Response of steroid-resistant graft-versus-host disease to lymphoblast antibody CBL1

Therapy of steroid-resistant graft-versus-host disease (GVHD) with antibodies to T cells or cytokines is of limited value because GVHD is mediated by a pleomorphic group of effective cells and cytokines. CBL-1, a murine monoclonal antibody, recognises an antigen on activated T cells, B cells, and natural killer cells. We administered CBL-1 to ten patients with grade III or IV steroid-resistant GVHD. Complete remissions occurred in five cases and partial remissions in four. The organ system(s) affected by GVHD was not a predictor of response. CBL-1 was well tolerated and did not exacerbate post-transplant immunodeficiency. Our findings support the use of CBL-1 in primary prophylaxis for GVHD.