Herpes Virus Could Kill Aggressive Breast Cancer

A genetically engineered version of the virus that causes herpes shows promise as a treatment for a particularly aggressive type of breast cancer, according to a new study in animals.

The virus targeted and killed triple-negative breast cancer cells in mice. Triple-negative breast cancer is a form of breast cancer that cannot be treated with hormone therapies, such as tamoxifen and Herceptin.

The results are preliminary, and it's not clear whether the therapy will have the same effect on tumors growing in people. Much more research is needed to determine this. If a treatment is developed, it will likely be used in conjunction with other cancer therapies, including chemotherapy and radiation, the researchers said.

The study was presented at the meeting of the American College of Surgeons in San Francisco.

Herpes therapy

Triple-negative breast cancer accounts for about 20 percent of all breast cancer cases. It disproportionally effects young, African-American women and is usually treated with chemotherapy. (Triple-negative breast cancers are not fueled by the hormone estrogen, so they do no respond to treatments designed to block the hormone.)

Study researcher Dr. Sepideh Gholami, a research fellow in the at Memorial Sloan-Kettering Cancer Center in New York City. and colleagues infected breast cancer cells in a dish with a herpes virus called NV1066. Within a week, the virus killed up to 90 percent of the tumor cells.

The researchers then injected breast cancer cells into mice. After treating the mice with the virus for 20 days, they saw the tumors had largely disappeared, Gholami said.

The dramatic response may be due to the fact that triple-negative breast cancer cells have high levels of a protein called p-MAPK. The herpes virus specifically targets cells with high levels of this protein, the researchers said.

The therapy is just one of many in recent years to explore the use of viruses as a means to target and destroy cancer cells. The herpes virus has been tested in people as a treatment for head and neck cancer, but not for breast cancer, the researchers said.

More research

The study is an "extremely exciting step" in the pursuit of a cancer therapy that uses the herpes virus, said Dr. Stefan Gluck, a medical oncologist at the University of Miami's Sylvester Comprehensive Cancer Center.

However, the researchers still need to show that this herpes virus is safe to use in patients. After all, the herpes virus is known to cause infection in humans, including infections in the brain. Proving the therapy's safety will likely be a lengthy process, and will involve testing it on other animals first, such as dogs and primates, Gluck said.

The researchers plan to figure out exactly how the virus works to kill the breast cancer cells, and try to bolster its effect.

Pass it on: The herpes virus can infect and kill breast cancer cells in a dish and in mice.

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