The chemotherapeutic CX-5461 primarily targets TOP2B and exhibits selective activity in high-risk neuroblastoma

• Published in: Nature communications Vol. 12; no. 1; pp. 6468 - 20
• Main Authors: Pan, Min, Wright, William C., Chapple, Richard H., Zubair, Asif, Sandhu, Manbir, Batchelder, Jake E., Huddle, Brandt C., Low, Jonathan, Blankenship, Kaley B., Wang, Yingzhe, Gordon, Brittney, Archer, Payton, Brady, Samuel W., Natarajan, Sivaraman, Posgai, Matthew J., Schuetz, John, Miller, Darcie, Kalathur, Ravi, Chen, Siquan, Connelly, Jon Patrick, Babu, M. Madan, Dyer, Michael A., Pruett-Miller, Shondra M., Freeman, Burgess B., Chen, Taosheng, Godley, Lucy A., Blanchard, Scott C., Stewart, Elizabeth, Easton, John, Geeleher, Paul
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 09-11-2021; Nature Publishing Group; Nature Portfolio
• Subjects: 13; 38; 45; 49; 631/154/555; 631/67/1059/602; Adverse events; Animal models; Animals; Anticancer properties; Antitumor agents; Benzothiazoles; Blotting, Western; Cardiotoxicity; Cell Line, Tumor; Clinical trials; Cytotoxicity; DNA topoisomerase; DNA topoisomerase (ATP-hydrolysing); DNA Topoisomerases, Type II - metabolism; Drug Synergism; Enzyme Activation - drug effects; Flow Cytometry; Fluorescent Antibody Technique; Humanities and Social Sciences; Immunotherapy; Indoles - therapeutic use; Inhibitors; Leukemia; Mice; Mice, Nude; Molecular Dynamics Simulation; Morpholines - therapeutic use; multidisciplinary; Naphthyridines; Neuroblastoma; Neuroblastoma - drug therapy; Neuroblastoma - metabolism; Neuroblastoma cells; Patients; Pediatrics; Pyrimidines - therapeutic use; Real-Time Polymerase Chain Reaction; Ribonucleic acid; Risk; RNA; Science; Science (multidisciplinary); Sulfonamides - therapeutic use; Survival; Tumors; Xenografts; Xenotransplantation
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-021-26640-x

Survival in high-risk pediatric neuroblastoma has remained around 50% for the last 20 years, with immunotherapies and targeted therapies having had minimal impact. Here, we identify the small molecule CX-5461 as selectively cytotoxic to high-risk neuroblastoma and synergistic with low picomolar concentrations of topoisomerase I inhibitors in improving survival in vivo in orthotopic patient-derived xenograft neuroblastoma mouse models. CX-5461 recently progressed through phase I clinical trial as a first-in-human inhibitor of RNA-POL I. However, we also use a comprehensive panel of in vitro and in vivo assays to demonstrate that CX-5461 has been mischaracterized and that its primary target at pharmacologically relevant concentrations, is in fact topoisomerase II beta (
TOP2B
), not RNA-POL I. This is important because existing clinically approved chemotherapeutics have well-documented off-target interactions with TOP2B, which have previously been shown to cause both therapy-induced leukemia and cardiotoxicity—often-fatal adverse events, which can emerge several years after treatment. Thus, while we show that combination therapies involving CX-5461 have promising anti-tumor activity in vivo in neuroblastoma, our identification of TOP2B as the primary target of CX-5461 indicates unexpected safety concerns that should be examined in ongoing phase II clinical trials in adult patients before pursuing clinical studies in children.
CX-5461 recently progressed through phase I clinical trial as a first-inhuman inhibitor of RNA-POL I. Here, the authors demonstrate that CX-5461 synergizes with topoisomerase I inhibitors to inhibit neuroblastoma cells and that its primary target in this disease is topoisomerase II beta and not RNA-POL I.