A multi-disciplinary team of University of Saskatchewan researchers is investigating a promising new cancer treatment option that could potentially be used to treat lymphoma in dogs as well as in people.
Metformin is an anti-diabetic drug that is commonly used to treat Type 2 diabetes. It induces a protein in the cells which is responsive to stress and helps to potentially clean up damaged cells.
“If it finds a cell with damaged DNA, it essentially makes a decision to fix the damage or get rid of the cell. We know that it can stop the growth of normal cancer cells and drug-resistant cancer cells,” said Dr. Troy Harkness, a professor at the U of S College of Medicine.
“The lymphomas that dogs get are very similar to human lymphomas, and they’re actually treated with the same drugs,” Harkness continued. “They’re a perfect model for human cancers, and we can get results much faster than with human trials.”
The collaborative research team includes veterinary medical oncologist Dr. Valerie MacDonald and small animal internal medicine specialist Dr. Casey Gaunt from the Western College of Veterinary Medicine. They’re working with Harkness, endocrinologist Dr. Terra Arnason and research associate Dr. Jerry Davies from the U of S College of Medicine. The team will begin treating canine lymphoma patients at the WCVM’s Veterinary Medical Centre with metformin early in 2013.
Canine patients enrolled in the study will receive metformin as part of their cancer treatments. During their therapy, Harkness and his team will analyze samples from the dogs to see if results are similar to those they’ve seen at a cellular level.
From the time of diagnosis, canine lymphoma patients have a median survival time of one year. Standard treatment involves a chemotherapy regimen, a multiple-drug protocol that includes 16 treatments over 19 weeks. To ensure that the dogs maintain a good quality of life, doses are relatively low when compared to human chemotherapy protocols.
“The doses we use are effective, but our intent is not to make them sick,” explained MacDonald. “We know that we’re not going to cure them of the disease, but we can keep it in remission for a period of time.”
Unfortunately, when canine lymphoma comes out of remission, the cancer cells are often resistant to drugs used during the initial chemotherapy protocol. For that reason, a second course of chemotherapy includes less-effective drugs that may cause more side effects.
Metformin could potentially help to add time to patients’ lives by killing drug-resistant cells and making it possible to reuse the initial drug protocol. Since drug resistance is a problem with all kinds of tumours, future studies could include other types of cancer and more patients in other centres.
To gather enough patients that fit the study’s requirements, MacDonald and Gaunt are asking local veterinarians to refer dogs that have already received chemotherapy but have developed drug resistance.
Harkness is hopeful that local dog owners will be more willing to include their animals in a U of S-based study. “I think it gives confidence to the public that this is all local work. These are all local people working with local animals, and they’re easily accessible to the dog owners if they want to talk to them and ask questions.