Although research moves slower than women with breast and ovarian cancer might hope, University researchers plan to begin a phase II clinical trial by the end of the year of a vaccine they hope will prevent the recurrence of these cancers in up to one third of women already afflicted.
Unlike treatments currently on the market, the vaccine assists the immune system in fighting the cancer. If successful, the body's defense system will recognize as foreign bodies cells that produce the Her-2/neu protein and kill them, thereby eradicating the cancer. About one third of all breast and ovarian cancer cells express the protein.
Dr. Michael Morse, an oncologist and the study's principal researcher, said this vaccine represents a different approach to cancer treatment. "This requires a person's own body to actually be able to fight the cancer," Morse said. "I'd call it a step in the right direction."
He said the phase I trial concluded that this vaccine does not have toxic effects when given to humans and the next stage-to be given the FDA go-ahead within about two months-tests whether the vaccine is beneficial to patients who receive it. If the vaccine reaches phase III, trials will compare it with current cancer treatments. Later phases will seek the Food and Drug Administration's approval to market the drug.
Morse said if the vaccine makes it that far, approval could still be as much as a decade away. He added that 1 to 5 percent of treatments that reach the phase II level are eventually approved by the FDA for marketing. Any treatment currently on the market has undergone this process.
"People who enroll in a study like this are obviously hoping this is the one," Morse said. The 25 patients in the phase II trial will come to the University to receive four infusions of the vaccine.
The Her-2/neu protein encourages non-adult cells to reproduce. In adult cells, its only expression is in tumors. "It causes cells to divide, period, which they shouldn't be doing as an adult," said Dr. Lyndsay Harris, a researcher with the clinical vaccine trials who does Her-2/neu research in her lab. She added that the protein may also aid the tumor cell in its metastasis and encourage the growth of blood vessels to the tumor.
For the vaccine to be effective, the immune system must recognize cells expressing the Her-2/neu gene and systematically eliminate them as it rids the body of any disease. Morse said that researchers take the patient's own dendritic immune cells, multiply them and mix them in a test tube with millions of Her-2/neu proteins. The combination of the two substances leads to a cell presenting the protein on its surface, and the vaccine is dripped back into the patient.
Once inside the body, the proteins presented on the dendritic cell are viewed as foreign, and the body's natural immune reaction kicks in. Some of the immune cells remember the Her-2/neu protein as foreign so when the body sees the expression of the protein, those cells will be eradicated.
With the completion of the phase II trials, "we'll learn whether people respond to these vaccines," Morse said. He added that even if this vaccine proves unsuccessful in the fight against cancer, "we're pretty excited that one of these days there'll be a vaccine."
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