Cell-based immunotherapy has shown encouraging results in solid cancers. However, major limitations of this approach include difficulty with isolation and generation of effective antigen-presenting or immune effector cells and the high cost of cell-based vaccines. In glioblastoma (GBM), the most common and lethal brain cancer in adults, inadequate migration of immune cells across the blood-brain barrier represents another major obstacle to cell-based immunotherapy. One approach to overcome these barriers is to convert GBM cells directly into immune cells of interest. Transdifferentiation, the transformation of one cell type other than stem cells directly into another cell type without an intermediate pluripotent stage, has shown early promise in regenerative medicine, but has had a limited role as a cancer therapy, especially for solid tumors. This is in large part due to the laborious and time-consuming process of identifying master fate determinants of the cell types of interest in the transdifferentiation. To enable this novel application, we have developed and experimentally validated two tandem computational platforms, GeneRep and nSCORE. Applying this novel algorithm to large quantities of published and in-house gene expression datasets, we successfully predicted cell fate determinants of tens of different cell types with several having been validated in transdifferentiation experiments by others and us, such as the conversions of astrocytes to neuronal stem cells, of astrocytes to glioma stem-like cells, of fibroblasts to macrophages, etc. Here, we describe the process of combining a unique core set of hematopoietic stem cell, myeloid, and macrophage or dendritic cell (DC) fate determinants—some have not been described as critical in these cell fates—as predicted and highly ranked by GeneRep-nSCORE to efficiently transdifferentiate GBM cells into functional macrophages or dendritic cells, respectively, while neutralizing their malignant phenotype. This novel transdifferentiation has the potential for transformative impacts in many areas, including DC vaccine immunotherapy and cancer therapy in general, and pioneers the concept that solid tumor cells can be converted into another cell type, and not just any cell type, but one that potentially can elicit a therapeutic response against itself.

Citation Format: Mathew Sebastian, Son B. Le, Changwang Deng, Nagheme Thomas, David D. Tran. Direct transdifferentiation of glioblastoma cells to antigen-presenting cells: A novel immunotherapeutic approach [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4072.