Abstract
Immunotherapy now plays a key role in supplementing and even replacing conventional agents in tumor treatment. Immune checkpoint inhibitors (ICIs), represented by atezolizumab and durvalumab, have shown encouraging therapeutic effects in the combination chemotherapy for extensive-stage small cell lung cancer (SCLC) and have become preferred regimens. It has marked a seminal shift in the treatment landscape with achieving for the first time that overall survival exceed 1 year. However, the extent to which SCLC patients can benefit from ICIs is limited, and ICIs' combination treatment strategies still need to be continuously explored. Beyond the ICIs in combination with radiotherapy, the anti-angiogenic target has been a combination option to improve effectiveness. And the novel formula of immune drugs, such as antibody-drug conjugates, bispecific T cell engager therapy, and chimeric antigen receptor T-cell immunotherapy, also promotes the potential option for SCLC patients. Based on the molecular development and biomarkers analysis of the sensitivity to immune checkpoint of the SCLC subtypes, the exploration of new targets and the development of drugs with novel mechanisms may provide fresh hope for immunotherapy in SCLC.