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Injections Kill Breast Cancer in Mice

But benefits to human victims remain uncertain

MONDAY, Sept. 30, 2002 (HealthDayNews) -- Injections designed to spur the body's immune system to attack tumors cured breast cancer in mice, a new study says.

Researchers inoculated six mice with genetically modified dentritic cells, an important immune system component. A single injection directly into breast cancer tumors in the mice destroyed the tumor in five mice and reduced the sixth's tumor to barely discernible size.

The researchers later injected the mice with more live breast cancer cells. None of the mice developed any new tumors.

"This suggests that the treatment not only fights tumors but generates a long-lasting immune system memory, which should protect the host in the same way that anti-infection vaccines do," says Zoya R. Yurkovetsky, the study's lead researcher and a doctoral candidate in the department of molecular genetics and biochemistry at the University of Pittsburgh School of Medicine.

The study was presented at this weekend's "Era of Hope" forum in Orlando, Fla. The forum was sponsored by the U.S. Department of Defense's Breast Cancer Research Program.

However, Dr. Jay Brooks, chief of hematology and oncology at the Ochsner Clinic Foundation in New Orleans, cautions it's too early to get overly hopeful about a cancer vaccine.

"Research like this is very exciting and very encouraging to clinicians like myself," Brooks says. "The problem is that breast cancer in mice is not the same as breast cancer is in women. To translate this work in patients is a gigantic leap of faith at this time."

Breast cancer in women is far more complex, usually developing over a long period of time and affected by a variety of factors, from genetics to environmental contributors. The mice, in contrast, had artificially induced breast cancer caused by a specific agent, Brooks says.

"There's been many cases in the past where we found drugs that were very effective in mice, but in humans they didn't hold up," Brooks adds.

Still, Yurkovetsky says, the research is another step toward the glimmering hope of a vaccine against cancer.

In the study, Yurkovetsky and her colleagues created an adenovirus that can transport genes into cells.

The added gene caused the dentritic cells to produce a protein called CD40L, Yurkovetsky says.

Dentritic cells with this protein on their surface become even more powerful immune system weapons that activate the body's disease fighting T-cells to make cytokines, or chemicals, that fight tumors, she says.

"When you place the CD40L on the dentritic cells, it increases their function, making them more powerful for fighting the tumor," she says. "It's the T-cells which actually kill the tumor cells."

The researchers plan to try similar experiments on other types of cancer tumors. They also want to see if injecting mice with the genetically altered dentritic cells will work to prevent the growth of cancer. In this study, the injection was directly into a tumor site.

In similar experiments involving colon cancer in mice, the injections significantly reduced the size of tumors but did not eradicate them, suggesting that lots more research needs to be done.

What To Do

For more information about breast cancer, including treatments and how to cope, visit the Susan G. Komen Breast Cancer Foundation, or the American Cancer Society.

SOURCES: Zoya R. Yurkovetsky, doctoral candidate, department of molecular genetics and biochemistry, University of Pittsburgh School of Medicine; Jay Brooks, M.D., chief, hematology and oncology, Ochsner Clinic Foundation, New Orleans; Sept. 28, 2002, study presentation, U.S. Department of Defense's "Era of Hope" forum, Orlando, Fla.
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