While a number of genes such as TP53, PTEN and CDKN2A/B are critical to tumor malignancy, in this review we focus on six druggable molecules: isocitrate dehydrogenase (IDH), telomerase reverse transcriptase (TERT), BRAF, O6-methylguanine-DNA methyltransferase (MGMT), histone3-lysine27 (H3K27)/histone3-guanine34 (H3G34), and NTRK/ROS1. The gene discussed is MGMT; the disease is neoplasm.