Canine Cancer research may speed advances

University of Illinois researchers are studying genetic similarities between some dog and human cancers, work they say may allow pet dogs to serve as useful models for studying new chemotherapies. University of Illinois veterinary clinical medicine professor Timothy Fan said pet dogs with naturally occurring cancers, rather than laboratory-induced tumors, are better subjects for early cancer drug trials.
"We have a lot of dogs in the United States, approximately 70 million of them, and it's believed that about 25 percent of pet dogs will develop some form of cancer in their lifetime," Fan said. "We're using dogs to help guide drug development for people, but at the same time we're offering new, innovative therapies that would otherwise never be available to dogs, to help them as well."

"Dogs tend to develop cancer as a geriatric population, just like people," he said. "Because the tumors develop spontaneously, there is heterogeneity in that tumor population, as a human being would have. The size of the tumors and the speed of growth of those tumors are comparable in dogs and human beings. So there are many attributes of a dog that develops cancer spontaneously that recapitulate the biology that we see in people."Fan demonstrated the effectiveness of an anti-cancer drug called PAC-1 in pet dogs with naturally occurring lymphomas and osteosarcomas. The results in dogs allowed the scientists to begin studying the drug as a potential therapy against human cancers in new clinical trials. Other experimental cancer drugs first tested in pet dogs include muramyl tripeptide, an immune-stimulating agent that could not be tested in immune-deficient mice or rats with induced cancers, Fan said.