet this metric, 61% of hysterectomies for endometrial cancer were performed using a minimally invasive approach. In high-MIS hospitals, patients were more likely to be white (87% vs 82%, p<.001), privately insured (53% vs 49%, p <.001), and have stage I disease (84% vs 82%, p = .002) and an endometrioid histology (79% vs 76%, p <.001). Surgery was more often performed robotically (80% vs 71%), and conversion to laparotomy was less likely (1.5% vs 3.2%, adjusted odds ratio [aOR], 0.47; 95% confidence interval [CI], 0.39-0.57) (both p <.001). Patients treated at high-MIS hospitals were more likely to have undergone lymph node assessment at the time of surgery (76% vs 69%; aOR, 1.43; 95% CI, 1.35-1.53) and been discharged on the same or next day (74% vs 57%; aOR, 2.27; 95% CI, 2.13-2.42) and were less likely to have an unplanned 30-day readmission (1.8% vs 2.9%; aOR, 0.64; 95% CI, 0.53-0.77). An MIS rate of ≥80% for endometrial cancer is feasible on a national scale and is associated with other hospital-level measurements of high-quality care.

Frizzled-7 Identifies Platinum-Tolerant Ovarian Cancer Cells Susceptible to Ferroptosis

Abstract Defining traits of platinum-tolerant cancer cells could expose new treatment vulnerabilities. Here, new markers associated with platinum-tolerant cells and tumors were identified using in vitro and in vivo ovarian cancer models treated repetitively with carboplatin and validated in human specimens. Platinum-tolerant cells and tumors were enriched in ALDH+ cells, formed more spheroids, and expressed increased levels of stemness-related transcription factors compared with parental cells. Additionally, platinum-tolerant cells and tumors exhibited expression of the Wnt receptor Frizzled-7 (FZD7). Knockdown of FZD7 improved sensitivity to platinum, decreased spheroid formation, and delayed tumor initiation. The molecular signature distinguishing FZD7+ from FZD7− cells included epithelial-to-mesenchymal (EMT), stemness, and oxidative phosphorylation-enriched gene sets. Overexpression of FZD7 activated the oncogenic factor Tp63, driving upregulation of glutathione metabolism pathways, including glutathione peroxidase 4 (GPX4), which protected cells from chemotherapy-induced oxidative stress. FZD7+ platinum-tolerant ovarian cancer cells were more sensitive and underwent ferroptosis after treatment with GPX4 inhibitors. FZD7, Tp63, and glutathione metabolism gene sets were strongly correlated in the ovarian cancer Tumor Cancer Genome Atlas (TCGA) database and in residual human ovarian cancer specimens after chemotherapy. These results support the existence of a platinum-tolerant cell population with partial cancer stem cell features, characterized by FZD7 expression and dependent on the FZD7–β-catenin–Tp63–GPX4 pathway for survival. The findings reveal a novel therapeutic vulnerability of platinum-tolerant cancer cells and provide new insight into a potential “persister cancer cell” phenotype. Significance: Frizzled-7 marks platinum-tolerant cancer cells harboring stemness features and altered glutathione metabolism that depend on GPX4 for survival and are highly susceptible to ferroptosis.

FTO-Dependent N 6 -Methyladenosine Modifications Inhibit Ovarian Cancer Stem Cell Self-Renewal by Blocking cAMP Signaling

FOXK2 promotes ovarian cancer stemness by regulating the unfolded protein response pathway

Understanding the regulatory programs enabling cancer stem cells (CSCs) to self-renew and drive tumorigenicity could identify new treatments. Through comparative chromatin-state and gene expression analyses in ovarian CSCs versus non-CSCs, we identified FOXK2 as a highly expressed stemness-specific transcription factor in ovarian cancer. Its genetic depletion diminished stemness features and reduced tumor initiation capacity. Our mechanistic studies highlight that FOXK2 directly regulated IRE1α (encoded by ERN1) expression, a key sensor for the unfolded protein response (UPR). Chromatin immunoprecipitation and sequencing revealed that FOXK2 bound to an intronic regulatory element of ERN1. Blocking FOXK2 from binding to this enhancer by using a catalytically inactive CRISPR/Cas9 (dCas9) diminished IRE1α transcription. At the molecular level, FOXK2-driven upregulation of IRE1α led to alternative XBP1 splicing and activation of stemness pathways, while genetic or pharmacological blockade of this sensor of the UPR inhibited ovarian CSCs. Collectively, these data establish what we believe is a new function for FOXK2 as a key transcriptional regulator of CSCs and a mediator of the UPR, providing insight into potentially targetable new pathways in CSCs.