Abstract 3023: Preclinical study of TR-412, a novel and highly selective CLK inhibitor for acute myeloid leukemia

Abstract Alternative splicing (AS) is a major mechanism for diversifying mRNA transcripts and regulating protein expression. Most tumors exhibit widespread splicing abnormalities relative to peritumoral healthy tissues, including frequent retention of normally excised introns, inappropriate expression of isoforms normally restricted to other cell types or developmental stages, and splicing errors that disable tumor suppressors or promote oncogene expression. The CDC2-like kinases (CLKs) and dual-specificity tyrosine-regulated kinases (DYRKs) are thought to govern the efficiency and specificity of AS by directly phosphorylating serine/arginine-rich splicing factors (SRSFs) and thereby influencing pre-mRNA splice junction selection. TR-412 is a novel inhibitor of CLK2/3 and DYRK1A/B, which was evaluated its anti-leukemic activities both in vitro and in vivo. TR-412 showed strong inhibitory effects in an exon-skipping luciferase reporter assay, achieving an IC50 of 120 nM. Furthermore, it significantly suppressed the proliferation of hematological malignancies, with a median IC50 of 350 nM. To understand the mechanism of anti-cancer cell growth, the effect of TR-412 on AS and protein expression of key tumor related biomarkers were examined. The experimental results showed that TR-412 effectively inhibited pSRSF (IC50 <100 nM in AML cells). In addition, RNA-seq analysis revealed that TR-412 induced global splicing changes, which typically resulted in exon exclusion (exon skipping) of cassette exon. To further investigate the effect of TR-412 on tumor growth in vivo, we established multiple AML-derived subcutaneous xenograft models (CDX), which were treated with varying doses of TR-412. In particular, complete tumor regression was achieved in the MV4-11 tumor model. Overall, the preclinical findings strongly support that this novel CLK inhibitor TR-412 is worthy of further exploration in hematologic malignancies. Citation Format: Wentao Zhang, He Tian, Mengyang Yan, Qian Shao. Preclinical study of TR-412, a novel and highly selective CLK inhibitor for acute myeloid leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3023.