Nikolina Radulovich

BKM120 and cediranib synergistically inhibit in vitro and in vivo growth of VENUS167 models. A, The combination of BKM120 and cediranib at varying concentrations demonstrates a synergistic effect in OPTO.85 organoids. Drug–response curves are based on 21-point concentration data. B, Targeted inhibition of VEGFR and AKT signaling pathways using single agents (0.1 μmol/L cediranib and 1 μmol/L BKM120) and combination treatment for 4 hours. C,In vivo confirmation of the effects of BKM120 (50 mg/kg) and cediranib (6 mg/kg) in OPTO.85 ODX models. N = 5 mice per group. Error bars represent the standard error of the mean (SEM). ****, P < 0.05, comparing single-agent treatment with combination therapy using a two-way analysis of variance multiple comparison test.

High-throughput screening of OPTO.85 PDO identifies sensitivity to the VEGFR inhibitor cediranib. A, Scatter plot comparing the drug response of OPTO.85 with the median response in PRISM’s uterus–endometrial cell lines. B, Boxplot showing increased sensitivity of the OPTO.85 PDO model to kinase inhibitors with higher selectivity for VEGFR. C, OPTO.85 PDO model shows sensitivity to the VEGFR inhibitor cediranib. D, AUC plot depicting cediranib drug–response differences between OPTO.85 PDO and HGSOC PDO models. The green dot represents OPTO.85 PDO.

We report a rare case of a young patient (VENUS 167) initially diagnosed with grade 1 endometrioid endometrial cancer, which, following endocrine treatment, presented with mixed aggressive carcinoma with three distinct histologic patterns: grade 1 endometrioid, large cell neuroendocrine, and undifferentiated carcinoma. The surgical specimen at the time of disease progression was used to establish OPTO.85, a patient-derived organoid (PDO), followed by a corresponding organoid-derived xenograft (ODX). Multi-omic analyses confirmed that OPTO.85 accurately reflected the patient’s tumor characteristics. Whole-exome sequencing analysis identified oncogenic alterations in PIK3CA, ARID1A, and CTNNB1. Further RNA sequencing and assay for transposase-accessible chromatin using sequencing analyses revealed enrichment in VEGF and Wnt signaling pathways, suggesting therapeutic vulnerabilities. A high-throughput drug screen was conducted using ApexBio-approved and epigenetic drug libraries, along with kinase inhibitor and tool compound libraries developed at the Ontario Institute of Cancer Research. The OPTO.85 PDO exhibited sensitivity to PI3K inhibitors and responsiveness to VEGF inhibition. Cediranib demonstrated synergy with BKM120, significantly reducing organoid growth. This combination also showed in vivo efficacy in the ODX model, in which dual inhibitors significantly suppressed tumor growth compared with single compounds. This case exemplifies the impact of genomic profiling and patient-derived models in identifying actionable molecular changes in rare cancers with limited therapeutic options and poor prognosis. It highlights that high-throughput sequencing for individual patient tumors and generation of patient-derived models are feasible in endometrial cancer. This preclinical model may assist clinical decision and personalized therapy requiring validation in prospective studies.Significance:This study characterizes a rare aggressive mixed endometrial carcinoma that developed after hormonal therapy. Patient-derived organoid and xenograft models revealed actionable targets in the VEGF and PI3K pathways. Combined cediranib and BKM120 treatment showed synergistic antitumor effects in vitro and in vivo. These findings highlight the potential of integrating molecular profiling and drug testing to guide personalized therapies in rare and recurrent endometrial cancers.

VENUS 167–derived organoid culture, OPTO.85, expands long-term in vitro and in vivo while maintaining the histologic architecture of the patient tumor. A, Brightfield images of OPTO.85 organoid culture. B, Immunofluorescent staining of the organoid model. Nuclei are stained with 4′,6-diamidino-2-phenylindole (DAPI; blue). Tight junctions are labeled with zonula occludens-1 (ZO-1; red). Actin filaments are visualized with F-actin (filamentous actin; green). C, Oncoprint displaying the concordance of genomic alterations in the most mutated endometrial carcinoma genes across patient tumor, PDO, and ODX tissues. D, Hematoxylin and eosin (H&E) and IHC staining of tumor sections, ODX, and PDO exhibit consistent morphologies and biomarker expression. Biomarkers include synaptophysin (SYP), cytokeratin (CAM5.2), neural cell adhesion molecule 1 (NCAM1), and tumor protein 53 (P53). Scale bar, 100 μm. White arrowheads indicate negative staining, and black arrowheads indicate positive staining.