[Isolated central nervous system relapse of Philadelphia chromosome-positive acute lymphoblastic leukemia during ponatinib maintenance therapy].

A 65-year-old man was diagnosed with Philadelphia chromosome-positive acute lymphoblastic leukemia with no initial central nervous system (CNS) involvement. Complete remission was achieved after the induction therapy. However, during consolidation therapy, he developed septic shock and pneumocystis pneumonia, leading to interruption in chemotherapy and allogeneic transplantation. Subsequently, he achieved complete molecular remission and ponatinib maintenance therapy was initiated. Two years later, he developed left leg paralysis and was diagnosed with isolated CNS relapse; however, radiation therapy improved CNS lesions and paralysis. Thus, ponatinib maintenance therapy alone is inadequate in preventing CNS relapse in patients who have not completed systemic chemotherapy for CNS relapse prevention.