Erasin (Erlotinib-resistance antagonizing STAT3 inhibitor) is a selective inhibitor of STAT3 with selectivity over STAT5 and STAT1 in cell-based assays. It was shown to increase the apoptotic rate of HCC-827 cells with acquired resistance against Erlotinib in addition to increasing the apoptotic rate of cultured NSCLC cells in a STAT3-dependent manner.