The Grapevine

Treatment With Erectile Dysfunction Drug, Flu Vaccine May Reduce Cancer Spread

Could the unconventional combination of the flu vaccine and erectile dysfunction drugs help the immune system fight cancer cells left behind after surgery? After a mouse study showed promising results, which were published in the journal OncoImmunology, the strategy is now being tested in the first clinical trial of its kind in the world.

"Surgery is very effective in removing solid tumors," said senior author Dr. Rebecca Auer, surgical oncologist and head of cancer research at The Ottawa Hospital, Canada. "However, we're now realizing that, tragically, surgery can also suppress the immune system in a way that makes it easier for any remaining cancer cells to persist and spread to other organs."

Dr. Auer, who is also an associate professor at the University of Ottawa, said the new findings suggested a combination of erectile dysfunction drugs and the flu vaccine may block this from happening and prevent the cancer from returning after surgery.

Researchers used a mouse model which replicated metastasis (or the spread of cancer) after surgery. The new study examined the effects of sildenafil (Viagra), tadalafil (Cialis) and an inactivated influenza vaccine (Agriflu) on the mice. 

The results showed the erectile dysfunction drugs helped in reversing the suppression of the immune system by reactivating natural killer (NK) cells which help in fighting cancer but were blocked by suppressor cells after surgery. The vaccine also reduced post-surgery metastasis by stimulating the NK cells.

An average of 129 metastases was found in the mouse lungs with cancer cells and surgery. After the administration of one of the erectile dysfunction drugs, the figure was 24 metastases. With the combination of one of the erectile dysfunction drugs and the flu vaccine, the researchers found only 11 metastases on average.

"We're really excited about this research because it suggests that two safe and relatively inexpensive therapies may be able to solve a big problem in cancer," said Dr. Auer. "If confirmed in clinical trials, this could become the first therapy to address the immune problems caused by cancer surgery."

Currently, Dr. Auer is leading the first clinical trial in the world of an erectile dysfunction drug (tadalafil) and the flu vaccine in people with cancer. Twenty four patients from the Ottawa Hospital, who are undergoing abdominal cancer surgery, will take part in the trial.

"Cancer immunotherapy is a huge area of research right now, but we're still learning how best to use it in the time around surgery," said first author Dr. Lee-Hwa Tai, an assistant professor at the Université de Sherbrooke, Canada, and a former postdoctoral fellow in Dr. Auer's lab. "This research is an important step forward that opens up many possibilities."

While the flu vaccine and erectile dysfunction drugs are easily available to most people, Dr. Auer cautioned cancer patients should not self-medicate. Instead, she encouraged them to seek advice from their oncologist if they wish to change their medication.