Clinical Report: Insights and Questions on Triple Negative Essential Thrombocythemia in Two Large Cohorts

Overview

Two large studies from Florence and Mayo Clinic each analyzed 1000 patients with essential thrombocythemia (ET), providing valuable data on triple negative (TN) patients. Differences in prognosis and clinical course between TN patients in the two cohorts raise important questions about disease heterogeneity and classification.

Background

Essential thrombocythemia is a myeloproliferative neoplasm characterized by elevated platelet counts and risk of thrombosis, myelofibrosis, and leukemia. Molecular profiling often identifies driver mutations, but a subset of patients are triple negative (TN), lacking common mutations. Understanding the clinical and biological features of TN ET patients is critical for prognosis and management. Two large cohorts from Florence and Mayo Clinic have contributed extensive data on ET, including TN subsets.

Data Highlights

Each cohort included approximately 1000 ET patients with detailed annotation and long-term follow-up. The Florence cohort TN patients demonstrated better prognosis in terms of myelofibrosis-free, leukemia-free, thrombosis-free, and overall survival compared to other groups. The Mayo Clinic TN patients showed improved overall survival, leukemia-free survival, and arterial thrombosis-free survival, but their clinical course was less favorable than the Florence TN group.

Key Findings

• Existence of TN patients completely negative for all clonal markers (including passenger mutations) remains unclear; their phenotype and bone marrow histology compared to other TN patients is not specified.
• Florence cohort TN patients exhibit a notably more benign clinical course with better survival outcomes and lower progression to myelofibrosis and leukemia.
• Mayo Clinic TN patients have a less favorable prognosis than Florence TN patients, though still better than non-TN groups in some survival metrics.
• Differences in outcomes between the two cohorts raise questions about disease classification and whether all TN patients represent bona fide ET.
• Authors seek hypotheses to explain the prognostic differences and whether these reflect biological heterogeneity or methodological variations.

Clinical Implications

Clinicians should recognize that TN ET patients may have variable prognoses depending on cohort characteristics, highlighting the need for careful molecular and clinical evaluation. The possibility that some TN patients lack clonal markers challenges diagnostic certainty and may influence risk stratification and management decisions. Further research is needed to clarify the natural history and optimal treatment approaches for TN ET.

Conclusion

The large Florence and Mayo Clinic cohorts provide valuable insights into TN essential thrombocythemia but also reveal heterogeneity in clinical outcomes. Addressing the questions raised about clonal markers and prognosis will enhance understanding and care of this subgroup.

References

1. Florence Myeloproliferative Neoplasm Group -- Large Cohort Study on ET
2. Mayo Clinic Myeloproliferative Neoplasm Group -- Large Cohort Study on ET