Efficacy of alectinib for ALK-positive anaplastic large cell lymphoma with central nervous system relapse after allogeneic bone marrow transplantation

Abstract

A 10-year-old boy was diagnosed with central nervous system (CNS) relapse of ALK-positive anaplastic large cell lymphoma (ALCL). Despite reinduction therapy and whole-brain and spinal cord proton beam irradiation, followed by allogeneic bone marrow transplantation, molecular relapse occurred at 12 weeks post-transplantation. CNS relapse of ALCL remains a therapeutic challenge because of limited drug delivery to the CNS and the lack of established treatment strategies. In this case, initiation of oral alectinib with intrathecal injection of hydrocortisone and cytarabine and withdrawal of immunosuppressants led to renewed negativity for NPM::ALK fusion via polymerase chain reaction analysis. Moreover, the patient remained in complete remission four years after transplantation. These results suggest that alectinib with favorable cerebrospinal fluid penetration is potentially effective for CNS diseases. Therefore, incorporating alectinib into treatment strategies may improve long-term outcomes in CNS-relapsed ALK-positive ALCL. Future studies, including pharmacokinetic evaluations, should optimize its application in relapsed/refractory cases.