A new cancer vaccine could boost the positive effects of existing immunotherapy drugs, improving the success rate of treatments from 20% to 75% of cases, according to a new study by immunologists from the University of Konstanz. The vaccine, which incorporates a new immunostimulant that is safe for use in humans, was shown to partially eliminate tumors in mice. However, the study further demonstrated that combining the vaccine with an immune checkpoint inhibitor—an established immunotherapy drug with a 20% success rate overall for patients—can vastly improve the proportion of individuals who respond to treatments, eliminating tumors in 75% of cases in mice. The results suggest that this new approach of using a vaccine in combination with established drugs may be a potent anti-cancer immunotherapy to be tested in future clinical trials. The findings appeared in Nature Communications on May 18, 2021.