Washington State University veterinarians are investigating whether a drug used to treat breast cancer in humans could be used to treat one of the most common forms of cancer in dogs.
In the recently launched clinical study at the WSU College of Veterinary Medicine, veterinary oncologists are examining whether the drug capecitabine, brand name Xeloda®, can safely slow the growth of cancerous epithelial tumors in dogs.
Carcinomas, malignancies of epithelial tissue, account for 80 to 90% of all cancer cases. Epithelial tissue is found throughout the body. It is present in the skin, as well as the covering and lining of organs and internal passageways.
The study will also measure the drug’s concentration in the blood to determine potential dosing regimens, and document any adverse events, as a next step toward using the drug as a safe treatment.
The study was conceived by Dr. Janean Fidel, WSU’s senior veterinary oncologist. Over the years, Fidel and her team have examined a host of anti-cancer therapies in humans for their potential use in dogs. Dr. Sarah Wetzel, an oncology resident, is leading the study with Clinical Trials Coordinator Valorie Wiss.
The study will determine capecitabine’s efficacy treating up to 10 dogs with carcinomas. The investigation uses client-owned dogs volunteered by their owners. Currently, the first patient enrolled is Rollie the Collie, an 80-pound Rough Collie with a carcinoma on the lining of his bladder.
Capecitabine is a well-tolerated, oral chemotherapy drug used in humans for a wide variety of carcinomas including breast cancer, colorectal cancer and head and neck carcinomas. The drug has a short half-life in humans, allowing for quick dose adjustments if side effects are noted.
Wetzel said current treatment options for dogs with carcinomas are limited by pet behavior, owner finances, time commitments, and local veterinarians’ capabilities.
“For carcinomas in particular, chemotherapy, surgery or radiation are your options, and in some cases, surgery is not an option; it’s not an option for Rollie,” Wetzel said.
Additionally, Wetzel said the drug is easily administered orally, doesn’t require frequent trips to the vet for treatment, and would be cheaper than most other chemotherapy, radiation, or surgical options.
After receiving the first dose of the drug, dogs in this study will spend at least 24 hours at the WSU Veterinary Teaching Hospital for routine monitoring by a veterinarian for potential adverse reactions and to measure the drug concentration in their blood.
In humans, the drug can cause nausea, vomiting, loss of appetite, sleepiness, headaches and dizziness.
Once the initial dose monitoring is over and if the first dose of capecitabine is well tolerated by their dog, owners will have the option to administer the drug to their dog daily, for a total of four weeks, with one week off in the middle. The study covers the cost of the drug, study-related blood testing and recheck imaging of the mass at the end of the five-week period.
If owners opt to continue beyond the first dose of the drug, they will need to bring their dog back to WSU oncologists intermittently to monitor the state of the carcinoma and health of the dog.
For candidates like Rollie, who is at risk of a bladder blockage and cannot undergo surgery, if the drug stops the growth of his carcinoma, WSU oncologist hope it could save his life.
“He’s really struggling to get pee out of his bladder,” Wetzel said. “If his tumor is smaller that’s a sign that we are winning.”
If Rollie responds well to the drug, his owners could choose to continue the drug after study completion at their expense, and under the supervision of WSU veterinary oncologists.
Wetzel and Wiss note no matter what they find with this study, more research is required to prove the drug is deemed safe and effective, but they’re hopeful.
“The lovely thing about veterinary oncology is that you’re always watching people rally behind their dogs to beat cancer,” Wiss said. “If this works, this could make a huge difference in that fight.”