Nonmyeloablative transplantation: an allogeneic-based immunotherapy for renal cell carcinoma.

High-dose chemotherapy followed by autologous hematopoietic stem cell transplantation has been explored as a method to enhance the efficacy of chemotherapy for advanced solid tumors. The failure of autologous hematopoietic stem cell transplantation to prolong survival in patients with metastatic solid tumors has sparked interest recently in studies exploring the potential of allogeneic hematopoietic stem cell transplantation for such patients. Allogeneic hematopoietic stem cell transplantation is widely accepted as a potent form of immunotherapy capable of curing patients with chemotherapy-refractory hematologic malignancies. However, it was not until the end of the 20th century that investigators initiated trials to test the potential of allogeneic hematopoietic stem cell transplantation as immunotherapy in malignancies of epithelial origin. Early pilot trials have established proof-of-principle that graft-versus-tumor effects can induce complete or partial remission in some treatment-refractory metastatic solid tumors. In this review, we discuss the rationale for pilot trials investigating the potential of nonmyeloablative allogeneic hematopoietic stem cell transplantation in advanced cytokine-refractory renal cancer, highlighting the preliminary success, limitations, and future clinical directions of this approach.