n DALLASA vaccine for breast cancer patients using fusions of dendritic
cells and cancer cells is currently in phase I clinical testing,
said Jianlin Gong, MD, Division of Cancer Pharmacology, Dana-Farber
Cancer Institute, and instructor in medicine, Harvard Medical School.
Although breast cancer cells carry distinct markers that identify
them as abnormal, they somehow escape recognition by the bodys
immune system, Dr. Gong said. It is believed that the cancer cells
prevent the stimulation of T cells directed against them. Other
problems that may prevent the immune system from detecting breast
cancer cells include the weak immunogenicity of tumor antigens, the
lack of costimulatory signals, and unidentified tumor antigens.
One exciting approach to effectively induce an antitumor immune
response is through the use of potent immune-stimulating cells known
as dendritic cells, Dr. Gong said.
Speaking at the Susan G. Komen Foundation 1999 National Grant
Conference, Dr. Gong reported that the fusion cells have been
designed to link costimulatory molecules derived from the dendritic
cells (essential for activation of T cells) with tumor markers that
guide the cells to the tumor.
Mice that were vaccinated with fusion cells did not develop tumors
when inoculated with breast cancer cells, while those that did not
receive the vaccine before the breast cancer cell inoculation died
rapidly. Most significantly, mice with preexisting breast
cancer metastasis in the lungs were cured of the disease after
receiving the vaccine, Dr. Gong said.
The researchers have now successfully fused human dendritic cells
with autologous breast cancer cells. The breast cancer
patients T cells exhibit strong killing of breast cancer cells
after being activated by the fusion cells, Dr. Gong said.