PDCD1 and non-small cell lung carcinoma: Before the era of molecular-targeted agents and immune checkpoint inhibitors (ICIs) such as a programmed cell death protein 1 (PD-1) antibody, the age of eligibility of elderly patients with advanced non-small cell lung cancer (NSCLC) in phase III randomized trials was often defined as 65 or 70 years [1], and only 30–50% of patients enrolled in these trials were aged ≥75 years [1].