Impressive Continuous Complete Response after Mogamulizumab in a Heavily Pretreated Sézary Syndrome Patient

BACKGROUND: Sézary syndrome (SS) is a rare lymphoproliferative neoplasm, almost incurable outside the setting of allogeneic transplantable patients. The prognosis for relapsed/refractory patients remains poor, as the available drugs confer short-lasting remission. In this setting, the anti-chemokine receptor type 4 (CCR4) monoclonal antibody mogamulizumab demonstrated efficacy in an international, open-label, randomized controlled phase 3 trial (MAVORIC) versus vorinostat. CASE DESCRIPTION: A heavily pretreated 57-year-old SS woman (stage IVA) was randomized in the mogamulizumab arm of MAVORIC at our Institution. She quickly achieved a response, but after 30 cycles, she was discontinued from therapy due to cutaneous toxicity. Nevertheless, she is still in complete response (CR). CONCLUSIONS: mogamulizumab is an anti-CCR4 monoclonal antibody that can induce long-lasting response also in very heavily pretreated patients not responding to any previous treatment. The extraordinary characteristic of our patient is that she is still in CR after 2.5 years since treatment discontinuation.