# Definition of subtypes of essential thrombocythaemia and relation to polycythaemia vera based on JAK2 V617F mutation status: a prospective study

Source: https://onco.cc/key-papers/paper-jak2-polycythaemia-vera-lancet-2005/  
OnCo record `paper-jak2-polycythaemia-vera-lancet-2005` (Key paper). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Phase 2 or 3 results paper on JAK2 in Polycythaemia vera, in The Lancet (2005), one of the most cited Europe PMC records with JAK2 in its title.

## Summary

Background: An acquired V617F mutation in JAK2 occurs in most patients with polycythaemia vera, but is seen in only half those with essential thrombocythaemia and idiopathic myelofibrosis. We aimed to assess whether patients with the mutation are biologically distinct from those without, and why the same mutation is associated with different disease phenotypes.

Methods: Two sensitive PCR-based methods were used to assess the JAK2 mutation status of 806 patients with essential thrombocythaemia, including 776 from the Medical Research Council's Primary Thrombocythaemia trial (MRC PT-1) and two other prospective studies. Laboratory and clinical features, response to treatment, and clinical events were compared for V617F-positive and V617F-negative patients with essential thrombocythaemia.

Findings: Mutation-positive patients had multiple features resembling polycythaemia vera, with significantly increased haemoglobin (mean increase 9.6 g/L, 95% CI 7.6-11.6 g/L; p<0.0001), neutrophil counts (1.1x10(9)/L, 0.7-1.5x10(9)/L; p<0.0001), bone marrow erythropoiesis and granulopoiesis, more venous thromboses, and a higher rate of polycythaemic transformation than those without the mutation. Mutation-positive patients had lower serum erythropoietin (mean decrease 13.8 U/L; 95% CI, 10.8-16.9 U/L; p<0.0001) and ferritin (n=182; median 58 vs 91 mug/L; p=0.01) concentrations than did mutation-negative patients. Mutation-negative patients did, nonetheless, show many clinical and laboratory features that were characteristic of a myeloproliferative disorder. V617F-positive individuals were more sensitive to therapy with hydroxyurea, but not anagrelide, than those without the JAK2 mutation.

Interpretation: Our results suggest that JAK2 V617F-positive essential thrombocythaemia and polycythaemia vera form a biological continuum, with the degree of erythrocytosis determined by physiological or genetic modifiers.

Indexed on Europe PMC as PubMed record 16325696 (DOI 10.1016/s0140-6736(05)67785-9). Its title names JAK2 and its text names Polycythaemia vera; PubMed types it as a clinical trial report (Research Support, Non-U.S. Gov't, Multicenter Study, Randomized Controlled Trial). It was matched automatically to the idea "Clearing the JAK2 clone in polycythaemia vera: interferon plus mutant-selective inhibitors as a route to treatment-free remission" and no figure has been checked by an editor.

## Fields

- Kind: Key paper
- Last checked: 2026-09-22
- Tags: europepmc-ingest
- Journal: The Lancet
- Year: 2005
- DOI: 10.1016/s0140-6736(05)67785-9
- Authors: Campbell PJ, Scott LM, Buck G, et al.
- What it means: One of the most cited trial reports Europe PMC returns for JAK2 in Polycythaemia vera, so it is a natural first reading for anyone weighing the idea it is linked from. The record was linked automatically by title and abstract; read the abstract above and the paper itself before relying on any figure.
- Caveats: Matched by JAK2 in the title and Polycythaemia vera in the title or abstract of the Europe PMC record; the summary reproduces the record's abstract and no figure has been verified against the full paper.; Chosen as a phase 2 or 3 report by the record's publication type or its own wording, not by reading the paper.

## Sources

- Lancet 2005: https://doi.org/10.1016/s0140-6736(05)67785-9
- PubMed: https://pubmed.ncbi.nlm.nih.gov/16325696/
- Europe PMC: https://europepmc.org/article/MED/16325696

## Connected records

- journals: [The Lancet](https://onco.cc/journals/lancet/)
- ideas: [Clearing the JAK2 clone in polycythaemia vera: interferon plus mutant-selective inhibitors as a route to treatment-free remission](https://onco.cc/ideas/idea-pv-clone-directed-therapy/)

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