Abstract 7066: Comparative in vivo evaluation of RG-7388, CM-272, and SGI-1027 to determine epigenetic targeting as an effective strategy for treating high-risk neuroblastoma.

Abstract Background: High-risk neuroblastoma remains a therapeutic challenge due to its chemoresistance, epigenetic modification, and TP53 pathway dysregulation. SK-N-AS cells, which harbor TP53 mutations and exhibit highly aggressive behavior, provide a clinically relevant model for evaluating novel epigenetic and apoptotic pathway-targeting agents. This study investigated the therapeutic efficacy of the MDM2 inhibitor (RG-7388), the dual DNMT1/G9a inhibitor (CM-272), and the DNMT inhibitor (SGI-1027) in an SK-N-AS xenograft mouse model. Methods: Athymic Nu/Nu mice bearing subcutaneous SK-N-AS tumors were randomized into treatment groups and administered RG-7388, CM-272, SGI-1027, or vehicle control (DMSO) according to an optimized dosing schedule. Tumor volumes, body weight, survival rate, and treatment-related toxicity were monitored over the study period. Excised tumors were analyzed for cell-cycle arrest markers, DNA-methylation regulators, apoptotic mediators, and histone acetylation/methylation levels via qRT-PCR and Western blot. Results: Treatment of Cell Derived Xenograft (CDX) animals with CM-272 significantly reduced tumor growth compared to control. Interestingly, treatment with RG-7388 also induced potent tumor suppression but exhibited a less durable response compared to CM-272. The anti-cancer effects produced by CM-272 was robust by showing significant reduction in tumor volume with minimal toxicity, accompanied by marked up-regulation of cell-cycle arrest markers, apoptotic mediators. In addition, a significant increase in the histone acetylation levels, which often serve as DNA/histone methylation regulators, indicated strong epigenetic reprogramming. Mechanistically, both CM-272 and SGI-1027 exhibited strong apoptotic activation, while RG-7388 primarily removed MDM2-associated stress signaling, despite the mutant/null status of TP53 in SK-N-AS cells. Survival analysis showed that CM-272 prolonged survival the most, followed by RG-7388 and SGI-1027. Conclusion: Epigenetic targeting of DNMT and G9a using CM-272 produced the strongest anti-tumor and survival benefit in the SK-N-AS CDX model, outperforming both RG-7388 and SGI-1027. CM-272’s ability to simultaneously inhibit DNMT1 and G9a, appears to reduce repressive chromatin marks, and activate apoptosis cascade that highlights its translational potential for treating TP53-mutant and epigenetically driven neuroblastoma. These initial findings suggest advancing preclinical optimization and combination-therapy strategies involving CM-272 for high-risk neuroblastoma. Acknowledgements: This work was supported by the National Pediatric Cancer Foundation (NPCF), the Florida Department of Health through a Bankhead-Coley Infrastructure Grant, and the Royal Dames of Cancer Research, Inc., Ft. Lauderdale, Florida. Citation Format: Umamaheswari Natarajan, Shyam S. Jaganathan, Appu Rathinavelu. Comparative in vivo evaluation of RG-7388, CM-272, and SGI-1027 to determine epigenetic targeting as an effective strategy for treating high-risk neuroblastoma 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 7066.