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Ashley and Evan Lewis of Caledon, Ont., with their dog, Missy (Dean Palmer for the Globe and Mail)
Ashley and Evan Lewis of Caledon, Ont., with their dog, Missy (Dean Palmer for the Globe and Mail)

HEALTH

Heal, boy: How companion animals can help find cures for human cancer Add to ...

Paul Woods offers a friendly farewell and a pat to Gypsy, a patient who has just received her final treatment of chemotherapy and who happens to be heading out the door with her human companion as I come in. Gypsy is a six-year-old golden retriever whose lymphoma is in remission after a course of treatment at the University of Guelph’s Mona Campbell Centre for Animal Cancer.

It has been a happy outcome for the beloved pet, whose active life has been restored by the treatment. Dr. Woods, a veterinary medical oncologist, says her type of cancer, similar to non-Hodgkins lymphoma in humans, is expected to relapse at some point, an eventuality he has discussed with her owner.

But while that means there will probably be difficult decisions in the future for Gypsy’s human family, the dog is fine for now. “All she knows is she feels much better than she did six months ago,” Woods says. “I got her into a spot where she doesn’t know she has cancer.”

The vignette encapsulates the mission of the three-year-old Mona Campbell Centre, which is to help companion animals, the animals who live and bond with us, and maintain their quality of life when possible. It is the first facility in Canada to provide a full range of options for treating animal cancers, including surgery and radiation therapy, with the best available standard of care.

A total of $13.75-million was raised to build the centre, with two thirds of that coming from a single donation. Its services, which typically run from hundreds to thousands of dollars, are generally paid for directly by pet owners or through private insurance.

Ashley and Evan Lewis of Caledon, Ont., with their dog, Missy. (Photo by Dean Palmer)

In a society where economic circumstance and personal philosophies on animal health fall across a broad spectrum, it’s easy to imagine the centre striking some people as a luxury.

But cancer researchers see it differently. In Woods and his colleagues, they have found a new and formidable set of partners in their quest for cures to human disease.

It’s easy to see why. Unlike genetically standardized laboratory mice, which are a mainstay of medical research, domestic dogs and cats are more diverse, just like humans. They also share our home environments and, often, our food. Their cancers are equally diverse and naturally occurring, unlike those of lab mice, which have to be deliberately implanted. This makes companion animals far better analogs for human cancer patients, a feature that has led to a growing number of clinical trials for new therapies in pets as a precursor to human trials.

“The philosophy is that if therapies can work in these companion-animal populations, they have a much better chance of successfully translating into humans,” says Byram Bridle, a viral immunologist at the Ontario Veterinary College at Guelph.

Bridle is collaborating with Woods and researchers at other universities on clinical trials that they hope will inform and potentially accelerate effective treatments for human patients.

The new centre at Guelph has made it possible to contemplate this approach for a number of reasons. First, it draws on a large pool of potential participants. During a typical week, there are about 100 appointments for animals – about 85 per cent are dogs – mostly from across Central Canada and the Northeastern United States, but occasionally from overseas. Second, it has the facilities to sample and bank thousands of animal tumours, allowing researchers to compare cancerous with non-cancerous cells in individual animals and also look at what changed when cancers recurred after treatment.

But what is equally important, if less obvious, is that the centre is ideally set up for clinical trials of cancer therapies precisely because its approach to treatment is like that of a human cancer hospital. That means animals are already provided with well-established treatments in addition to any exploratory therapies they may be offered as part of a clinical trial, just as human patients would.

For Bridle, this is crucial because a major stumbling block for many experimental cancer treatments comes when a therapy developed in isolation with mice is introduced into the real-world setting of a cancer ward, where it will interact in unpredictable ways with other treatments and protocols already under way.

Missy receiving radiation therapy at the Mona Campbell Centre for Animal Cancer in Guelph, Ontario. (Photo by Dean Palmer)

“That’s one of the key advantages of this kind of trial,” he says. “We’re trying to get these therapies to work in that context.”

Bridle’s research focuses on immune therapy, an area that has shown huge promise in recent years as scientists learn how to ramp up the body’s immune system so that it can be harnessed to identify and kill cancer cells. A handful of drugs have already been approved for cancer patients, but scientists are finding that they may work best when used in combination.

The problem is that trials that can test all the possible combinations of immune-therapy treatments to find the most effective ones are expensive and time-consuming. Human trials require enormous regulatory and administrative infrastructure to maintain standards and safety. Dog trials are also closely regulated, but the process is far less costly. By using dogs, Bridle and his collaborators hope to accelerate the discovery process. For the same cost of one human trial, about 10 trials can be run in dogs, any one of which may identify a winning treatment.

This has proved to be the big attraction for Jason Moffat and Sachdev Sidhu, two molecular geneticists at the University of Toronto who are known for their work identifying and synthesizing antibodies – proteins that can be tailored to help identify cancer cells and block the cancer’s ability to switch off the immune system.

With federal funding through BioCanRx, a newly created research network designed to boost immune-therapy research in Canada, the U of T group is now eager to move its work into clinical trials with dogs. The project is particularly well positioned to leverage what the Mona Campbell Centre can offer. Rather than simply working with antibodies found in nature, the group has developed expertise in building antibodies made to order, like Tinkertoy machines made from a standard set of parts. That means they have the potential for taking an antibody with demonstrated effectiveness against canine tumours and rebuild it specifically to work in humans.

The group is working toward a clinical trial in dogs with melanoma starting about a year from now. At the same time, Bridle has been funded by the Terry Fox Foundation to begin a dog trial using an immune-therapy approach to bone cancer.

The strategy is a dramatic shift in thinking from a time when cancer treatments moved from mice into humans and then, only later, might be attempted on pets. Now, researchers are more inclined to embrace what is known as comparative oncology, which examines the phenomenon of cancer across species.

For Arlene Weintraub, a New York-based science journalist and author of Heal, a new book that explores the growing role of dogs in the search for cancer cures, the developments at Guelph are part of a trend to enlist companion animals just as human patients have been enlisted for years in groundbreaking research.

“When I started this, like a lot of people, I had a vague notion that dogs get cancer, but I had no idea that they get cancers that are so similar to many of the worst types of cancers that affect people,” she says.

The idea that discoveries meant to improve animal health could also translate into extending and saving human lives is a powerful motivator for those who donate to facilities such as the Mona Campbell Centre, says Kim Robinson, managing director of Pet Trust, a fundraising arm of the Ontario Veterinary College that channels donations toward animal health.

Missy has rhabdomyosarcoma, a relatively rare form of cancer that can strike children and also occurs in young dogs. (Photo by Dean Palmer)

“The commonality among all our donors is that they love their pets,” Robinson says. “But if the advances we can make in animal medicine are going to help people, then it’s a win-win. Everybody wants to fight this disease.”

Woods agrees. He stresses that the centre’s main aim is helping animals, but that its wider importance is appreciated by the pet owners who come in and may find themselves deciding whether to include their pets in a trial.

The Guelph centre is now the first Canadian member of a broader 20-centre consortium managed by the U.S. National Cancer Institute with the goal of designing clinical trials in companion dogs with cancer to assess the efficacy of new therapies. The membership brings the 1,200-square-foot facility into the leading edge of a growing field. By extension, that pets and pet owners in Canada will probably have an opportunity to advance the frontier of cancer research both in animals and people.

“The pet population mirrors our population,” Woods says. “If we can do better treating that pet population, we’re hoping some of that will translate into helping people as well.”

In her book Heal, science writer Arlene Weintraub describes several research advances made possible in recent years with the help of pets who were enlisted in clinical trials much as human patients would be.

Oncept, a therapeutic melanoma vaccine for dogs approved by the U.S. Food and Drug Administration in 2007, was based on an idea by Jedd Wolchok, a researcher at the Memorial Sloan Kettering Cancer Center in New York. While successful in trials with companion dogs, the drug ended up not working in people. However, “it did inform the development of many other melanoma immunotherapies that have completely changed the treatment paradigm for the disease,” Weintraub says.

In 2012, the San Diego-based biotech company Genelux recruited companion dogs for a trial of V-VET1, a genetically modified form of cowpox virus that can invade cancer cells. Since then, many more companies have been working on engineering viruses to perform a similar role.

The Mona Campbell Centre for Animal Cancer in Guelph is involved in a clinical trial involving pet cats of a tumour-fighting virus developed at McMaster University to attack breast cancer cells. Cats have turned out to be very good models for human breast cancer. A similar virus-based treatment to the one being tested at Guelph may be approved by the FDA later this month.

Editor's note: An earlier digital version of this story stated that the Mona Campbell Centre was established with a $9.5-million private donation; however, a total of $13.75 million was raised to build the centre, with two thirds coming from a single donation. This version has been updated for clarification.

Companions in cancer science

In her book Heal, science writer Arlene Weintraub describes several research advances made possible in recent years with the help of pets who were enlisted in clinical trials much as human patients would be.

-Oncept, a therapeutic melanoma vaccine for dogs approved by the U.S. Food and Drug Administration in 2007, was based on an idea by Jedd Wolchok, a researcher at the Memorial Sloan Kettering Cancer Center in New York. While successful in trials with companion dogs, the drug ended up not working in people. However, “it did inform the development of many other melanoma immunotherapies that have completely changed the treatment paradigm for the disease,” Weintraub says.

-In 2012, the San Diego-based biotech company Genelux recruited companion dogs for a trial of V-VET1, a genetically modified form of cowpox virus that can invade cancer cells. Since then, many more companies have been working on engineering viruses to perform a similar role.

-The Mona Campbell Centre for Animal Cancer in Guelph is involved in a clinical trial involving pet cats of a tumour-fighting virus developed at McMaster University to attack breast cancer cells. Cats have turned out to be very good models for human breast cancer. A similar virus-based treatment to the one being tested at Guelph may be approved by the FDA later this month.

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