PACCELIO - FDG-PET Based Small Volume Accelerated Immuno Chemoradiotherapy in Locally Advanced NSCLC

Inclusion Criteria: * Written informed consent * Patients irrespective of sex and gender, aged 18 years or older at the time of signing the ICF * Patients must be willing and able to comply with scheduled visits, treatment schedule, laboratory testing, and other requirements of the study as determined by the investigator * Patients with histologically or cytologically documented NSCLC who present with locally advanced, unresectable (Stage III) disease (according to version 8 of the International Association for the Study of Lung Cancer Staging Manual in Thoracic Oncology (IASLC Staging Manual in Thoracic Oncology 2016)) * Patients fit for simultaneous chemoradiotherapy and consolidation immunotherapy according to interdisciplinary consensus * Histologically proven PD-L1-expression of ≥ 1% (tumor proportion score; TPS) in tumor sample as assessed in routine staging using a validated test such as Ventana SP236 assay * Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0 or 1 at enrolment * Tumor assessment by FDG-PET CT within 21 days prior to start of chemoradiotherapy. * Adequate pulmonary function test results * Pre- or post-bronchodilator forced expiratory volume 1 of 1.0 L or \>40% of predicted AND * Diffusing capacity of the lung for carbon monoxide (DLCO) \>30% of predicted * Adequate bone marrow and organ function at enrolment * Hemoglobin ≥9.0 g/dL * Absolute neutrophil count \>1.5 × 109/L * Platelet count \>100 × 109/L * Serum bilirubin ≤1.5 × upper limit of normal (ULN) * Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤2.5 × ULN * Measured creatinine clearance (CrCl) \>40 mL/min or calculated CL \>40 mL/min as determined by Cockcroft-Gault (using actual body weight) * Body weight of \>30 kg at enrolment * Evidence of post-menopausal status, or negative urinary or serum pregnancy test for female pre-menopausal patients. Women will be considered post-menopausal if they are amenorrhoic for 12 months or more without an alternative medical cause. The following age-specific requirements apply: * Women \<50 years old would be considered post-menopausal if they have been amenorrhoic for 12 months or more following cessation of exogenous hormonal treatments with luteinizing hormone and follicle-stimulating hormone levels in the post-menopausal range for the institution * Women ≥50 years old would be considered post-menopausal if they have been amenorrhoic for 12 months or more following cessation of all exogenous hormonal treatments, radiation-induced oophorectomy with last menses \>1 year ago, chemotherapy-induced menopause with \>1 year interval since last menses, or surgical sterilization (bilateral oophorectomy or hysterectomy) * Women of childbearing potential (WOCBP) and 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 during the treatment phase of this study and for at least 90 days after the last dose durvalumab or 6 months after the last dose of chemotherapy, whichever occurs last Exclusion Criteria: * Mixed small cell and NSCLC histology * Neuroendocrine tumor * Distant metastases * Malignant pleural effusion or pericardial effusion * Acute superior vena cava obstruction * Receipt of prior or current cancer treatment for NSCLC, including but not limited to, surgical resection, radiation therapy, investigational agents, chemotherapy, and monoclonal antibodies (mAbs). Exception: Prior surgical resection of limited metachronous NSCLC (i.e., stage I or II) is permitted. * Receipt of live attenuated vaccine within 30 days prior to the start of therapy. Note: Patients, if enrolled, should not receive live vaccine during treatment phase and up to 30 days end of treatment * Major surgical procedure (as defined by the Investigator) within 28 days prior start of treatment. * Prior exposure to immune-mediated therapy, including but not limited to, other anti-CTLA-4, anti-PD-1, anti-PD-L1 (including durvalumab), and anti-PD-L2 antibodies, including therapeutic anticancer vaccines * Current use of ongoing long-term immunosuppressive medication. The following are exceptions to this criterion * Intranasal, inhaled, topical steroids, or local steroid injections (e.g., intra articular injection) * Systemic corticosteroids at physiologic doses not to exceed 10 mg/day of prednisone or its equivalent * Steroids as premedication for hypersensitivity reactions (e.g., CT scan premedication) * History of allogeneic organ transplantation * Active or prior documented autoimmune or inflammatory disorders including inflammatory bowel disease \[e.g., colitis or Crohn's disease\], diverticulitis \[with the exception of diverticulosis\], systemic lupus erythematosus, Sarcoidosis syndrome, Wegener syndrome \[granulomatosis with polyangiitis, Graves' disease, rheumatoid arthritis, hypophysitis, uveitis, etc.\]). The following are exceptions to this criterion: * Patients with vitiligo or alopecia * Patients with hypothyroidism (e.g., following Hashimoto syndrome) stable on hormone replacement * Any chronic skin condition that does not require systemic therapy * Patients without active disease in the last 5 years at randomization may be included but only after consultation with the local study physician * Patients with celiac disease controlled by diet alone * Uncontrolled intercurrent illness, including but not limited to, ongoing or active infection, symptomatic congestive heart failure, uncontrolled hypertension, unstable angina pectoris, cardiac arrhythmia, ILD, serious chronic gastrointestinal conditions associated with diarrhea, or psychiatric illness/social situations that would limit compliance with study requirement, substantially increase risk of incurring AEs, or compromise the ability of the patient to give written informed consent * Patients with oxygen dependence * Acute inflamma