Study to Identify and Describe Predictive Factors for Thromboembolic Events in Patients With High-risk Polycythemia Vera

This is a prospective observational study that will enroll patients with high-risk
Polycythemia Vera (PV) with at least one Thromboembolic Event (TE) after diagnosis or up
to 2 years prior to diagnosis.

This is a non-randomized study, and to ensure a sufficient number of patients in both
cohorts, enrollment in each cohort will be terminated once the target of 150 patients has
been reached. All patients are already on treatment with hydroxyurea or ruxolitinib at enrollment as
per clinical practice and independently of their participation in this study. In
addition, the follow-up visits and the evaluation procedures required in the study
protocol correspond to current clinical practice. According to local regulations related
to observational studies, assessments such as blood tests are justified by the purpose
and rationale of the study (i.e., the identification of possible predictive factors of
TEs) and are considered current clinical practice. Data related to other procedures will
be collected only if such procedures are performed as per clinical practice but are not
required otherwise.

Patients in both cohorts will be followed for 3 years after enrollment and will have
visits at Months 6, 12, 18, 24, 30 and 36. A time window of ± 1 month is permitted for
all visits.