Robert H. Vonderheide, MD, PhD (Damon Runyon-Lilly Clinical Investigator ‘00-‘05) and colleagues at University of Pennsylvania School of Medicine, Philadelphia, reported that the drug daclizumab (Zenapax) improved the survival of breast cancer patients taking a cancer vaccine by 30 percent (seven months), compared to those patients not taking the drug. Daclizumab, approved for use in preventing transplant rejection, targets Tregs (regulatory T cells) that normally prevent the immune system from detecting and attacking tumors. The researchers tested the drug in ten patients with metastatic breast cancer prior to giving them an experimental breast cancer vaccine. The tumors stopped growing in six of these patients. This drug, in combination with other immunotherapy, may be useful for treatment of other cancer types as well. These promising results were published in the journal Science Translational Medicine.