Splicing-associated network PAK1-CLK1/4-SRRM1 is a vulnerability to overcome chemoresistance in human and mouse acute myeloid leukemia.

Chemotherapy resistance in acute myeloid leukemia (AML) remains a major clinical challenge. Integration of multiomic profiling and in vivo functional genomics revealed splicing dysregulation as a determinant of chemoresistance in AML. We uncovered a network involving the splicing regulator SRRM1 and the CLK1/4 and PAK1 kinase families as vulnerabilities in chemoresistant AML cells. Both kinase families are hyperactivated in chemoresistant cells, promoting SRRM1 phosphorylation and altering its scaffolding function. We also identified a relapse-associated PAK1 variant, c.1429G>T p.(Ala477→Ser), that confers chemotherapy resistance. Combined PAK1 and CLK1/4 inhibition recapitulated the splicing changes induced by SRRM1 loss, preferentially targeting chemoresistant AML and enhancing chemotherapy efficacy in cell lines, primary cells, and mouse models. Last, we pinpointed MAP2K5 as a critical downstream effector because missplicing of exons 17 and 18 of MAP2K5 upon SRRM1 depletion sensitized cells to chemotherapy. Our findings highlight a therapeutic strategy to overcome AML relapse by targeting splicing dysregulation.