Combinatorial CRISPR screen revealsFYNandKDM4as targets for synergistic drug combination for treating triple negative breast cancer

Tyrosine kinases play a crucial role in cell proliferation and survival and are extensively investigated as targets for cancer treatment. However, the efficacy of most tyrosine kinase inhibitors (TKIs) in cancer therapy is limited due to resistance. In this study, we identify a synergistic combination therapy involving TKIs for the treatment of triple negative breast cancer. By employing pairwise tyrosine kinase knockout CRISPR screens, we identifyFYNandKDM4as critical targets whose inhibition enhances the effectiveness of TKIs, such as NVP-ADW742 (IGF-1R inhibitor), gefitinib (EGFR inhibitor), and imatinib (ABL inhibitor) bothin vitroandin vivo. Mechanistically, treatment with TKIs upregulates the transcription ofKDM4, which in turn demethylates H3K9me3 atFYNenhancer forFYNtranscription. This compensatory activation ofFYNandKDM4contributes to the resistance against TKIs.FYNexpression is associated with therapy resistance and persistence by demonstrating its upregulation in various experimental models of drug-tolerant persisters and residual disease following targeted therapy, chemotherapy, and radiotherapy. Collectively, our study provides novel targets and mechanistic insights that can guide the development of effective combinatorial targeted therapies, thus maximizing the therapeutic benefits of TKIs.