S932
Clinical - Mixed sites & palliation
ESTRO 2026
Stewart, L., Ghersi, D., et al. (2007). Practical methods for incorporating summary time-to-event data into meta-analysis. Trials, 8(1). https://doi.org/10.1186/1745-6215-8-16 Keywords: high-dose radiation, immunotherapy, metastases Digital Poster 5018 PD-L1 and GPA Accuracy in Lung Cancer Brain Metastases Treated with WBRT Claudia Laborda 1 , Claudia Colom 1 , Ana Galán 1 , Andrea Ochoa 1 , Tomás Gonzalez 2 , Javier Diez 2 , Maria Cerrolaza 1 , Javier Tomás Anchuelo 1 , Reyes Ibañez 1 1 Radiation Oncology, HUMS, Zaragoza, Spain. 2 Physics, HUMS, Zaragoza, Spain Purpose/Objective: To evaluate whether PD-L1 expression influences the predictive accuracy of the Graded Prognostic Assessment (GPA) in lung cancer patients with brain metastases treated with whole-brain radiotherapy (WBRT). The study aimed to determine if PD-L1 status modifies the likelihood of major deviation between predicted and observed survival, providing insight into the biological variability underlying GPA performance. Material/Methods: A retrospective analysis was conducted on 155 lung cancer patients with brain metastases treated with WBRT. For each patient, the GPA index and estimated survival were calculated according to diagnosis- specific criteria. The difference between estimated and observed survival was categorized as mild ( ≤ 4 months), moderate (5-8), or severe deviation ( ≥ 9). Severe deviation was defined as the main outcome. PD-L1 status was classified as positive, negative , or not applicable , this last one was not included in the analysis. PD-L1 positivity was identified in 36.7 % of evaluable cases. A logistic regression model was used to evaluate the association between PD-L1 positivity and severe deviation, both unadjusted and adjusted for Karnofsky Performance Status (KPS), extracranial disease, and GPA index. Results: In the unadjusted model, PD-L1 expression was not significantly associated with severe deviation (OR = 1.02, 95 % CI 0.45–2.32, p > 0.05). After adjustment, the association remained nonsignificant (adjusted OR = 0.88, 95 % CI 0.30–2.59, p > 0.05), although the direction suggested a trend toward lower deviation risk among PD-L1–positive patients. Conversely, extracranial disease showed a strong and nearly significant association with major deviation (OR = 4.18, 95 % CI 0.99–17.6, p ≈ 0.05), while higher KPS
difference in OS was found between ICI-RT compared to ICI only group [hazard ratio (HR) [95% CI] = 0.86 [0.59-1.24], p = 0.41]. Similarly, for PFS, no significant difference was found between the groups [HR [95% CI] = 0.85 [0.69-1.06], p = 0.14]. Pooled safety data indicated that ICI-RT combination did not significantly increase the risk of grade 3–5 TRAEs [Peto-Odds ratio (OR), [95% CI] = 0.86 [0.46-1.60], p = 0.63] (Figure 1).
Conclusion: In metastatic solid tumours, ICI-RT combination was not associated with an OS or PFS benefit compared to ICIs only, however, safety profile was comparable. Further research is warranted to evaluate optimal RT parameters, timing, patient selection, and underlying biological mechanisms that may better identify subgroups who could derive meaningful clinical benefit. References: 1. Colciago, R. R., Fischetti, I., Giandini, C., et al. (2023). Overview of the synergistic use of radiotherapy and immunotherapy in cancer treatment: current challenges and scopes of improvement. Expert Review of Anticancer Therapy, 23(2), 135– 145. https://doi.org/10.1080/14737140.2023.21731752 . Wang, B., Kuang, B., & Lin, G. (2022). Immunotherapy Alone or in Combination with Stereotactic Body Radiotherapy in Advanced Lung Cancer: A Pooled Analysis of Randomized Clinical Trials. Journal of Oncology, 2022, 1–8. https://doi.org/10.1155/2022/75063003. Tierney, J.,
Made with FlippingBook - Share PDF online