Protagonist PH3 PTG-300 in Polycythemia Vera

This study is divided into 3 parts: Part 1a, Part 1b, and Part 2.

If you are eligible to join the study and choose to do so, during Part 1a you will:
- Continue taking all of your prescribed medications for PV
- Be randomly assigned (like a coin flip) to take the study drug or placebo (inactive substance) once per week
- Visit our clinic about 10 times

Part 1a lasts for 32 weeks. If you finish Part 1a, you can choose to continue on to Part 1b. During Part 1b, you will:
- Continue taking all of your prescribed medications for PV
- Take the study drug once per week regardless of whether or not you received the study drug in Part 1a
- Visit our clinic about 5 times

Part 1b lasts for 20 weeks. If you received the study drug in Part 1a, you will receive the same dose of the study drug in Part 1b unless your study doctor thinks it should be adjusted. If you received the placebo in Part 1a, your starting dose of the study drug in Part 1b will be 20 mg, but your study doctor can adjust the dose to as much as 90 mg if they think you will benefit.

You can choose to continue to Part 2 when Part 1b ends. During Part 2, you will continue to take the study drug, but your dose can be raised to a higher level than Part B if your study doctor thinks it is appropriate. Your study doctor might also change your schedule to take the study drug from once per week to twice per week or once every other week. Part 2 will last for about 2 years and you will visit our clinic once per month for the first four months, and then you will visit our clinic every 3 months after the 4th month of Part 2.

The study drug is given as an injection (shots) under your skin. We will teach you how to give yourself these shots at home. If you are not comfortable or not able to give yourself the shots, you can come to our clinic to get them.