Recently, significant success has been observed in the treatment of small cell lung cancer with both international Programmed cell death ligand-1 (PD-L1) inhibitors, such as atezolizumab and durvalumab, and localized Programmed cell death protein-1 (PD-1)/PD-L1 inhibitors, such as serplulimab and adebrelimab (Horn et al. 2018; Paz-Ares et al. 2019; Cheng et al. 2022; Wang et al. 2022) However, not all patients benefit from immunotherapy. Here, PDCD1 is linked to small cell lung carcinoma.