Donor Immune Cells Shrink Metastatic Breast Tumors

A phase I trial has found that immune cells from a genetically matched donor can attack and shrink metastatic tumors in breast cancer patients, a response known as graft-versus-tumor effect. These results were presented at the annual meeting of the American Society of Clinical Oncology in Chicago (IL, USA).

In the trial, 13 patients had received multiple previous treatments for metastatic breast cancer. In the current study, they 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 HLA (human leukocyte antigen)-matched siblings, after the T cells were removed from the stem cells.

The T cells were given to the patients in an initial infusion 42 days after the stem cell transplants and then in two follow-up infusions over the next two months. Since the T cells were not given immediately after chemotherapy, the researchers were able to attribute any tumor cell death to the transplanted T cells rather than to the chemotherapy. In four patients, tumors shrank at least 50% in response to the treatment. A minor response was seen in three of the other patients, but none of the tumors was eliminated entirely.

"Graft-versus-tumor effects have been shown to be useful in treating cancers of the blood, such as leukemia and lymphoma. 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,” said lead author Michael Bishop, M.D., of the National Cancer Institute's Center for Cancer Research.




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