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"Mini" bone marrow transplants work against hemotologic malignancies.

An international team of researchers report that "mini" transplants of bone marrow or peripheral blood stem cells-defined as transplant without myeloablation and its sometimes fatal consequences-can be effective against a variety of hematologic malignances and may even prove superior to conventional transplants.

"I believe the mini-transplant will eventually replace myeloablative conditioning, certainly for patients with a low tumor load," said Shimon Slavin, MD of Hadassah Hospital, Jerusalem, Israel. Slavin and colleagues described their findings at the 13th International Symposium on Molecular Biology of Hematopoiesis and Treatment of Leukemia and Cancer held in July in New York City.

In mini-transplantation, a relatively mild dose of chemotherapy and radiation is administered-ideally, just enough to provide sufficient immunosuppression to enable engraftment of allogeneic bone marrow or stem cells, according to Richard Champlin, MD of the University of Texas MD Anderson Cancer Center in Houston. After transplantation, any remaining malignant blood cells would be recognized by the donor blood cells as foreign and would be destroyed in a graft-versus tumor effect.

In trials at MD Anderson, Champlin restricted mini-transplants to patients older than 55 years and those with comorbidities that made them ineligible for a conventional transplant. About half of the patients diagnosed with recurrent acute or chronic myeloid leukemia who responded to chemotherapy and were treated with mini-transplants had complete remissions lasting up to 4 years. "This is about as good as we can do with an ablative regimen," Champlin said, "but bear in mind that these are elderly patients who could not have received myeloablative therapy."

In a trial in Israel involving 19 patients with severe chronic myeloid leukemia, Slavin reported a disease-free survival rate of 81% after 4 years. Only a single patient experienced a relapse.

Megan Sykes, MD of Massachusetts General Hospital in Boston reported combined complete and partial response rates of up to 50% in groups of patients with various leukemias. Some of her patients who did well either were very sick or had experienced disease recurrence following conventional transplants.

The success of the mini-transplants appears to depend on the specific diagnosis, disease severity, chemoresistance, and the closeness of the donor cell match, among other variables, the researchers said. The most worrisome side effect of the procedure is graft-versus-host disease, with a severity that can range from very mild to fatal.
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Comment:"Mini" bone marrow transplants work against hemotologic malignancies.
Publication:Transplant News
Article Type:Brief Article
Geographic Code:7ISRA
Date:Aug 12, 2000
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