New therapeutic canine melanoma vaccine approved

San Diego

-- The U.S. Department of Agriculture (USDA) has granted full licensure to Oncept, a canine melanoma vaccine, to Vical Incorporated's licensee Merial Limited.

This therapeutic DNA vaccine is designed to help extend the survival of dogs that have oral melanoma. Merial will launch Oncept at the North American Veterinary Conference in Orlando this weekend.

Oncept contains a gene encoding human tyrosinase, which is an enzyme associated with skin pigmentation. The tyrosinase produced from the human DNA in the vaccine is similar to canine tyrosinase and stimulates an immune response against canine melanoma cells producing tyrosinase. Using DNA from a noncanine species produces tyrosinase that is considered foreign by a dog's immune system, resulting in a potent immune response. However, the human tyrosinase is similar enough to canine tyrosinase that the immune response will target canine melanoma cells.

Typically, dogs with stage II or III malignant melanoma survive less than six months after surgery to remove the primary tumors. In a controlled study, dogs vaccinated with Oncept after tumor removal surgery had significantly better survival times than dogs that did not receive the vaccine after surgery. A median survival time could not be determined because more than half of the dogs receiving the vaccine were still alive when the study was published.