In the domain of the veterinary oncologist, the reality of gravely ill patients tends to trump any natural tendency toward optimism.
So when someone like Gregory K. Ogilvie, DVM, Dipl. ACVIM (oncology), Dipl. ECVIM (oncology), peers into the immediate future of cancer treatment and says, “We’re looking at some tremendous breakthroughs,” it’s a moment to savor.
“I’ve been in this for over 25 years,” he adds, “and it feels like we started with sticks and stones compared to the treatment options we have today.”
Add the voice of Douglas Thamm, VMD, Dipl. ACVIM (oncology), to those express-ing hope that 2009 will be a watershed year in the cancer fight.
“This is a really exciting time,” he says. “The long and short of it is we’ve just scratched the surface of how to use these new therapies.”
Ditto Katherine Skorupski, DVM, Dipl. ACVIM (on-cology): “Absolutely I’m excited about these new treatments. … If they work as well as they should and could, we may be choosing them over chemotherapy or even surgery.
“They have a huge potential to impact the way we practice veterinary oncology.”
So what exactly is all the rosy hubbub about?
For starters, this year the veterinary community is expecting to welcome two new therapies that target canine mast cell tumors at the molecular level, while on the horizon are expanded efforts to empower dogs’ immune systems to combat cancer and suppress relapse.
But it’s not just that these drugs would immediately add new arrows to the veterinary oncology quiver. They could also open new fronts in the cancer fight, heralding whole new classes of drugs and other therapies.
What’s more, for an industry in which the norm is off-label use of human-market medications, it’s significant that these new products are being developed directly for veterinary application.
“It really signals there is a market for these kinds of medications, and that drug companies have recognized this fact,” says Dr. Thamm, assistant professor of oncology at Colorado State University.
"Oncology is the most rapidly advancing specialty in veterinary medicine."
~ Gregory K. Ogilvie, DVM, Dipl. ACVIM, Dipl. ECVIM ~
Of course, there are still regulatory hurdles to clear, side effects to manage and much more for cancer specialists and general practitioners to learn about the treatment opportunities these new therapies may offer.
Still, a hopeful spirit pervades.
“It’s a new era of cancer therapy,” says Dr. Ogilvie, director of the Angel Care Cancer Center at California Veterinary Specialists in San Marcos and Carlsbad, Calif. “Rather than use chemicals to kill the cancer or radiation to fry it, we can use our knowledge of cancer to outsmart it.”
These days along with hope, a sense of purpose undergirds the cancer fight, says Patricia Olson, DVM, president and chief executive officer of the Denver-based Morris Animal Foundation, which since 2007 has mounted a Canine Cancer Campaign.
One in four dogs will die of cancer, the foundation notes. In addition, in a foundation survey, 41 percent of respondents who indicated an interest in dogs said cancer was their No. 1 health concern. Heart disease was second, identified by just 7 percent.
“So we know this is a big issue,” Dr. Olson says. “And now with the whole dog genome sequenced, it should be a solvable problem.”
AB Science USA and Pfizer Animal Health are among the companies seeking to provide those solutions, most immediately with targeted molecular therapies progressing toward launch. On the human side, the FDA has approved more than a dozen targeted molecular agents to treat cancer-related indications, the National Cancer Institute says. By contrast, the AB Science and Pfizer products would be the first veterinary targeted therapies to gain FDA approval.
Pfizer, of New York, declined to comment on its new cancer therapy, citing confidentiality, but oncologists say it is similar to that of AB Science.
Albert Ahn, DVM, president of AB Science USA in Short Hills, N.J., says his company’s targeted molecular therapy for canine mast cell tumors is “getting closer” to FDA approval. He notes that the drug, administered as a pill, has progressed through Phase 3 trials at as many as 15 veterinary hospitals nationwide.
The therapy—scientific name mastinib mesylate—is a protein tyrosine kinase inhibitor that “destroys or disables specific types of cells or tissues,” Dr. Ahn says.
The class of drugs also shows promise in treating cancers such as T-cell lymphoma, melanoma, hemangiosarcoma and osteo-sarcoma, as well as a variety of inflammatory diseases, Ahn says.
The specificity of targeted treatments excites oncologists, who are used to managing the collateral damage to healthy tissue that comes with chemotherapy and radiation treatment. With the AB Science mast cell tumor drug, side effects so far have been limited to rare instances of vomiting and/or diarrhea, Ahn says.
So instead of high-dose, short-term therapy, practitioners may gain a low-dose, long-term option, says Dr. Skorupski, assistant professor of oncology at the Center for Companion Animal Health at the University of California, Davis.
“The tumors may not go away but instead stabilize for years,” she says.
Some dogs may be on the drug for life, says Ahn, who draws the analogy to lifetime use of a heartworm preventive.
Thamm expects to use targeted molecular therapy in conjunction with surgery, chemotherapy and radiation. Of course the X factor in planning such a treatment strategy may be cost.
Ahn says only that his company hopes “to deliver the drug at a competitive price when compared with the cost of today’s treatment of mast cell tumors.”
Skorupski notes that the UC Davis veterinary hospital charges $3,500 for a six-month round of chemotherapy for lymphoma, the most common type of cancer it treats. And radiotherapy can cost up to $7,000.
“We still treat a lot of cases, usually five to 10 at any one time,” she says.
Cost won’t impede the success of the new canine cancer therapies, predicts Brett Cordes, DVM, medical director of the veterinary pharmacy for The Apothecary Shops, a national specialty pharmacy.
“They won’t be outpriced,” he says. “When you look at the course of treatment, this will be a great option, possibly a great value.”
On the immunotherapy side, Merial of Duluth, Ga., has had its conditional license renewed for its melanoma vaccine as it awaits final USDA approval, which the company anticipates applying for “in the near future,” says Bob Menardi, DVM, director of operations for field veterinary services at Merial.
Field efficacy studies are measuring the long-term benefits, “namely survival time,” Dr. Menardi says. The vaccine is available only to specialists, he says, because “we wanted to make sure its introduction into veterinary medicine was with the folks best qualified to stage and manage cases and assess patient response during the conditional period.”
Merial has collected data on the treatment of about 2,000 dogs so far, Menardi says. “The terms of the conditional license do not allow us to report field data prior to full licensure.”
“The melanoma vaccine is a big deal,” Skorupski notes, “because it’s one of the first immunotherapies in the world, period.”
She anticipates such therapies will be particularly effective in suppressing cancer relapse.
“We won’t be able to ask it to kill billions of cells, but we will likely use it to kill what we can.”
Imulan BioTherapeutics of Prescott, Ariz., is among those at the forefront of immunotherapies.
For 2009, the company will continue work on treatment options that it hopes will “decamouflage” tumors so they can be exposed to patients’ tumor-specific immunity, says Craig Woods, DVM, MS, MBA, Imulan’s CEO. Lymphoma, mast cell tumors and fibrous sarcoma are likely areas of focus.
With immunotherapy and targeted molecular agents joining existing treatment options, the need for robust education programs will become even more acute, Ogilvie says.
“It’s important that veterinarians understand these therapies can offer tremendous benefits, but they also have the potential for toxicity if used inappropriately,” he notes. “Many of these therapies will be used nowhere else in the world, so we are creating knowledge as we go.
“The onus will be on veterinarians to really step up and acquire this knowledge.”
The good news is that with these high doses of new responsibility come heaping helpings of opportunity.
“Oncology is the most rapidly advancing specialty in veterinary medicine–and that’s not only to the benefit of our patients,” Ogilvie says.
“We lead the way in showing human health care how to incorporate new therapies that not only are effective but are compassionate.
“[With these advances] we don’t have to sacrifice quality of life while extending life.”