Comprehensive evaluation of MEK inhibitors for malignant peripheral nerve sheath tumors reveals differences in efficacy and drug resistance development

Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive soft-tissue sarcomas which lack effective drugs. Previous studies support the usefulness of MEK inhibitors (MEKis) for treating RAS-driven tumors, however, the lack of preclinical assessment of MEK inhibitors in MPNSTs limit the clinical application as well as the development of combination therapy. In this study, we comprehensively evaluated 8 MEK inhibitors in terms of efficiency, safety and mechanisms of resistance for treating MPNSTs. We identified the most promising MEK inhibitor, trametinib, for the treatment of MPNSTs. Through high-throughput transcriptomic sequencing and drug screening, we discovered the upregulation of integrin signaling contributing to MEK inhibitor resistance, termed as cell adhesion-mediated drug resistance (CAM-DR). We also confirmed MET overactivation in MEKi-resistant MPNST cells. These targets are potential solutions to overcome MEKi- resistance in clinical applications. The mRNA profiles of resistant and non-resistant MPNST cell lines were generated by deep sequencing, in triplicate, using Illumina GAIIx.