New tricks in canine cancer aim to treat humans, too – Charlotte Observer
When the session is over, Martha MaloneyHuss, a veterinarian at the University of Pennsylvania’s Ryan Veterinary Hospital, glances at the images. “I don’t see anything hugely obvious,” she says, “but we’ll see what the radiologist says.” Oblivious to the good news, Flyer hops down the hall on three legs, eager to find her owner.
After the 8-year-old retriever began limping last year, she was diagnosed with osteosarcoma, a painful, aggressive cancer that often strikes Great Danes, Irish wolfhounds and other large breeds. At Penn Vet, she got the standard treatment: One of her left legs was amputated, and she underwent chemotherapy.
Yet even as she adjusted to chasing squirrels, her prognosis was bleak. Most dogs die in about a year when the disease resurfaces in the lungs. The Penn vets recommended an experimental vaccine designed to prevent or delay the cancer’s return; Flyer’s owner was enthusiastic. The dog got three intravenous doses as part of a clinical trial and now returns to Penn periodically for X-rays.
“Every day I pray that she will stay cancer-free,” said her owner, Bob Street, who lives in Mullica Hill, N.J. “And that this treatment will work for other dogs and for people.”
Flyer is part of a burgeoning field called “comparative oncology.” It focuses on finding new ways to treat cancer in pets, mostly dogs, in an effort to develop innovative treatments for people and animals.
The growing interest in dogs reflects researchers’ frustration with the standard approach to developing cancer treatments: testing them in lab animals, especially mice. Mice don’t normally get cancer – it must be induced – and the immune systems in many strains of lab mice have been altered. That makes them especially poor models for immunotherapy, a rapidly growing field of medicine that directs patients’ own immune systems to fight their cancer.
Dogs, on the other hand, get cancer naturally, just as people do, and have intact immune systems.
“Genetically, you are a lot more like your dog than that mouse running around a cage in the lab,” said Nicola Mason, a veterinarian and immunologist who oversees the vaccine and several other canine trials at Penn’s School of Veterinary Medicine. “Where dogs really stand out is in the way they generate tumors and react to treatments, which is a lot like people.”
The vaccine Flyer got, for example, is now in an early trial for people after it showed impressive results in a previous Penn dog study. The company sponsor hopes to develop it for children and adolescents, who are more likely than adults to get osteosarcoma.
The dog and human versions of that cancer involve many of the same genes and are biologically similar. “What we learn in one species can be applied to the other,” said Robert Petit, chief scientific officer of Advaxis, the company testing the vaccine in people.
Across the country, medical and veterinary schools are partnering to find new treatments for malignancies from lymphoma and melanoma to brain and bladder cancer. The National Cancer Institute is overseeing canine trials at almost two dozen academic vet schools, and animal-health foundations are stepping up their support.
Immunotherapy is the latest rage in veterinary medicine, just as in human cancer treatments. Researchers hope studies in dogs can help explain why some people benefit from the approach and others don’t. Amy LeBlanc, director of NCI’s Comparative Oncology Program, said dog data can give drug companies “the necessary reassurance” to move forward with a promising treatment.
Not everyone is sold on the idea that pets will be that helpful for testing treatments in people. Many experiments are in the early stages. Laurence Baker, an oncologist at the University of Michigan who specializes in bone cancer, said that while he is “agnostic” about using pets for research, “in this area, as in too many areas of research, there is a lot more hype than success.”
Proponents of comparative oncology dispute that, saying the similarities of some cancers suggest benefits for both species. Cancer is the biggest health threat facing dogs, killing half of those 10 and older. “They are patients, not lab animals,” said Mason, whose office is filled with photos of dogs she has treated, including Aspen, a greyhound wearing bunny ears, and Bogie, a Great Dane.
Most cancer drugs for dogs were developed first for humans. Take Harley, a striking 4-year-old black boxer with aggressive leukemia. He recently came to Penn for a treatment called CAR T-cell therapy, which has shown some promising results in trials for people with blood cancers. The immunotherapy procedure for dogs is similar to the human one: T cells, a key component of the immune system, are extracted, genetically modified in the lab to bolster their cancer-killing abilities, increased in number and then reinfused.
Mason began working on the treatment for dogs when she was a postdoctoral fellow in the lab of Carl June, a prominent researcher at Penn’s Perelman School of Medicine and a CAR T-cell pioneer. She consults with him frequently.
Owners of dogs in the Penn Vet trials get much of the care free, including treatments and follow-up visits. But there can be related expenses. In the osteosarcoma trial, owners are required to pay for the amputation and chemo.
If these canine treatments end up being sold outside clinical trials, they could carry hefty price tags. The human version of CAR T-cell therapy, for example, which is still in clinical trials, could cost hundreds of thousands of dollars once it hits the market. Scientists hope more progress will lower the cost for people and dogs alike.