Mini-Transplants of Stem Cells for Older Patients

A study has found that low-dose radiation therapy combined with immunosuppressive drugs allows donor stem-cell transplants in patients who cannot have conventional stem-cell transplants, such as people over 50 years of age with leukemia or some other potentially fatal blood cancer. The study, conducted by researchers at the Fred Hutchinson Cancer Research Center (Seattle, WA, USA) and four other centers, was published in the June 1, 2001, issue of Circulation.

The toxic effects of conventional stem-cell transplants are a major problem for older patients as well as young patients. The study involved 45 patients diagnosed with acute and chronic leukemia, multiple myeloma, non-Hodgkin's lymphoma, and other diseases. The researchers used non-myeloablative stem-cell transplants, also known as mini-transplants. The mini-transplant procedure involved very low doses of radiation, coupled with post-transplant immune suppression, to establish a stable state of tolerance between donor cells and the patient's own tissues, a phenomenon called "mixed hematopoietic chimerism.”

Few of the patients required hospitalization and most experienced only mild to moderate treatment-related toxicities. Patients did not lose their hair. Eight patients with chronic leukemia entered a complete molecular remission. Survival rate among the patients was 66%. To date, more than 300 patients have been treated with this procedure. The researchers attribute the positive responses to graft-versus-tumor effect and the use of post-engraftment immunosuppression.

"The revolutionary part of the whole concept is that the cancer is eliminated through the donor T-cells rather than with high-dose chemo-radiation therapy,” said Dr. Rainer Storb, senior investigator of the study and professor of medicine at the University of Washington (Seattle, USA).




Related Links:
Fred Hutchinson Cancer Center