Overview
Juvenile myelomonocytic leukemia (JMML) is a rare, aggressive myeloproliferative neoplasm primarily affecting infants and young children, characterized by excessive proliferation of myelomonocytic cells 1.Diagnosis
Clinical Presentation: Persistent monocytosis (>1 × 10^9/L), hepatosplenomegaly, and often associated with genetic mutations (NF1, RAS, or SH2B3) 1.
Laboratory Tests: Complete blood count showing monocytosis, bone marrow biopsy revealing hypercellularity with myelomonocytic proliferation 1.
Genetic Testing: Identification of specific mutations (e.g., NRAS, KRAS, PTPN11, CBL) crucial for diagnosis 1.Management
First-Line Treatment: Chemotherapy regimens aimed at inducing remission; response criteria vary (e.g., International JMML Symposium criteria I and II) 1.
Complete Response (CR) Rates: Varying significantly with different criteria (46.6% with criteria I, 28.8% with criteria II) 1.
Allogeneic Hematopoietic Cell Transplantation (HCT): Recommended for curative intent, especially in younger patients; conditioning regimens evolving from Busulfan/Cyclophosphamide to Busulfan/Fludarabine 2.
Prognostic Factors: Higher hemoglobin F levels, abnormal cytogenetics, and matched sibling donors associated with better outcomes 2.
Chimerism Monitoring: Important for assessing graft success; below 99% donor chimerism linked to higher relapse rates 2.Special Populations
Pediatrics: Majority of cases occur in children under 4 years; treatment strategies heavily focused on pediatric populations 12.Key Recommendations
Consider Allogeneic HCT Early for eligible JMML patients to improve survival outcomes (Evidence: Moderate) 2.
Monitor Donor Chimerism Post-HCT to guide management and predict relapse risk (Evidence: Moderate) 2.
Utilize Updated Response Criteria for assessing chemotherapy efficacy in JMML patients to guide treatment decisions (Evidence: Weak) 1.References
1 Yi ES, Baek HJ, Ju HY, Kim SK, Lee JW, Cho B et al.. Response to chemotherapy in juvenile myelomonocytic leukemia and its clinical implications for survival: A retrospective registry-based study of the Korean Pediatric Hematology-Oncology Group. Leukemia research 2023. link
2 Yi ES, Kim SK, Ju HY, Lee JW, Cho B, Kim BK et al.. Allogeneic hematopoietic cell transplantation in patients with juvenile myelomonocytic leukemia in Korea: a report of the Korean Pediatric Hematology-Oncology Group. Bone marrow transplantation 2023. link