The FDA-approved drug daclizumab improves the survival of breast cancer patients taking a cancer vaccine by 30% compared with those patients not taking daclizumab, according to a recent study published in Science Translational Medicine.
A team from the Perelman School of Medicine and the Abramson Family Cancer Research Institute at the University of Pennsylvania proposed that daclizumab would be effective in diminishing regulatory T cells (Tregs) and rebuilding the immune system’s ability to fight tumors.
The clinical trial, directed by coauthor Kevin Fox, MD, professor of medicine, involved 10 patients with metastatic breast cancer. The patients were administered daclizumab prior to receiving an experimental breast cancer vaccine developed and manufactured at Penn.
“Daclizumab worked incredibly well,” says senior author of the study, Robert H. Vonderheide, MD, DPhil, associate professor of medicine. The T-cell conversion in the patients on daclizumab lasted 2 months, and there were no detectable side effects. Although the tumors didn’t shrink, in 6 out of the 10 patients the tumors ceased growing. Compared with patients on the cancer vaccine alone, the daclizumab patients had an increased survival of about 7 months. According to Vonderheide, all previous attempts to eliminate Tregs have been toxic and short-lived, but the effects of daclizumab were observed to be rapid, prolonged, and consistent.
“Although we tested our approach in patients with breast cancer, we know that Tregs can block the immune response against most human cancers,” says Vonderheide. “Drugs like daclizumab might be useful for most cancer patients, especially those receiving other types of immune therapy. Although Tregs do help prevent autoimmunity, we did not observe an autoimmune response because we did not convert all Tregs in the body, only those cells that seem to protect the tumor. Going after only some, but not all Tregs, we believe, was an important and unique aspect of our study. Although there is a great deal of work to do to confirm our findings, we believe this will have major implications for cancer vaccine regimens in other types of cancer.”
Source: Penn Medicine.