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Analysis of CALR-mutated essential thrombocythemia as a distinct disease entity compared with JAK2 V617F-mutated and
Gökhan Sami Aydin1, Elif Aksoy1, İpek Yönal Hindilerden2
1Division of Hematology, Department of Internal Medicine, Bakırköy Dr. Sadi Konuk Training and Research Hospital, İstanbul, Turkiye.
Insights
Calreticulin (CALR) mutations in essential thrombocythemia (ET) are linked to distinct patient features and thrombosis rates. While CALR mutations show associations with lower thrombosis, this protective effect was not independent in multivariable analysis.
Area of Science:
- Hematology
- Molecular Biology
- Oncology
Background:
- Calreticulin (CALR) mutations are key drivers in essential thrombocythemia (ET).
- These mutations are associated with specific clinical and laboratory characteristics, including age, platelet counts, and thrombosis risk.
- Understanding the prognostic impact of CALR mutations is crucial for managing ET patients.
Purpose of the Study:
- To analyze the demographic, laboratory, and clinical features of patients with CALR mutations in ET.
- To evaluate the prognostic impact of CALR mutations on thrombosis rates and survival outcomes.
- To compare the characteristics and outcomes of CALR-mutated ET patients with JAK2 V617F-positive and triple-negative ET patients.
Main Methods:
- The study included 391 patients diagnosed with essential thrombocythemia (ET).
- Demographic, laboratory (platelet count, leukocyte count, Hb, Hct), and clinical data (thrombosis history) were collected and analyzed.
- Multivariable analysis was employed to identify independent predictors of thrombosis and survival.
Main Results:
- CALR-mutation patients exhibited lower leukocyte and hemoglobin/hematocrit levels, and higher platelet counts compared to JAK2 V617F-positive patients.
- Total thrombosis rates were lower in CALR-mutated ET patients (20.8%) versus JAK2 V617F-positive patients (37.8%).
- Cardiovascular risk was the sole independent predictor of total thrombosis; younger age (<60 years) and female gender were associated with lower arterial thrombosis risk.
Conclusions:
- CALR mutations in ET are associated with specific hematological profiles, including lower leukocyte and Hb/Hct levels and higher platelet counts.
- While CALR mutations appear linked to reduced thrombosis, this association was not found to be independently protective in multivariable analysis.
- Myelofibrosis-free survival was notably longer in patients with type 2 CALR mutations.
Background/Aim:
Calreticulin (CALR) mutations in essential thrombocythemia (ET) are associated with younger age, higher platelet counts, and lower thrombosis rates. The present study analyzes the demographic, laboratory, and clinical features of the CALR mutation and its prognostic impact.
Materials And Methods:
The clinical impact of CALR mutations was assessed in 391 ET patients.
Results:
CALR-mutation patients were more commonly male than JAK2 V617F-positive and triple-negative patients. Age at diagnosis was similar across all groups, although patients with type 2 CALR mutations were younger than those with nontype 1/nontype 2 mutations. Compared with JAK2 V617F-positive patients, CALR-mutation patients had lower leukocyte counts (9.6 × 109/L vs. 10.9 × 109/L), lower hemoglobin (Hb) and hematocrit (Hct) levels, higher platelet counts (1078.5 × 109/L vs. 858.1 × 109/L), and lower total thrombosis rates (20.8% vs. 37.8%), while the CALR-mutated and triple-negative patients had lower venous thrombosis rates than in the JAK2 V617F-positive patients. The arterial thrombosis rate before and at the time of diagnosis was lower in the CALR-mutation patients than in the JAK2 V617F-positive patients, and the total venous thrombosis rate in patients aged <60 years at the time of diagnosis was lower in the CALR-mutation and triple-negative patients than in the JAK2 V617F-positive patients. Multivariable analysis revealed cardiovascular (CV) risk to be the only independent predictor of total thrombosis. Female gender, absence of CV risk, and platelet count ≥1000 × 109/L were associated with a lower incidence of arterial thrombosis. Age <60 years was associated with lower risks of arterial and venous thrombosis. Overall, thrombosis-free, and leukemia-free survival were similar across all groups, while myelofibrosis-free survival was longer in the type 2 CALR-mutation group.
Conclusion:
The CALR mutation was lower among females, and was associated with lower leukocyte counts, and Hb and Hct levels, and with higher platelet counts. In multivariable analysis, the apparent protective association of CALR with thrombosis was not independent.
