A clinical trial using novel vaccines could lead to better treatments for breast cancer treatment in both animals and humans, according to researchers at the University of Guelph Ontario Veterinary College (OVC) and McMaster University’s Immunology Research Center.
The universities recently teamed up to treat breast cancer in cats using new vaccines designed to boost the immune system and kill tumor cells without harming healthy tissue.
OVC announced the clinical trial on its website in late October.
Researchers are studying cats because breast cancer occurs naturally in the species. Breast cancer in cats is also similar to that in humans, said Professor Paul Woods, one of the lead investigators. Woods is also a veterinary cancer specialist at OVC and co-director of University of Guelph’s Institute for Comparative Cancer Investigation (ICCI).
“Breast cancer in cats tends to by highly aggressive and doesn’t respond well to chemotherapy,” Woods said. “By the time a mammary tumor is detected and diagnosed, the disease has often spread to other parts of the body. So while there’s a lot we can do for cats with standard treatment—which is surgery to remove the tumor—the patient will typically relapse in six to eight months. Our goal with these vaccines is to extend that time as much as possible and to maximize their quality of life.”
The clinical trial is expected to involve up to 30 cats over the next two years.
Maci, a 12-year-old cat, has already received the therapy at OVC’s Mona Campbell Center for Animal Cancer. Maci responded well to her therapy and is recovering at home with her family in Toronto, according to OVC.
“OVC is a unique resource in Canada that not only gives us access to top-notch research infrastructure, but provides a large catchment area of several million people and their pets,” said Brian Lichty of McMaster’s Immunology Research Center. “In order to develop and test new biological therapeutics, we need realistic animal models of human cancer, which is exactly what a large, genetically diverse population of cats with naturally occurring cancer provides. The hope is that, in addition to developing an effective therapy for cats, we’ll be able to apply what we learn here toward strengthening our strategy for treating breast cancer in people.”
Lichty has been working with Byram Bridle, a viral immunologist in OVC’s Department of Pathobiology. The pair developed a strategy for getting oncolytic viruses and the cat’s immune system to mount a coordinated attack on cancer cells.
Each cat in the study will receive two vaccines, one prior to surgery and one after, according to the University of Guelph. Each vaccine contains a virus modified to carry three genes associated with breast cancer.
The first is an injection of a non-replicating adenovirus vaccine intended to trigger an anti-tumor immune response. About four weeks after the tumor is removed via surgery, the second vaccine will be delivered by an intravenous infusion. It employs a novel oncolytic Maraba virus that can only replicate in tumor cells, according to the University of Guelph.
“In effect, this virus hunts down cancer cells anywhere in the body, infecting and killing them directly,” the university noted. “This causes them to express the target protein, generating an even greater immune response.”
Everyone is excited to get the clinical trial underway, Woods said.
“It’s precisely this kind of work that we had in mind when we first launched the ICCI and the animal cancer center,” he said. “Pets are part of the family, and many of our clients are keen to try novel therapies—especially when they know that they are contributing to advancing cancer treatment for future human and animal patients.”