Background: Improving the outcome of locally advanced non-small cell lung cancer (NSCLC) is one of the major challenges in thoracic oncology. SAKK substantially contributed to establish a standard of care for patients with stage III NSCLC: The trial SAKK 16/96 established neoadjuvant chemotherapy with three cycles of cisplatin and docetaxel. The randomized trial SAKK 16/00 showed no benefit by adding radiotherapy as third treatment modality to chemotherapy and surgery. Our results consistently showed a 5-year overall survival (OS) of 37%. However, it seems very difficult to further improve the OS by conventional therapies. Methods: This is a single-arm phase II clinical trial designed to evaluate the addition of perioperative immunotherapy with the anti-PD-L1 antibody durvalumab to the previously established standard of care for stage IIIA(N2) patients, which is based on the trials SAKK 16/96 and SAKK 16/00. Eligible patients with WHO performance status 0-1 and age of 18-75 years must have pathologically proven NSCLC stage IIIA(N2) (T1-3 N2 M0) according to the 7th edition of the TNM classification, irrespective of histological subtype, genomic aberrations or PD-L1 expression status. Tumor tissue has to be available for the mandatory translational research. Patients whose tumor is deemed resectable at diagnosis receive three cycles of chemotherapy with cisplatin 100 mg/m² and docetaxel 85 mg/m² every three weeks followed by two cycles of durvalumab 750 mg every two weeks. Following surgery, patients will be treated with durvalumab 750 mg every two weeks for 12 months. Patients with R1/R2 resection and patients with extracapsular spread of mediastinal lymph node metastases may undergo standard radiotherapy prior to adjuvant treatment with durvalumab. The primary endpoint of the trial is event-free survival at 12 months. Secondary endpoints include OS, objective response, nodal down-staging, complete resection, pattern of recurrence and toxicity. Additionally, a large translation research program accompanies the trial investigating potential predictive biomarkers of anti-PD-L1 therapy. Clinical trial information: SNCTP000001480.