CD8⁺ T cells are critical for elimination of cancer. A major limitation of therapeutic cancer vaccines is their inability to activate andmobilize CD8⁺ T cells for infiltration into tumor. A vaccine formulation containing SA-4-1BBL and MPL as a novel adjuvant system shows robust efficacy in activating and recruiting CD8⁺ T cells into the tumor, with subsequent effective tumor destruction in preclinical models. For details, see article by Srivastava and colleagues on page 6441.