ESTRO 2025 - Abstract Book

S3892

Radiobiology - Microenvironment

ESTRO 2025

855

Digital Poster In vivo changes of the cytokine signature in cerebrospinal fluid caused by intraoperative radiotherapy after resection of intracerebral metastases Klaus-Henning Kahl 1 , Zuzanna Mielewczyk 2 , Ehab Shiban 3,4 , Friederike Liesche-Starnecker 2 1 Klinik für Strahlentherapie und Radioonkolgie, University hospital Augsburg, Augsburg, Germany. 2 Institut für Pathologie und Molekulare Diagnostik, University hospital Augsburg, Augsburg, Germany. 3 Klinik für Neurochirurgie, University hospital Augsburg, Augsburg, Germany. 4 Klinik für Neurochirurgie, Medizinische Universität Lausitz- Carl Thiem, Cottbus, Germany Purpose/Objective: Intraoperative radiation therapy (IORT) is an ascending treatment approach which provides targeted radiation, reduced local recurrence and induction of an anti-tumor effect by activating an immune response and modulating the tumor-micro-environment (TME). Aim of our study is to characterize changes in the cytokine profile of the cerebrospinal fluid (CSF) induced by IORT after resection of brain tumors (BT). Material/Methods: A prospective clinical study from 05.2023 till 12.2023 was performed. Patients with BT that needed surgical treatment were screened. Patients with previous radiotherapy and or immunotherapy were excluded. IORT was indicated according to the local tumor board recommendation. Cerebrospinal fluid (CSF) was obtained from patients in the study (IORT) group as well as from the control (non-IORT) group. Cerebrospinal fluid (CSF) was obtained 1. Intraoperatively, before tumor resection (“BASELINE”), 2. Intraoperatively, after tumor resection +/- IORT (“EARLY”) and 3. ~24 h postoperatively from the surgical drainage (“LATE”). Using the Isoplexis technology and the modular panel “human Innate Immune’” 19 different cytokines of were simultaneously quantified using multiplex analyses in patients with or without IORT. The cytokine signatures were correlated with clinical data and compared between both groups. Results: A total of 10 patients in the IORT and 9 patients in the non-IORT group were enrolled. Their median age was 70 (range 26-86) years and the median KPS was 80 (70-90). There were 11 brain metastases, 6 Gliomas, one malignant meningioma and one vascular lesion. IORT did not increase the perioperative toxicity of brain surgery . All of these patients had been already discharged from hospital after brain surgery and most of them had even received another course of systemic treatment before their death. An increase of signal intensity was observed for 16 of the 19 analyzed cytokines (84%) in the test group, of which 7 (37%) displayed significant differences between baseline and postoperative time points: IL-1β, IL-6, IL-8, IP-10, MCP-1, MIP-1β and VEGF. Within these cytokines, a noticeable increase is evident for IL-1β, IL-8, IP-10, and MIP-1β when comparing the control and test groups. Conclusion: Our study allows first conclusions about changes in the cytokine profile of cerebrospinal fluid after IORT of primary and secondary brain tumors. The results indicate that IL-1β, IL-8, IP-10 and MIP-1β are involved in the inflammatory response induced by exposure to ionizing radiation of the tumor bed during surgery.

Keywords: Cytokine, CSF, Radiation