Abstract 5872: CLK inhibitor BH-30236 synergizes with venetoclax in anti-leukemia activity via splicing modulation in preclinical AML and CLL models

Abstract Alterations of splicing patterns are increasingly recognized as a hallmark of cancer by promoting proliferation, evading apoptosis, changing cell signaling, and driving drug resistance through aberrantly spliced isoforms. In hematologic malignancies of both myeloid and lymphoid lineages, including myelodysplastic syndromes (MDS), acute myeloid leukemia (AML), and chronic lymphocytic leukemia (CLL), frequent mutations or overexpression of RNA splicing factors are associated with aberrant alternative splicing. CDC-like kinases (CLKs) regulate alternative splicing by phosphorylating serine/arginine-rich splicing factors (SRSFs) which are essential for splice site recognition and spliceosome assembly. Thus, targeting CLKs represents a promising therapeutic strategy, especially in hematologic malignancies with splicing dysregulation. BH-30236 is a novel, potent, orally bioavailable, ATP-competitive, small molecule kinase inhibitor of CLK1/2/4. BH-30236 inhibited the phosphorylation of SRSFs in cancer cells, leading to modulation of splicing patterns and RNA/protein expression of genes related to apoptosis and DNA damage response pathways, thereby promoting apoptosis. In addition, the expression of stem cell markers was downregulated by BH-30236 in AML cell lines. BH-30236 effectively inhibited the proliferation of hematologic cancer cell lines or leukemia cells from AML or CLL patients. In addition, effective anti-tumor activity of BH-30236 was observed in tumor models derived from AML cell lines or leukemia patients. A synergistic anti-cell proliferation effect between BH-30236 and venetoclax, a BCL2 inhibitor, was consistently observed across multiple hematologic cancer cell lines of diverse lineages. The synergy is likely driven by BH-30236 mediated suppression of anti-apoptotic and pro-survival proteins including MCL1, a pro-survival factor whose upregulation is associated with resistance to venetoclax. Moreover, the combination of BH-30236 and venetoclax synergistically induced complete tumor regression in the highly resistant MOLM13 cell-derived xenograft tumor model. This in vivo synergistic effect was observed even when BH-30236 or venetoclax was administered at low dose levels. Notably, modification of combinatory treatment regimen after achieving complete tumor regression to single agent BH-30236 treatment sustained tumor-free survival in mice and maintained tumor free for more than 80 days, even after treatment discontinuation. This finding is consistent with BH-30236 modulation of leukemia stem cells via regulation of alternative splicing. BH-30236 is currently under clinical investigation, either as a single agent or in combination with venetoclax, in adults with relapsed or refractory AML or higher risk MDS in a Phase 1/1b clinical trial (NCT06501196). Citation Format: Wei Deng, Ping Jiang, Zhenping Wang, Yue Hu, Nancy Ling, Danan Li, Joshua Choi, Eugene Y. Rui, Zachary Zimmerman, Geoffrey Oxnard, J. Jean Cui, . CLK inhibitor BH-30236 synergizes with venetoclax in anti-leukemia activity via splicing modulation in preclinical AML and CLL models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 5872.