Background: Concurrent platinum-based chemoradiotherapy (CRT) followed by durvalumab maintenance treatment represents the new standard of care in unresectable stage III non-small cell lung cancer (NSCLC). In this prospective hypothesis-generating single-center study, we aim to identify a framework of prognostic and predictive biomarkers by longitudinal characterization of tumor-and patient (host)-related parameters over all phases of multimodal treatment.

Methods: This study will enroll 40 patients (>= 18 years, Eastern Cooperative Oncology Group performance status (ECOG PS) 0-2, with a diagnosis of PD-L1 positive (>= 1%), inoperable stage III NSCLC) with an indication for CRT followed by maintenance treatment with durvalumab according to European Medicines Agency (EMA) approval. Comprehensive analysis will include peripheral blood cellular and humoral immunophenotyping and circulating tumor DNA as well as gut/saliva microbiota analyses. Additional morphological analysis with18F-FDG-PET/computed tomography (CT) before, 6 weeks, 6 and 12 months after the end of CRT is included. Statistical analysis using multiple testing will be used to examine the impact of different parameters on progression-free survival (PFS) and overall survival (OS) as well as tumor response and response duration.

Discussion: This protocol describes the methodology of a comprehensive biomarker study in order to identify a framework of prognostic and predictive markers for unresectable stage III NSCLC in a real-world setting.