Gene therapy shows promise in fighting melanoma

Dogs used in vaccine study

By Norma Bennett Woolf

A University of Wisconsin research team is successfully treating melanoma in dogs with a new cancer vaccine that could help fight the disease in humans.

Professor Gregory MacEwan and research scientist Gary Hogge of the UW-Madison School of Veterinary Medicine have developed a gene therapy method to help the animal's immune system find and attack cancer cells. The researchers reported in the September issue of Human Gene Therapy that the vaccine helped some dogs live longer and shrunk the tumor in about 20 percent of the patients.

"This is important work with melanoma because there are currently no other treatment alternatives," MacEwan said. "Melanoma is resistant to chemotherapy drugs and surgery doesn't always help because melanoma's spread is so aggressive. We're trying to establish this as a standard of care."

The study involves 16 dogs with advanced stages of melanoma. The researchers removed as much of the tumor as possible, extracted and purified individual cells from the tumor, injected DNA into those cells to accelerate production of chemicals called cytokines, and injected the altered cells back into the body as a vaccine to stimulate production of certain white blood cells to fight the cancer.

"This is a way to trick the immune system and get the body to fight the tumor," Hogge said.

Dogs are a good model for understanding cancer in humans, MacEwan said; the causes and behaviors of cancers in humans and dogs are very similar. In dogs, oral melanomas are a common type of cancer; in humans, this type of tumor usually attacks the skin and spreads rapidly. In both species, its virulence makes it deadly.