Persistent complete remission of acute leukemic-phase CCR4-positive gamma-delta peripheral T-cell lymphoma by autologous stem cell transplantation with mogamulizumab.

Peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS), frequently shows a poor outcome. Especially, expressions of CC chemokine receptor 4 (CCR4) and γδ T-cell receptor (TCR) are associated with worse prognosis in PTCL-NOS. We here report successful treatment with autologous peripheral blood stem cell transplantation (auto-PBSCT) combined with anti-CCR4 antibody mogamulizumab for a very rare case of CCR4+γδTCR+ PTCL-NOS that coexisted with Hodgkin's lymphoma. PTCL-NOS in this patient progressed to leukemic phase, whereas Hodgkin's lymphoma disappeared with standard chemotherapies within 4 years of the initial diagnosis. Leukemic-phase PTCL-NOS was refractory to several chemotherapies. However, auto-PBSCT following high-dose chemotherapy combined with pre- and post-transplant mogamulizumab, which is a humanized monoclonal antibody to CCR4, provided persistent complete remission of PTCL-NOS, despite residual γδTCR+ in the transplanted stem cell product, suggesting a purging effect of mogamulizumab. At 15 months after transplantation, we also found markedly fewer effector regulatory T cells, which may have contributed to prolonged remission. This case suggests that autologous stem cell transplantation combined with mogamulizumab may have a potential to cure T-cell neoplasms that express CCR4 including leukemic-phase PTCL-NOS.