As shown in Figure 1A, besides SCLC‐A (ASCL1‐dominant), SCLC‐AN (combined ASCL1/NEUROD1), SCLC‐N (NEUROD1‐dominant), and SCLC‐P (POU2F3‐dominant), cluster analyses identified a fifth, quadruple‐negative SCLC subtype (SCLC‐QN) characterized by the low expression of all four investigated transcription factors. This evidence concerns the gene ASCL1 and small cell lung carcinoma.