In the nearly 40 years since the nation declared war on cancer, great advances have been made in breast cancer screening, early detection and treatment. The death rate for breast cancers has fallen. More is discovered all the time about the genetics and biology of the disease.
But a cure remains elusive. Cancer, which is actually a variety of diseases, changes constantly and can spread throughout the body in ways that can be difficult to detect. Even when stopped in its tracks, it can often adjust and evade treatments that once worked against it.
In most cases, the body's immune system learns to go after a foreign invader like a virus or a bacteria. But along with knowing what to attack, it knows what to ignore, namely those molecules that are part of the body. And that is what most tumors are: normal cells that have taken a bad turn and grown without controls.
Because the immune system sees cancer cells as part of the body, they avoid detection and destruction, leaving them free to invade breasts, bones, the brain and other major organs.
Johns Hopkins oncologist Dr. Leisha Emens' goal is to change that equation, to harness the power of the immune system to fight off breast tumors. Her design builds on work of colleagues at Hopkins and scientists at the Massachusetts Institute of Technology who determined through experiments with mice more than a decade ago that a vaccine using cancer cells genetically modified with a protein called granulocyte-macrophage-colony stimulating factor, or GM-CSF, could prevent tumors.
GM-CSF is something the body uses naturally to fight off illness.
In building a vaccine, Emens chose two separate lines of tumor cells from a repository in Washington for their ability to reproduce rapidly. Then she modified them to make and secrete GM-CSF at high levels. She injected a small piece of DNA with the cells - irradiated so they could not cause cancer - to create the vaccine.
These cells are part of a mixture injected under the skin, 12 doses at a time, four times over the course of about six months. Once injected, the GM-CSF-modified cells act as messengers, alerting the immune system to the presence of vaccine cells and drawing what are called dendritic cells to the vaccine site. Once the dendritic cells arrive, the vaccine cells are recognized as interlopers and are engulfed.
