Experimental: Immunotherapy, chemotherapy, radiotherapy and surgery

Durvalumab 1500 mg administered intravenously every 3 weeks for the first 4-6 cycles (during chemotherapy);~Tremelimumab 75mg administered intravenously every 3 weeks for the first 4-6 cycles (only cohort 2)~4-6 cycles of chemotherapy, carboplatin AUC5 every 3 weeks plus paclitaxel 175 mg/m2, every 3 weeks;~Stereotactic body radiotherapy (SBRT) of all oligo-metastatic lesions, in a maximum of 10 treatment fractions over 2 weeks, starting after week one of chemotherapy cycle 1 and completed within four weeks after start of durvalumab treatment;~Restaging at 3 months; if no disease progression, proceed to definitive local treatment (surgical resection of primary tumour or radiotherapy at a minimum dose of 60-66Gy to the primary tumour). Durvalumab continues at 1500 mg intravenously every 4 weeks until progression of disease or for a maximum of 1 year from start of treatment.