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Risk Model for Advanced Systemic Mastocytosis


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As reported in the Journal of Clinical Oncology, Jawhar et al have developed a risk model for advanced systemic mastocytosis that differentiates low-, intermediate-, and high-risk disease.

"The MARS is a validated, five-parameter, WHO-independent prognostic score that defines three risk groups among patients with [advanced systemic mastocytosis] and may improve upfront treatment stratification for these rare hematologic neoplasms.”
— Jawhar et al

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Study Details

The study included 383 patients with advanced systemic mastocytosis from the German Registry on Disorders of Eosinophils and Mast Cells (training set, n = 231) and from several centers for mastocytosis in the United States and Europe within the European Competence Network on Mastocytosis (validation set, n = 152).

Identification of Risk Groups

On multivariate analysis in the training set, factors significantly associated with overall survival were age > 60 years old, anemia (hemoglobin < 10 g/dL), thrombocytopenia (platelets < 100 x  109/L), presence of one high–molecular-risk gene mutation (in SRSF2, ASXL1, and/or RUNX1), and presence of two or more high–molecular-risk gene mutations.

Assignment of hazard ratio–weighted points to these variables resulted in discrimination of three risk groups: low risk, with median overall survival not reached; intermediate risk, with median overall survival of 3.9 years; and high risk, with median overall survival of 1.9 years (P < .001 for both high vs intermediate and low vs intermediate). This mutation-adjusted risk score was independent of World Health Organization (WHO) classification. Use of this mutation-adjusted risk score identified low-risk (median overall survival of 12.2 years), intermediate-risk (median overall survival of 4.4 years), and high-risk (median overall survival of 1.9 years) groups in the validation set (P = .01 for high vs intermediate, P = .009 for low vs intermediate).

KEY POINTS

  • A mutation-adjusted risk score model differentiated low-, intermediate-, and high-risk disease based on overall survival.
  • The model was also predictive of leukemia-free disease.

During median follow-up of 2.2 years, 63 of the 383 patients (16%) had leukemic transformation to secondary mast cell leukemia or secondary acute myeloid leukemia. The mutation-adjusted risk score was significantly predictive of leukemia-free survival in both sets, with median durations in the combined sets being 12.4 years in the low-risk group, 3.9 years in the intermediate-risk group, and 1.4 years in the high-risk group (P < .001 for both comparisons).  

The investigators concluded, “The [mutation-adjusted risk score] is a validated, five-parameter, WHO-independent prognostic score that defines three risk groups among patients with [advanced systemic mastocytosis] and may improve upfront treatment stratification for these rare hematologic neoplasms.”

Mohamad Jawhar, MD, of the Department of Hematology and Oncology, University Hospital Mannheim, Heidelberg University, is the corresponding author of the Journal of Clinical Oncology article.

Disclosure: The study was supported by the Deutsche José Carreras Leukämie-Stiftung, the SEED program of the Mannheim Medical Faculty, Heidelberg University, the Austrian Science Fund, and others. For full disclosures of the study authors, visit jco.ascopubs.org.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
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