Safety evaluation of nivolumab added concurrently to radiotherapy in a standard first line chemo-radiotherapy regimen in stage III non-small cell lung cancer—The ETOP NICOLAS trial

•Immune- plus chemo-radiotherapy as promising strategy in curative setting of NSCLC.•Concurrent PD-1/L1-inhibition and radiotherapy not yet assessed in clinical trials.•Safety results of prospective trial of concurrent nivolumab and chemo-radiotherapy.•No unexpected adverse events or increased risk for severe pneumonitis observed.