A dendritic cell vaccine for both vaccination and neoantigen-reactive T cell preparation for cancer immunotherapy in mice.

Adoptive cell transfer (ACT) using neoantigen-specific T cells is an effective immunotherapeutic strategy. However, the difficult isolation of neoantigen-specific T cells limits the clinical application of ACT. Here, we propose a method to prepare neoantigen-reactive T cells (NRT) for ACT following immunization with a tumor lysate-loaded dendritic cell (DC) vaccine. We show that the DC vaccine not only induces a neoantigen-reactive immune response in lung cancer-bearing mice in vivo, but also facilitate NRT cell preparation in vitro. Adoptive transfer of the NRTs as combinatorial therapy into DC vaccine-immunized, LL/2 tumor-bearing mice allows infiltration of the infused NRTs, as well as the enrichment of neoantigen reactive, non-ACT/NRT T cells into the tumor microenvironment with the function of these neoantigen-reactive T-cell receptors validated in vitro. In summary, we propose a method for preparing NRTs that increases ACT efficacy and paves the way to the design of personalized immunotherapies.