In cancer immunotherapy, mRNA vaccines work by encoding tumor-associated antigens or tumor-specific neoantigens, which are translated into proteins after cellular uptake and presented via major histocompatibility complex (MHC) class I and II molecules to activate cytotoxic CD8+ T cells and helper CD4+ T cells (Figure 1) [2,5,6,7]. The gene discussed is CD8A; the disease is neoplasm.