Bone Marrow Hematopoietic-Stem-Cell Transplantation Among Oldest Forms of Cancer Immunotherapy Targeted therapies that mobilize the body’s immune system to attack cancer cells continue to emerge as promising weapons in the arsenal of cancer treatment options. But the idea behind cancer immunotherapy is not a new one. More commonly known as bone-marrow transplantation (BMT), hematopoietic-stem-cell transplantation (HSCT) has been performed in the United States for more than 40 years to support patients undergoing treatment for cancers such as acute myeloid leukemia (AML), multiple myeloma or lymphoma. This image illustrates in detail the characteristic morphologic features of the myeloid response following G-CSF stem cell mobilization. Photo: American Society of Hematology STORY HIGHLIGHTS Hematopoietic-stem-cell transplantation has been performed in the United States for more than 40 years to support patients undergoing treatment for cancers such as acute myeloid leukemia, multiple myeloma or lymphoma. While using allogeneic stem cells carries major risks of infection and graft- versus-host disease, newer strategies have led to fewer complications and improved outcomes. UCLAHEALTH.ORG “Few immune therapies have the track record and demonstrated effi cacy that we observe with HSCT,” says Gary Schiller, MD, director of the Hematologic Malignancies/Stem Cell Transplant Unit at UCLA. “It is the most common immune therapy done in the world for cancer and is the immune therapy for which there is the greatest experience.” In fact, more than 60,000 HSCTs are performed internationally each year, according to Dr. Schiller. Approximately half of transplanted hematopoietic stem cells (those capable of reconstituting bone marrow and blood) are autologous, in which the recipient acts as his or her own donor. The other half are allogeneic, in which stem cells are donated from related (usually a sibling with closely matched human leukocyte antigens) or unrelated adults or from the umbilical-cord blood of a newborn. Both procedures are done to replace bone marrow damaged or destroyed by chemo or radiation therapies delivered to treat malignancies with healthy bone-marrow stem cells. Allogeneic HSCTs, however, also serve another purpose. “Allogeneic HSCTs deliver an immunoreactive organ, which is more likely to favorably impact 1-800-UCLA-888 (1-800-825-2888) the disease,” Dr. Schiller explains. “When using allogeneic stem cells, the chemo and radiation therapies do not necessarily need to completely kill every last malignant cell because some of the heavy lift ing will be done by the donor’s immune system.” The procedure carries major risks. Infection and graft-versus-host disease, an inflammatory condition in which the immune cells of the donor attack the recipient’s tissues, are major complications of allogeneic HSCT. Newer strategies, however, have led to fewer complications and improved outcomes. “Few ‘immune therapies’ have the track record and demonstrated effi cacy that we observe with HSCT. It is the most common immune therapy done in the world for cancer.” “We have become better at identifying and matching potential donors; we have begun to reduce the chemo and radiation therapy we use to treat malignancies because we are more skilled in harnessing the immune effect of donor cells; and we have more effective antibiotics that we use to prevent infections,” Dr. Schiller says. These developments have enabled physicians to expand allogeneic HSCTs to broader populations of patients for whom the risks of transplantation might have previously been too great. For example, “mini-transplant” procedures have been