Cancer immunotherapies are achieving promising results in the clinic, yet further improvements are desired. These most likely will be obtained from approaches that includes enhanced stimulation of tumor-specific T-cells, as well as reducing the immunosuppression caused by the tumor. Our results demonstrated for the first time that the combination of retinoic acid-loaded polymeric nanoparticles and a virus vaccine, Ad5-OVA, can increase the blood levels of tumor-specific T-cells and improve the survival of tumor challenged mice.