Abstract 5472: Direct cytotoxicity of hu14.18K.322A in high-risk neuroblastoma

Abstract

Abstract Background: Neuroblastoma is a childhood cancer of the sympathetic nervous system and is associated with disialoganglioside GD2 overexpression. The main goal of this study is to investigate the involvement of GD2 targeting humanized antidisialoganglioside monoclonal antibody hu14.18K.322A (hu14) in high-risk neuroblastoma direct cell cytotoxicity, assess for synergy with induction chemotherapy agents, and delineate the mechanisms involved in cell death. Methods: For this study, we used a panel of GD2 expressing cell lines [SK-N-BE (2), SK-N-BE (1), LAN5, CHLA15] and a GD2 non-expressing cell line LAN6. We measured surface expression of GD2 and performed cell cycle analysis using flow cytometry. The role of hu14 in neuroblastoma cell death was assessed using cell viability assays, proliferation assays, real time PCR and western blot analysis. We measured synergy between hu14 and induction phase chemotherapy drugs. Further, we employed next generation sequencing (NGS) to analyze the transcriptomic changes in human neuroblastoma cell lines in response to hu14 treatment to understand the pathways involved and the molecular mechanisms of hu14-mediated cellular response. Results: Using a cell viability assay, we found that CHLA15 and SK-N-BE (1) cell lines were sensitive to hu14 treatment whereas SK-N-BE (2), LAN5, LAN6 were resistant. Hu14 treatment resulted in a dose dependent reduction in cell proliferation in these cell lines. We also found that hu14 treatment resulted in increased expression of apoptotic and autophagy pathway proteins, but not ferroptosis or necroptosis pathways proteins. Hu14 induced cell death was partially inhibited by a pan-caspase inhibitor, confirming that caspase-dependent pathways are involved. Western blot analysis also showed decreased levels of p53 phosphorylation in both sensitive cell lines upon hu14 treatment suggesting an important control mechanism centered on the p53 pathway. Hu14 treatment reduced the surface expression of GD2 in the sensitive cells suggesting direct inhibition of the GD2 synthesis pathway. However, PCR analysis of GD2 synthesis genes did not show any significant difference upon treatment suggesting posttranscriptional control of these genes. Furthermore, NGS analysis revealed alterations in several pathways, but these changes were distinct between the cell lines reconfirming the complexity of therapy response in high-risk Neuroblastoma. Conclusion: Taken together, our findings suggest that hu14.18K322A induces direct cell cytotoxicity in a subset of high-risk Neuroblastoma and synergizes well with standard chemotherapy drugs. Furthermore, our research highlights the complex nature of signaling pathways involved in hu14-mediated cytotoxicity that can be harnessed towards targeted therapy. Citation Format: Manu Gnanamony, Maria Thomas, Thu Hien Nguyen, Amber M. D'Souza, Pedro de Alarcon. Direct cytotoxicity of hu14.18K.322A in high-risk neuroblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5472.