Abstract 5171: Development of preclinical models of NTRK fusion-driven cancers

Abstract Introduction: Oncogenic fusions involving the neurotrophic receptor tyrosine kinase genes, NTRK1, NTRK2, or NTRK3 are detected in both adult and pediatric cancers, including in 1% of a broad range of common cancer types such as lung, colorectal, and breast, 25% of thyroid and gastrointestinal stromal tumors, and >90% of several rare tumor types, such as congenital infantile fibrosarcoma (1). Fusions arise by intra- or extrachromosomal rearrangement, fusing the NTRK kinase domain to a 5’ upstream gene partner, leading to constitutive kinase activation, thereby driving oncogenesis. This seems to occur primarily via activation of PI3K, MAPK and/or PLCg signaling, however our understanding of NTRK fusion biology is limited by a scarcity of disease models (1). Aim: The aim of this project is to generate additional preclinical models to further our understanding of NTRK fusion-driven oncogenesis and response to treatment. Methods and Results: We identified a novel SGK3-NTRK3 fusion in a patient, with breast cancer and brain metastases, treated at our center. We generated cellular models in HEK293 (human embryonic kidney cell line) and MCF7 (breast adenocarcinoma cell line) by transfecting with a plasmid encoding the fusion construct, with and without a CMV promoter, and demonstrated that the fusion induces AKT activation. To employ more physiologically relevant models, we additionally generated the fusion in these cell lines by CRISPR-gene editing, utilizing sgRNAs that induce double stranded breaks in the relevant genomic loci for this specific fusion. A genetically engineered mouse model of the fusion was further developed in a C57BL/6J background by intracranial injection of an adeno-associated viral construct (GFP/Cre) with sgRNAs targeting SGK3, NTRK3, and TP53. Tumors developed in 50% of the mice within four months, suggesting that this novel fusion acts as an oncogenic driver. Fluorescence In Situ Hybridization to further validate and localize the fusion, gene expression analysis to further characterize the fusion’s biological impact, and viability assays to assess its sensitivity to NTRK inhibition are underway. Conclusions: These findings suggest that the SGK3-NTRK3 fusion is a strong oncogenic driver in a glioma setting, and we are currently extending these investigations to a breast cancer setting. Through the integration of these novel models, our research seeks to advance our understanding of NTRK fusion-driven cancer biology and to improve therapeutic strategies for these cancers. References: Cocco E, Scaltriti M, Drilon A. NTRK fusion-positive cancers and TRK inhibitor therapy. Nat Rev Clin Oncol. 2018;15(12):731-47. Citation Format: Aram Arshadi, Mathilde Søbye Blaavand, Sofie Krarup Thomsen, Sofie Andersen, Kathe Thuesen Munk, Britt Ardal, Emil Aagaard Thomsen, Britt Elmedal Laursen, Jacob Giehm Mikkelsen, Martin Kristian Thomsen, Maria Rusan. Development of preclinical models of NTRK fusion-driven cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5171.