Abstract
Since the initial US FDA approval of an immune checkpoint inhibitor (ICI) for the treatment of non-oncogene-driven non-small-cell lung cancer (NSCLC) nine years ago, this therapeutic strategy has been cemented as a crucial component of treatment for most of these patients. However, there is a clear efficacy-effectiveness gap whereby patients in the 'real world' seem to have more modest clinical outcomes compared to those enrolled in landmark clinical trials. This gap may be driven by the under-representation of important patient populations, including populations defined by clinical or molecular characteristics. In this review, we summarize the data outlining the evidence of ICIs in patients with poor Eastern Cooperative Oncology Group performance status (ECOG PS), underlying autoimmune disease (AID), older age, active brain metastases (BMs), and molecular aberrations such as EGFR mutations, ALK fusions, BRAF mutations and ROS1 fusions.