Supporting our finding, rising evidence of RNA-seq showed the HDAC inhibitor sensitive gene signature of NEUROD1-subtype SCLC, but the immune system-enriched HDAC inhibitor resistant gene signature of SCLC-Y [40], which was consistent with the enrichment of immune signaling pathways in SCLC-Y [8,41,42]. Here, HDAC9 is linked to small cell lung carcinoma.