ERK Inhibitor ASN007 Effectively Overcomes Acquired Resistance to EGFR Inhibitor in Non-small Cell Lung Cancer

Abstract The emergence of acquired resistance limits the long-term efficacy of EGFR tyrosine kinase inhibitors (EGFR-TKIs). Thus, development of effective strategies to overcome resistance to EGFR-TKI is urgently needed. Multiple mechanisms to reactivate ERK signaling have been successfully demonstrated in acquired resistance models. We found that in EGFR mutant non-small cell lung cancer (NSCLC) patients, acquired resistance to EGFR-TKIs was accompanied by increased activation of ERK. Increased ERK activation was also found in in vitro models of acquired EGFR-TKI resistance. ASN007 is a potent selective ERK1/2 inhibitor with promising antitumor activity in cancers with BRAF and RAS mutations. ASN007 treatment impeded tumor cell growth and the cell cycle in EGFR-TKI-resistant cells. In addition, combination treatment with ASN007 and EGFR-TKIs synergistically decreased the survival of resistant cells, enhanced induction of apoptosis, and effectively inhibited the growth of erlotinib-resistant xenografts, providing the preclinical rationale for testing combinations of ASN007 and EGFR-TKIs in EGFR-mutated NSCLC patients. This study emphasizes the importance of targeting ERK signaling in maintaining the long-term benefits of EGFR-TKIs by overcoming acquired resistance.