We’ve featured Dr. Fan’s work before on our blog. Here’s another article on Dr. Fan, who has been researching osteosarcoma and how these malignant bone tumors spread to other parts of the body in dogs, who are particularly vulnerable. The study could eventually help children with bone cancer as well.
By Paul Wood
Do you have dogs and cats?
My family has seven dogs and three cats. Five of the dogs are small, my wife’s favorites. While I do have two coon hounds, they’re my dogs. They’re all dogs that are not that hard to care for. Our three sons do participate in the day-to-day care, making it a family affair.
What drew you to oncology?
If I took my top-five cases during my internal-medicine residency at Cornell University, four of the five were dogs or cats with some kind of cancer. From a clinical perspective, it was just a really rich field. After my earlier study here as a rotating small-animal intern (1995-1996), when I came back here in 1998 and did two additional years of purely clinical cancer study, I would see how cancer affected these dogs and cats and wanted to understand a little bit more from a research perspective — why are these cancers acting this way, and what can we learn from these cancers?
What are the benefits?
If we can study cancer in dogs and cats, a broader, more global motivation, many cancers are similar in pets and humans. If we make inroads into understanding and treating cancer in dogs and cats, can those same inroads be valuable in the management of cancer in people? There’s always the cherry on top.
Is there some reason there is some similarity in cancer between pets and young humans?
It depends upon the tumor type. Osteosarcoma, the bone tumor, is very common in dogs … diagnosed about 10 to 50 times more common in dogs compared to people. In people, this tumor is predominantly found in young adolescents, 10 to 13 years old.
Why is cancer common in dogs?
One reason is that, from a health care perspective, we’ve become very good at preventive medicine. We don’t have a lot of cats and dogs that die due to infections disease any more. We’re really good at vaccination, we’re really good at having heartworm preventive therapies, uniform good-quality diets, so most dogs and cats live to a much older age. We know that cancer many times is a disease of age. It’s similar in humans. Once, when you were 15, you could get eaten by a lion; now you can live to 80.
What else helps?
We have much more advanced diagnosis, so we are able to detect cancer more easily. We may not have more cancer, but it’s just easier for us to find it now. The ability to find one cancer cell in a billion means the diagnosis of cancer is much easier.
What role do owners play?
A factor is simply the human-animal bond; we’re in a society at this time that companion animals may be very integral family members. Young millennials may choose to have dogs or cats in lieu of having children. Because they’re integrated into the fabric of the family unit, there is much greater motivation to help those dogs and cats. They’ll go to much greater lengths to have these pets treated.
Has any of this translated directly to human children at this point?
Yes, there are certainly examples where therapies evaluated in pet dogs and cats have helped inform human cancers, and I think the value of comparative oncology inflection point now is because of immune therapies for cancer, there really is a huge surge on interest in how pet dogs and cats might provide new and valuable information not answerable with traditional mouse models. At a very scientific research level, it’s something that’s not new; it’s been around more than 100 years. It’s been nurtured over the last several decades, but it’s really been solidified in a much more systematically developed level in the last 10 to 15 years, and probably the last five years, we have seen a rapid acceleration of comparative oncology research.
What do you do in your immunotherapy research?
The research that we are doing uses a small molecule that tricks the immune system into believing there is an infection. We’re using what we call CpG ODN, which is a DNA sequence that is recognized as foreign, a pathogen. Because it is a pattern that is expressed by pathogens that are not mammalian, as a mammal, our immune systems will recognize that pattern as a danger signal. Where that is a virus, fungi, bacterium, you launch an immune system against it.
How have you refined your method?
We’re using the small molecule in combination with radiation therapy to really amplify the body’s immune system to get excited, and fight the cancer that arises within the bones of these dogs and also fight the cancer that often spreads to the lungs. The radiation causes some of the tumor cells to die — that type of death that occurs stimulates immunogenic cell death.
Have you been able to save some animals?
What we’ve done is some very interesting and convincing work in a mouse model of osteosarcoma in which we can show the very, very strong protective effect of CpG ODN. When you give it to mice even once or twice, by an injection just underneath their skin, it extends their survival time by 300 or 400 percent. We’ve found the same molecule can safely stimulate the immune system in dogs.
What’s next?
The grant we have funded is to begin one step further, we’ve shown that it works in mice, and that it stimulates the immune system in dogs with osteosarcoma. These next three years we want to show that the stimulation of the immune system is dogs translates into a meaningful benefit in these dogs. These are clinical trials that are completely voluntary and we hope that we can help pet dogs with osteosarcoma live longer and healthier lives. Currently, 90 percent of dogs die of their disease within two years of osteosarcoma diagnosis.
Veterinary oncologist Dr. Timothy Fan is with the University of Illinois Small Animal Clinic in Urbana.
