ASCL1 and small cell lung carcinoma: In the respective analysis of the two patient cohorts and cell lines, SCLC was classified into four subtypes: SCLC-A of ASCL1+, SCLC-I of CD274+ (PD-L1), SCLC-N of NEUROD1+, and SCLC-P of POU2F3+ (Figure 1A,B).