Recent studies revealed that the classic subtype is driven by high ASCL1 expression (hence renamed as SCLC-A), whereas the variant subtype is driven by high NEUROD1 expression (renamed as SCLC-N), both broadly defined as NE subtypes, contrasting with two non-NE subtypes further identified as SCLC-P and SCLC-Y9 (Fig. 1a). Here, NEUROD1 is linked to small cell lung carcinoma.