A younger age at bone marrow transplant appears to predict a better outcome. Donor:  Transplants from a matched family donor (MFD), matched unrelated donor (MUD), and matched unrelated umbilical cord blood donors have all shown similar relapse rates, though transplant-related deaths are higher with MUDs and mostly due to infectious causes. Extra medicinal protection, therefore, is usually given to recipients of MUD transplants to protect the child from Graft Versus Host Disease (GVHD). JMML patients are justified for MUD transplants if no MFD is available due to the low rate of survival without a bone marrow transplant. Conditioning regimen: The COG JMML study involves 8 rounds of total-body irradiation (TBI) and doses of cyclophosphamide to prepare the JMML childs body for bone marrow transplant. Use of TBI is controversial, though, because of the possibility of late side-effects such as slower growth, sterility, learning disabilities, and secondary cancers, and the fact that radiation can have devastating effects on very young children. It is used in this study, however, due to the concern that chemotherapy alone might not be enough to kill dormant JMML cells. The EWOG-MDS JMML Study includes busulfan in place of TBI due to its own research findings that appeared to show that busulfan was more effective against leukemia in JMML than TBI. The EWOG-MDS study also involves cyclophosphamide and melphalan in its conditioning regimen. Post transplant management: patients can experience relapse, causing treatment failure. It can be prevented by starting the patient with withdrawal of immunosuppressants and/or begin donor lymphocyte infusion.
Relapse rate has been recorded as high as 50%. Many children have been brought into remission after a second stem cell transplant.After bone marrow transplant, the relapse rate for children with JMML may be as high as 50%. Relapse often occurs within a few months after transplant and the risk of relapse drops considerably at the one-year point after transplant. A significant number of JMML patients do achieve complete remission and long-term cure after a second bone marrow transplant, so this additional therapy should always be considered for children who relapse. Frequency
JMML accounts for 1–2% of childhood leukemias each year; in the United States, an estimated 25-50 new cases are diagnosed each year, which also equates to about 3 cases per million children. There is no known environmental cause for JMML. Since about 10% of patients are diagnosed before 3 months of age, it is thought that JMML is a congenital condition in these infants

History
Juvenile myelomonocytic leukemia (JMML) is a myelodysplastic and myeloproliferative disorder. The diagnostic criteria were originally laid down by Neimeyer et al. in 1997 and 1998 and were incorporated in the WHO classification in 2008. See also
List of cutaneous conditions
Hematologic disease
List of cancer types

References


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