Inclusion Criteria:  Subjects with histologically or cytologically-documented NSCLC Locally advanced, unresectable (Stage III) NSCLC World Health Organization (WHO) performance status 0-1 At least one measurable lesion, not previously irradiated Must have a life expectancy of at least 12 weeks at randomization Adequate lung function: Pre- or post-bronchodilator forced expiratory volume 1 of 1.0 L or >40% predicted value and DLCO >30% predicted value Must provide an archived tumor tissue block(or at least 15 newly cut unstained slides)≤3 years old; if archived sample unavailable then must provide a recent(≤3 months) tumor biopsy.  Exclusion Criteria:  Mixed small-cell and NSCLC histology Receipt of prior or current cancer treatment, including but not limited to, radiation therapy, investigational agents, chemotherapy, Durvalumab and mAbs. Prior exposure to immune-mediated therapy, including but not limited to, other anti- CTLA-4, anti-PD-1, anti-PD-L1, and anti-PD-L2 antibodies. Patients whose radiation treatment plans are likely to encompass a volume of whole lung receiving ≥20 Gy in total (V20) of more than 35% of lung volume Planned radiation cardiac dose V50>25% Any medical contraindication of platinum-based doublet chemotherapy as listed in the local labelling or known allergy/hypersensitivity to investigational product and/or its excipients History of the following: allogeneic organ transplantation, active or prior autoimmune or inflammatory disorders, another primary malignancy, leptomeningeal carcinomatosis, active primary immunodeficiency Uncontrolled intercurrent illness or active infection