Study: Vaccines could prevent cancer in dogs, eventually humans
Trilly, a 9-year-old Gordon setter with fluffy brown and black fur, lay down on a raised table surrounded by doctors, veterinary technicians and photographers in the University of Wisconsin Oncology Clinic.
Her big brown eyes darted around the room, as her legs and body shook. Her owner, Caroline Randy, stroked her head to calm her.
“Good girl,” Randy said affectionately.
In a white lab coat, UW Veterinary Care oncologist David Vail put one of his hands gently on Trilly and administered a shot with the other.
“Number one,” Vail said. “History maker.”
On Thursday, Trilly became the first dog in the nation to receive an injection as part of a study involving 800 dogs to test whether a vaccine could prevent many types of cancer in dogs — and eventually humans.
Three veterinary centers from across the country, including the University of Wisconsin School of Veterinary Medicine, are participating in the five-year study — the largest clinical trial of a veterinary medicine in history. The vaccine trains the immune system to recognize a group of abnormal proteins that are common across many cancers, allowing the body to recognize and destroy the cancerous cells.
If the trial is successful, the Center for Innovation in Medicine at Arizona State University will create a cancer vaccine for humans, said Director Stephen Johnston, who invented the canine cancer vaccine. Johnston said they have the technology to make the human vaccine right now, but it would be five to 10 years until it actually becomes a product.
But that’s only if the canine trial actually works.
“I don’t know if this is going to work, and I don’t know what the odds are. It could be 10% it could be 0%,” said Johnston, who went to graduate school at UW-Madison. “But I would say that, if it did work in a dog, it will probably work in people. I would almost count on it.”
Cancer is the number one killer of aging dogs, and would be the number one killer of the aging human population if it weren’t for heart disease, Vail said.
There are some cancer vaccines for humans on the market today, but they are for treating a particular type of cancer, rather than preventing many different types. And they can cost upwards of $100,000. This vaccine would be far cheaper, Vail said, making it affordable to many in even impoverished nations.
A randomized half of the 800 dogs, 280 of which will be cared for at UW-Madison, will receive the vaccine, while the other half will get a placebo. The two groups will then be compared to see whether one has higher rates of cancer. All of the dogs in the study are between the ages of 6 and 10 and are currently cancer free.
Researchers working with the dogs will not know which pets have received the placebo and which have received the vaccine until the end of the study. So Trilly could have received the vaccine or the placebo. She will receive three more shots over the next six weeks to finish the administering process.
Either way, Trilly will get cancer screenings and high-quality medical care while she participates in the study.
“Hopefully she can help us all learn,” Randy, who has lost six of her thirteen dogs to cancer, said of Trilly.
Norton, a 9-year-old rat terrier, was also given a vaccine or placebo Thursday as a part of the study. His owner, Abbey Ace, said her grandmother recently died of pancreatic cancer, and she wanted Norton to be able to help others who get cancer in the future.
In theory, the vaccine will train the dogs’ immune systems to recognize cancerous cells before they can be detected by an MRI, Vail said.
“This vaccine is essentially putting out wanted posters to the immune system saying, ‘When you start seeing those cells, go ahead and kill them,’” Vail said.
Vail said there is a “cocktail of abnormal proteins” present in many types of cancer that the vaccine will target. Johnston has worked for the past 12 years to identify 30 abnormal proteins present in different types of cancerous tumors. The vaccine injects those 30 abnormal proteins into the dog, so its immune system can recognize the proteins in cancerous cells in the future.
If any kind of cancer arises in a dog, Johnston said there is around a 95% chance that the tumor will have around 50% of those abnormal proteins. Johnston said that should be enough for the immune system’s memory of the abnormal proteins from the vaccine to become activated and destroy the cancer before it grows larger — regardless of what type of cancer it is.
This strategy of preventing multiple cancers with one vaccine is a “paradigm shift” in how researchers approach fighting cancer, Vail said.
Focused on RNA
Though many cancer researchers are skeptical of Johnston’s method, Johnston said it sidesteps a common teaching in the field of cancer research — that tumors are individualized to each person.
Cancer researchers have tried to make vaccines to prevent cancer in the past by targeting common mutations in the DNA of cancerous tumors. But all tumors have different DNA that is specific to each individual, making it impossible to create a vaccine against all the unique mutations.
However, in the cancerous tumors’ RNA — chains of cells that use information from DNA to create proteins in the body — there are mutations that are common across different types of cancer in different dogs, or different humans, he said. These common abnormalities in the RNA of cancerous cells are what Johnston’s vaccine would train the immune system to identify and attack.
“Everybody assumed that the important mutations were occurring at the DNA level,” Johnston said. “They didn’t look under the right lamppost.”
This is the first cancer vaccine developed using this new strategy, Johnston said.
‘Like a race’
But Johnston still has worries. He said the vaccine might not prompt a strong enough response in the immune system to find the cancer cells fast enough.
“It’s sort of like a race,” Johnston said.
If the immune system doesn’t attack fast enough, cancer tumors can hide by tricking the immune system into thinking they are healthy cells, Johnston said. But even if the vaccine doesn’t prevent the primary tumor from growing, Johnston said it could help prevent the cancer from spreading, which is what most people with cancer ultimately die from.
As for Randy, she’s just happy Trilly could be a part of it. As a veterinary technician at UW-Madison, she’s excited to see where the clinical trial could go.
“This study has the potential to be just huge,” Randy said. “We haven’t had anything like this before in science.”