MUCIN 1 confers inflammatory memory of tyrosine kinase inhibitor resistance in non-small cell lung cancer.

Resistance of NSCLCs to osimertinib, an EGFR tyrosine kinase inhibitor (TKI), is mediated by pleotropic mechanisms that pose a significant challenge for subsequent treatment. We report that the oncogenic MUC1-C/M1C protein confers resistance to osimertinib by regulating the STAT1 and interferon (IFN) type I/II pathways. Studies of osimertinib-resistant NSCLC cell lines selected for growth in the absence of drug demonstrate dependence on MUC1-C and the STAT1 pathway for memory of the refractory phenotype. This inflammatory memory of TKI resistance is mediated through activation of the MUC1 gene at (i) a proximal enhancer-like signature 1 (pELS-1) by MUC1-C and STAT1 and (ii) a pELS-2 by MUC1-C, JUN/AP-1, and PBAF. Our results further reveal that the MUC1-C-driven STAT1 inflammatory response promotes resistance of patient-derived (i) EGFR mutant NSCLC cells with MET amplification to the combination of osimertinib+MET TKIs, and (ii) EGFR(T790M/C797S) NSCLC cells to the 4th generation EGFR TKI TQB3804. Of clinical significance, we report that NSCLC cells dependent on MUC1-C for TKI resistance are druggable with an antibody-drug conjugate (M1C ADC) in vitro and in a PDX tumor model. These findings demonstrate that MUC1-C (i) is essential for TKI resistance of NSCLC cells by driving an inflammatory memory response and (ii) is a target for M1C ADC treatment of TKI-refractory NSCLCs.