Stem Cell Transplantation Shrinks Kidney Tumors

A study has demonstrated that allogenic peripheral-blood stem cell transplantation can cause regression of metatastic kidney cancer in some patients who had no response to conventional immunotherapy, even causing the cancer to completely disappear in certain patients. The study, conducted by researchers at the U.S. National Heart, Lung, and Blood Institute, was reported in The New England Journal of Medicine (2000;343:750-758).

The study involved 19 patients whose cancer had not responded to therapy. Each patient accepted had to have as a donor a sibling with matching human leukocyte antigen (HLA) or a mismatch at a single locus. The patients were administered drugs to weaken their immune systems and prevent them from rejecting transplanted cells. The stem cells were collected from each donor's bloodstream and transfused into the patients.

At the time of the last followup, nine of the patients were alive 287-831 days following the transplantation. Two died from causes related to the transplantation and eight died from progressive disease. In four patients, all traces of cancer have disappeared. In the other five, the tumors have shrunk by more than half. Ordinarily, patients with metastatic renal-cell carcinoma have a median survival of less than a year. Cytotoxic chemotherapy is not usually effective, and interleukin-2 and interferon alfa, while effective for some patients, have an overall response rate of less than 20%.

The reason tumor-killing drugs do not work well is partly due to the immunogenic properties of renal-cell carcinoma. Since allogeneic bone marrow transplantation has been shown to induce powerful graft-versus-leukemia effects, the researchers in the current study reasoned that donor stem cells might be able to kill the cancer.