Establishment of an in-vivo and in-vitro platform for evaluating ileal siNETs from patient-derived tumours

Background Gastroenteropancreatic neuroendocrine tumours (GEP-NETs) are rising in incidence, with small intestine neuroendocrine tumours (siNETs) being the most common subtype. Despite their low grade, siNETs show highly variable outcomes after resection. Their low mutational burden hinders the identification of predictive molecular markers, and suitable in vivo models remain limited. Although multi-omic studies have sought to classify siNETs, translation to treatment response in patients is still lacking. Methods We developed a dual platform combining two complementary models: (a) an in vivo zebrafish xenograft (PDX), and (b) an in vitro 3D tumoroid (PDT) system derived from n=7 patient ileal siNETs. Both platforms were treated with drugs commonly used for GEP-NETs—Sunitinib, Everolimus, and Temozolomide. Bulk RNA sequencing untreated and treated tumoroids was performed to identify molecular pathways potentially linked to patient-specific responses. To further validate the robustness of the platform the same methodology was applied to the GOT-1 siNET cell line. Results Both PDX and PDT models proved suitable for siNET studies. We confirmed that siNET cells xenotransplanted in the zebrafish remained viable and capable of proliferating. Moreover, we observed patient specific responses to the different treatments, which were also detected at the transcriptomic level, which some tumours responding more to one drug than to the others. Conclusion Our integrated in vivo/in vitro approach demonstrates that ileal siNETs exhibit individualised molecular and functional behaviours, underscoring the importance of patient-tailored evaluation to improve therapeutic strategies.