evidence: The history of cancer vaccines has been the subject of excellent reviews14, most of which have focused on the physical structure of the antigen being introduced: whole tumor, tumor cells, protein, peptides (long or short), RNA or DNA (directly or virally); and the adjuvants with which antigen is introduced: carrier protein, cells (for example, dendritic cells (DCs)), proteins (for example, CD40 ligand (CD40L)) or chemicals (for example, oil–water emulsions and Toll-like receptor (TLR) agonists). Here, we classify current cancer vaccines differently, based on (1) what is known of a tumor’s specific immunogenic antigen, (2) which patients’ tumors express those antigens and (3) how the antigens become colocalized with professional antigen-presenting cells (APCs). Vaccines can incorporate either predefined (known) or anonymous (unknown) antigens (Fig. 1a). The former includes either predefined shared antigens (expressed in many patient tumors) or predefined personalized antigens (exclusively determined for each patient). Anonymous antigen vaccines can be colocalized with APCs either ex vivo (in a laboratory) or in situ (at the tumor site; Fig. 1a).