"Man's best friend" took on a new meaning and a step forward recently at the American College of Veterinary Internal Medicine's national convention in Seattle.

After 6 1/2 years of research and testing at Animal Medical Center and Memorial Sloan-Kettering Cancer Center in New York, a vaccine aimed at treating canine skin cancer (melanoma) patients was introduced by the drug company Merial, after receiving conditional approval March 26 from the U.S. Department of Agriculture.

Dr. Philip Bergman, director of AMC's Donaldson-Atwood Cancer Clinic and Flaherty Comparative Oncology Laboratory, who partnered the research lead with Dr. Jedd Wolchok, an oncologist on the Clinical Immunology Service at Sloan-Kettering, called the breakthrough a landmark in veterinary medicine.

Not only is this the first veterinary cancer vaccine on the market, but it also offers hope for human patients with melanoma. The conditional licensure is for surgically removed oral melanoma, but Bergman sees many oncologists using it off-label for other melanomas.

"The vaccine," Bergman said, "tricks the body into recognizing cancer as a foreign entry. Then the body acts to eliminate it. The same strategy we have used in dogs is now working in people." The aggressive diseases are very similar and metastasize in the same places (namely the mouth, toenail bed and foot pad), and are chemotherapy-resistant.

While the vaccine is still on a USDA conditional status, it nevertheless offers canine melanoma patients' owners considerable hope. Prior to testing in 2000, dogs diagnosed with the disease and treated with conventional means (surgery, radiation and chemotherapy) survived only weeks or months. Patients from that initial study enjoyed a median survival of 389 days, but some lived between three and five years, succumbing to a cause other than melanoma.

The vaccine will be available only through veterinary oncologists, since it is still considered a test product, which allows Merial stronger data control. Four vials (one is injected every two weeks into the inner thigh) begin the treatment, followed by boosters at six-month intervals for the remainder of the animal's life. The four-vial packet is priced at $1,000 to practitioners, who will then determine the markup price. Dosage is the same for a 150-pound Great Dane and 10-pound Chihuahua.