Long-term remission of primary refractory ALK-positive anaplastic large cell lymphoma after allogeneic hematopoietic stem cell transplantation.

ALK-positive anaplastic large cell lymphoma (ALK+ ALCL) has a favorable prognosis in general; however, some cases are resistant to chemotherapy, which leads to a poor clinical outcome. We herein report the case of a 32-year-old male with aggressive ALK+ ALCL who presented with hemorrhage from a large tumor in the duodenum and multiple tumors in the lungs, mediastinum, and peritoneal cavity. Although induction chemotherapy resulted in a marked reduction of the tumor lesions, premature progression with massive pulmonary infiltration and central nervous system invasion occurred immediately after the completion of chemotherapy. The patient was then promptly treated with brentuximab vedotin (BV) and high-dose methotrexate, which resulted in complete remission. Subsequently, he successfully underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) from an unrelated donor and has been healthy and did not relapse for more than 3 years after transplantation without any additional therapy. Allo-HSCT may be a promising treatment option for ALK+ ALCL due to its graft-versus-lymphoma effect. In addition, molecular targeting agents, such as BV, may be promising as a bridging therapy before allo-HSCT to achieve disease remission.