How Close Is a Breast Cancer Vaccine, Part 1

Scientists are continually working on new approaches to breast cancer, a disease that poses innumerable intellectual challenges for those in the laboratory as well as for doctors tending patients at their bedsides. This is not to say that current treatment modalities do not work — they do. More women are surviving breast cancer today than at any other point in history.

Doctors attribute those successes largely to early detection and the therapies — and combination of therapies — that help to bring breast cancer under control. But even as new approaches to the disease are being developed, doctors know that it is not the primary tumor, but the disease’s potential for spread that makes breast cancer a lethal disease.

To that end, treatments under development are targeting the cancer’s ability to spread, a form of treatment that could dramatically aid in preventing breast cancer from coming back. Metastasis, the spread of cancer, occurs when breakaway cells leave the mother tumor, hitch a ride aboard the blood and travel to distant sites in the body where new cancers are spawned.

One approach that focuses on breast cancer’s metastatic potential is the breast cancer vaccine. This anti-tumor approach enlists the body’s immune system to destroy any escaped cells that are likely to seed new tumors in distant sites, such as the lungs or bones. Several research institutions in the United States and abroad are looking into the challenging area of cancer immunotherapy. Among the leading institutions is Memorial Sloan-Kettering Cancer Center in New York City, which is testing an anti-breast cancer vaccine in clinical trials. Other centers working on breast cancer vaccines include the University of Washington in Seattle and Dana Farber Cancer Institute in Boston. In addition, several biotechnology companies are working on the vaccines.

In principle, an anticancer vaccine is not much different than those aimed at an infectious disease, such as polio or measles. Doctors introduce a fragment of the disease-causing agent into the patient. The immune system then recognizes the material as alien and mounts an attack against it.

Yet as progressive as the idea of a cancer vaccine may seem, perhaps even like a kind of 21st century approach to malignant disease, it is, in fact, one with roots in the Victorian era. Dr. William Coley of Memorial Hospital in New York City is believed to have been the first physician ever to attempt to cure cancer patients by way of a vaccine. He had hoped his “toxins” would somehow target his patients’ cancers. And in some instances there were extraordinary — yet inexplicable — remissions. Coley, despite the stroke of genius to attempt such a treatment in the early 1890s, could not fully explain how his anticancer toxins worked.

Coley’s vaccines were made up of deactivated bacteria, which, from today’s understanding of the immune system, would clearly elicit an immune response, recruiting the body’s warrior cells and proteins to mount an attack. The trouble with the toxins, today’s researchers say in retrospect, is that they lacked tumor specificity. And it would take the better part of the 20th century for scientists to begin fully understanding the intricate workings of the human immune system, let alone fashioning highly specific vaccines that could fight cancer.

At the University of Washington, for example, scientists have developed an experimental breast cancer vaccine that generates an immune response against a protein that is some patients overproduce.

The vaccine is manufactured from fragments of HER-2/neu, a protein found on the surface of breast cancer cells that is important because it is produced by 25 percent to 30 percent of breast cancer patients. Moreover, HER-2/neu is responsible for revving up the speed at which cancer cells grow, so finding ways to block it is vital and is the subject of many scientific pursuits. In recent years, the protein has captured a spotlight because it is also the target of Herceptin, a revolutionary drug that aids women with metastatic breast cancer.

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