Immune checkpoint inhibitors in special populations. A focus on advanced lung cancer patients

Immune checkpoint inhibitors (ICIs), including those targeting programmed cell death 1 (PD-1), its ligand 1 (PD-L1), or cytotoxic T-lymphocyte antigen 4 (CTLA-4) have become the standard treatment for several malignancies, including lung cancer. However, some patient populations have been routinely excluded from clinical trials or are underrepresented in these studies, as is the case of elderly patients or patients with poor performance status, brain metastases, solid organ transplant, autoimmune diseases, chronic viral infections (such as human immunodeficiency virus or chronic viral hepatitis B and C), or organ dysfunction. Thus, the safety and efficacy of ICIs in these special populations is still unclear, despite regulatory approval of these agents. This review analyzes and summarizes the available information on the efficacy and safety of ICIs in these special populations, focusing on patients with lung cancer.