P-288 Individual drug-screening and heterogeneity analyses of patient-derived tumoroids: A roadmap to improving therapy in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive cancers due to high metastatic potential and already advanced stages at diagnosis. Only 20% of patients receive curative-intent surgery, followed by adjuvant chemotherapy, and another 20% with locally advanced disease are evaluated for secondary resection after neoadjuvant chemotherapy. Just one third of patients respond to chemotherapy and reliable biomarkers for response prediction are still missing. PDAC tumors display a wide heterogeneity, including different subtypes with distinct genetic signatures. As basal subtypes grow more aggressively than classical subtypes, the effect of reversible, epigenetic changes on subtype characteristics has become of interest in medical research. Patient-derived three-dimensional (3D) tumor organoids (tumoroids) constitute a novel technology for pre-therapeutic drug-response profiling of cancer patients. Tumoroids closely recapitulate a patient’s tumor and can aid in individualizing cancer therapy. We have succeeded in establishing proliferative tumoroid cultures from numerous PDAC patients and aim to design a robust drug-testing procedure to measure and evaluate patient-specific responses to different single and combination compounds in 50 patients. These data sets are correlated with clinical follow-up data. We further analyse the tumor subtypes of PDAC tumoroid cultures, to investigate tumor heterogeneity in the context of drug responsiveness. PDAC tissue (of all stages) is collected directly after surgical resection. Subsequent to mechanical and enzymatic tissue dissociation, tumor fragments are plated onto an extracellular matrix supporting 3D-growth, submerged in culture media for PDAC tumoroids. Patient-specific growth characteristics of tumoroids are monitored and cultures are expanded prior to analysis. Clinically approved compounds for PDAC treatment are employed to establish an in vitro drug-testing platform for PDAC tumoroids based on 2cureX’s IndiTreat technology. Subtype-specific features of PDAC tumoroids are analysed via immunofluorescence (IF) staining for EpCAM and GATA6 (classical subtype), as well as Vimentin and S100A (basal subtype). Patients included in this study will be followed for 24 months. Over the past 14 months, 40 PDAC tissue samples of different PDAC subtypes have been collected and processed for tumoroid generation. We were able to successfully derive tumoroids from 85% of PDAC tissue samples. For 65% of samples, initial tumoroid growth could be sustained in subsequent passages, allowing multiplication of tumoroids for experimental use and at times also cryo-conservation. Initial drug-screening results employing tumoroids, point at individual differences in response to treatment doses and compounds. Tumoroid characteristics vary between PDAC patients regarding multiplication time, morphology and mobility within the 3D-matrix. Preliminary IF staining results indicate that both classical and basal marker proteins can be detected in patient-specific tumoroids. The established procedures for PDAC tumoroid generation, cultivation, and long-term storage serve as a robust foundation for tumor heterogeneity and functional drug-screening analyses. Pre-therapeutic testing of patient-specific responses to a panel of clinically relevant compounds will eventually assist decision-making processes in clinical care and support individualization of a patient’s cancer treatment. In vitro studies on PDAC tumor subtypes and inducible shifts during chemotherapeutic treatment may support the identification of additional future drug targets in treating PDAC.