Trial tests unusual drug combo to treat cancer
Flu vaccine and erectile dysfunction drugs come together in clinical trial
Combine erectile dysfunction drugs and a dose of flu vaccine and what do you get?
Researchers at The Ottawa Hospital are beginning the first clinical trial in the world to test whether the surprising drug combination can reduce the spread of cancer after surgery.
Researchers, led by Dr. Rebecca Auer, an oncologist and head of cancer research at the hospital, published a study in the medical journal Oncolmmunology showing the unconventional strategy reduced the spread of cancer by more than 90 per cent in mice.
Surgery, which is the most effective treatment for many forms of cancer, suppresses the immune system, which can pave the way for the spread of cancer to other parts of the body in some patients.
Auer said the combination of the erectile dysfunction drugs — known as phosphodiesterase type 5 inhibitors — and the flu vaccine help to avoid immune suppression after surgery by hyper-stimulating so-called natural killer cells using the flu vaccine, while at the same time blocking a kind of immune cell that fights those natural killer cells, using the erectile dysfunction drug.
The results, when tried on mice, were significant. The study used Viagra and Cialis (both erectile dysfunction drugs) along with a flu vaccine and counted the number of metastasis (spread of cancer) on mouses’ lungs to measure efficacy. They found an average of 129 metastases after surgery compared with 11 after surgery with erectile dysfunction drugs and flu vaccine.
Now researchers will begin testing the treatment combination on humans, beginning with a Phase 1 trial.
Jackie Fletcher, an Ottawa Hospital nurse who is currently on leave after cancer surgery, was the first person to consent to take part in that trial.
She said she quickly agreed when Auer explained the research to her — in part because she works in health care and knows firsthand the importance of research, but also because, as a cancer patient, “it gives you hope.”
Fletcher’s cancer diagnosis came as a shock.
She was having some tests done in advance of another, unrelated surgery, when doctors found a large tumour in her abdomen. Fletcher said she had no symptoms, even though the tumour, a rare form of abdominal cancer called liposarcoma, was the size of a football and wrapped around her kidney.
She required surgery to remove the growth, but Fletcher said it is a type of cancer that can grow back, requiring more surgeries.
She leapt at a chance to take part in a clinical trial that has potential to reduce the spread of cancer.
“It sounded safe and wasn’t that invasive, if it was going to boost my immune system, sure.”
She admits she found the drug combination unusual.
“I laughed and said I always wanted to try one of those erectile dysfunction drugs.”
Auer said researchers wanted to find drugs that “had a pretty good safety profile” for the trial, especially since they would both be given to patients right around the time of surgery — the erectile dysfunction drug a few days ahead of surgery and the flu vaccine in the operating room.
The initial clinical trial will evaluate the safety of the drug combination. Auer said if things go well, researchers could be starting a larger late-stage clinical trial in five years or so to test how the drugs work in stopping the spread of cancer.
They are also looking for drugs that have similar impacts on the immune system after surgery that might work better and have fewer side-effects. Cialis has the obvious side-effect of causing erections in men, although it has no effect on women. The bigger issue, said Auer, is that if the wrong dose is used, it can inhibit other immune cells.
She calls the impact of surgery on cancer an “unmet need” in oncology.
Auer notes that although erectile dysfunction drugs and flu vaccine are readily available, people with cancer should not self-medicate.