A Study of Rusfertide in Japanese Adults With Polycythemia Vera

Polycythemia vera (PV) is a rare blood cancer in which the body makes too many red blood cells. This can make the blood thicker and may increase the risk of serious health problems such as blood clots. Many people with PV need regular phlebotomy, which is a procedure to remove blood, to help keep their hematocrit level under control. Hematocrit is the proportion of red blood cells in the blood. The main aim of this study is to evaluate whether rusfertide helps Japanese participants with PV keep their hematocrit under control and avoid the need for phlebotomy. All participants in this study will receive rusfertide. This study is open-label, which means both the participants and the study team will know what treatment is being given. Participants will be followed for up to about 244 weeks, including a screening period, a 52-week initial treatment period, a long-term extension period, and a 4-week safety follow-up period.

Inclusion Criteria: 1. Japanese male and female participants aged 18 years or older at the time of signing informed consent. 2. Participant understands the trial procedures, is willing and able to adhere to trial requirements and agrees to participate in the trial by giving written informed consent. 3. Meet revised 2016 WHO criteria for the diagnosis of PV. 4. Phlebotomy requiring defined as ALL of the following: 1. At least 3 phlebotomies due to inadequate hematocrit control in 28 weeks before trial intervention or at least 5 phlebotomies due to inadequate hematocrit control in 1 year before trial intervention, and 2. Last phlebotomy due to inadequate hematocrit control within 3 months before trial intervention, and 3. No phlebotomy within 6 days prior to trial intervention (do not include day of phlebotomy and day of trial intervention in the 6-day count). Note: Phlebotomies performed within an 8-day period will be counted as a single phlebotomy. 5. Hematology test values at screening: 1. Hematocrit \