LAUSR

Dear Editor, Chronic myelomonocytic leukemia (CMML) is a clonal disorder of aging hematopoietic stem cells characterized by overlapping features of myeloproliferation and myelodysplasia, with a median overall survival (OS) of ≤36 months. Hypomethylating agents (HMAs) have an overall response rate of about 30–40%; however, these agents are ineffective in altering the natural disease biology due to inability to prevent acquisition of molecular abnormalities and transformation to acute myeloid leukemia (AML). Allogeneic hematopoietic stem cell transplantation (alloHCT) is a potentially curative option, with 20–50% patients achieving long-term remissions. However, as the median age of presentation is 73 years, only a fraction (<20%) of CMML patients are eligible for alloHCT. Prognostic models such as the Mayo Prognostic Model (MPM), Mayo Molecular Model (MMM), Groupe Francais des Myelodysplasies, and the CMML-specific prognostic scoring system (CPSS) are important tools to identify patients at high risk for disease progression and death. Several retrospective analyses of outcomes in alloHCT patients have identified adverse cytogenetics, blast percentage, HCT-comorbidity Index, time to alloHCT, disease control at the time of alloHCT and acute and chronic graft vs. host disease (GVHD) as factors influencing OS and AML-free survival (LFS). In the absence of randomized controlled trials, the questions of optimal timing of alloHCT in CMML, prealloHCT use of HMA vs. cytotoxic chemotherapy, and the selection of patients who should be treated upfront with alloHCT remain unanswered. We performed this study to assess the outcomes and therapeutic impact of alloHCT in patients with CMML.