Commenting on the trial of bone marrow vs peripheral blood stem cell transplants, Frederick R. Appelbaum, MD, at the Fred Hutchinson Cancer Research Center, wrote that the results should change practice. But he added in his editorial, “it will be interesting to see whether it really does.”1
The initial benefits of peripheral blood transplants—more rapid engraftment can cut hospital stays by 4 or 5 days or more—account for some of its current popularity, Dr. Appelbaum said in an interview. Its major risk, ie, the heightened chance of developing chronic graft-vs-host disease, doesn’t show up until later, after the patient has left the transplantation center.
Peripheral blood transplants also may be preferred by some donors because they do not involve general anesthesia. But both kinds of donation are a major commitment, noted Dr. Appelbaum. Donors who give peripheral blood must take large doses of colony-stimulating factor, which can cause pain for several days before the procedure, sometimes requiring strong medication.
Most important, the increased risk of chronic graft-vs-host disease in patients who receive peripheral blood stem cells is a serious one. Though usually manageable, the disease can make it necessary for some patients to be on immunosuppressive drugs for a number of years. Complications can range from mild to fatal.
Although practice should change for most patients as a result of this trial, there are some groups of patients who should have peripheral blood transplants, Dr. Appelbaum said. For instance, patients who have reduced-intensity chemotherapy have a greater risk of graft failure, and they should use peripheral blood transplants because of the higher engraftment rates.
Eventually, new drugs could influence the choice of bone marrow or peripheral blood transplants. One area of study, he said, is better methods of preventing graft-vs-host disease, which, if successful, could remove the main disadvantage of peripheral blood transplants. Also under study are methods to improve engraftment after bone marrow transplants, which would remove its principal disadvantage.
In the meantime, the need for unrelated donors for all patients who need stem cell transplants remains an important issue. Donors can be found for most whites, but because of greater HLA polymorphism and underrepresentation in the registries, most blacks, Hispanics, Asians, and Native Americans cannot be matched with a donor.
Researchers are investigating ways to identify allowable HLA mismatches as well as the use of haploidentical donors and mismatched cord-blood transplants, Dr. Appelbaum wrote in the editorial. “These efforts must be successful if we are to reach the long-sought goal of having an acceptable source of allogeneic hematopoietic stem cells for every patient in need.” ■
Disclosure: Dr. Appelbaum reported no potential conflicts of interest.
1. Appelbaum FR: Pursuing the goal of a donor for everyone in need. N Engl J Med 367:1555-1556, 2012.