Prolonged KRAS-MAPK Inhibition Induces Interferon-mediated Epithelial-to-Mesenchymal Transition and Reveals Therapeutic Opportunities.

Direct targeting of KRAS to inhibit the MAPK cascade is poised to transform the therapeutic landscape of pancreatic ductal adenocarcinoma (PDAC). However, analyses of PDAC samples from patients treated with KRASG12C inhibitors have revealed secondary mutations restoring MAPK signaling and promoting epithelial-to-mesenchymal transition (EMT) as key mechanisms of acquired resistance. Here, we show that human PDAC specimens and patient-derived cell lines treated with the ERK inhibitor ulixertinib display upregulation of EMT-associated and inflammatory gene programs, particularly those linked to the interferon response. Using the GeneRep-nSCORE computational framework to reconstruct and rank regulatory networks enriched in ERKi and KRASi-resistant PDAC cells, we identified TRIM22, an interferon-inducible E3 ubiquitin ligase, as a critical mediator of EMT and treatment resistance. Mechanistically, TRIM22 promotes proteasomal degradation of IκBα, leading to activation of NF-κB signaling, a known driver of EMT. Notably, we identify TACSTD2, encoding Trophoblast Cell Surface Antigen 2 (TROP2), as an NF-κB target gene upregulated following EMT. Functionally, combining ulixertinib or the KRAS inhibitor MRTX1133 with the TROP2-directed antibody-drug conjugate sacituzumab govitecan significantly suppressed the growth of PDAC patient-derived xenografts. Together, our work identifies TRIM22 as a molecular link between interferon signaling and EMT and reveals TROP2 as a druggable vulnerability to sustain the therapeutic efficacy of KRAS-MAPK pathway inhibitors.