Nearly a decade ago, Bonini et al demonstrated the control of graft-versus-host disease (GVHD) in human allogenic bone-marrow transplant recipients by coinjection of suicide-gene transduced donor T-cells with the T-cell depleted graft, while maintaining the graft-versus-leukemia (GVL) effect.
Why does GVHD continue to be a major cause of post-transplant mortality today? What's wrong with the suicide gene approach? Why was it not pursued much more intensively in the past decade?