NEUROD1 and small cell lung carcinoma: We did not observe high expression of either CD274 (PD‐L1) or CTLA4 in malignant cells (Figure S3e, Supporting Information), consistent with previous findings that PD‐L1 expression was lower in SCLC than in other tumor types.[22] Based on the expression of ASCL1 and/or NEUROD1, all the malignant cells could be clustered into 4 subpopulations: 1) an ASCL1‐positive subpopulation (A+), 2) a NEUROD1‐positive subpopulation (N+), 3) a double‐positive (A+N+) subpopulation, and 4) a small population of a double‐negative (A‐N‐) subpopulation (Figure 2c).