Main Inclusion Criteria: All subjects must meet ALL of the following inclusion criteria to be enrolled. 1. Male and female subjects aged 18 years or older. 2. Meet revised 2016 World Health Organization (WHO) criteria for the diagnosis of polycythemia vera. 3. Records of all phlebotomies performed for at least 24 weeks (preferably up to 52 weeks) before screening are available. 4. Subjects who are not receiving cytoreductive therapy must have been discontinued from any prior cytoreductive therapy for at least 24 weeks before screening and have recovered from any adverse events due to cytoreductive therapy. 5. Subjects receiving cytoreductive therapy with hydroxyurea, interferon, or ruxolitinib must be on a stable dose for at least 24 weeks and be on a stable dose for at least 8 weeks before screening and with no planned change in dose. Main Exclusion Criteria: Subjects must meet NONE of the following exclusion criteria to be enrolled: 1. Active or chronic bleeding within 4 weeks of screening. 2. Meets the criteria for post-PCV myelofibrosis as defined by the International Working Group-Myeloproliferative Neoplasms Research and Treatment (IWG-MRT). 3. Known primary or secondary immunodeficiency. 4. Any surgical procedure requiring general anesthesia within 1 month prior to screening or planned elective surgery during the study.