Researchers from Ottawa have found that a combination of a flu vaccine and erectile dysfunction drug was able to reduce the number of cancer metastases following tumor removal surgery in a mouse model. While surgery is an effective first step in removing cancerous tumors, the surgery can suppress the immune system – giving an advantage to the cancer cells remaining in the body and supporting metastases to other organs. In the mouse study, the number of metastases was higher following surgery (129) than without surgery (37). But with the combination treatment, the number of metastases dropped to 11.
The treatment helps the immune system to fight the cancer. Natural killer (NK) cells usually attack metastatic cancer cells, but after surgery another cell called myeloid derived suppressor cell (MDSC) becomes active in blocking NK cells. The researchers found that erectile dysfunction drugs block MDSCs following surgery which allows the NK cells to fight the cancer. The flu vaccine further stimulates the NK cells.
A clinical trial is already underway to test the effects of tadalafil (Cialis) and inactivated flu vaccine (Agriflu) on metastases in humans following abdominal cancer surgery. Being able to re-purpose two existing medications should lead to market availability for cancer treatment much sooner than new drug development. Plus, the medications are inexpensive and widely available.