What’s new in aplastic anemia research and treatment?

New understanding about the causes of some forms of inherited aplastic anemia, especially Fanconi Anemia, Diamond-Blackfan Syndrome, and Schwachman-Diamond Syndrome, may provide entirely new approaches to treatment of aplastic anemia in the future.

Other major advances in treating aplastic anemia may come from further research on the immune system. As doctors learn more about how the immune system works, they can develop new methods of suppressing it. Researchers are working to improve the drugs used for immunosuppression and stem cell transplantation. The goal is to find treatments that have fewer side effects and better results than the current treatments.

One drug under study is called daclizumab (Zenapax^®). This is a monoclonal antibody (a laboratory-made antibody that attaches to specific substances) that blocks the action of interleukin-2 (IL-2). IL-2 is a normal part of the immune system that stimulates the immune response. Blocking IL-2 suppresses the immune system in a different way from anti-thymocyte globulin (ATG). Allergic reactions to this drug are rare. It is currently being used as a part of stem cell transplants, and is under study as a treatment for aplastic anemia.

Another drug being looked at is called mycophenolate mofetil. It is already used as an immunosuppressant in people who have received organ transplants and is being studied as a treatment for acquired aplastic anemia.

A new drug called eltrombopag (Promacta^®) has become available to treat some people with low platelet counts caused by the immune system. In one study of patients with acquired aplastic anemia that was no longer responding to immunosuppression, it helped improve blood counts in some patients. This drug didn’t just affect platelet counts. In some patients, it improved white counts and/or red blood cell counts. More studies of this drug in aplastic anemia are going on now.

Alefacept is a new drug that can turn off T cells. It has been helpful in treating psoriasis and graft-versus-host disease and is now being studied in the treatment of severe acquired aplastic anemia.

Researchers are also studying the possibility of using gene therapy to treat some inherited forms of aplastic anemia. Another approach is to give a drug called amifostine (Ethyol^®) to help protect the bone marrow in children with Fanconi anemia.

Doctors are also trying to make stem cell transplants safer and more available. One approach is to use stem cells that come from the umbilical cord blood of newborns. This is a very rich source of stem cells. Efforts are being made nationwide to develop storage facilities for cord blood. The advantage of cord blood stem cells is that they may lead to less graft-versus-host disease. The disadvantage is that there may be too few cells to successfully “take.” In one case, doctors have overcome this by transplanting cord blood stem cells from 2 separate donors. This has proven successful and may have an even lower risk of graft versus host disease. This method is currently under study.