Matthew A. Powell

Multiomic Characterization of Pre- and Post-Neoadjuvant Chemotherapy–Treated Ovarian Cancer Reveals Mediators of Tumorigenesis and Chemotherapy Response

Abstract High-grade serous ovarian cancer (HGSC) accounts for more than 200,000 deaths each year. Despite recent advances in treating HGSC with neoadjuvant chemotherapy, the majority of patients ultimately develop chemotherapy resistance. HGSC is characterized by TP53 mutations and widespread copy-number alterations and occurs frequently in the setting of deleterious germline BRCA1/2 variations, but many cases lack putative driver mutations. In this study, we performed whole-exome, whole-genome, and whole-transcriptome sequencing along with mass spectrometry to characterize the molecular landscape of HGSC in 22 paired samples obtained before and after neoadjuvant chemotherapy. Responsiveness to chemotherapy was determined for each patient. Evidence at the DNA, RNA, and protein level revealed numerous defects in cell–cell and cell–matrix interactions, as well as disruption of cell polarity and cytoskeletal regulation in HGSC, indicating that defects in epithelial integrity were present in the majority of patients with HGSC. Nonresponsive HGSC harbored subclones with putative survival mutations. Additionally, ineffective nonsense-mediated decay resulted in the persistence of transcripts with frameshift mutations that were translated into aberrant proteins detectable in HGSC samples. Together, these findings suggest that HGSC may arise through defects in the maintenance of epithelial integrity that lead to the shedding of malignant cells throughout the peritoneum, and the presence of resistant subclones prior to chemotherapy may decrease the chemosensitivity of patients. Significance: Comprehensive longitudinal characterization of ovarian cancer identifies pathways that promote tumorigenesis and provides insights into regulators of chemotherapy response, which could help develop strategies to improve outcomes for patients.

Long-Term Follow-Up and Overall Survival in NRG258, a Randomized Phase III Trial of Chemoradiation Versus Chemotherapy for Locally Advanced Endometrial Carcinoma

This randomized phase III trial aimed to determine whether treatment with cisplatin and volume-directed radiation followed by carboplatin and paclitaxel for four cycles (chemoradiotherapy [C-RT]) increased recurrence-free survival (RFS) and overall survival (OS) when compared with carboplatin and paclitaxel for six cycles (chemotherapy [CT]) in locally advanced endometrial cancer (UC). Previously reported results showed that C-RT did not improve RFS compared with CT. Here we report the final OS analysis. Patients with International Federation of Gynecology and Obstetrics (FIGO) 2009 stage III-IVA UC or stage I/II serous or clear cell UC and positive cytology were enrolled. The primary objective was RFS. Secondary objectives were OS, toxicity, and quality of life. Cumulative probabilities of OS were estimated using the Kaplan-Meier method. Subgroup analyses of treatment effect for FIGO stage, age, race, gross residual disease, histology, lymph-vascular space invasion, and body mass index were performed. In total, 813 patients were randomly assigned (407 C-RT and 406 CT). The median follow-up was 112 months. Median OS was not achieved in either arm. The stratified hazard ratio for death comparing C-RT versus CT was 1.05 (95% CI, 0.82 to 1.34, log-rank two-sided P value = .72). None of the factors analyzed predicted OS benefit from C-RT. Although C-RT reduced the rate of local recurrence compared with CT, it did not increase OS or RFS in stage III/IVA UC.

Stromal DDR2 Promotes Ovarian Cancer Metastasis through Regulation of Metabolism and Secretion of Extracellular Matrix Proteins

Abstract Ovarian cancer is the leading cause of gynecologic cancer–related deaths. The propensity for metastasis within the peritoneal cavity is a driving factor for the poor outcomes associated with this disease, but there is currently no effective therapy targeting metastasis. In this study, we investigate the contribution of stromal cells to ovarian cancer metastasis and identify normal stromal cell expression of the collagen receptor, discoidin domain receptor 2 (DDR2), that acts to facilitate ovarian cancer metastasis. In vivo, global genetic inactivation of Ddr2 impairs the ability of Ddr2-expressing syngeneic ovarian cancer cells to spread throughout the peritoneal cavity. Specifically, DDR2 expression in mesothelial cells lining the peritoneal cavity facilitates tumor cell attachment and clearance. Subsequently, omentum fibroblast expression of DDR2 promotes tumor cell invasion. Mechanistically, we find DDR2-expressing fibroblasts are more energetically active, such that DDR2 regulates glycolysis through AKT/SNAI1 leading to suppressed fructose-1,6-bisphosphatase and increased hexokinase activity, a key glycolytic enzyme. Upon inhibition of DDR2, we find decreased protein synthesis and secretion. Consequently, when DDR2 is inhibited, there is reduction in secreted extracellular matrix proteins important for metastasis. Specifically, we find that fibroblast DDR2 inhibition leads to decreased secretion of the collagen crosslinker, LOXL2. Adding back LOXL2 to DDR2 deficient fibroblasts rescues the ability of tumor cells to invade. Overall, our results suggest that stromal cell expression of DDR2 is an important mediator of ovarian cancer metastasis. Implications: DDR2 is highly expressed by stromal cells in ovarian cancer that can mediate metastasis and is a potential therapeutic target in ovarian cancer.

RAD51 Foci as a Biomarker Predictive of Platinum Chemotherapy Response in Ovarian Cancer

Abstract Purpose: To determine the ability of RAD51 foci to predict platinum chemotherapy response in high-grade serous ovarian cancer (HGSOC) patient-derived samples. Experimental Design: RAD51 and γH2AX nuclear foci were evaluated by immunofluorescence in HGSOC patient-derived cell lines (n = 5), organoids (n = 11), and formalin-fixed, paraffin-embedded tumor samples (discovery n = 31, validation n = 148). Samples were defined as RAD51-High if >10% of geminin-positive cells had ≥5 RAD51 foci. Associations between RAD51 scores, platinum chemotherapy response, and survival were evaluated. Results: RAD51 scores correlated with in vitro response to platinum chemotherapy in established and primary ovarian cancer cell lines (Pearson r = 0.96, P = 0.01). Organoids from platinum-nonresponsive tumors had significantly higher RAD51 scores than those from platinum-responsive tumors (P < 0.001). In a discovery cohort, RAD51-Low tumors were more likely to have a pathologic complete response (RR, 5.28; P < 0.001) and to be platinum-sensitive (RR, ∞; P = 0.05). The RAD51 score was predictive of chemotherapy response score [AUC, 0.90; 95% confidence interval (CI), 0.78–1.0; P < 0.001). A novel automatic quantification system accurately reflected the manual assay (92%). In a validation cohort, RAD51-Low tumors were more likely to be platinum-sensitive (RR, ∞; P < 0.001) than RAD51-High tumors. Moreover, RAD51-Low status predicted platinum sensitivity with 100% positive predictive value and was associated with better progression-free (HR, 0.53; 95% CI, 0.33–0.85; P < 0.001) and overall survival (HR, 0.43; 95% CI, 0.25–0.75; P = 0.003) than RAD51-High status. Conclusions: RAD51 foci are a robust marker of platinum chemotherapy response and survival in ovarian cancer. The utility of RAD51 foci as a predictive biomarker for HGSOC should be tested in clinical trials.

A Phase III Study of Pafolacianine Injection (OTL38) for Intraoperative Imaging of Folate Receptor–Positive Ovarian Cancer (Study 006)

PURPOSE The adjunctive use of intraoperative molecular imaging (IMI) is gaining acceptance as a potential means to improve outcomes for surgical resection of targetable tumors. This confirmatory study examined the use of pafolacianine for real-time detection of folate receptor–positive ovarian cancer. METHODS This phase III, open-label, 11-center study included subjects with known or suspected ovarian cancer, scheduled to undergo cytoreductive surgery. The objectives were to confirm safety and efficacy of pafolacianine (0.025 mg/kg IV), given ≥ 1 hour before intraoperative near-infrared imaging to detect macroscopic lesions not detected by palpation and normal white light. RESULTS From March 2018 through April 2020, 150 patients received a single infusion of pafolacianine (safety analysis set); 109 patients with folate receptor–positive ovarian cancer comprised the full analysis set for efficacy. In 33.0% of patients (95% CI, 24.3 to 42.7; P < .001), pafolacianine with near-infrared imaging identified additional cancer on tissue not planned for resection and not detected by white light assessment and palpation, exceeding the prespecified threshold of 10%. Among patients who underwent interval debulking surgery, the rate was 39.7% (95% CI, 27.0 to 53.4; P < .001). The sensitivity to detect ovarian cancer was 83%, and the patient false-positive rate was 24.8%. Investigators reported achieving complete R0 resection in 62.4% (68 of 109) of patients. Drug-related adverse events were reported by 30% of patients (45 of 150) and most commonly included nausea, vomiting, and abdominal pain. No drug-related serious adverse events or deaths were reported. CONCLUSION This phase III study of pafolacianine met its primary efficacy end point, identifying additional cancers not otherwise identified or planned for resection. Pafolacianine may offer an important real-time adjunct to current surgical approaches for ovarian cancer.

Randomized Phase III Trial of Paclitaxel and Carboplatin Versus Paclitaxel and Ifosfamide in Patients With Carcinosarcoma of the Uterus or Ovary: An NRG Oncology Trial

PURPOSE This phase III randomized trial ( NCT00954174 ) tested the null hypothesis that paclitaxel and carboplatin (PC) is inferior to paclitaxel and ifosfamide (PI) for treating uterine carcinosarcoma (UCS). PATIENTS AND METHODS Adults with chemotherapy-naïve UCS or ovarian carcinosarcoma (OCS) were randomly assigned to PC or PI with 3-week cycles for 6-10 cycles. With 264 events in patients with UCS, the power for an overall survival (OS) hybrid noninferiority design was 80% for a null hazard ratio (HR) of 1.2 against a 13% greater death rate on PI with a type I error of 5% for a one-tailed test. RESULTS The study enrolled 536 patients with UCS and 101 patients with OCS, with 449 and 90 eligible, respectively. Primary analysis was on patients with UCS, distributed as follows: 40% stage I, 6% stage II, 31% stage III, 15% stage IV, and 8% recurrent. Among eligible patients with UCS, PC was assigned to 228 and PI to 221. PC was not inferior to PI. The median OS was 37 versus 29 months (HR = 0.87; 90% CI, 0.70 to 1.075; P < .01 for noninferiority, P > .1 for superiority). The median progression-free survival was 16 versus 12 months (HR = 0.73; P = < 0.01 for noninferiority, P < .01 for superiority). Toxicities were similar, except that more patients in the PC arm had hematologic toxicity and more patients in the PI arm had confusion and genitourinary hemorrhage. Among 90 eligible patients with OCS, those in the PC arm had longer OS (30 v 25 months) and progression-free survival (15 v 10 months) than those in the PI arm, but with limited precision, these differences were not statistically significant. CONCLUSION PC was not inferior to the active regimen PI and should be standard treatment for UCS.

Differential Responses to Immune Checkpoint Inhibitors are Governed by Diverse Mismatch Repair Gene Alterations

Abstract Purpose: The response to immune checkpoint inhibitors (ICI) in deficient mismatch repair (dMMR) colorectal cancer and endometrial cancer is variable. Here, we explored the differential response to ICIs according to different mismatch repair alterations Experimental Design: Colorectal cancer (N = 13,701) and endometrial cancer (N = 3,315) specimens were tested at Caris Life Sciences. Median overall survival (mOS) was estimated using Kaplan–Meier. The prediction of high-, intermediate-, and low-affinity epitopes by tumor mutation burden (TMB) values was conducted using R-squared (R2). Results: Compared with mutL (MLH1 and PMS2) co-loss, the mOS was longer in mutS (MSH2 and MSH6) co-loss in all colorectal cancer (54.6 vs. 36 months; P = 0.0.025) and endometrial cancer (81.5 vs. 48.2 months; P < 0.001) patients. In ICI-treated patients, the mOS was longer in mutS co-loss in colorectal cancer [not reached (NR) vs. 36 months; P = 0.011). In endometrial cancer, the mOS was NR vs. 42.2 months; P = 0.711]. The neoantigen load (NAL) in mutS co-loss compared with mutL co-loss was higher in colorectal cancer (high-affinity epitopes: 25.5 vs. 19; q = 0.017, intermediate: 39 vs. 32; q = 0.004, low: 87.5 vs. 73; q < 0.001) and endometrial cancer (high-affinity epitopes: 15 vs. 11; q = 0.002, intermediate: 27.5 vs. 19; q < 0.001, low: 59 vs. 41; q < 0.001), respectively. R2 ranged from 0.25 in mutS co-loss colorectal cancer to 0.95 in mutL co-loss endometrial cancer. Conclusions: Patients with mutS co-loss experienced longer mOS in colorectal cancer and endometrial cancer and better response to ICIs in colorectal cancer. Among all explored biomarkers, NAL was higher in mutS co-loss and may be a potential driving factor for the observed better outcomes. TMB did not reliably predict NAL.

OTL38 for Intra-operative Imaging of Folate Receptor Positive Ovarian Cancer

This is a phase 3, randomized, multi-center, single dose, open label, pivotal study in patients diagnosed with, or with high clinical suspicion of, ovarian cancer scheduled to undergo primary surgical cytoreduction, interval debulking, or recurrent ovarian cancer surgery.

Paclitaxel and Carboplatin or Ifosfamide in Treating Patients With Newly Diagnosed, Persistent or Recurrent Uterine, Ovarian, Fallopian Tube, or Peritoneal Cavity Cancer

This randomized phase III trial studies paclitaxel and carboplatin see how well they work compared with paclitaxel and ifosfamide in treating patients with fallopian tube, or peritoneal cavity cancer that is newly diagnosed, persistent, or has come back (recurrent). Drugs used in chemotherapy, such as paclitaxel, carboplatin, and ifosfamide, work in different ways to stop the growth of tumor cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. It is not yet known whether paclitaxel is more effective when given with carboplatin or ifosfamide in treating patients with uterine, ovarian, fallopian tube, or peritoneal cavity cancer.