How Low Can the Doses Go? Transplanters Look To Less Toxic Future

Extract

This is the second of a two-part series.

When the first scientific papers describing less toxic bone marrow transplants for leukemia and lymphoma appeared in the journal Blood in 1997 and 1998, they sparked a movement that spread across the transplant community and gave rise to dozens of variations on the procedure. (See News, Aug. 2, p. 1200.) But the goal for all of these treatments—called low-dose, mini, or in scientific parlance, non-myeloablative transplants—is the same: minimize side effects while harnessing a phenomenon called the graft-versus-tumor effect to fight the cancer.

Slowly, information is emerging about when and where to use these transplants. The toxicity reduction means that older, sicker patients who would not do well with conventional transplants can tolerate the procedures. And evidence is mounting that because the graft-versus-tumor phenomenon takes months to build strength, slow-growing or indolent diseases like chronic myelogenous leukemia and chronic lymphocytic leukemia make better candidates than fast-growing or bulky tumors.