Adult-type Ovarian Granulosa Cell Research Articles

Abstract 453: Targeting FOXL2C402Gvulnerabilities in adult type ovarian granulosa cell tumors

Abstract Background: Nearly all adult-type granulosa cell tumors of the ovary (aGCTs) carry the same oncogenic mutation affecting the second winged helix domain of the Forkhead family transcription factor FOXL2 (c.C402G; p.C134W). There are no currently available therapies that exploit the high prevalence of FOXL2 mutations in this disease. Objectives: Exploit FOXL2-C402G oncogenic addiction in order to identify FDA-approved compounds with differential potency in KGN-FOXL2WT/C402G cells and isogenic KGN-FOXL2—/— cells. Methods: CRISPR/Cas9 was used to generate isogenic derivatives of KGN, a cell line derived from a recurrent aGCT. Parental cells (KGN-FOXL2WT/C402G) or isogenic cells lacking both FOXL2 alleles (KGN-FOXL2—/—) were functionally characterized and loss of Foxl2 protein was confirmed by immunoblot. Two drug libraries comprising a total of 2,416 compounds (majority FDA approved) were screened for effectiveness in KGN-FOXL2WT/C402G cells and KGN-FOXL2—/— cells. Our assay included staining with DAPI, followed by automated image analysis of each well to enumerate nuclei/cell numbers. Based on Fraction Affected (FA) statistics, compounds were ranked according to effectiveness in KGN-FOXL2WT/C402G cells. FA-area under the curve (FA-AUC) cutoff >0.1 yielded 152 drug candidates, categorized into 13 drug classes. 40 drug candidates, including the top 1-4 hits in each drug class were chosen for further validation. Validation rate in the confirmatory screen was at 95%. A novel primary tumor organoid culture system for aGCT was developed and validated using whole exome sequencing and immunophenotype. Selected candidate compounds were further investigated in aGCT organoid cultures from two relapsed tumors. Results: We identified classes of drugs such as the inhibitors of Bromodomain family proteins and Hydroxy-Camptothecin analogs, with enhanced activity in KGN-FOXL2WT/C402G cells relative to KGN-FOXL2—/— cells. Unexpectedly glucocorticoids as a class were found to stimulate proliferation of KGN-FOXL2WT/C402G cells whereas they lacked this activity in KGN-FOXL2—/— cells. For 36 glucocorticoids present in the screen, FA-AUC ranged from -0.3191 to -0.1342 (highest proliferation index among all test compounds) in KGN-FOXL2WT/C402G cells compared to -0.0353 to +0.1667 in KGN-FOXL2—/— cells. In recurrent aGCT organoids, the high-potency glucocorticoid dexamethasone induced cell proliferation and co-treatment with glucocorticoids increased the IC50 of paclitaxel in KGN-FOXL2WT/C402G cells from 1.43 nM to 4.04 nM. Conclusion: Mutant FOXL2 mediates a proliferative response to glucocorticoids in cultured cells and primary aGCT organoids. Paclitaxel is a standard of care chemotherapy in the treatment of aGCTs and is often administered with glucocorticoid pre-medication. The adverse effect of glucocorticoids on paclitaxel efficiency shown here should thus be taken into consideration in the clinic. Citation Format: Thomas Welte, Veena Vuttaradhi, Eleonora Khlebus, Barrett Lawson, Robert T. Hillman, Nghi Nguyen, Mary Sobieski, Reid T. Powell, Clifford Stephan. Targeting FOXL2C402Gvulnerabilities in adult type ovarian granulosa cell tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 453.

Assessment of predictive biomarker prevalence in molecularly defined adult-type ovarian granulosa cell tumors.

5567 Background: The FDA has separately approved pembrolizumab for all advanced solid tumors with either microsatellite instability or high tumor mutational burden (≥10 mutations per megabase), and homologous recombination deficiency is an established biomarker for response to poly ADP ribose polymerase inhibitors in epithelial ovarian cancer. The detection of these predictive biomarkers in adult-type ovarian granulosa cell tumors could identify novel treatment strategies in this rare disease. The primary objective of this study was to determine the prevalence of established predictive biomarkers among molecularly defined adult-type ovarian granulosa cell tumors. Methods: With institutional review board approval, we performed a cross-sectional study examining de-identified FoundationOne companion diagnostic molecular profiles for 423 women with molecularly defined (FOXL2 c.C402G positive) adult type ovarian granulosa cell tumors. The dataset was comprised of coding variants for up to 406 genes as well as genomic signatures including microsatellite instability, tumor mutational burden, and genome wide loss of heterozygosity. PD-L1 expression by immunohistochemistry was also available for a subset of tumors. Descriptive statistics were used for comparison between groups and all statistical tests were two-sided. Results: Women in this cohort had a mean age of 57 years (range 24-87) at the time of sample submission for molecular profiling. The median tumor mutational burden was 1.3 mutations per megabase [mut/Mb] (range 0-8.8 mut/Mb). TP53-mutated aGCT had a higher tumor mutation burden than TP53 non-mutated tumors (median 2.4 mut/Mb, 95% CI 1.7-3.0 mut/Mb vs median 1.3 mut/Mb, 95% CI 1.5-1.9 mut/Mb; P=.02). All 384 tumors with available microsatellite instability testing were microsatellite stable. Sixty-seven tumors had PD-L1 expression measured and of these 94% (63/67) were negative with the remainder “low positive.” No tumors were positive for genome wide loss of heterozygosity. Apart from FOXL2 c.C402G, the most frequent short variants were TERT promoter mutations (-124C>T: 190/423, 45.0%; -146C>T: 39/423, 9.2%). Other frequently observed variants included truncating mutations in KMT2D/MLL2 (71/423, 16.8%), pathogenic TP53 mutations (35/423, 8.3%), CDKN2A/B deletions (43/423, 10.2%), and activating PIK3CA mutations (23/423, 5.4%). Conclusions: No women with molecularly defined adult-type ovarian granulosa cell tumors in this large cross-sectional study would be eligible for FDA-approved pembrolizumab based on either microsatellite instability or high tumor mutational burden. No tumors exhibited evidence of homologous recombination deficiency and molecularly targetable mutations were rare. The development of novel precision treatment options remains a critical unmet need for this rare disease.

Prognostic factors in adult granulosa cell tumors of the ovary: a retrospective analysis of 80 cases

Ovarian granulosa cell tumors are rare malignancies with a relatively favorable prognosis. However, patients still suffer from disease-related mortality. Therefore, the prognostic factors should be clarified. The purpose of this study was to investigate the clinical and pathologic characteristics related with disease recurrence and mortality in adult type ovarian granulosa cell tumors. Eighty surgically staged patients with granulosa cell ovarian tumor treated at the Hacettepe University Hospital between 1982 and 2006 were retrospectively reviewed. Clinical and pathological characteristics were analyzed. Granulosa cell ovarian tumors accounted for 4.3% of malignant ovarian neoplasms. Mean age was 47.6 years. The most common presenting symptom was abnormal uterine bleeding (53.7%). Endometrial pathology was detected in 51.2% of patients preoperatively. Seventy percent of patients were diagnosed at stage I, and 53.8% of patients received adjuvant treatment. Mean follow-up was 67.5 months. Overall 5-year and 10-year survival was 91% and 86%, respectively. Mean survival was 147.1 months. Recurrence rate was 11.2%. In univariate analysis, advanced stage, advanced age, residual disease after surgery, and need for adjuvant treatment were associated with disease-related mortality and advanced stage disease and absence of initial staging surgery were associated with disease recurrence. However, in multivariate analysis, only initial stage was found to be a significant prognostic factor. Initial stage seems to be the single most important prognostic factor in ovarian granulosa cell tumors. Therefore, a comprehensive staging surgery should be attempted to document the real extent of disease and to estimate the oncologic outcome more accurately.