Abstract Endometrial carcinoma (EC) is the most common gynecological malignancy and fibroblast growth factor receptor 2 (FGFR2) is a frequently dysregulated receptor tyrosine kinase. FGFR2b and FGFR2c are the two main splice isoforms of FGFR2 and are normally localized in epithelial and mesenchymal cells, respectively. Previously, we demonstrated that FGFR2c mRNA expression was associated with aggressive tumor characteristics, shorter progression‐free survival (PFS), and disease‐specific survival (DSS) in endometrioid ECs (EECs). The objectives of this study were to investigate the spatial expression of FGFR2b in normal and hyperplasia with and without atypia of human endometrium and to assess the prognostic significance of FGFR2b expression in EC. FGFR2b and FGFR2c mRNA expression was evaluated in normal (proliferative [ n = 10], secretory [ n = 15], and atrophic [ n = 10] endometrium), hyperplasia with and without atypia ( n = 19) as well as two patient cohorts of EC samples (discovery [ n = 78] and Vancouver [ n = 460]) using isoform‐specific BaseScope RNA in situ hybridization assays. Tumors were categorized based on FGFR2 isoform expression (one, both, or neither) and categories were correlated with clinicopathologic markers, molecular subtypes, and clinical outcomes. The FGFR2b splice isoform was exclusively expressed in the epithelial compartment of normal endometrium and hyperplasia without atypia. We observed FGFR2c expression at the basalis layer of glands in 33% (3/9) of hyperplasia with atypia. In patients with EEC, FGFR2b+/FGFR2c− expression was found in 48% of the discovery cohort and 35% of the validation Vancouver cohort. In univariate analyses, tumors with FGFR2b+/FGFR2c− expression had longer PFS (hazard ratio [HR] 0.265; 95% CI 0.145–0.423; log‐rank p < 0.019) and DSS (HR 0.31; 95% CI 0.149–0.622; log‐rank p < 0.001) compared to tumors with FGFR2b−/FGFR2c+ expression in the large EEC Vancouver cohort. In multivariable Cox regression analyses, tumors with FGFR2b+/FGFR2c− expression were significantly associated with longer DSS (HR 0.37; 95% CI 0.153–0.872; log‐rank p < 0.023) compared to FGFR2b−/FGFR2c+ tumors. In conclusion, FGFR2b+/FGFR2c− expression is associated with favorable clinicopathologic markers and clinical outcomes suggesting that FGFR2b could play a role in tailoring the management of EEC patients in the clinic if these findings are confirmed in an independent cohort.
Abstract Background Endometrial cancer (EC) is a major gynecological cancer with increasing incidence. It comprised of four molecular subtypes with differing etiology, prognoses, and response to chemotherapy. In the future, clinical trials testing new single agents or combination therapies will be targeted to the molecular subtype most likely to respond. Pre-clinical models that faithfully represent the molecular subtypes of EC are urgently needed, we sought to develop and characterize a panel of novel EC patient-derived xenograft (PDX) models. Methods Here, we report whole exome or whole genome sequencing of 11 PDX models and the matched primary tumor. Analysis of multiple PDX lineages and passages was performed to study tumor heterogeneity across lineages and/or passages. Based on recent reports of frequent defects in the homologous recombination (HR) pathway in EC, we assessed mutational signatures and HR deficiency scores and correlated these with in vivo responses to the PARP inhibitor (PARPi) talazoparib in six PDXs representing the different molecular subtypes of EC. Results PDX models were successfully generated from all four molecular subtypes of EC and uterine carcinosarcomas, and they recapitulated morphology and the molecular landscape of primary tumors without major genomic drift. We also observed a wide range of inter-tumor and intra-tumor heterogeneity, well captured by different PDX lineages, which could lead to different treatment responses. An in vivo response to talazoparib was detected in two p53mut models consistent with stable disease, however both lacked the HR deficiency genomic signature. Conclusions EC PDX models represent the four molecular subtypes of disease and can capture intra-tumoral heterogeneity of the original primary tumor. PDXs of the p53mut molecular subtype showed sensitivity to PARPi, however, deeper and more durable responses will likely require combination of PARPi with other agents.
Abstract Purpose: Endometrial cancer (EC) is the most frequently diagnosed gynaecological cancer. The majority of women with EC are treated surgically and have a good outcome, however 25-30% of patients presenting with metastases or recurrent disease do not have effective therapies and have <12 months survival. Recent investigations demonstrated radio-chemotherapy has little benefit for women with high-risk EC within the deficient mismatch repair (dMMR) and p53 wild type (p53wt) molecular subtypes. We reported isoform switching from the FGFR2b (epithelial) splice-isoform to the FGFR2c (mesenchymal) splice-isoform in 40% of dMMR and 30% of p53wt ECs. This isoform switching was associated with adverse clinicopathologic markers, shorter recurrence free survival and disease specific survival in the Canadian cohort used to identify and validate the ProMisE molecular risk stratification approach. The objectives of the current study were i) to identify patient derived xenograft (PDX) models with FGFR2c expression and develop PDX derived organoids (PDXOs) for preclinical drug testing, ii) assess the efficacy of the BGJ398 FGFR inhibitor (FGFRi) in FGFR2c expressing models and generate preclinical data that would support an early phase clinical trial in FGFR2c stratified EC patients. Method: BaseScope RNA ISH was used to detect FGFR2c expression in patient tumours, PDX models and PDXOs. PDXOs derived from three independent PDX tumours were established from each of five PDX models (3 showing high FGFR2c expression, 2 showing low/no FGFR2c expression). Each PDXO culture was treated with 300nM BGJ398 (pan-FGFRi) or DMSO for 72 h and assessed using a live-dead assay and confocal microscopy. PDXs from three models were engrafted subcutaneously into 8 weeks female NSG mice and when tumours reached 100-150mm3, mice were randomized (4 mice/arm) and treated with 30mg/Kg BGJ398 or vehicle daily for 21 days. Tumours were measured 3x/week and mice sacrificed when tumours reached 900mm3. Results and conclusion: FGFR2c expression was higher in PDXs representing the dMMR and p53wt subtype compared to p53mut subtype and similar expression levels were seen between patient tumours, PDXs and PDXOs. In vitro FGFRi with BGJ398 showed significant cell death occurred in PDXOs with high FGFR2c expression (p< 0.0001, 2-way ANOVA). These in vitro findings were validated in vivo using PDX68 carrying a FGFR2 C383R mutation and PDX52 and PDX59, both showing FGFR2 isoform switching. Significant tumour growth inhibition and a ~2-fold increase in survival was seen in all three models (PDX68, p<0.0001 and p<0.007; PDX52, p<0.02 and P<0.03; and PDX59 P<0.0001 and P<0.0006 respectively). In conclusion, our investigation revealed FGFRi (BGJ398) was effective in EC PDX models representing both mutational activation and isoform switching of FGFR2. As FGFR isoform switching occurs most commonly in the dMMR subtype where immune checkpoint inhibitors (ICIs) are approved, we propose the combination of ICIs and FGFRi may be more effective in women with FGFR2 activation compared to ICIs alone. Citation Format: Asmerom T Sengal, Vanessa Bonazzi, Olga Kondrashova, Lewis Perrin, Naven Chetty, Deborah Smith, Antonio Gil-Moreno, Eva Colas, Pamela M Pollock. Targeting FGFR2c isoform, a novel therapeutic target with FGFR inhibitor in endometrial cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr LBA020.
Abstract Introduction: Women with atypical hyperplasia (AH) or well-differentiated endometrioid endometrial carcinoma (EEC) who wish to retain fertility and/or with severe comorbidities that preclude surgery, are treated with progestin. Previously, we reported FGFR2c was associated with aggressive tumour behaviour and poor survival outcome in EEC. The purpose of this study was to estimate the response rate of Levonorgestrel IUD treatment and determine the association of FGFR2b and FGFR2c expression with outcome in women with AH/borderline histology (BL) and EEC treated with progestin. Method: BaseScope RNA ISH and immunohistochemistry assays were deployed to detect (FGFR2b and FGFR2c mRNA) and (FGFR2 protein and progesterone receptors), respectively in 89 diagnostic biopsies of patients with AH/BL and EEC treated with progestin. Kaplan Meier Curve and Cox regression model analyses were performed to evaluate the predictive value of FGFR2b and FGFR2c in this cohort. Results: The complete resolution rate (CRR) and overall response rate (ORR) at any time point in the whole cohort were 26/82 (32%) and 35/82 (43%), respectively. When stratified by histologic diagnosis CRR was 47.5% and 17% and ORR 63% and 24% for AH/BL and EEC, respectively. The recurrence rate was 28.7%. FGFR2c expression was documented in 12/72 (15%) cases. Both univariable and multivariable Cox regression analyses showed women with FGFR2c expression were 5-fold more likely to progress compared with FGFR2b positive women (HR 5.4, P<0.0001) and (HR, 5, P<0.001), respectively. Conclusion: Progestin treatment is less effective in patients with EEC. Notably, FGFR2c expression appears to be strongly associated with progestin treatment failure. Citation Format: Asmerom Sengal, Deborah Smith, Rebecca Rogers, Cameron Snell, Elizabeth Williams, Pamela Pollock. FGFR2 isoform switching strongly associates with progestin treatment failure in atypical hyperplasia and well-differentiated endometrial cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference: Endometrial Cancer: New Biology Driving Research and Treatment; 2020 Nov 9-10. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(3_Suppl):Abstract nr PO033.
Abstract Endometrial cancer (EC) patients with metastatic/recurrent disease have limited treatment options and poor survival outcomes. Recently, we discovered the FGFR2c isoform is associated with poor prognosis in EC patients. Here we report the establishment of 14 EC patient-derived xenografts (PDX)-derived organoids (PDXOs) with or without FGFR2c expression. Treatment of 5 EC PDXOs with BGJ398 showed significant cell death in 3 models with FGFR2c expression. PDXs with FGFR2c+ showed significant tumour growth inhibition (TGI) following 21-day treatment with FGFR inhibitors (BGJ398 or pemigatinib) and significantly prolonged survival in 4/5 models. Pemigatinib + cisplatin combination therapy (n=5) resulted in significant TGI and prolonged survival in one of two p53abn PDXs. All five models treated with cisplatin alone showed de novo resistance and no survival benefit. Seven-day treatment with BGJ398 revealed a significant reduction in angiogenesis and CD206+ M2 macrophages. This data collectively supports the evaluation of FGFR inhibitors in a clinical trial.
Purpose The objective of this study was to compare tumor characteristics, biomarkers, and surrogate subtypes of breast cancer between Sudanese and German women. Methods Tumor characteristics and immunohistochemistry markers (estrogen receptor [ER], progesterone receptor [PR], and human epidermal growth factor receptor 2 [HER2]) were collected from the routine assessment of consecutive patients with invasive breast cancer diagnosed from 2010 to 2015 (Gezira University Pathology Laboratory, Gezira, Sudan) and from 1999 to 2013 (Breast Centre, Martin-Luther-University, Halle, Germany). Results A total of 2,492 patients (German [n = 1,932] and Sudanese [n = 560]) were included. Age at diagnosis ranged from 20 to 94 years. Sudanese women were, on average, 10 years younger than German women, with a mean (± standard deviation) age of 48.8 (13.5) and 58.6 (12.4) years, respectively. The Sudanese women had a higher grade, larger tumor, and more lymph node positivity compared with German women. ER-, PR-, and HER2-negative proportions were 55%, 61.8%, and 71.3%, respectively, for Sudanese women versus 22.7%, 32.3%, and 82.5%, respectively, for German women. The triple-negative subtype was more prevalent in Sudanese women (34.5%) than in German women (14.2%). The strongest factor associated with ER-negative disease was grade III (odds ratio, 19.6; 95% CI 11.6 to 33.4; P < .001). Sudanese patients were at higher risk for ER-negative breast cancer, with an odds ratio of 2.01 ( P = .001; adjusted for age, size, nodal status, histologic type, and grade). Stratified by grade, the influence of origin was observed in grade I and grade II tumors, but not in grade III tumors. Conclusion Sudanese women had more aggressive tumor characteristics and unfavorable prognostic biomarkers. After adjustment, Sudanese origin was still associated with hormone receptor–negative disease, especially in grade I and II tumors. These findings suggest differences in tumor biology among these ethnic groups.
<div>AbstractPurpose:<p>The two most common molecular subtypes of endometrial cancers, mismatch repair deficient (MMRd) and p53 wild-type (p53wt) comprise the majority of endometrial cancers and have intermediate prognoses where additional risk stratification biomarkers are needed. Isoform switching of FGFR2 from FGFR2b to FGFR2c (normally expressed in mesenchymal cells), has been reported in other solid carcinomas. The objective of this study was to investigate the role of FGFR2c in risk stratification of endometrial cancer.</p>Experimental Design:<p>We have developed and optimized a BaseScope RNA ISH assay to detect FGFR2c. FGFR2c expression was determined in a preliminary screening cohort of 78 endometrial cancers and a clinically and molecularly annotated Vancouver cohort (<i>n</i> = 465). Cox regression model analyses were performed to assess the prognostic value of FGFR2c.</p>Results:<p>Univariate and multivariate analyses revealed FGFR2c expression was significantly associated with shorter disease-specific survival (DSS) and progression-free survival (PFS) in endometrioid endometrial cancer (EEC, <i>n</i> = 302). Notably, FGFR2c expression was significantly associated with shorter PFS and DSS in patients with grade 3 EECs (<i>P</i> < 0.003 and <i>P</i> < 0.002) and the European Society Medical Oncology (ESMO) high-risk group (<i>P</i> < 0.0001 and <i>P</i> < 0.002), respectively. Moreover, within the MMRd subtype, FGFR2c expression was significantly associated with shorter PFS (<i>P</i> < 0.048) and DSS (<i>P</i> < 0.001).</p>Conclusions:<p>FGFR2c expression appears an independent prognostic biomarker in patients with EEC and further discerns the outcomes within grade 3 tumors, ESMO high-risk groups, as well as within the MMRd and p53wt subtypes. FGFR2c inclusion into future molecular subtyping can further refine risk stratification of EEC.</p></div>
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