Graft-versus-host disease in mini-transplant

Mini-transplant has been used popularly in recent years. The intensity of conditioning regimens is less in mini-transplant, thus the anti-tumor effect is mainly carried by an immunological reaction, called graft-versus-leukemia (GVL)/graft-versus-tumor (GVT) effect. Thus, graft-versus-host disease (GVHD) in mini-transplant has drawn much attention as a surrogate marker for GVL/GVT effect. However, as the regimen-related toxicity is less in mini-transplant, it is also true that GVHD is the single most worrisome adverse event after mini-transplant. As opposed to early predictions, the incidence and severity of GVHD after mini-transplant does not seem to be much different from the one after conventional stem cell transplant (CST). In addition, researchers find that host antigen presenting cells (APC) may play an important role in the development of GVHD, and thus the existence of donor-host chimerism may be critical. As a result, the theory regarding GVHD after mini-transplant is getting more confusing. A comprehensive understanding of GVHD after mini-transplant is necessary.