Premal H. Thaker

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.

Characteristics and real-world outcomes of patients with epithelial ovarian cancer who received niraparib plus bevacizumab first-line maintenance therapy in the COMB1NE study

In the phase 2 OVARIO trial (NCT03326193) investigating niraparib-bevacizumab first-line maintenance, median progression-free survival was 14.2 months (95% confidence interval (CI) 8.6 to 16.8) for patients with homologous recombination (HR)-proficient (HRp) epithelial ovarian cancer, and 12.1 months (95% CI8.0-not evaluated) for patients with undefined HR status. However, real-world data are limited for patients who receive niraparib-bevacizumab first-line maintenance therapy. The COMB1NE study describes real-world clinical outcomes (time to treatment discontinuation; time to next treatment) in patients with epithelial ovarian cancer who received niraparib-bevacizumab first-line maintenance, regardless of first-line bevacizumab use. This real-world, retrospective study used a US nationwide electronic health record-derived deidentified database. Eligible patients were 18 years or older at initial epithelial ovarian cancer diagnosis and initiated niraparib-bevacizumab first-line maintenance (January 1, 2017-September 2, 2022) following first-line treatment. The index date was the start of first-line maintenance. Patients were followed until death, last clinical activity, or end of study, whichever occurred first. Time to treatment discontinuation and time to next treatment, a proxy for real-world progression-free survival, were estimated using the Kaplan-Meier method. Among 59 included patients, the median age was 67 years (interquartile range (IQR) 61-76), and 81.4% had stage III/IV epithelial ovarian cancer at diagnosis. Overall, 83.1% of patients had In this real-world study of patients receiving niraparib-bevacizumab first-line maintenance, the majority of whom had HRp/HR status unknown, the median time to next treatment was consistent with observed progression-free survival in patients with similar HR status in the OVARIO study.

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.

Influence of Genomic Landscape on Cancer Immunotherapy for Newly Diagnosed Ovarian Cancer: Biomarker Analyses from the IMagyn050 Randomized Clinical Trial

Abstract Purpose: To explore whether patients with BRCA1/2-mutated or homologous recombination deficient (HRD) ovarian cancers benefitted from atezolizumab in the phase III IMagyn050 (NCT03038100) trial. Patients and Methods: Patients with newly diagnosed ovarian cancer were randomized to either atezolizumab or placebo with standard chemotherapy and bevacizumab. Programmed death-ligand 1 (PD-L1) status of tumor-infiltrating immune cells (IC) was determined centrally (VENTANA SP142 assay). Genomic alterations, including deleterious BRCA1/2 alterations, genomic loss of heterozygosity (gLOH), tumor mutation burden (TMB), and microsatellite instability (MSI), were evaluated using the FoundationOne assay. HRD was defined as gLOH ≥ 16%, regardless of BRCA1/2 mutation status. Potential associations between progression-free survival (PFS) and genomic biomarkers were evaluated using standard correlation analyses and log-rank of Kaplan–Meier estimates. Results: Among biomarker-evaluable samples, 22% (234/1,050) harbored BRCA1/2 mutations and 46% (446/980) were HRD. Median TMB was low irrespective of BRCA1/2 or HRD. Only 3% (29/1,024) had TMB ≥10 mut/Mb, and 0.3% (3/1,022) were MSI-high. PFS was better in BRCA2-mutated versus BRCA2–non-mutated tumors and in HRD versus proficient tumors. PD-L1 positivity (≥1% expression on ICs) was associated with HRD but not BRCA1/2 mutations. PFS was not improved by adding atezolizumab in BRCA2-mutated or HRD tumors; there was a trend toward enhanced PFS with atezolizumab in BRCA1-mutated tumors. Conclusions: Most ovarian tumors have low TMB despite BRCA1/2 mutations or HRD. Neither BRCA1/2 mutation nor HRD predicted enhanced benefit from atezolizumab. This is the first randomized double-blind trial in ovarian cancer demonstrating that genomic instability triggered by BRCA1/2 mutation or HRD is not associated with improved sensitivity to immune checkpoint inhibitors. See related commentary by Al-Rawi et al., p. 1645

Efficacy and Safety of Avutometinib ± Defactinib in Recurrent Low-Grade Serous Ovarian Cancer: Primary Analysis of ENGOT-OV60/GOG-3052/RAMP 201

PURPOSE This study evaluated the efficacy and safety of avutometinib (rapidly accelerated fibrosarcoma/mitogen-activated extracellular signal-regulated kinase [MEK] clamp) alone or in combination with defactinib (focal adhesion kinase inhibitor) in patients with recurrent low-grade serous ovarian cancer (LGSOC). METHODS In this phase II, open-label study, patients with recurrent, measurable LGSOC after ≥1 line of platinum chemotherapy were stratified by tumor Kirsten rat sarcoma virus homolog ( KRAS ) mutation status and randomly assigned to oral avutometinib 4.0 mg two times per week monotherapy or avutometinib 3.2 mg two times per week in combination with oral defactinib 200 mg two times per day. The combination was selected as the go-forward regimen for expansion. The primary end point was objective response rate (ORR) by blinded independent central review. RESULTS A total of 115 patients received the go-forward combination regimen. Patients had a median of 3 (range, 1-9) prior lines of therapy, including hormonal (86%), bevacizumab (51%), and MEK inhibitor (22%). Confirmed ORR was 31% (95% CI, 23% to 41%) with a median duration of response of 31.1 months (95% CI, 14.8 to 31.1). ORR was 44% in KRAS- mutant and 17% in KRAS wild-type cohorts. The median progression-free survival was 12.9 months (95% CI, 10.9 to 20.2) overall and 22.0 months (95% CI, 11.1 to 36.6) and 12.8 months (95% CI, 7.4 to 18.4) in KRAS- mutant and wild-type cohorts, respectively. The most frequent grade ≥3 treatment-related adverse events (AEs) were elevated creatine phosphokinase (24%), diarrhea (8%), and anemia (5%). Ten percent of patients discontinued because of AEs. CONCLUSION The efficacy and safety profile of avutometinib in combination with defactinib support this combination as a potential standard of care for recurrent LGSOC. A randomized phase 3 study of avutometinib and defactinib versus investigator's choice of therapy for women with recurrent LGSOC is currently enrolling (RAMP301; ClinicalTrials.gov identifier: NCT06072781 ).

A Study of Avutometinib (VS-6766) + Defactinib (VS-6063) in Recurrent Low-Grade Serous Ovarian Cancer

This study will assess the safety and efficacy of avutometinib (VS-6766) in combination with defactinib versus Investigator's choice of treatments (ICT) in subjects with recurrent LGSOC who have progressed on a prior platinum-based therapy.

A Study of Avutometinib (VS-6766) v. Avutometinib (VS-6766) + Defactinib in Recurrent Low-Grade Serous Ovarian Cancer With and Without a KRAS Mutation

This study will assess the safety and efficacy of avutometinib (VS-6766) monotherapy and in combination with defactinib in subjects with recurrent Low-Grade Serous Ovarian Cancer (LGSOC)

A Study of Atezolizumab Versus Placebo in Combination With Paclitaxel, Carboplatin, and Bevacizumab in Participants With Newly-Diagnosed Stage III or Stage IV Ovarian, Fallopian Tube, or Primary Peritoneal Cancer

This is a Phase III, global, double-blind, 2-arm randomized study designed to compare the efficacy and safety of atezolizumab + paclitaxel + carboplatin + bevacizumab versus placebo + paclitaxel + carboplatin + bevacizumab. Study participants will have Stage 3 or 4 ovarian cancer (OC), fallopian tube cancer (FTC), or primary peritoneal cancer (PPC) with macroscopic residual disease postoperatively (i.e., after primary tumor reductive surgery) or who will undergo neoadjuvant therapy followed by interval surgery.