Immunochemotherapy, Surgery or Chemoradiation, and Durvalumab for Stage IIIA/B NSCLC

Inclusion Criteria: 1\. Patient is capable of giving signed informed consent which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in this protocol. Written informed consent and any locally required authorization (European Union \[EU\] Data Privacy Directive in the EU) obtained from the patient/legal representative prior to performing any protocol-related procedures, including screening evaluations. 2\. Patient is willing and able to comply with the protocol for the duration of the study 3. Age ≥ 18 years and \< 75 years. 4. All sex and gender. 5. Female patients of childbearing potential as well as male patients with partners of childbearing potential must agree to always use a highly effective form of contraception according to the Clinical Trials Facilitation and Coordination Group (CTFG) during the course of this study and for at least 90 days after the last dose of durvalumab or 6 months after the last dose of chemotherapy, whichever occurs last. 6\. Evidence of post-menopausal status or negative serum pregnancy test for female pre-menopausal patients. Women will be considered post-menopausal if they have been amenorrhoeic for 12 months without an alternative medical cause. 7\. Histologically and / or cytologically proven NSCLC (EGFRm-, ALK-). 8. Selected patients with NSCLC stage IIIA/B: 1. IIIA: one or more lymph node levels involved at EBUS/mediastinoscopy T1/T2 N2. 2. IIIB: one or more lymph node levels involved at EBUS/mediastinoscopy T3/T4 N2. 9. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. 10. Given technical/oncologic complete resectability (R0) at the time of inclusion. 11. Sufficient functional reserves for the planned surgery 12. Fulfilment of adequate criteria for functional and medical resectability as described in the European Respiratory Society (ERS)/ European Society of Thoracic Surgeons (ESTS) guidelines (Brunelli et al. 2009) and acceptable general clinical condition for multimodality treatment (interdisciplinary committee). 13\. Life expectancy of \> 12 weeks. 14. Body weight \> 30 kg. 15. Adequate normal organ and bone marrow function as defined below: a. Hemoglobin ≥ 9.0 g/dL. b. Absolute neutrophil count (ANC) ≥ 1.5 × 109/L. c. Platelet count ≥ 100 × 109/L. d. Serum bilirubin ≤ 1.5 × institutional upper limit of normal (ULN). (This will not apply to patients with confirmed Gilbert's syndrome (persistent or recurrent hyperbilirubinemia that is predominantly unconjugated in the absence of hemolysis or hepatic pathology), who will be allowed only in consultation with their physician. e. Alanine aminotransferase (ALT/SGPT) and aspartate aminotransferase (AST/SGOT) ≤ 2.5 × institutional ULN. f. Measured creatinine clearance (CL) ≥ 60 mL/min or calculated creatinine CL ≥ 60 mL/min by the Cockcroft-Gault formula (Cockcroft and Gault 1976) or by 24-hour urine collection for determination of creatinine clearance. 16\. Stable cardiac function (no myocardial infarction (MI) within 6 months, no heart failure NYHA III-IV). 17\. Discussion in a multidisciplinary tumor board which supports participation in this clinical trial, indicating that both chemoradiotherapy and surgery are possible local treatments. Patients should only be randomized if all of the following inclusion criteria are fulfilled at the time of randomization: 1. Given technical/oncologic complete resectability (R0) at the time of randomization. 2. Sufficient functional reserves for the planned surgery 3. Adequate normal organ and bone marrow function as defined before Exclusion Criteria: 1\. Unresectable disease. 2. Mixed histology with areas of small cell carcinoma (neuroendocrine markers). 3. ALK+/ EGFRm disease. 4. Clinically symptomatic vena cava superior syndrome. 5. Diffuse mediastinal involvement. 6. Patients with N3 tumors (IASLC/UICC 8). 7. Invasion of the thoracic aorta (T4 - aorta) or the heart (except left atrium - T4 - heart) or the esophagus (T4 - esophagus), or invasion of spine (T4 - spine) NOTE: T4 with invasion of diaphragm are eligible. 8. Pancoast-syndrome in tumors of the superior sulcus (T3-4 Nx). 9. Metastatic disease (M1). 10. Endobronchial tumor extension to the contralateral main stem bronchus. 11. Lung or heart function not allowing the intended surgical procedure at the time of inclusion. 12\. Prior treatments including prior mediastinal irradiation. 13. Insufficient patients' compliance (e.g., symptomatic psychiatric disorder) or missing written informed consent or definitive refusal for participation. 14\. Prior randomization of treatment in a previous durvalumab clinical study regardless of treatment arm assignment. 15\. Patients who have received prior anti-PD-1, anti-PD-L1, or anti-CTLA-4: 1. Must not have experienced a toxicity that led to permanent discontinuation of prior immunotherapy. 2. All AEs while receiving prior immunotherapy must have completely resolved or resolved to baseline prior to screening for this study. 3. Must not have experienced a ≥ Grade 3 immune related AE or an immune related neurologic or ocular AE of any grade while receiving prior immunotherapy. NOTE: Patients with endocrine AE of ≤ Grade 2 are permitted to be enrolled if they are stably maintained on appropriate replacement therapy and are asymptomatic. 4. Must not have required the use of additional immunosuppression other than corticosteroids for the management of an AE, not have experienced recurrence of an AE if re-challenged, and not currently require maintenance doses of \> 10 mg prednisone or equivalent per day. 16\. Participation in another clinical study with an investigational product during the last 12 months. 17\. Concurrent enrollment in another clinical study, unless it is an observational (non-interventional) clinical study or during the follow-up period of an interventional study. 18\. History of idiopathic pulmonary fibrosis, pneumonitis (including d