Clinical, pathological, and comprehensive molecular analysis of the uterine clear cell carcinoma: a retrospective national study from TMRG and GINECO network

Abstract

Background: Uterine clear cell carcinomas (CCC) represent less than 5% of uterine cancers. Their biological characteristics and clinical management remain uncertain. A multicenter study to explore both clinical and molecular features of these rare tumors was conducted.

Methods: This multicenter retrospective national study was performed within the French TMRG (Rare Gynecologic Malignant Tumors) network. Clinical data and, when available, FFPE blocks were collected. Clinical features, treatments, and outcome (progression-free survival (PFS) and overall survival (OS)) were analyzed and correlated to the protein (tissue micro-array), RNA (Nanostring nCounter^® technology), and DNA (array-Comparative Genomic hybridization and target-next generation sequencing) levels using the tumor samples available.

Results: Sixty-eight patients with uterine CCC were enrolled, 61 from endometrial localization and 5 with cervix localization. Median age at diagnosis was 68.9 years old (range 19-89.7). Most tumors were diagnosed at an early stage (78% FIGO stage I-II). Hysterectomy (performed in 90%) and lymph node dissection (80%) were the most frequent surgical treatment. More than 70% of patients received external beam radiotherapy and 57% received brachytherapy. Nearly half (46%) of the patients received chemotherapy. After a median follow-up of 24.7 months, median PFS was 64.8 months (95 CI [5.3-124.4]) and median OS was 79.7 (IC95 [31.0-128.4]). Low hormone receptor expression (13% estrogen-receptor positive), frequent PI3K pathway alterations (58% PTEN loss, 50% PIK3CA mutations), and P53 abnormalities (41%) were observed. Mismatch repair deficiency was identified in 20%. P16 expression was associated with shorter PFS (HR = 5.88, 95 CI [1.56-25], p = 0.009). Transcriptomic analyzes revealed a specific transcriptomic profile notably with a high expression of immune response-associated genes in uterine CCC displaying a very good overall prognosis.

Conclusions: Uterine CCC reported to be potentially MSI high, hormone receptors negative, and sometimes TP53 mutated. However, some patients with immune response-associated features and better prognosis may be candidate to treatment de-escalation and immunotherapy.

Keywords: Clear cell carcinoma; Gene expression profiling; Genomics; Tissue micro-array; Uterine cancer.

Fig. 1

Study flow chart. FFPE: formalin-fixed paraffin-embedded; TMA: tissue micro-array; aCGH: array-based comparative genomic hybridization; NGS: next-generation sequencing

Fig. 2

Gene expression profile of uterine CCC according to the 786-gene panel. A Hierarchical clustering (N = 47) with main three quality threshold clusters with Pearson correlation > 0.6 and including at least 20 genes defined by expression of genes related to epithelial-mesenchymal transition (EMT), immune response, and cell cycle. B Correlation with main clinical and pathological data. Pvclust R-package was used to explore clusters robustness, with approximately unbiased p-values. C Kaplan Meier curves of overall survival

Fig. 3

Analysis of gene expression profiles of uterine CCC, endometrioid tumors from TCGA, and ovarian clear cells (OvCC) tumors [19, 20]. A t-SNE (t-distributed Stochastic Neighbor Embedding) unsupervised analysis based on all 786 genes showing that centroid of the UCCC set is closer to all endometrial carcinoma than to ovarian clear cell carcinoma. B Volcano plot of differential mRNA expression between uterine CCC and the TCGA endometrioid endometrial carcinoma data set with 154 genes differentially expressed (moderated t-test: p < 5%, q < 10% and |FC|> 1.5x). C Ontology analysis based on the Reactome database. The best 20 pathways are represented

Fig. 4

Alterations identified with sequencing-NGS (N = 19). A Details of gene mutations classified by genes and types of mutations. B Distribution of gene alterations in the main pathways of interest

Fig. 5

Kaplan Meier curves for progression-free survival according to A P16 expression, and B EZH2 expression