Could a shot in the arm help destroy a growing tumor? That concept is looking more and more plausible.
Scientists have been investigating the potential of vaccines to prevent various types of cancer for several years. In 2010, one study found that a single vaccination prevented breast cancer tumors from forming in mice.
A team of researchers at the National Cancer Institute's Laboratory of Tumor Immunology and Biology now is reporting in the journal Clinical Cancer Research that a vaccine might show promise in treating (as opposed to preventing) both metastatic breast cancer and ovarian cancer.
Led by cancer researcher James Gulley, the team assigned 26 patients to monthly Panvac vaccinations, which are a recombinant poxviral vaccines that contain transgenes for MUC1, CEA (carcinoembryonic antigen), and three T cell co-stimulatory molecules. While the clinical trial was very small, it was on actual humans, not mice or other animals.
The patients all had advanced stages of the disease, and as such, they had been heavily pretreated, with 21 of the 26 having undergone at least three chemotherapy regimens before enrolling in the trial.
Among the 12 patients with breast cancer, the median overall survival was 13.7 months; among the 14 patients with ovarian cancer, median overall survival was 15 months. (Without a control group, it's tough to say what sort of improvement this might be.)
One notable improvement was seen in a woman with breast cancer who had already had a lumpectomy, radiation therapy, chemotherapy, and a hysterectomy. After three years, tumors that had already spread to her lymph notes regressed, and she exhibited a complete response to the vaccine.
"With this vaccine, we can clearly generate immune responses that lead to clinical responses in some patients," Gulley, director and deputy chief of the clinical-trials group, said in a statement. "The sustained benefit seen in some patients in this study underscores the potential for therapeutic vaccines to impact clinical outcomes without toxicity."
Gulley does stress that this is just the first of what will surely be many studies investigating the vaccine's efficacy, defining appropriate patient populations, and, of course, determining when to administer the vaccine, should it prove to be effective.
With vaccines being used to target bacteria, cancerous cells, and infectious diseases, what's next?