Through unsupervised clustering of tumor cells from the scRNA-seq datasets, we identified the distinct subtype (MS1) of human SCLC characterized by CRACDlow, EZH2-mediated gene repression, and MHC-I pathway suppression, distinguished from MS2, with CRACDhigh and a functional MHC-I pathway. Here, EZH2 is linked to small cell lung carcinoma.