High-throughput screening identified pacritinib as a promising therapeutic approach to overcome lenvatinib resistance in hepatocellular carcinoma by targeting IRAK1.

Lenvatinib resistance presents a significant challenge in the clinical management of advanced hepatocellular carcinoma (HCC). To address this issue, we established lenvatinib resistant HCC cells and performed high-throughput screening using FDA-approved anti-cancer drug library. Through quantitative selective drug sensitivity scoring (sDSS), pacritinib, a well-known JAK inhibitor, emerged as the top candidate, displaying the highest sDSS score among 219 compounds. We further demonstrated that pacritinib reduced the viability of a panel of HCC cell lines in a dose-dependent manner, while exhibiting minimal effects on normal liver cells. Interestingly, pacritinib, but not other JAK inhibitors such as ruxolitinib, upadacitinib, or filgotinib, acted synergistically with lenvatinib in HCC cells. In lenvatinib-resistant HCC cells, pacritinib significantly decreased proliferation and induced apoptosis. Rescue studies using IL-1 receptor-associated kinase 1 (IRAK1) overexpression and knockdown revealed that pacritinib's effects are mediated through IRAK1, with minimal impact on normal liver cells. In a xenograft model of lenvatinib-resistant HCC, oral administration of pacritinib significantly reduced tumor size without affecting body weight. Immunohistochemical analysis of tumor sections revealed that pacritinib reduced Ki67 staining and phosphorylated IRAK1. Our findings suggest that pacritinib may be a promising therapeutic option for the treatment of advanced HCC, particularly in patients who have developed resistance to lenvatinib.