Second, unlike other PD-1 inhibitors, serplulimab demonstrated anti-tumor activity in small cell lung cancer in the ASTRUM-005 trial (11), raising the hypothesis that it may offer benefit in small cell esophageal carcinoma (SCEC) as well, which is an aggressive and poorly characterized histology that has not been investigated in prior immunotherapy trials. This evidence concerns the gene PDCD1 and neoplasm.