By incorporating both fresh samples and FFPE-archived tissues, our scRNA-seq profiling recaptured the previous NE-based molecular subtypes defined by ASCL1, NEUROD1, and POU2F3 but, more importantly, added a cellular transformation trajectory from peripheral blood immunity to local immunity highlighting potential roles of Mono/myeloid cell populations in regulating the TIME dynamics of SCLC, a finding also supported at protein level by our fluorescence in situ profiling. Here, NEUROD1 is linked to small cell lung carcinoma.