ESTRO 2025 - Abstract Book

S415

Clinical - Biomarkers

ESTRO 2025

References: 1. Deek, M. P. et al. Long-Term Outcomes and Genetic Predictors of Response to Metastasis-Directed Therapy Versus Observation in Oligometastatic Prostate Cancer. J Clin Oncol 40 (2022). 2. Wu, K. et al. Hypoxia promotes conversion to a stem cell phenotype in prostate cancer cells by activating HIF 1α/Notch1 signaling pathway. Clin Transl Oncol 25 (2023). 3. Xi, Y. et al. Genetic evidence supporting a causal role of Janus kinase 2 in prostate cancer. Aging Male 26 (2023). 4. Mancini, M. et al. DNMT3A epigenetically regulates key microRNAs involved in epithelial-to-mesenchymal

transition in prostate cancer. Carcinogenesis 42 (2021). 5. Lafront, C. et al. https://doi.org/10.1172/JCI170809 6. DOI: 10.7754/Clin.Lab.2014.141210

2305

Digital Poster The role of proteomics in predicting the risk of radiation necrosis following SRS treatment for brain metastases Paola Anna Jablonska 1 , Nuria Galán 2 , Jennifer Barranco 2 , Sergio Leon 2,3 , Alfonso Calvo 2,4 , Diego Serrano 2,4 , Javier Aristu 5 1 Radiation Oncology, Hospital Universitario de Navarra, Pamplona, Spain. 2 IDISNA and Program in Solid Tumors, Center for Applied Medical Research (CIMA), Pamplona, Spain. 3 Department of Pathological Anatomy, Clinicia Universidad de Navarra, Pamplona, Spain. 4 Department of Pathology, Anatomy and Physiology, School of Medicine, University of Navarra, Pamplona, Spain. 5 Radiation Oncology, Clinicia Universidad de Navarra, Madrid, Spain Purpose/Objective: Cerebral radiation necrosis (RN) is a deleterious adverse event following stereotactic radiosurgery (SRS) for brain metastases (BMs). Prior authors demonstrated that radiation-induced brain injury can be traced in peripheral blood using plasma based biomarkers [1]. We sought to identify predictive biomarkers of symptomatic RN in liquid biopsies from BMs patients obtained at the time of SRS and to develop a risk prediction model. Material/Methods: Fifty-four patients treated for BMs were monitored before and after SRS. Plasma samples (5-10mL EDTA) collected at the time of SRS were analysed for 92 related human proteins using matched antibodies and real-time polymerase-chain reaction with a high throughput Olink Immuno-Oncology Panel [2]. Statistical analysis was conducted using GraphPad Prism 9.0. Receiver-operating characteristic (ROC) curves were performed for selected biomarkers. Multivariate Cox proportional hazard (PH) regression was conducted to assess predictor variables related to patients, SRS treatment and baseline plasma biomarkers, and the risk of RN. Results: We analysed 24 patients diagnosed with symptomatic RN and 30 patients who experienced a successful ablation of their BMs as controls. Significantly higher levels of inflammatory biomarkers CD8a , CXCL10 and FASLG (p<0.05) and significantly lower levels of MUC-16 (p=0.009) were found in the samples pertaining to RN patients compared to the controls. On multivariate Cox PH analysis, the volume of brain receiving 12Gy (V12) (p<0.001), MUC_16 (p<0,05) and CD8a (p<0.05) were statistically significant for predicting RN. The levels of CXCL11 and IL8 were close to statistical significance (p=0.05-0.1). Multiple regression model showed that combining the V12 parameter with MUC_16, CD8A, CXCL11 and IL8 improved the ROC curve for V12 from AUC=0.78 to AUC=0.91 (Figures 1 and 2).