Allogeneic hematopoietic stem cell transplantation for solid tumors in the United States: a review

The field of bone marrow transplantation has undergone dramatic changes over the past few decades. Not only has the terminology changed (e.g., hematopoietic stem-cell transplantation), but the role of allogeneic transplantation has been modified from supportive to immunotherapeutic and the applications have expanded from hematologic malignancies to solid tumors. The development of nonmyeloablative conditioning regimen has greatly increased the number of patients eligible for this kind of treatment. Use of hematopoietic stem-cell transplantation as a form of adoptive immunotherapy in the treatment of cancer depends on advances in tumor immunology, particularly the identification of tumor antigens and mechanisms of immunotherapy. The earliest use of allogeneic transplantation of immunogenic cells for the treatment of solid tumors in the late 1960s and early 1970s produced no definite graft-versus-tumor effects. However, as conventional allogeneic hematopoietic stem-cell transplantation methods for the treatment of hematologic malignancies have matured, these methods have reestablished the foundation for expanding their application to solid tumors. From the first case reports on medulloblastoma and breast cancer to subsequent case series reports on breast cancer and renal cell carcinoma, allogeneic hematopoietic stem-cell transplants have demonstrated graft-versus-tumor effect. At present, the most common solid tumor for which this treatment is used is advanced renal cell carcinoma, but allogeneic hematopoietic stem-cell transplants have proven feasible for other solid tumors as well. Directions for future study include the identification of the definitive tumor antigens involved in the graft-versus-tumor effect and means of selecting those patients who will benefit the most from this form of treatment. This review summarizes the peer-reviewed literature on the use of allogeneic transplantation for solid tumors based on US studies.