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Luspatercept (Reblozyl) was recently approved for treating patients with transfusion-dependent lower-risk myelodysplastic syndrome (MDS) with ring sideroblasts (RS) and/or SF3B1 mutation who were not eligible for erythropoiesis-stimulating agents (ESAs) or patients for whom those agents failed. Luspatercept acts as an activin receptor type IIB fusion protein ligand trap that targets the altered transforming growth factor beta pathway in MDS, which is associated with impaired terminal erythroid maturation. Treatment with luspatercept results in decreased SMAD signaling, which enables erythroid maturation by means of late-stage erythroblast differentiation and thus improves anemia. ESAs, the current standard first-line therapeutic option for anemic lower-risk patients with MDS, also improve red cell parameters mainly by expanding proliferation of early erythroid progenitor cells. However, erythropoietin (EPO) and its receptor (EPO-R) are also required for survival of late-stage definitive erythroid cells, and they play an essential role in promoting proliferation, survival, and appropriate timing of terminal maturation of primitive erythroid precursors. Thus, luspatercept joins the mechanism of ESAs in promoting erythroid maturation. Especially in the subgroup of MDS patients with RS, luspatercept showed high clinical activity for the treatment of anemia in the phase 2 (PACE-MDS) trial and subsequently in the phase 3 (MEDALIST) trial, which resulted in approval by both the US Food and Drug Administration and the European Medicines Agency in April 2020. Additional studies are needed to better understand the mechanism of action and pharmacodynamics of this novel agent in MDS., (© 2021 by The American Society of Hematology.)

Objective: Azacitidine and decitabine are used to treat patients with myelodysplastic syndromes (MDS) in the United States (US). This study sought to assess their relative cost-effectiveness., Design and Methods: The authors developed a cost-effectiveness Markov model (1-month cycles) tracking hypothetical cohorts of MDS patients treated with azacitidine or decitabine over 2 years. The model used a US payer perspective and 2009 costs. Health states modeled included MDS with Transfusion Dependence, MDS with Transfusion Independence, Progression to Acute Myelogenous Leukemia (AML), and Death. Incremental cost-effectiveness outcomes included cost per quality-adjusted life year (QALY), cost per life year (LY), cost per patient-month of transfusion independence, and cost per case of AML progression avoided. One-way sensitivity analyses were performed on key model parameters., Results: Compared to decitabine, azacitidine was associated with better survival (1.512 LYs vs 1.292), more QALYs gained (1.041 vs 0.870), more patient-months with transfusion independence (8.328 vs 6.224), and a greater proportion of patients avoiding progression to AML (50.9% vs 28.5%). Total per-patient costs over 2 years for azacitidine were lower than for decitabine ($150,322 vs $166, 212)., Limitations: To inform and update the model over time, it will be important that randomized or observational clinical studies be conducted to directly compare azacitidine and decitabine, provide new information on how these medicines are used, and on their relative clinical effectiveness., Conclusion: Results demonstrate that azacitidine provides greater clinical benefit and costs less than decitabine across all key outcomes. These results accentuate the positive role of azacitidine in providing cost-effective care for MDS.

The classification of myelodysplastic syndromes is based on the morphological criteria proposed by the French-American-British (FAB) and World Health Organization (WHO) groups. Accurate enumeration of blast cells, although essential for diagnosis of myelodysplastic syndrome and for assignment to prognostic groups, is often difficult, due to imprecise criteria for the morphological definition of blasts and promyelocytes. An International Working Group on Morphology of Myelodysplastic Syndrome (IWGM-MDS) of hematopathologists and hematologists expert in the field of myelodysplastic syndrome reviewed the morphological features of bone marrows from all subtypes of myelodysplastic syndrome and agreed on a set of recommendations, including recommendations for the definition and enumeration of blast cells and ring sideroblasts. It is recommended that (1) agranular or granular blast cells be defined (replacing the previous type I, II and III blasts), (2) dysplastic promyelocytes be distinguished from cytologically normal promyelocytes and from granular blast cells, (3) sufficient cells be counted to give a precise blast percentage, particularly at thresholds that are important for diagnosis or prognosis and (4) ring sideroblasts be defined as erythroblasts in which there are a minimum of 5 siderotic granules covering at least a third of the nuclear circumference. Clear definitions and a differential count of a sufficient number of cells is likely to improve precision in the diagnosis and classification of myelodysplastic syndrome. Recommendations should be applied in the context of the WHO classification.