Unrelated donor bone marrow transplantation for acute mixed lineage (myeloid and B-lymphoid lineage) leukemia in an adult with Down syndrome

This article describes a rare case of bone marrow transplantation (BMT) from an unrelated donor (URD) in an adult Japanese male with Down syndrome (DS) diagnosed as having acute mixed lineage leukemia. Examination of peripheral blood demonstrated WBC 6.2×10⁹/l with 45.5% blasts at admission. Leukemic blasts with positive peroxidase stain, but negative periodic acid–Schiff stain comprised 91.6% on bone marrow specimen. Surface marker analysis of these blasts showed the following: CD3^-, CD5^-, CD7^-, CD10⁺, CD19⁺, CD13⁺, CD14^-, CD33⁺, CD34⁺, CD41a^-, and CD56^-. Based on these data, he was diagnosed as having acute mixed lineage (myeloid and B-lymphoid lineage) leukemia. He achieved complete remission (CR) by lymphoid-oriented chemotherapy performed after ineffective myeloid-oriented therapy. After four courses of consolidation chemotherapy for lymphoid lineage blasts, recurrence due to proliferation of myeloblasts had occurred. Thereafter, a second CR was obtained by low dose cytosine arabinoside (AraC) therapy. As this patient was considered to have a high risk of relapse, we selected allogeneic BMT from URD. Severe stomatitis due to methotrexate (MTX) occurred probably due to altered pharmacokinetics usually observed in DS patients. Though acute graft-versus-host disease (GVHD) of systemic skin (grade II) and pneumonia were observed during neutropenia due to the post-conditioning regimen, he could be discharged from our hospital on the 135th day after BMT. On day 205 post-BMT, however, bronchiolitis obliterans (BO) occurred as a chronic GVHD disorder. Despite therapy with prednisolone and FK506, he died on day 400 post-BMT because of respiratory failure due to BO. In DS patients, superfluous toxicities due to MTX and AraC treatment have been reported, and these toxicities have been considered due to altered pharmacokinetics in patients with DS. This patient could tolerate the transplant conditioning regimen commonly used in patients without DS.