Vical heralds regulatory approval of melanoma vax for dogs

San Diego-based Vical says that Sanofi subsidiary Merial Limited has won approval from the Department of Agriculture for a dog melanoma vaccine that Merial in-licensed from the developer. And Vical says the regulatory approval marks a step forward in its quest to gain an approval to use a therapeutic cancer vaccine on dogs' best friends: people.

"The approval of Oncept is a milestone in the cancer vaccine field and a significant advancement for our DNA delivery technology platform," said Vijay B. Samant, Vical's president and CEO. "Therapeutic vaccines--the holy grail of vaccinology--are delivered after disease onset to impede disease progress for the patient's benefit. Oncept is to our knowledge the only therapeutic vaccine approved, and we believe this achievement is a major step toward the initial approvals of therapeutic vaccines for humans."

Oncept contains a gene encoding human tyrosinase, an enzyme associated with skin pigmentation. The tyrosinase produced from the human DNA used in this vaccine is similar to canine tyrosinase and has been shown to stimulate an immune response against canine melanoma cells producing tyrosinase. The use of DNA from a noncanine species causes production of tyrosinase that is considered foreign by the canine immune system (thereby stimulating a potent immune response), yet is similar enough to canine tyrosinase that the dog's immune response will target canine melanoma cells.

In a controlled study, dogs vaccinated with Oncept following surgery had significantly better survival times than unvaccinated dogs. Median survival time could not be determined for vaccinated dogs, since more than 50 percent of the treated dogs were still alive at the time the study was published.

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