The Canadian STOP-GAP study (NCT02821013) [38], is a phase 3 trial which randomises eligible patients within 16 weeks of starting anti-PD-1 therapy to standard treatment of 2 years or to treatment until maximal tumour response (defined by at least 2 radiological measurements 3 months apart) with re-treatment at time of progression. This evidence concerns the gene PDCD1 and neoplasm.