Dendritic cell cancer vaccines work by loading dendritic cells with tumor antigens to activate T-cells and cytotoxic T-lymphocytes to eliminate cancerous cells. There are currently 52 dendritic cell cancer vaccines in clinical development targeting various cancer types. Most are in Phase 2 trials. Three dendritic cell cancer vaccines have been approved for prostate cancer, renal cell carcinoma, and melanoma. Challenges include improving antigen presentation and developing vaccines that can target multiple cancer types. However, genetically modified dendritic cell vaccines show potential for hard to treat cancers like brain tumors.