ESTRO 2023 - Abstract Book

S816

Monday 15 May 2023

ESTRO 2023

Conclusion Treatment of frail patients with COVID-19 pneumonia with SoC plus LD-RT 0.5 Gy single dose improved respiratory parameters, reduced period of hospitalization, decreased rate of one-month mortality, and prolonged actuarial overall survival compared to SoC alone. PD-0969 FDG PET/CT follow up imaging of durvalumab maintenance in inoperable stage III NSCLC patients A. Holzgreve 1 , M. Unterrainer 2 , J. Taugner 3 , P. Müller 2 , A. Tufman 4,5 , N. Reinmuth 6 , M. Li 3 , L.M. Unterrainer 1 , P. Bartenstein 1,7 , W.G. Kunz 2 , J. Ricke 2 , C. Belka 3,5,8 , C. Eze 3 , F. Manapov 3,5,7 , L. Käsmann 3,5,7 1 University Hospital, LMU Munich, Department of Nuclear Medicine, Munich, Germany; 2 University Hospital, LMU Munich, Department of Radiology, Munich, Germany; 3 University Hospital, LMU Munich, Department of Radiation Oncology, Munich, Germany; 4 University Hospital, LMU Munich, Department Internal Medicine V, Munich, Germany; 5 Member of the German Center for Lung Research (DZL), Comprehensive Pneumology Center Munich (CPC-M), Munich, Germany; 6 Asklepios Lung Clinic, Department of Pneumology, Munich, Germany; 7 German Cancer Consortium (DKTK), Partner Site Munich, Munich, Germany; 8 German Cancer Consortium (DKTK), Partner Site Munich, Munich, Munich, Germany Purpose or Objective Durvalumab is an anti-PD-L1 immune checkpoint inhibitor that significantly improves clinical outcome after chemoradiotherapy (CRT) in patients with unresectable stage III NSCLC. However, metabolic changes of tumoral lesions and secondary lymphoid organs during durvalumab treatment are unknown until now. Therefore, we assessed metabolic patterns on 18F-FDG PET/CT in patients after durvalumab initiation versus patients undergoing CRT alone. Materials and Methods 18F-FDG PET/CTs both before the initiation and after the completion of standard CRT were analyzed in 43 patients with inoperable stage III NSCLC. Thereof, 16 patients received additional durvalumab. Metabolic changes in tumor sites and secondary lymphoid organs were assessed and directly compared in the CRT alone and the durvalumab groups. Furthermore, scans were evaluated with regard to findings suspicious for immunotherapy-related adverse events (irAE), the readers being blinded for the durvalumab administration. Results Before durvalumab administration, uptake characteristics were comparable in both groups, e.g. median tumoral SUVmax was 12.6 without vs. 13.4 with durvalumab (p = 0.452). With the initiation of durvalumab, however, uptake patterns in PET/CT diverged: A significantly higher reduction of tumoral uptake intensity was noted in the durvalumab group in