PDCD1 and neoplasm: It has been reported that NSCLC in smokers has a distinct mutation signature leading to increased neoantigen generation which contributes to the efficacy of immune checkpoint inhibitors so that former or current smokers with NSCLC have a significantly higher response rate to PD-1 inhibitors compared with patients with minimal/no tobacco exposure.16–18 Assuming that NSCLC with a driver gene mutation may harbour fewer mutations than smokers, EGFR mutation-positive tumours may have less neoantigen and may be less responsive to nivolumab.