TMIC-66. FIBROBLAST ACTIVATION PROTEIN: TISSUE EXPRESSION, POSITRON-EMISSION TOMOGRAPHY UPTAKE AND ITS PROGNOSTIC SIGNIFICANCE IN GLIOSARCOMAS AND GLIOBLASTOMAS

Abstract BACKGROUND Although histologically distinct, gliosarcomas and glioblastomas are treated according to the same standards. Fibroblast-activation-protein (FAP) is a component of tumor-specific subpopulation fibroblasts that play critical role in tumor growth invasion. Few case studies suggest an elevated expression FAP glioblastoma particularly strong gliosarcoma, possibly for its predominant mesenchymal differentiation. However, prognostic impact gliosarcoma unclear. Question:What clinical relevance FAP-expression how does it correlate with FAPI46-PET-uptake? METHODS In retrospective analysis, patients diagnosed were enrolled. Histological examination was performed using immunohistochemical FAP-staining quantitative analysis standardized FAP-Score (0 3,with higher values indicating stronger expression). subset patients, FAPI46-PETs have been performed. The SUV planned be correlated tissue. Data obtained from brought into perspective clinically relevant factors, including survival estimates. RESULTS A total 45 On staining, expressed significantly more (average FAP-Score,2.3) than FAP-Score,0.7,p< 0.0001). While confined perivascular space, neoplastic cells themselves -in addition extracellular matrix- FAP. Initial analyses indicate tissue tracer uptake on FAPI46-PET. Further correlation data currently underway. CONCLUSIONS This study indicates much abundant as opposed glioblastomas. could open not only diagnostic but also therapeutic gap. association FAP-tissue FAPI46-PET will reported at time abstract presentation.