Principal inclusion criteria :

1. Subjects with histologically- or cytologically-documented NSCLC
2. Locally advanced, unresectable (Stage III) NSCLC
3. World Health Organisation (WHO) performance status 0-1
4. At least one measurable lesion, not previously irradiated
5. Must have a life expectancy of at least 12 weeks at randomization

Principal exclusion criteria :

1. Receipt of prior or current cancer treatment, including but not limited to, radiation therapy, investigational agents, chemotherapy, Durvalumab and mAbs.
2. 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, excluding therapeutic anticancer vaccines.
3. History of allogeneic organ transplantation
4. Active or prior documented autoimmune or inflammatory disorders
5. Uncontrolled intercurrent illness
6. History of another primary malignancy / leptomeningeal carcinomatosis / active primary immunodeficiency
7. Active infection including tuberculosis, hepatitis B, hepatitis C, or human immunodeficiency virus
8. Mixed small cell and NSCLC histology
9. Any medical contraindication to treatment with platinum-based doublet chemotherapy as listed in the local labelling
10. Known allergy or hypersensitivity to any of the IPs or any of the IP excipients.
11. 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.