Relapse-free survival of a patient with PTPN11 mutation-positive juvenile myelomonocytic leukemia with blast crisis after salvage haploidentical transplantations for graft failure after cord blood transplantation

Abstract

The prognosis of PTPN11 mutation-positive juvenile myelomonocytic leukemia (JMML) with blast crisis remains very poor. A 3-year-old girl presented with fever, hepatosplenomegaly, anemia, and thrombocytopenia. Bone marrow examination showed refractory anemia with excessive blasts, but we diagnosed her as having JMML with blast crisis on the basis of the finding of PTPN11 mutation positivity and spontaneous colony assay results. Because of graft failure after single-allele mismatch cord blood transplantation, we performed salvage transplantation of haploidentical peripheral stem cells from her mother. She achieved complete chimerism along with grade III acute GVHD; however, she developed donor-type aplasia thereafter. Since donor cell infusion from her mother did not lead to hematopoiesis recovery, she underwent haploidentical bone marrow transplantation from her father. She remains disease-free for more than one year after the last transplantation. Haploidentical hematopoietic stem cell transplantation (HSCT), via its potent GVL effects, may be effective for treating the most severe type of JMML such as PTPN11 mutation-positive JMML with blast crisis, which cannot be cured by conventional HSCT.