ASCL1 and small cell lung carcinoma: Although NE subtypes based on the expression of those TFs have been previously described in SCLC7,10, the existence of these subtypes in treatment-emergent NEPC was unanticipated, as ASCL1 and NEUROD1 have been specifically associated with lung NE cells8,9,27, the putative cell of origin of the de novo SCLC.