The initial dichotomy between the two molecular subtypes of neuroendocrine (NE) SCLCs followed from the identification of the NE transcription factors ASCL1 (achaete-scute homologue 1) and NEUROD1 (neurogenic differentiation factor) as ASCL1-high and NeuroD1-high SCLC tumors, respectively [10,11]. Here, NEUROD1 is linked to small cell lung carcinoma.