Abstract 3076: Autologous ECM-composed scaffolds and zebrafish PDXs for individualized theranostics in rare neuroendocrine neoplasms

Abstract Background: Neuroendocrine neoplasms (NENs) are a subgroup of poorly characterized rare tumors with challenging management. Identification of clinically useful biomarkers for patient stratification and treatment tailoring is urgently needed. This study proposes the use of near-patient models based on autologous extracellular matrix (aECM)-scaffolds and zebrafish (ZF) xenografts integrated with next generation multi-omics analysis for the phenotype and genotype mapping of NEN cells. The aim is to uncover molecular signatures associated with disease aggressiveness and to detect oncogenic drivers for targeted treatment. Methods: Primary tumor cells isolated from surgical specimens of NEN patients were cultured in aECM scaffolds or injected into ZF embryos. Autologous ECM-scaffolds were synthesized starting from the patients’ matrices and recellularized with primary cells derived from matched patients. In aECM scaffolds we evaluated tumor cell proliferation and neuroendocrine differentiation. In ZF we evaluated cell angiogenic ability and distant invasiveness. For each primary culture, we performed exome and transcriptome analysis of the original tumor tissue compared to the matched healthy counterpart. Results: We demonstrated that ZF xenografting faithfully recreates the behavior that tumor cells exhibit in patients. Specifically, we derived a primary culture from an ileal grade 1 neuroendocrine tumor from both the primary and the metastatic lesions. When injected into ZF embryos, cells derived from the primary tumor displayed low invasive ability with a metastatic rate of only 23%. Conversely, cells derived from the metastatic lesion were able to invade the ZF circulation and form distant metastases in 79% of embryos. Consecutively, we derived three primary cultures of neuroendocrine Merkel cell carcinoma (MCC). The 3 MCC cultures into ZF embryos showed high aggressiveness with metastatic rates of 81%, 50% and 64%. For one culture, angiogenic ability was also observed. RNA-sequencing of these aggressive MCC specimens highlighted the involvement of the following pathways: ECM remodeling, TNF-ⲁ and PI3K-Akt signaling, epithelial-mesenchymal transition and regulation of apoptotic processes. Next, we demonstrated that aECM-scaffolds morphologically resemble a native tumor tissue, and tumor cells, once seeded on them, preserved the expression of neuroendocrine markers. Conclusions: Here we developed innovative neuroendocrine tumor models that are expected to generate new knowledge on the disease molecular determinants. All identified genomic and genetic alterations will be correlated with the clinical outcomes of enrolled patients, to validate their clinical significance and to ultimately introduce a biomarker-based approach for NEN patients. Citation Format: Chiara Calabrese, Giacomo Miserocchi, Silvia Vanni, Alessandro De Vita, Alberto Bongiovanni, Chiara Spadazzi, Claudia Cocchi, Nicoletta Ranallo, Federica Pieri, Michela Tebaldi, Flavia Foca, Giorgio Ercolani, Davide Cavaliere, Carlo Alberto Pacilio, Giovanni Martinelli, Laura Mercatali, Chiara Liverani. Autologous ECM-composed scaffolds and zebrafish PDXs for individualized theranostics in rare neuroendocrine neoplasms [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3076.