Exploring CLK2 as a novel therapeutic target in rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children and young adults. RMS treatment needs optimal multimodal therapies including chemotherapy, local disease control via surgical resection and/or radiotherapy. Unfortunately, the five-year event-free survival rate for patients with metastasis at diagnosis is below 30% and this has not been changed in the past 30 years. The 5-year progression-free survival rate for intermediate risk patients with relapsed RMS of all stages was only 17%. The long-term sequelae including cardiotoxicity and secondary cancer by intensive chemotherapy and radiotherapy have remained to be a great challenge to improve the life quality of survivors. This proposal aims to explore a new therapeutic avenue by targeting Cdc2-like kinase 2 (CLK2), a kinase that plays a key role in regulating premRNA splicing. Pre- mRNA splicing is a process to produce mature mRNA, which is tightly coupled with gene transcription. Recent studies have revealed pre-mRNA splicing deregulation in RMS. Our preliminary data show that CLK2 is one of the top ranked splicing genes that are highly expressed in RMS in comparison with normal muscle, and essential to RMS cell survival. We hypothesize that cancer cells like RMS with high transcriptional dependency are sensitive to disruption of splicing, and this vulnerability can be leveraged to develop effective therapies. The objective of this application is to test the translational feasibility of CLK2 inhibition in high-risk RMS. First, we will investigate the efficacy of CLK2 inhibition in a variety of RMS models using genetic and pharmacologic approaches (Aim 1). Second, we will determine the mechanism of action of CLK2 inhibition in RMS cells by RNA-seq analysis and functional validation (Aim 2). Our innovative proposal has the translation potential to the clinic in near future, and is impactful for patients with high-risk RMS, and other pediatric cancers that are driven by oncogenic TFs and have dysregulated splicing. Mouse models are essential for this project because they enable evaluation of CLK2 function within an intact tumor microenvironment, including stromal and immune components that critically influence tumor growth and therapeutic responses but cannot be recapitulated in vitro. Project Number: 1R21CA307748-01A1 | Fiscal Year: 2026 | NIH Institute/Center: National Cancer Institute (NCI) | Principal Investigator: Jun Yang | Institution: ST. JUDE CHILDREN'S RESEARCH HOSPITAL, MEMPHIS, TN | Award Amount: $475,681 | Activity Code: R21 | Study Section: Special Emphasis Panel[ZRG1 CTH-X (81)] View on NIH RePORTER: https://reporter.nih.gov/project-details/11454705