Abstract PO012: In silico drug repurposing identifies mebendazole as a treatment option for chemoresistant hepatoblastoma

Abstract Resistance to conventional chemotherapy remains a huge challenge in the clinical management and treatment of hepatoblastoma, the most common liver tumor of childhood. The in silico repurposing of drugs with known pharmacokinetics and safety profiles, which have been approved for other indications, represents a promising strategy to identify new drugs effective in chemoresistant hepatoblastoma. In this study, we integrated RNA sequencing-derived gene expression data into the pharmacologic perturbation prediction tool Connectivity Map (CMap) and identified the clinical widely used anthelmintic drug mebendazole as a putative drug to circumvent chemoresistance in hepatoblastoma. Consequently, we experimentally validated the efficacy of mebendazole in permanent and patient-derived xenograft cell lines that are resistant to cisplatin, the therapeutic backbone of hepatoblastoma treatment. Viability assays clearly indicated a potent reduction of tumor cell growth upon mebendazole treatment in a dose-dependent manner. In contrast, similar mebendazole concentrations had little inhibitory effect on the growth of normal neonatal and adult skin fibroblasts. The combination of mebendazole and cisplatin revealed a strong synergistic effect, which was comparable to the one seen with cisplatin and doxorubicin (cardiotoxic), the current standard treatment for high-risk hepatoblastoma patients. Moreover, mebendazole treatment resulted in reduced colony formation capability, induction of apoptosis, and cell cycle arrest of hepatoblastoma cells. Immunofluorescent staining of alpha-tubulin showed that mebendazole causes blockage of microtubule formation and subsequent RNA sequencing analyses confirmed the transcriptional downregulation of tubulins as the major mode of action of mebendazole treatment. Most importantly, mebendazole significantly reduced tumor growth in a subcutaneous xenograft transplantation mouse model. In conclusion, our results strongly support the clinical use of mebendazole as a replacement for doxorubicin in the treatment of chemoresistant hepatoblastoma. This could potentially not only improve outcome but also reduce severe long-term side effects. Citation Format: Qian Li, Salih Demir, Xuanwen Bao, Alexandra Wagner, Yanxin Fan, Stefano Cairo, Roland Kappler. In silico drug repurposing identifies mebendazole as a treatment option for chemoresistant hepatoblastoma [abstract]. In: Proceedings of the AACR Special Conference: Advances in the Pathogenesis and Molecular Therapies of Liver Cancer; 2022 May 5-8; Boston, MA. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(17_Suppl):Abstract nr PO012.