Isolated central nervous system relapse in lymphoid blast crisis chronic myeloid leukemia and acute lymphoblastic leukemia in patients on imatinib therapy

Philadelphia chromosome positive ALL and CML have shown remarkable responses to imatinib (Gleevec, STI571) in phase I, II and III studies. However, imatinib has very poor penetration of the blood brain barrier resulting in subtherapeutic levels in the CNS. We present 2 cases of patients treated with imatinib that achieved complete cytogenetic remission within 3 months who subsequently developed CNS relapses while remaining in complete cytogenetic remission on bone marrow examination. Both patients went on to achieve CNS remission following treatment with intrathecal methotrexate and cytarabine.