[Reduced-intensity allogeneic hematopoietic stem cell transplantation (mini-transplantation) for solid tumors]

There are accumulating evidence of immunological therapeutic effect induced by reduced-intensity allogeneic hematopoietic stem cell transplantation (mini-transplantation) for solid malignancies. The reduced toxicity of a mild preconditioning regimen in mini-transplantation has facilitated its application to patients with various solid tumors. The so-called graft-versus-tumor (GVT) effect usually appears when graft-versus-host disease develops. Therefore, it is suggested that the fundamental mechanism of the GVT effect is a reaction by T-lymphocytes against various tumor-associated alloantigens of the tumor cells. Although mini-transplantation appears effective in some patients with renal cell carcinoma or breast cancer, it is still unclear whether the therapeutic mechanism could work on other solid tumors. Well-designed prospective clinical trials are warranted in order to determine the role of mini-transplant in the therapeutic strategy for solid tumors.