Prospective study for the development of a non-invasive score for differentiating prefibrotic myelofibrosis from essential thrombocytosis and overt myelofibrosis.

The diagnostic criteria for myeloproliferative neoplasia have recently been revised in the WHO 2016 classification, which now recognizes a new entity between essential thrombocythemia (TE) and overt myelofibrosis (or primary myelofibrosis): prefibrotic myelofibrosis. Prefibrotic myelofibrosis patients seem to have a poorer prognosis compared to essential thrombocythemia in term of overall survival and myelofibrotic evolution. The dichotomy between these diseases is based on the bone marrow biopsy evaluation and is challenging with a lack of reproducibility showed in the literature.

This study aims to develop a diagnostic non-invasive score for differentiating prefibrotic myelofibrosis from essential thrombocytosis and overt myelofibrosis.

The parameters studied are :

• spleen fibrosis by elastography
• plasma cytokines levels
• mutationnal landscape by NGS
• CD34 circulating cells

Bone marrow biopsy were reviewed by 2 anatomopathologists. Number of patients to be enrolled : 130

Inclusion Criteria:

• Adult (18 years of age or older) with the diagnosis of essential thrombocytosis, prefibrotic myelofibrosis or overt myelofibrosis according to WHO 2016 criteria;
• Patient who has not received specific treatment for neoplasms;
• Patient who has signed the consent to participate in the study;
• Patient who has consented to be included in the "Malignant Haemopathies" collection at the University Hospital of Angers or Brest and for whom the samples necessary for the study are available in the biocollection.

Exclusion Criteria:

• Patient with another hematologic neoplasm or progressive cancer at the time of diagnosis;
• Patient with a diagnosis of secondary myelofibrosis;
• Pregnant or breastfeeding woman;
• Person prived of liberty by judicial or administrative decision;
• Person subject to a legal protection measure;

Data of study protocol, Statiscal analysis plan and the infromed consent form will be made available after the study completion

Data will be available within 1 year of study completion

Data access requests will be reviewed and requestors will be required to sign a data acess agreement