The Absolute Monocyte Count at Diagnosis Affects Prognosis in Myelodysplastic Syndromes Independently of the IPSS-R Risk Score

Abstract

The absolute monocyte count (AMC) is associated with mortality in a variety of medical conditions. Its prognostic impact in myelodysplastic syndromes (MDSs) is less well studied. Therefore, we investigated its potential prognostic value in a cohort from the Düsseldorf MDS registry in relationship to the revised international prognostic scoring system (IPSS-R). An AMC below the population’s median (<0.2 × 109/L) was associated with several adverse disease features such as lower haemoglobin levels, lower count of neutrophils and platelets, and a higher percentage of blasts in the bone marrow. MDS patients with an AMC < 0.2 × 109/L had a significantly higher risk of progression into acute myeloid leukemia (AML). In a univariate, proportional hazards model the effect of the AMC as a continuous variable was modelled via p-splines. We found a U-shaped effect with the lowest hazard around 0.3 × 109/L. Accordingly, an AMC within the last quartile of the population (0.4 × 109/L) was associated with a reduced overall survival independently of IPSS-R, but not with the risk of secondary AML. Considering monocytopenia as a risk factor for AML progression in MDS may provide an additional argument for allogeneic transplantation or the use of hypomethylating agents in patients who are not clear candidates for those treatments according to current prognostic scoring systems and/or recommendations. Further studies are needed to assess the prognostic impact of the AMC in the context of prognostic scoring systems, considering the molecular risk profile, and to identify the mechanisms responsible for the higher mortality in MDS patients with a subtle monocytosis.

Chronic myelomonocytic leukemia with ring sideroblasts/SF3B1 mutation presents with low monocyte count and resembles myelodysplastic syndromes with-RS/SF3B1 mutation in terms of phenotype and prognosis

“…and Silzle et al., which, in a population of MDS with low blast count, have recently shown that monocytosis >0.6 x10 9 /L is associated with a shorter OS, also in the subtype enriched with RS. This suggests that MDS with monocytosis and CMML with RS may be located in a “gray zone” that makes diagnosis challenging but, on the other hand, supports a therapeutically similar approach in these cases ( 14 , 15 ). Altogether, this study supports the notion that classifications based on selected clinical characteristics, generally with arbitrarily chosen thresholds, have always inherent limitations.…”

“…Within the RS phenotype, 20% of patients show monocytosis and there seems to be a positive correlation between the percentage of RS and absolute monocyte count, with the overall survival (OS) being significantly shorter ( 14 ). Moreover, the absolute monocyte count at diagnosis may affect the prognosis in MDS independently of the Revised International Prognostic Score System (IPSS-R) risk score, and monocytopenia (<0.2 x10 9 /L) may be associated with a higher risk of acute myeloid leukemia (AML) transformation ( 15 ).…”