Identification and Evaluation of Novel Antigens for Use with Oncolytic Vaccines
Harsimrat Birdi1,2, Fanny Tzelepis1, Mohsen Hooshyar1, Jean-Simon Diallo1,2* 1Center for Innovative Cancer Research, Ottawa Hospital Research Institute, Ottawa, ON, Canada; 2Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada *Corresponding Author
Cancer immunotherapies focused on tumor-specific T cell responses are promising therapeutic alternatives to chemotherapy because in addition to eliminating cancer cells, they can also establish an active and long-term surveillance against relapsing tumors. The premise for active immunotherapy is the recognition of tumor-specific and/or tumor-associated antigens by immune cells. Approaches that have been explored to this end include cancer vaccines and transfer of autologous T-cell receptor (TCR) or chimeric antigen receptor (CAR)-transduced cells. Importantly, the applicability of T-cell focused therapies depends on identifying a suitable tumor antigen, and in some instances also knowing its associated TCR. This poses a technological challenge and is a key bottleneck for the development of new and/or personalized active immunotherapies. Current methodologies for antigen discovery have important drawbacks in that they can be prohibitively time-consuming (e.g. generation of T cell clones) or are ineffective to identify truly immunogenic antigens and matching T cell receptors (TCR). To address this, we are developing a new/improved strategy for the simultaneous discovery of targetable tumor antigens and their matching TCR. A lynchpin of this methodology is a novel approach to isolate target cell-T cell pairs by flow cytometry. Here we describe the optimization of this approach in the context of a test antigen ovalbumin, allowing us to isolate antigen-specific doublets of ovalbumin-specific T-cells and cells expressing their cognate antigen. We expect that this method will lead to new targetable antigens for cancer as well as a new methodology applicable to a wide range of applications from cancer immunotherapy to infectious disease.