CD8A and cancer: An important, but nuanced, biological advantage of mRNA vaccines is the recent discovery that in order for immunotherapy to eliminate solid tumors, there needs to be a functioning intratumoral “triad” of synergistic activity between i) antigen-presenting cells (APCs)/dendritic cells; ii) activated CD4+ T cells and iii) activated CD8+ T cells which licenses CD8+ T cell cytotoxicity and elimination of cancer cells (41).