Eosinophil, monocyte and leukocyte counts could correlate with the severity of systemic mastocytosis (SM) and predict outcomes, according to a recently published study in JACI in Practice.
Although the hallmark of SM is the KIT D816V mutation, which is present in over 90% of patients, the presence of additional noninherited (somatic) mutations, especially in genes such as ASXL1, SRSF2 and TET2, has been increasingly recognized as a marker of poor prognosis in advanced SM.
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The cellular component of the blood contains many different cell types, including eosinophils (a cell type involved in allergic response), monocytes (cells involved in immunological responses against infections) and other leukocytes (white blood cells). The number of these cells in every square millimeter of blood can be easily measured. Therefore, finding specific cell counts that correlate with disease severity can represent a valuable and easily accessible tool for physicians treating SM.
While eosinophilia (increased eosinophile count) has previously been associated with adverse outcomes, the implications of leukocytosis (increased leukocyte count) and monocytosis (increased monocyte count) had not been fully characterized. In this context, researchers aimed to analyze data from 596 patients with SM in order to analyze the potential prognostic value of monocyte, eosinophil and leukocyte counts.
The study included 270 patients with advanced SM and 326 with nonadvanced forms. The researchers examined leukocyte, monocyte and eosinophil counts at diagnosis, identifying significant differences between advanced and nonadvanced SM patients.
The authors observed that elevated counts were associated with higher KIT D816V allele burden and greater numbers of additional somatic mutations. Monocytosis, in particular, showed strong correlations with mutations in ASXL1, SRSF2 and TET2.
Researchers noted that the presence of these hematologic abnormalities significantly impacted overall survival (OS). Patients with leukocytosis had a median OS of 1.6 years, versus 4.7 years for those without. Similarly, monocytosis and eosinophilia were linked to reduced median OS (2.9 versus 4.8 years and 1.7 versus 5.0 years, respectively).
The combination of monocytosis and eosinophilia defined a high-risk subgroup with a median OS of just 1.6 years, compared to 6.9 years in patients without either abnormality.
“In summary, our study provides valuable insights into the clinical and prognostic significance of leukocytosis, monocytosis and eosinophilia in SM and AdvSM [advanced SM],” the authors concluded. “Utilizing a differential blood count is cost-effective, highly reliable and objective, making it a practical tool for physicians being involved in the management of SM patients across different specialties.”
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