Eun-Young Kang

Clinicopathologic Features, Molecular Landscape, and Prognostic Implications of Ovarian Low-grade Serous Tumors with Histologic Transformation

Abstract Purpose: The purpose of this study was to characterize the clinicopathologic features, molecular genetic landscape, and clinical behavior of ovarian low-grade serous tumors with histologic transformation (LGS-HT) to indeterminate/high-grade carcinoma. Experimental Design: LGS-HT were retrospectively identified from an institutional cohort of patients with ovarian cancer and underwent central pathology re-review. Data on clinicopathologic characteristics, including age, stage, surgical outcomes, systemic treatments, and overall survival (OS), were collected. IHC profiling and next-generation sequencing were performed. OS comparisons were performed with our institutional cohorts of ovarian low-grade serous carcinoma (n = 109) and high-grade serous carcinoma (n = 1,672). Results: From 4,371 ovarian serous cancers, 40 (0.9%) LGS-HT were identified: 30 with synchronous low-grade and higher-grade tumor components at initial diagnosis and 10 with an ovarian low-grade serous neoplasm that recurred as a higher-grade carcinoma. The most common somatic driver mutations included TP53 (38.5%), KRAS (21.8%), NF1 (15.6%), BRAF (15.6%), and NRAS (12.5%), with coexisting TP53 and RAS/RAF mutations in 18.8% of cases. Alterations in DNA damage response genes (BRCA2, PALB2, CHEK2, ATM, NBN, and RECQL4) were identified in LGS-HT lacking TP53 genetic alterations. Synchronous low-grade and higher-grade tumor components at initial diagnosis were associated with poorer OS (median, 59.7 months) compared with low-grade serous carcinoma (median, 105.4 months; P = 0.026) and were similar to high-grade serous carcinoma (median, 48.8 months; P = 0.61). Severe nuclear atypia and the absence of RAS/RAF-driver mutations were significant adverse prognostic factors. Conclusions: LGS-HT exhibit both low-grade and high-grade morphologic and molecular features, representing an exception to the dualistic classification of ovarian serous neoplasms. The presence of a definitive high-grade carcinoma component in a low-grade serous tumor portends aggressive clinical behavior.

Concurrent RB1 Loss and BRCA Deficiency Predicts Enhanced Immunologic Response and Long-term Survival in Tubo-ovarian High-grade Serous Carcinoma

Abstract Purpose: The purpose of this study was to evaluate RB1 expression and survival across ovarian carcinoma histotypes and how co-occurrence of BRCA1 or BRCA2 (BRCA) alterations and RB1 loss influences survival in tubo-ovarian high-grade serous carcinoma (HGSC). Experimental Design: RB1 protein expression was classified by immunohistochemistry in ovarian carcinomas of 7,436 patients from the Ovarian Tumor Tissue Analysis consortium. We examined RB1 expression and germline BRCA status in a subset of 1,134 HGSC, and related genotype to overall survival (OS), tumor-infiltrating CD8+ lymphocytes, and transcriptomic subtypes. Using CRISPR-Cas9, we deleted RB1 in HGSC cells with and without BRCA1 alterations to model co-loss with treatment response. We performed whole-genome and transcriptome data analyses on 126 patients with primary HGSC to characterize tumors with concurrent BRCA deficiency and RB1 loss. Results: RB1 loss was associated with longer OS in HGSC but with poorer prognosis in endometrioid ovarian carcinoma. Patients with HGSC harboring both RB1 loss and pathogenic germline BRCA variants had superior OS compared with patients with either alteration alone, and their median OS was three times longer than those without pathogenic BRCA variants and retained RB1 expression (9.3 vs. 3.1 years). Enhanced sensitivity to cisplatin and paclitaxel was seen in BRCA1-altered cells with RB1 knockout. Combined RB1 loss and BRCA deficiency correlated with transcriptional markers of enhanced IFN response, cell-cycle deregulation, and reduced epithelial–mesenchymal transition. CD8+ lymphocytes were most prevalent in BRCA-deficient HGSC with co-loss of RB1. Conclusions: Co-occurrence of RB1 loss and BRCA deficiency was associated with exceptionally long survival in patients with HGSC, potentially due to better treatment response and immune stimulation.