Severe graft-versus-host disease of the lower intestinal tract after pomalidomide administration in a plasma cell leukemia patient following bone marrow transplantation.

Posttransplant treatment is performed to treat hematopoietic diseases but can lead to allogeneic-specific complications in addition to those seen in a non-transplant setting. Immunomodulatory drugs (IMiDs) activate cytotoxic T cells and suppress regulatory T cells. The optimal timing and optimal dose of IMiDs after allogeneic transplantation (allo-HSCT) to reduce complications and increase antitumor efficacy are difficult to determine because the degree of recovery of donor immune cells varies depending on the time after allo-HSCT. We experienced a patient with allo-HSCT who developed severe late acute graft-versus-host disease (GVHD) of the lower intestinal tract after receiving pomalidomide as a posttransplant therapy eight months after allo-HSCT. It is possible that pomalidomide induced acute GVHD by altering the activity of donor immune cells. This first case report highlights that the use of pomalidomide after allo-HSCT may lead to severe late acute GVHD. When pomalidomide is used after allo-HSCT, it is desirable to start with a small dose and gradually increase the dose while monitoring cytokine and lymphocyte subsets for the onset of GVHD.