March 23, 2009 -- Researchers with the Cleveland Clinic have successfully treated cancer in dogs without toxic side effects or discomfort. The feat could soon lead to a powerful new strategy for treating the disease in people.
Joseph A. Bauer, PhD, with the Center for Hematology & Oncology Molecular Therapeutics at the Cleveland Clinic, detailed the extraordinary achievement at the 237th national meeting of the American Chemical Society in Salt Lake City.
Bauer's team's success story begins with a "miracle dog" named Oscar, a 10-year-old male Bichon Frise stricken with an extremely aggressive form of cancer called anal sac adenocarcinoma. Chemotherapy and radiation failed to treat the dog's disease, which left him unable to walk. Oscar had about 3 months left to live.
'Trojan Horse' Kills Cancer
The NO-Cbl drug targets cancer cells like a biological "Trojan horse." A Trojan horse is a damage-causing substance hidden in something apparently harmless.
In this case, the drug is made of a cancer-killing substance called nitric oxide, which is attached to vitamin B12. Substances called receptors on a cell's surface attract the vitamin and help it enter the cell. Cancer cells grow abnormally fast with extra B12 receptors. NO-Cbl spots these receptors, sneaks into cancer cells, and releases the nitric oxide, which kills the cancer cells from within.
Scientists have been trying for more than 60 years to develop a successful B12-based "Trojan horse" to fight cancer, according to a news release from the American Chemical Society.
Bauer's team is reporting promising results in two other dogs without any negative side effects. Ultrasound and MRI imaging showed significant reductions in tumor size in all three dogs. Nine months of NO-Cbl treatment shrank a spinal tumor in a 6-year-old golden retriever named Buddy by 40%. Buddy, who once had nerve damage in his right hind leg, is now taking 2-mile walks. The treatment also significantly reduced inoperable thyroid cancer in a 13-year-old female Giant Schnauzer. The dog had a 77% reduction in tumor size in less than 10 weeks. The team is now treating a spinal tumor in a fourth dog, a golden retriever named Haley.
The team wants to successfully treat 10 dogs with NO-Cbl and then quickly get FDA approval to test the drug in people. Bauer points out that people and dogs are genetically similar, which may help the drug's "chance of getting through the FDA’s strict drug approval chain."
Focus on Pets, Too
Each year in the U.S., an estimated 6 million dogs are diagnosed with cancer. Pets with cancer afford researchers an opportunity to study cancer treatments in animals that are more genetically similar to people.
“The [National Cancer Institute] gets data on pets that are exposed to the same environmental factors their owners are," Bauer says in a news release. "They breathe the same polluted air and drink the same polluted water that you and I do every day. If you can find an agent to treat cancer that occurs in a dog with success, there is a higher likelihood that you can take that to the human population and have a much higher response rate than with mice.”
Such research also provides pets access to potential life-saving therapies, such as the case with Oscar.
“We are one of the few research groups that is offering to treat dogs with cancer that otherwise have no hope,” Bauer says. “With no other options available, most people in this situation opt to euthanize so that their pets don’t go through the pain of disease and trauma of surgery.”
Bauer, a dog owner, says his research is "one of the most rewarding things I’ve ever done in my life."