Study:Transplanted Immune Cells Attack Advanced Breast Cancer

Specialized immune cells that recognize foreign cells that have invaded the body which are transplanted from a genetically matched brother or sister can attack and shrink tumors in patients with advanced breast cancer, according to researchers from the National Cancer Institute.

The researchers, reporting at the annual meeting of the American Society of Clinical Oncology, said they had clearly demonstrated for the first time that the type of immune response known as graft-versus-tumor effect will work against breast cancer.

"Graft-versus-tumor effects have been shown to be useful in treating cancers of the blood, such as leukemia and lymphoma. Breast cancer, however, has generally been resistant to immune-based therapies," said Dr. Michael Bishop of the National Cancer Institute.

"Although the tumors of patients in this study were not completely eliminated by the treatment, the responses we saw provide hope that immunotherapies for breast cancer are worth pursuing," Bishop added.

In the study, 13 patients who had received multiple prior treatments for advanced breast cancer received conventional doses of chemotherapy to kill cancer cells and reduce the cells in their immune system so that donor cells could replace them. They then received stem cells from the blood of a genetically matched brother or sister.

T cells, specialized immune cells that recognize and kill foreign cells that have invaded the body, were removed from the pool of donated stem cells prior to transplant. These T cells were given to patients in an initial infusion 42 days after stem cell transplant, then in two follow-up infusions over the next two months.

Because T cells were not given immediately following chemotherapy, researchers were able to attribute any tumor cell death to the transplanted T cells rather than to anti-tumor effects of the chemotherapy drugs.

In four patients, tumors shrunk at least 50 percent in response to the treatment. A minor response was seen in three of the other patients. Although not all patients in the study responded to treatment, and none of the tumors was eliminated entirely, researchers said the results of the trial provided evidence that transplanted T cells can attack tumors in patients with metastatic breast cancer.

Other Sources: National Cancer Institute