In addition, we also performed immunohistochemistry (IHC) on formalin-fixed paraffin-embedded (FFPE) tissues from a large cohort of 90 SCLC patients (Supplementary Table S5), in which, the expression of ASCL1 and NEUROD1 were evaluated at the protein level (Supplementary Fig. S6g). Here, NEUROD1 is linked to small cell lung carcinoma.