Mogamulizumab (Mog), an anti-C-C motif chemokine receptor 4 (CCR4) antibody, is a therapeutic for adult T-cell leukemia/lymphoma (ATL). Injuries of normal regulatory T cells (Tregs) which express CCR4 by Mog could result in immune-related adverse events including graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). In this study, we retrospectively analyzed 25 patients among 39 patients with ATL who received allo-HSCT. We found that the risk of grade II to IV GVHD was higher in patients who received Mog before or after allo-HSCT (Mog+) than in those who did not (Mog-). The incidence of severe intestinal GVHD and cytomegalovirus (CMV) enteritis were significantly higher in Mog + patients and resulted in death from GVHD or CMV enteritis. Treg numbers were suppressed until Mog serum concentrations became undetectable. Measuring the concentration of Mog and/or the number of Tregs at the time of allo-HSCT might predict the risk of GVHD.
Keywords: ATL; GVHD; allogeneic hematopoietic stem cell transplantation; mogamulizumab; regulatory T cell.