First-line treatment for patients with polycythemia vera, essential thrombocythemia, and pre-myelofibrosis is based on hydroxyurea or pegylated interferon. The objective of treatment is to prevent thrombotic complications and leukemic transformation. Despite overall good response rates, some patients do not respond to treatment and others lose their response over time. Both situations are associated with worse survival and there are to date no clear predictive factors for response although the existence of additional mutations seems unfavorable.

In this exploratory study, we hypothesize that biological factors at diagnosis are associated with hematological response at 12 months. We will more specifically study the association between mutational profile, assessed by next-generation sequencing, and cytokine profile with hematological response.

This study will help in identifying patients who will not respond to hydroxyurea or pegylated interferon and give the opportunity to try other treatments upfront, in the perspective of precision medicine. On the basic science side, this study will help in understanding the molecular and immunological factors involved in resistance to treatment.

Inclusion Criteria:

• Adults with polycythemia vera, essential thrombocythemia, or pre-myelofibrosis.
• Indication for first-line treatment with hydroxyurea or pegylated interferon.
• Consent to participate.
• Affiliated to social security.

Exclusion Criteria:

• Previous treatment.
• Other on-going malignancy, including overt myelofibrosis.
• Other treatment such as phlebotomy solely, ruxolitinib, anagrelide, or pipobroman.

Adults with polycythemia vera, essential thrombocythemia, or pre-myelofibrosis requiring first-line treatment with hydroxyurea or pegylated interferon.