S184
Clinical - Biomarkers of clinical response
ESTRO 2026
Andrea Baehr 14 , Annika Hardt 15 , Raphael Bodensohn 16,17 , Lukas Käsmann 16 , Maria
23 Department of Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany. 24 Department of Radiation Oncology, University Hospital Dusseldorf, Medical Faculty, Heinrich-Heine- University Dusseldorf, Düsseldorf, Germany. 25 Department of Radiation Oncology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany. 26 Department of Radiation Oncology, Cyberknife and Radiotherapy, Faculty of Medicine and University Hospital Cologne, Cologne, Germany. 27 Institute of Medical Statistics and Computational Biology, Faculty of Medicine and University Hospital Cologne, Cologne, Germany. 28 Department of Radiation Oncology, Ernst von Bergmann Hospital Potsdam, Potsdam, Germany Purpose/Objective: Whether biological sex is associated with abscopal effects (AbE) and survival among patients receiving combined radiotherapy (RT) and immune checkpoint inhibition (ICI) remains unexplored. We aimed to identify sex-specific clinical prognostic factors. Material/Methods: This is a subanalysis of a retrospective, non- interventional, multicentre study which included patients with metastatic solid tumours treated with RT during or after ICI from 2015–2021. At least one non- irradiated lesion (NIL) outside the 10% isodose and serial imaging were required. NILs were assessed per iRECIST; abscopal response (AR) was ≥ 30% decrease, abscopal progression (AP) ≥ 20% increase, and abscopal control (AC) in-between. Abscopal benefit (AB) combined AR, ≥ 1 AR, and AC. Overall survival (OS) and progression-free survival (PFS) were estimated by Kaplan-Meier. Sex-stratified multivariable Cox models evaluated associations of age, ICI-to-RT interval, RT location (brain vs other), RT type (stereotactic vs hypofractionated vs other), body mass index (BMI ≥ 25 vs <25 kg/m ² ), prior RT, smoking, and C-reactive protein (CRP ≥ 5 vs <5 mg/L). Results: Of 3,773 screened cases, 142 patients met the inclusion criteria (female 38.0% [n=54], male 61.9% [n=88]). AR and AC were more frequent in females (AR 24.1% vs 13.6%; AC 35.2% vs 30.7%), yielding AB in 68.5% of females vs 56.8% of males; AP was rare in females (1.9% vs 9.1%). Median OS did not differ by sex (female 16 months, male 17 months; p=0.81). In sex-specific Cox models, a longer ICI-to-RT interval predicted improved OS (females HR 0.748, p=0.002; males HR 0.903, p=0.012), while BMI ≥ 25 kg/m ² predicted worse OS (females HR 4.801, p=0.028; males HR 4.282, p=0.008). Elevated CRP ( ≥ 5 mg/L) was adverse in males only (HR 4.764, p=0.028). Sensitivity analyses excluding CRP increased analyzable cases and yielded comparable estimates for other
Waltenberger 18,19 , Eleni Gkika 1 , Davide Scafa 1 , Julian P. Layer 1,20 , Esther G.C. Troost 21,22 , Sally A. Elkhamisy 23 , Danny Jazmati 24 , Ilinca Popp 25 , Sebastian Neppl 26 , Anna Hagemeier 27 , Angela Besserer 28 , Simone Ferdinandus 26 1 Department of Radiation Oncology, Faculty of Medicine and University Hospital Bonn, Bonn, Germany. 2 Department I of Internal Medicine, Center of Integrated Oncology Aachen Bonn Cologne Düsseldorf, University Hospital of Cologne, Cologne, Germany. 3 Department of Radiation Oncology, Medical Center, Faculty of Medicine, University of Freiburg,, Freiburg, Germany. 4 Department of Radiation Oncology, University of Leipzig Medical Center, Leipzig, Germany. 5 Department of Radiation Oncology, Charité - University Medicine Berlin, Corporate Member of Freie Universität Berlin and Humboldt Universität zu Berlin, Berlin, Germany. 6 German Cancer Consortium (DKTK), partner site Berlin, a partnership between DKFZ and Charité, Universitätsmedizin Berlin, Berlin, Germany. 7 Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander- Universität Erlangen-Nürnberg, Erlangen, Germany. 8 Comprehensive Cancer Center, Erlangen-EMN, Erlangen, Germany. 9 Department of Radiation Oncology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany. 10 Department of Radiation Oncology, Jena University Hospital, Jena, Germany. 11 Clinician Scientist Program OrganAge, Jena University Hospital, Jena, Germany. 12 Clinician Scientist Program, Interdisciplinary Center for Clinical Research (IZKF), Jena University Hospital, Jena, Germany. 13 Clinic for Radiation Oncology and Radiotherapy, Lüdenscheid Clinic, Lüdenscheid, Germany. 14 Department of Radiation Oncology, University Medical Hospital, Hamburg-Eppendorf, Hamburg, Germany. 15 Department of Radiation Oncology, Outpatient Center of the University Medical Hospital Hamburg-Eppendorf, Hamburg, Germany. 16 Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany. 17 Department of Radiation Oncology, University Hospital Tübingen, Tübingen, Germany. 18 Department of Radiation Oncology, Hospital of Bolzano (SABES- ASDAA), Bolzano-Bozen, Germany. 19 Department of Radiation Oncology, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany. 20 Institute of Experimental Oncology, University Hospital Bonn, Bonn, Germany. 21 Institute of Radiooncology – OncoRay Helmholtz- Zentrum Dresden-Rossendorf, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, and Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany. 22 National Center for Tumor Diseases (NCT/UCC), Dresden, German Cancer Research Center (DKFZ), Heidelberg, Heidelberg, Germany.
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