Targeting TLK2 with antisense oligonucleotides as a new strategy in acute myeloid leukemia.

Introduction: Tousled-like kinase 2 (TLK2) is a serine/threonine kinase that plays a role in DNA replication, chromatin remodeling, and DNA damage response. TLK2 has been implicated in the pathogenesis of various types of cancer, including breast cancer, glioblastoma, and acute myeloid leukemia (AML). However, no potent and selective TLK2 inhibitors have been developed. Methods: We evaluated the efficacy of a human TLK2 antisense oligonucleotide (ASO) alone and in combination with gilteritinib in AML cell lines. To assess in vivo efficacy and toxicity, we administered a mouse TLK2 ASO alone or in combination with gilteritinib in a murine model of AML. Results: TLK2 ASO treatment resulted in a dose-dependent reduction of TLK2 mRNA levels and decreased cell viability in FLT3-mutant AML cell lines, with enhanced cytotoxicity observed when combined with gilteritinib. In a murine AML model, TLK2 ASO achieved approximately 50% knockdown efficiency. Both TLK2 ASO alone and in combination with gilteritinib significantly reduced spleen size, leukemia burden, and bone marrow progenitor cell populations. The treatment was generally well tolerated, with only minimal toxicity observed. Discussion: This study demonstrates that TLK2 ASO is a promising therapeutic strategy for AML, particularly in combination with FLT3 inhibition, and may apply to other TLK2-driven cancers. Future efforts should focus on improving ASO delivery and knockdown efficiency to maximize therapeutic benefit.