ECP 2023 Abstracts

S351 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 Conclusion: On the basis of morphological, immunohistochemical, and molecular findings, the diagnosis of EHE with YAP-1-TFE3 fusion was established. Due to its aggressiveness, EHE’s diagnostic approach in the limited tissue of endobronchial biopsy is crucial. Immunohisto- chemical markers and molecular techniques may be helpful. E-PS-21-050 Inflammatory fibroblastic tumour (IMT) of the right lung - a case report C. Valavanis*, E. Souka, E. Fergadis, N. Baltagiannis, G. Stanc *Molecular Pathology Unit Metaxa Cancer Hospital, Greece Background & objectives: IMT of the lung represents an extremely rare type of inflammatory pseudo-tumour. It is most common in chil- dren and young individuals, mostly in first and second decades. IMT are extremely rare in adults and comprise <1% of adult lung tumours. Methods: A 49-year-old female presented with cough and dyspnea. Chest CTscan showed solitary, circumscribed lobulated lesion on the lower right lobe. FNB of the lung was performed and the diagnosis of inflammatory fibroblastic tumour was made followed by right lobe pneumonectomy On gross examination a circumscribed yellow lobu- lated tumour, 1,5cm in great diameter was found. Results: Microscopic examination revealed a neoplasm with spindle cells, without nuclear atypia and no mitotic figures. The cells are seen as interlacing fascicles among a polymorphous inflammatory infiltrate consisting of mature plasma cells and small lymphocytes. Immunochemistry displayed Vimentin (+), Calponin (+), Desmin (+), ALK (+) and Ki-67 positivity in 1-5% of the tumour cells. Negative were CKAE1/AE3, CK7, TTF-1, Napsin A and GATA-3. The diagnosis of inflammatory fibroblastic tumour of the lung was made. Conclusion: IMT of the lung are rare, with incidence <1% of all lung tumours. IMTs show typically benign clinical behaviour. Malignant evolution has been described including recurrent (2-25% of cases) and meta- static disease (<5% of cases). Clinical symptomatology of pulmonary IMTs is various and nonspe- cific. In approximately 70% of the cases, the disease is discovered incidentally on imaging exams requested for other reasons. The diagnosis of IMT is difficult to establish, and histologic examina- tion is always required. E-PS-21-051 Tissue culture for organ-on-chip approaches to study interactions between non-small cell lung cancer tumours and proximal lymph nodes I. Vamvakaris*, K. Potaris, K. Tsilingiri, C. Karakostas, G. Zachou, M. Chliara, I. Zergioti, A. Klinakis *SOTIRIA, Greece Background & objectives: Metastasis to the lymph nodes is often the first step before distal tumours are established. In this work, we are optimizing a microfluidic organ-on-chip to examine the interaction between precision-cut tumour slices and immune cells. Methods: In this work, standard tissue culture techniques are coupled with advanced microfluidic circuit optimization. Potential interaction between cancer cells and immune cells are assessed in both traditional transwell culture settings (vertical movement of cancer cells) as well as on a novel organ-on-chip platform connected to a microfluidic circuit which provides fresh media throughout the culture (horizontal move- ment of cancer cells). Results: We have set up co-culture conditions which promote viability of both tissue types (tumour and lymph node) for up to 5 days. Tis- sue viability is assessed with haematoxylin and eosin staining, while cell viability is assessed via flow cytometry. Slices remain in good condition throughout the experiment on both transwells and microflu- idic chips. We have so far observed only vertical movement of cancer cells for two out of eight samples tested. Initial evaluations indicate that cell migration is increased in the presence of lymph node slices or immune cell suspensions. We have retrospectively confirmed that highly migrating cells came from tumours of metastatic patients, undi- agnosed at the time of surgery. Conclusion: We are optimizing a state-of-the-art organ-on-chip set up to observe migration of metastasizing cancer cells in real time. To this end, we have determined optimal co-culture conditions guaranteeing viability of tissue slices for up to 5 days. We have shown that a media flow of 2μL per minute on a microfluidic chip is sufficient to maintain tissues in good condition. Molecular analyses will be performed on sorted metastasizing cells to highlight genetic and functional differ- ences between metastatic and non-metastatic clones. E-PS-21-052 Generation of a predictive xenograft platform of patients with bronchial neuroendocrine tumours in zebrafish I. Vamvakaris*, G. Evangelou, A. Bianchi, G. Lolas, L.D. Jensen, K. Syrigos *SOTIRIA, Greece Background & objectives: Neuroendocrine tumours of the lung con- stitute a wide spectrum of neoplasms. At one extreme are the bronchial carcinoids with an excellent prognosis, at the other are the poorly dif- ferentiated carcinomas, with a poor prognosis regardless of the thera- peutic combination. Methods: A key barrier to improving treatment efficacy and patient survival is the lack of predictive biomarkers for most treatment regimens. Preclinical platforms, such as patient derived xenografts (PDX) models, which aim to predict the efficacy of drugs in each individual patient before the actual administration of drugs, are under development. Results: In zebrafish tumour xenografts (ZTX) models, patients’ cancer cells are labelled with red fluorescent dyes and implanted into the subcutaneous tissue located between the skin (epidermis) and the yellow epithelial membrane, known as the periperitoneal space. In the present study, we first constructed NENs xenografts in zebrafish using patient-derived tumour biopsies. The main advantage of zebrafish is the non-invasive in vivo imaging of cancer progression as well as the limited time required to monitor these responses, which in most cases ranges from 3–6 days compared to several weeks in mouse models. Conclusion: The specific objectives of the ZTX zebrafish model are as a drug screening platform and to examine the optimal sequencing of available therapies as well as to provide evidence on the feasibility and accuracy of the proposed preclinical platform for the personalized treatment of bronchial NETs. E-PS-21-053 Comparative analysis of a new IHC assay for PD-L1 expression in non-small cell lung carcinomas D. Wang*, S. Nielsen, M.K. Stensballe, A. Saxena, V.M. Calero, J. LaMar, R. DeCamillis *Sakura Finetek USA, USA Background & objectives: Program death ligand-1 (PD-L1) IHC expression is used to select patients with non-small cell lung carcinoma (NSCLC) for immunotherapy. This study is to determine analytical concordance between PD-L1 IHC 22C3 pharmDx and PD-L1 IHC Assay (clone RM320) in NSCLC. Methods: 104 human formalin-fixed paraffin-embedded (FFPE) NSCLC cases from three microarrays were analysed by the two IHC