[Haploidentical transplantation using post-transplant high-dose cyclophosphamide for adult T-cell lymphoma after mogamulizumab treatment].

A 53-year-old man diagnosed with adult T-cell lymphoma (ATL) was treated with mLSG15 chemotherapy and achieved a first complete remission. Subsequently, a liver tumor emerged that was pathologically diagnosed as ATL (first relapse). A second remission was achieved after local irradiation and four cycles of mogamulizumab treatment. The patient received peripheral blood stem cell transplantation (HSCT) from a one haplotype HLA-mismatched daughter after total body irradiation and the administration of fludarabine as a myeloablative conditioning regimen, followed by post-transplant cyclophosphamide. While subsequent acute graft-versus-host disease (GVHD) was never more than Grade I, severe chronic GVHD (cGVHD) developed in the oral cavity and skin that was resistant to escalated doses of cyclosporine and prednisolone. The patient subsequently had a second relapse of ATL as a subcutaneous mass and eventually died of disease progression. Mogamulizumab is a humanized monoclonal IgG that targets CC chemokine receptor 4 (CCR4) and is a key treatment option for relapsed ATL. It reportedly increases the risk of acute GVHD after HSCT due to the depletion of CCR4-positive regulatory T-cells; however, information on its impact on cGVHD is unavailable. Here, we discuss the potential risks and benefits of mogamulizumab, particularly in a haploidentical donor setting during a HSCT for ATL.