小细胞肺癌的免疫特征

Small cell lung cancer (SCLC) is a type of malignancy with poor prognosis, and no advance in medication has been made for about 30 years except immune checkpoint inhibitor (ICI), which demonstrated efficacy in recent years. The response rate of programmed death-1 (PD-1) inhibitor alone or its combination with cytotoxic T-lymphocyte antigen-4 (CTLA-4) inhibitor as subsequent therapy was 10%-33% and the response duration was persistent. The combination of programmed death ligand-1 (PD-L1) inhibitor with chemotherapy resulted in longer survival versus chemotherapy alone. Nevertheless, comparing with immunotherapy-sensitive tumors such as non-small cell lung cancer (NSCLC), efficacy in SCLC is still unsatisfied and this is maybe associated with its immune inhibitory characteristics. This review describes the current research about immune characteristics of SCLC, including tumor infiltrating of lymphocytes (TIL) and immune inhibitory cells, PD-L1 and major histocompatibility complex (MHC) expression in tumor as well as changes of peripheral immune cells. We also review the prognostic and predictive values of these immune characteristics.