Stem cell transplantation for Waldenstrom macroglobulinemia

Stem cell transplants (SCT) let doctors use higher doses of chemotherapy than would normally be tolerated. High-dose chemotherapy destroys the bone marrow, which keeps new blood cells from forming. This could lead to life-threatening infections, bleeding, and other problems due to low blood cell counts.

Doctors try to get around this problem by giving an infusion of stem cells after treatment. Stem cells can create new blood cells.

Blood-forming stem cells used for a transplant are obtained either from blood (for a peripheral blood stem cell transplant, or PBSCT) or from the bone marrow (for a bone marrow transplant, or BMT). Peripheral blood stem cells are obtained using a procedure similar to that for a blood donation, while bone marrow donation is usually done in an operating room (while the donor is asleep under general anesthesia). Bone marrow transplants were more common in the past, but they have largely been replaced by PBSCTs.

There are 2 main methods of SCT: allogeneic and autologous.

Autologous stem cell transplant

This is the type of transplant used most often in Waldenstrom macroglobulinemia (WM). In an autologous stem cell transplant, a patient's own blood-forming stem cells are removed from his bloodstream and stored to use later. Then high doses of chemotherapy are given to kill the WM cells. The high doses of chemotherapy kill the normal bone marrow cells as well as the cancer cells. After chemotherapy, the frozen stem cells are thawed and returned to the body (like a blood transfusion). Autologous transplants can help some people with WM, but doctors are still trying to figure out which patients will benefit the most.

Allogeneic stem cell transplant

This is a treatment that is still being studied for WM, and experts recommend it be done as part of a clinical trial. In an allogeneic stem cell transplant, the stem cells that the patient receives after chemotherapy are from someone else (a donor). The donor has to match the patient in certain inherited basic cell characteristics, so the donor is usually a close relative — often a brother or sister. If there is no sibling that matches, someone who isn’t related who matches may be a donor, although this makes the transplant more risky.

Blood-forming stem cells can be taken from the bone marrow (usually in the operating room) or they can be separated from the peripheral (circulating) blood by a process known as apheresis.

Allogeneic transplantation has more risks and side effects than an autologous transplant. It is also difficult sometimes to find a matched donor.

A newer approach to allogeneic (donor) stem cell transplant is called non-myeloablative transplant. In this type of transplant, lower doses of chemotherapy or radiation therapy are used than in traditional allogeneic transplant. Patients are given drugs to suppress their immune reaction. This allows the donor cells to grow and partly take over the patient's immune system. The donor cells then begin reacting against the lymphoma cells and killing them. The problem is that the donor cells also react against the patient's normal cells. This leads to graft-versus-host disease (GVHD), which can make patients very sick. Doctors are trying to refine this treatment so that the reaction against the lymphoma cells will occur but not the reaction against normal cells.

Stem cell transplant is a complex treatment. If the doctors think the patient may benefit from transplantation, the best place to have it done is at a cancer center where the staff has experience with the procedure and with managing the recovery period. Patients should not hesitate to ask the doctor about the number of times he or she has done this procedure and how patients responded to the treatment. Experience and knowledge are key factors in providing the best care.

For more information about stem cell transplantation, please see our document, Bone Marrow and Peripheral Blood Stem Cell Transplants.