Successful non‐T‐cell‐depleted HLA‐haploidentical 3‐loci mismatched bone marrow transplantation

  A 17‐year‐old boy with therapy‐related acute myelocytic leukemia (FAB classification‐M0) successfully received allogeneic non‐T‐cell depleted (non‐TCD) bone marrow transplantation (BMT) from his 3‐loci HLA‐mismatch mother, although pre‐BMT detection of feto‐maternal microchimerism was negative. The BMT was performed with reduced intensity conditioning (total body irradiation; 4 Gy, fludarabine; 20 mg/m 2  × 6, and melphalan; 70 mg/m 2  × 2) and short‐course methotrexate and tacrolimus for GVHD prophylaxis. Complete donor chimera was obtained on day 19, associated with Grade 3 acute GVHD (skin: Stage 1, liver: Stage 0, gut: Stage 3) that was well controlled with immunosuppressive therapies. At day 200 of transplantation, he was in complete remission with no signs of chronic GVHD. Our case suggests that non‐TCD HLA‐haploidentical 3‐loci mismatched BMT can be safely performed from mother to offspring even when feto‐maternal microchimerism is barely detectable with the current detection procedure.