Abstract 514: Therapeutic potential of antidepressant amitriptyline in medulloblastoma

Abstract Introduction: Medulloblastoma, the most common malignant brain tumor in children, primarily arises in the posterior fossa, predominantly affecting the cerebellum. Accounting for approximately 20% of all pediatric brain tumors, medulloblastoma has an annual incidence of about 500 cases in the United States, with a peak age of diagnosis between 5 and 7 years and a slight male predominance. Advances in genomic and epigenomic profiling have identified four distinct subgroups—WNT, Sonic Hedgehog (SHH), Group 3, and Group 4—each characterized by unique molecular features, patient demographics, and prognostic outcomes. Current treatment strategies, including surgical resection, craniospinal irradiation, and adjuvant chemotherapy, have improved survival rates; however, up to 40% of patients experience incurable recurrence or metastasis, the leading cause of mortality. Furthermore, survivors often endure debilitating long-term side effects from these aggressive therapies, underscoring the urgent need for more effective and less toxic therapeutic approaches. Methods: To evaluate the anticancer activity of Amitriptyline, we utilized SHH (DAOY) and Group 3 (HDMB03, D556, D425) medulloblastoma cell lines. Cell viability, survival, and apoptosis were assessed through established functional assays. The impact of Amitriptyline on cancer stemness was investigated using sphere formation and extreme limiting dilution assays. Mechanistic studies were conducted through RNA sequencing, quantitative RT-PCR, and Western blot analysis to elucidate molecular pathways. The therapeutic potential of Amitriptyline was further validated in vivo using orthotopic xenograft mouse models of medulloblastoma. Results: Amitriptyline treatment significantly inhibited cell viability, colony formation, and migratory capacity while promoting apoptosis in medulloblastoma cell lines. Additionally, Amitriptyline reduced the viability and sphere-forming ability of medulloblastoma stem cells, indicating a potent effect on cancer stemness. Notably, Amitriptyline enhanced the therapeutic efficacy of Vincristine in medulloblastoma cell lines. In vivo studies demonstrated that Amitriptyline treatment significantly prolonged survival in the orthotopic xenograft mouse model, with no sign of toxicity, highlighting its therapeutic potential. Conclusion: Collectively, our findings suggest that Amitriptyline may serve as a viable therapeutic option for medulloblastoma, providing a basis for potential clinical application. Citation Format: Frank B. Wang, Prabhakar Pitta Venkata, Andrew Brenner, William Kelly, Gangadhara R. Sareddy, Manjeet K. Rao. Therapeutic potential of antidepressant amitriptyline in medulloblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 514.