Vaccine research takes aim at cancer

Labs at Duke and UNC-Chapel Hill try to enlist the body's natural defenses in the fight against breast cancer

In all of cancer research, few targets are as tantalizing as a vaccine to mobilize a patient's own immune system as a weapon against cancers.

Better still, the right vaccine could prevent cancer from ever occurring.

Developing effective cancer vaccines remains one of medicine's most difficult puzzles -- and it is a puzzle that researchers in the Triangle are working to solve.

Scientists at Duke University last week won a $4.5 million grant to develop and test new vaccines in patients.

Researchers run into the same problem again and again. To the body's immune system, cancer cells look much like normal, healthy cells, so the immune system balks at killing them.

The treatments being developed at Duke will use harmless viruses to trick cancer patients' bodies into seeing their disease as a foreign invader.

Researchers at UNC-Chapel Hill, meanwhile, are using a similar virus-based approach to test vaccines in mice and expect eventually to test them in humans.

"It sort of sets up the danger response in the body," said Dr. Michael Morse, a Duke oncologist who is helping design studies that will test the vaccines in breast cancer patients. "The body sees the virus as a threat, and it brings out the immune troops to fight it."

There are now just two cancer vaccines approved for use by the U.S. Food and Drug Administration. Both are designed to prevent cancer from developing, and both work by targeting viruses that cause specific types of cancer.

One prevents infection with hepatitis B, which is linked to liver cancer. The other, approved by FDA this year, targets two types of virus that together cause 70 percent of all cervical cancers.

Physicians and scientists hope one day to develop vaccines that can prevent other types of cancers. But for now, most cancer vaccine research is focused on therapies that treat active disease.

Several vaccines are in large, late-stage clinical trials among cancer patients in the United States. Vaccines for prostate cancer, melanoma, lymphoma and myeloma are among those furthest along.

Breast cancer trials

If the research at Duke and UNC-CH produces promising results, it would be a small step toward an effective vaccine for one of the most aggressive and difficult-to-treat types of breast cancer.

Researchers at both universities are working with vaccines designed to seek out cancer cells that produce high levels of a protein known as HER-2. Patients with HER-2-positive cancers -- between 25 percent and 30 percent of breast cancer patients -- often become resistant to existing treatments.

Scientists at GlaxoSmithKline, the British pharmaceutical company that has a U.S. headquarters in Research Triangle Park, recently put forward another potential weapon against HER-2 positive cancers. GSK this month asked the FDA for regulatory approval to market Tykerb, an oral drug that, in clinical trials, shrank tumors in patients with advanced, metastatic breast cancer.

A vaccine for breast cancer is likely still years away, researchers say. So far, most studies with breast cancer vaccines have been small trials to determine safety and efficacy.

Even if Duke's latest grant leads to a testable virus-based vaccine, the test would involve no more than 50 patients. If the results were stellar, the FDA still would require data from a much larger patient trial before it would consider approving a therapy.

Dr. Jonathan Serody, a UNC immunologist who has led several cancer vaccine studies, said scientists still have much to learn about how different vaccines work.