ECP 2023 Abstracts

S51 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 Methods: Sample pairs (primary tumours and their brain metastasis) of 11 LUAD and 11 BC (total 44 samples) were investigated in this study. RNA was extracted from the FFPE samples and the targeted gene expression profiles were measured using the PanCancer IO360™ Panel that includes 770 cancer-related genes (NanoString technology). Data were analysed using the nSolver software. Results: LUAD and BC show differences in genes and pathways to reach the brain. We identified 12 common up-regulated genes in the brain metastases irrespective of their origin (LUAD or BC). Pathway analysis revealed higher metabolic stress in the BC-derived brain metastases compared to LUAD. In addition, we found the immune regulatory molecule VISTA to be highly expressed in the primary tumours of LUAD and their matched brain metastases. Conclusion: Our study demonstrates that LUAD and BC utilize dif- ferent genes/pathways to metastasize into the brain. However, once in brain there are particular genes upregulated that are common for the seedings of both primary lineages. LUAD and their brain metastasis express high levels of VISTA. The results urge the development of lineage-tailored therapeutic approaches to successfully prevent or treat brain metastases. Funding: Foundation "Help Casper". OFP-13-008 A simple, low-cost pipeline for patient specific, cell free DNA based liquid biopsy S. Tsuriel*, V. Hannes, A. Refael, D. Mirelman, D. Hershkovitz *Tel Aviv Sourasky Medical Centre, Israel Background & objectives: Liquid biopsy (LB) can identifies relapse with before visible in imaging. Detecting a small fraction of tumour somatic DNA variants is required, and testing a large mutation panel improves sensitivity. We developed a pipe-line for tumour-specific multiplex based LB. Methods: This pipeline is based on tumour mutational profile driven from commercial, ~500 genes panel that is part of the standard of care in Israel for a number of malignancies. It includes the selection of vari- ants, primers design, in-silico PCR testing against the human genome and reduction of potential primer dimers. The pipeline can be based on online free bioinformatics tools. Results: We used this pipeline to design costume panels for 30 patients with 2- 25 variations. We tested the panels on urine and plasma DNA and got high uniformity and low limit of detection enabling us to detect changes in ctDNA level following treatment. Conclusion: We present the method’s applicability to clinical prac- tice. This pipeline is based on ion-torrent platform, it has a relatively lower costs and user-friendly bioinformatics tools can be applied for the analysis. The library preparation process is simple and short which make it feasible in many pathology institute. OFP-13-009 Oculo-cerebral lymphoma: a monocentric retrospective study of 56 cases M. Quintyn-Ranty*, R. Bouchoucha, P. Marty, E. Cornet, E. Emery, G. Damaj, J. Quintyn *Caen University Hospital, France Background & objectives: We described the characteristics of patients with oculo-cerebral lymphoma (all types) in our institution and evalu- ated the prognostic value of cell of origin (COO), MYC and BCL2 in primary diffuse large cell B-cell lymphoma (CNS-PDLBCL). Methods: Retrospective study of lymphomas with a primary cerebral localization according to the French oculo-cerebral lymphoma network at Caen University Hospital from January 2011 to September 2019 (collection of clinical, imaging, biological and treatment data). Immunophenotypic evaluation on FFPE of CNS-PDLBCL. COO subtyping was determinated thanks to Hans algorithm. A report was made to the local ethics committee. Results: 56 patients had CNS lymphoma, of which 15 had ocular involvement. The median age was 66 years (32% under 60 years), with mostly focal neurological signs (60%), neuropsychiatric signs and intracranial hypertension (36%), comital crisis (11%). The median time from diagnosis to the start of treatment was 18 days. The median overall survival was 29.7 months with a three-year over- all survival rate of 47%. We had FFPE material for 38 patients with CNS-PDLBCL. The GC phenotype was in the minority (6/38). There was no no difference in overall (OS, p=0.84) or progression- free survival (PFS, p=0.46) with COO stratification, or neither with ocular involvement or not (OS, p=0.816; PFS, p=0.373). Conclusion: Patients without ophthalmologic involvement were more likely (71% versus 33%, p=0.043) to have a single lesion on MRI. The lymphoma diagnosis was made on flow cytometry alone in 12% of cases. There were no significant differences in clinical data and treatment response between the GC and non-GC groups. Dual expression of MYC and BCL2 was associated with a OS decreased (median of 5.34 months for dual expressors and 12 months for other patients, p=0.009). OFP-13-010 Lymphoma classification using the World Health Organisation (WHO) 5th edition and International Consensus Classification 2022: an audit of cases diagnosed in Cork University Hospital in 2021 G. Crilly*, B. D. Hayes *Pathology Department, Cork University Hospital, Ireland Background & objectives: Lymphomas are classified using the World Health Organisation 5th edition (WHO-HAEM5) or International Consensus Classification 2022 (ICC). These divergent systems reflect advances in immunophenotypic and molecular lymphoma classifica- tion, defining new/emerging entities and redefining existing ones. Methods: All lymphomas cases diagnosed in Cork University Hospi- tal in 2021 were identified by SNOMED search. Each diagnosis was compared using WHO-HAEM5 and ICC 2022. Results: 190 lymphomas were identified - 33 Hodgkin-lymphoma, 142 B-cell and 11 T-cell lymphomas. Diffuse large B-cell lymphoma was the most frequent diagnosis (42 cases). In 96% of cases the diagnosis according to WHO-HAEM5 and ICC was identical. Divergent diagno- ses included four cases of nodal TFH lymphoma, angioimmunoblastic type (WHO-HAEM5) / follicular helper T-cell lymphoma, angioim- munoblastic type (ICC), and a case of primary cutaneous marginal zone lymphoma (WHO-HAEM5) / primary cutaneous marginal zone lymphoproliferative disorder (ICC). Among DLBCL cases, 10% were classified as DLBCL / high grade B-cell lymphoma with MYC-and BCL2-rearrangements (WHO-HAEM5) / high grade B-cell lymphoma with MYC-and BCL2-rearrangements (ICC). No “triple hit” DLBCLs or MYC/BCL6-rearranged DLBCLs were identified. Conclusion: Our audit showed that WHO 5th edition and ICC 2022 lymphoma classification mirror each other for the most part. However, there is now a deviation in how the WHO and ICC recommends DLBCL classification. This is the most commonly encountered lymphoma which requires immunohistochemistry / molecular work-up. Follow-up studies will be necessary to see if this has any treatment/prognostic implications. Additionally, new entities have been added to the WHO 5th edition which are not necessarily reflected in the ICC. Conclusion: A wide spectrum of TKD mutation was noted in 25% of the patients tested. T315I was the most common TKD mutation and was found to be associated with advanced disease. The finding from our study was in conjunction with similar studies.