Abstract 4216: Tipifarnib inhibits the secretion of tumor-derived small extracellular vesicles and enhances the immunotherapeutic efficacy of dinutuximab in neuroblastoma

Abstract

Abstract Anti-GD2 monoclonal antibody (Dinutuximab) immunotherapy has significantly improved the overall survival rate for high-risk neuroblastoma patients. However, 40% of patients fail to respond or develop resistance to the treatment, and the molecular mechanisms by which this occurs remain poorly understood. Here we utilize the syngeneic 9464D-GD2 mouse model to investigate the role of neuroblastoma tumor-derived small extracellular vesicles (sEVs) in developing resistance to the anti-GD2 monoclonal antibody Dinutuximab. Neuroblastoma-derived sEVs significantly attenuated the efficacy of Dinutuximab treatment in vivo. Mechanistically, both RNA-sequencing and flow cytometry analysis of whole tumors demonstrated that neuroblastoma-derived sEVs modulate immune cells tumor infiltration upon Dinutuximab treatment to create an immunosuppressive tumor microenvironment, which contains more tumor-associated macrophages (TAMs) and fewer tumor-infiltrating NK cells, in addition to suppression of splenic NK cell maturation in vivo. Moreover, neuroblastoma-derived sEVs suppressed Dinutuximab-mediated NK cell antibody-dependent cellular cytotoxicity in vitro. Importantly, Tipifarnib, a farnesyltransferase inhibitor that inhibits sEV secretion, drastically enhanced the efficacy of Dinutuximab in vivo and reversed the immunosuppressive effects of neuroblastoma-derived sEVs. Notably, Tipifarnib modulated immature myeloid cells in the bone marrow to disfavor the formation of CD11b+Ly6ChighLy6Glow subpopulations, which are the precursors for TAMs. Taken together, these preclinical findings uncover a novel mechanism by which neuroblastoma-derived sEVs modulate the immune system to promote resistance to Dinutuximab and suggest that Tipifarnib-mediated inhibition of sEV secretion may serve as a viable treatment strategy to improve immunotherapy in high-risk patients. Citation Format: Xiaoming Liu, Carson A. Wills, Longgui Chen, Jiawen Zhang, Yuanjun Zhao, Mi Zhou, Jeffrey M. Sundstrom, Todd D. Schell, Vladimir S. Spiegelman, Megan M. Young, Hong-Gang Wang. Tipifarnib inhibits the secretion of tumor-derived small extracellular vesicles and enhances the immunotherapeutic efficacy of dinutuximab in neuroblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4216.