Each subject will participate in the trial until death, drop out, or loss-to follow-up from the time the subject signs the Informed Consent Form (ICF) through the final contact. After a screening phase of up to 28 days, each eligible subject will receive nivolumab. Two weeks after start of nivolumab the patients will receive radiotherapy (RT) to a total dose of 60 Gy, given as 1.5 Gy fractions twice daily for a total period of 4 weeks. Treatment with nivolumab will continue until disease progression, unacceptable adverse event(s), intercurrent illness that prevents further administration of treatment, Investigator's decision to withdraw the subject, noncompliance with trial treatment or procedures requirements, subject receives nivolumab for 12 months, pregnancy, or administrative reasons.