When asked to describe the field of comparative oncology, Carolyn Henry says, “You would probably get a different definition depending on who you ask that question, [but] when we think of comparative oncology here at the Vet School, we think of treating animals that develop cancer on their own just like people do and finding ways to treat that cancer better and that may translate into better treatments for people as well.” Henry’s interest in oncology began while she was working in private practice as a veterinarian. “It seemed like the cancer patients were the ones I found the most interesting and the most rewarding to treat,” she explains of her decision to pursue training and certification in veterinary oncology.
Comparative oncologists translate the experience of many years of oncology in the human medical field into treatments for companion animals, and at the same time use information gained from studying companion animals with cancer into new diagnostic and therapeutic options for human patients. Thus, although Henry was trained as a veterinarian, the dual nature of her research translated into joint appointments as Associate Professor of Oncology in both the Department of Veterinary Medicine and Surgery and in the School of Medicine. This arrangement allows her to treat cancer in animals of any size, as well as conduct clinical trials, develop new products to detect cancer earlier, and discover ways to provide better treatment for both animal and human patients.
In addition to the College of Veterinary Medicine and the School of Medicine at MU, Henry also works with the National Cancer Institute (NCI) and its Comparative Oncology Trial Consortium (COTC), the first of its kind. Sponsored by the NCI, the program involves only thirteen U.S. universities. Under the NCI umbrella, individuals, universities, and pharmaceutical companies can propose a study to be conducted through the COTC. The NIH then selects sites from the Consortium to carry out the trial. MU was one of only four schools to be involved in the first trial, which evaluated a novel cancer therapy in pet dogs with cancer. The intent is to eventually move into human clinical trials with this product.
This new therapy is based on a method that efficiently targets the blood vessels that feed a tumor. Henry clarifies, “Tumors require a blood supply so that they can get nutrients required to keep growing. Once they grow to a certain size, they will outgrow that blood supply and have to develop new vessels on their own.” In this study, they are employing a technology that allows targeting of the blood vessels feeding a tumor and delivery of Tumor Necrosis Factor-alpha (TNF-Î±), a potent anti-cancer compound. The first part of the trial showed that the technology promoted efficient focusing on the vessels of the tumors, while the second part of the trial is intended to determine how well the treatment shrinks tumors. “It’s something that will definitely translate into human oncology, which is the mission of studies conducted by the COTC,” Henry comments; “it’s also nice that when we do these types of trials it allows us to have some funding for veterinary patients. Clients that have pets with cancer but can’t afford treatment may be able to benefit from enrollment in a clinical trial such as this.”
The Consortium has been operating for only about a year, and being a part of it “has allowed MU to work with some of the best schools in the country and to do research more quickly because we can enroll cases more quickly using a number of institutions working together, versus the University of Missouri trying to do a large trial just centered here.” The trials are designed to have quick endpoints, allowing them to move forward more quickly with new treatments, whereas “we used to traditionally look at survival time or metastasis-free interval as our endpoint, but those studies can take years to complete because all the patients have to be enrolled and then followed for a certain amount of time. By looking at biomarkers and certain other biological endpoints such as tumor targeting and tumor response, these studies will be completed in months versus years.”
Henry highlights another benefit of this program: “I still run across lots of people who seem surprised that dogs and cats even get cancer, and so we’ve gone beyond that step to say, ‘look these are patients that make very good models of what would happen in you or me if we had cancer,’ versus taking a mouse, causing it to develop cancer and then trying to cure it, which is a very contrived model. It’s a very different situation, and I think dogs and cats that develop cancer spontaneously are doing so for the same reasons you or I would, because of our environment or genetic changes, and so I believe it’s a much truer picture of how cancer is going to act in people. And if we see good results in our patients, that’s more likely, I think, to translate to positive results in people.”
Henry is also involved in a number of research projects outside of the COTC, focusing on spontaneously occurring cancer in animals, more specifically breast cancer, bone cancer, and bladder cancer. Chuckling, she remarks, “So I guess any tumor that starts with a ‘b’ is what I’m focused on right now.” Those tumors, she explains, are not only what they see spontaneously occurring in animals; they’re very similar to diseases found in people and need better treatments. Almost any treatment possibility for humans is also available for animal patients, including surgery, radiation therapy, chemotherapy, immunotherapy, photodynamic therapy, and nuclear medicine. “The problem is,” she explains, “we don’t have much in the way of pet insurance that people take advantage of, so cost can become a very real issue for our patients.”
The veterinary oncology program at MU is growing very quickly, she notes: “Right now we’ve got four boarded veterinary oncologists, a veterinary radiation therapist, and residents and interns interested in oncology.” In September 2006, the Veterinary Medical Teaching Hospital opened a Cell Culture Lab that has made tumor cell research easier to conduct. As the program gets bigger, Henry says, “the public is beginning to understand that there are these treatment options available for their pets, and we’re going to continue to see that growth. It’s exciting here at the University of Missouri because there are so many other groups that we can interact with.” A good example is the MU Research Reactor, where radiopharmaceutical drugs to target bone cancer in dogs have been developed. After conducting clinical trials with dogs, the drug Samarium was approved; it’s now marketed under the name Quadramet and used for treatment of bone cancer in people. Other collaborative efforts include trials with pharmaceutical companies, vet schools around the country, and the Veterinary Cooperative Oncology Group. The latter is a collaborative research division of the Veterinary Cancer Society, an international group for which Henry recently served as president.
On another note, the Barkley House, in the early stages of becoming a reality, was also Henry’s brainchild. Similar to the Ronald McDonald House for patients at a human hospital, Barkley House would serve as a guesthouse for patients and their owners at the Veterinary Medical Teaching Hospital. “I think there’s a real need for this around the country,” she says. “For instance, here we have patients that come from Arkansas, Iowa, and other long distances, and if they’re coming for radiation therapy, the pet may need to stay here for a month… So we wanted to develop a guesthouse right across the street from the teaching hospital where they can stay with their pet. And we’ve got the blessing from the campus in terms of a site for the building, but the monies to build the house need to come from private funds and so we’re continually in a fundraising campaign.”
Some of Henry’s other projects include writing a comprehensive clinical textbook for veterinarians treating cancer patients, with information about chemotherapy drugs, different tumor types, and guidelines on when it is appropriate to refer cases to a specialist. Overall, explains Henry, the concept of “one medicine” is prevalent in comparative oncology at MU: “It doesn’t matter if you’re a dog, a cat, or a person. If you have cancer you’re fighting the same disease, and so let’s work together and find a cure for it no matter what the species.”