S853
Clinical - Lung
ESTRO 2026
Digital Poster 5054
increase in Ki-67+CD8+ T-cells at four weeks post-SBRT from baseline. Both arms observed a mean increase in expanding Ki-67+CD8+ T-cells post SBRT (21.4% optimized-arm, and 18.8% in standard arm) but not significant. Conclusion: For the first time, we demonstrate that optimized radiotherapy (RT) planning can significantly spare the proliferating fraction of CD4+ T-cells compared to the standard of care. Although the proliferating fraction of CD8+ T-cells increased in both groups after SBRT, the increase was not statistically significant. These findings suggest that preserving existing tumor-reactive T-cells through optimized RT may enhance the efficacy of immunotherapy and strengthen anti-tumor immune responses.
Tumor infiltrating lymphocyte is associated with favorable outcome in resectable non-small cell lung cancer treated with neoadjuvant chemoradiotherapy Gabriela Oses 1,2 , Daniel Martínez 3,2 , Cristina Teixido 3,2 , Francesc Casas 1 , Gabriela Antelo 1 , Arturo Navarro- Martín 1 , Silvia Muñoz Borrajo 4 , Cristina Urbano 4 , Sergi Castillo 5 , Marta Parera 6 , Marta Marginet 3 , Ingrid Lopéz 3 , Laura Mezquita 7,2 , Meritxell Mollà 1,2 1 Department of Radiation Oncology, Hospital Clínic of Barcelona, Barcelona, Spain. 2 Department of Medicine,
University of Barcelona, Barcelona, Spain. 3 Department of Pathology, Hospital Clínic of
Barcelona, Barcelona, Spain. 4 Department of Medical Oncology, General Hospital of Granollers, Barcelona, Spain. 5 Department of Medical Oncology, Hospital of Mollet, Barcelona, Spain. 6 Department of Medical Oncology, Hospital of Vic, Barcelona, Spain. 7 Department of Medical Oncology, Hospital Clínic of Barcelona, Barcelona, Spain Purpose/Objective: Resectable stage III non-small cell lung cancer (NSCLC) represents approximately 25% of all NSCLC cases. Neoadjuvant chemotherapy (NeoCT) or chemoradiotherapy (NeoCT-RT) can modulate the tumor microenvironment (MTE), potentially affecting tumor-infiltrating lymphocytes (TILs) density. This study aimed to evaluate the clinical impact of TIL density within the TME following NeoCT or NeoCT-RT. Material/Methods: A multicenter retrospective study was conducted including 50 patients with resectable stage III NSCLC treated between Feb.2012 to Jul.2021. Approved by the hospital ethics committee. Patients considered for trimodality treatment were selected based on resectability criteria rather than fragility. TIL density was morphologically assessed on H&E-stained surgical specimens by an lung cancer pathologist. A high-TIL density (high-TILs) was defined as ≥ 10% infiltration. Correlation with clinical, pathological characteristics and outcomes, including overall survival (OS) and progression-free survival PFS) were performed using IBM SPSS v25.0. Results: A total of 50 patients were included: 19 treated with NeoCT and 31 with NeoCT-RT; all had PS ≤ 1. Median (m) follow-up was 26 months (mo.) for NeoCT and 63.5 mo. for NeoCT-RT. In the NeoCT cohort (median age 65 years), most of the population were smokers (90%), women (79%), with adenocarcinoma histology (63%). Median TILs was 10% (range 1-60), with high TILs observed in 48%. No differences were observed in PFS (p=0.34)/OS (p=0.25). In the NeoCT-RT cohort (median age 58 years), most of the population were smokers
References: 1.NIH -PAR-18-011: Early Phase Clinical Trials in Imaging and Image-Guided Interventions: “Ameliorating lymphocyte depletion and functional impairment following lung SBRT”; - Sep 2019 –Sep 20222.Colen J., Nguyen C, Liyanage S, Aliotta E, Chen J, Alonso C, Romano K, Peach S, Showalter T, Read P, Larner J and Wijesooriya, K., Predicting Radiation Induced Immune Suppression in Lung Cancer Patients Treated with Stereotactic Body Radiation Therapy. Med Phys. 2024 (1-16). PubMed ID: 38837261DOI: 10.1002/mp.17181 https://pubmed.ncbi.nlm.nih.gov/38837261/ https://aa pm.onlinelibrary.wiley.com/doi/full/10.1002/mp.17181 Keywords: SBRT, Immune modulation, immune profiling
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