Protagonist Therapeutics receives FDA approval for polycythemia vera drug

Protagonist Therapeutics has received FDA approval for MIMRYLO, a drug designed to treat polycythemia vera, an abnormal condition where the body produces too many red blood cells. The approval includes a $275 million payment to the company, consisting of a $200 million opt-out fee and $75 million in approval milestones. Protagonist is also eligible for up to $875 million in potential milestone payments and royalties of 14% to 29% on worldwide net sales.

The drug was approved based on the Phase 3 VERIFY study, which showed that 76.9% of patients receiving MIMRYLO experienced a clinical response compared to 32.9% receiving a placebo. MIMRYLO works by mimicking the action of hepcidin, a hormone that regulates iron availability, thereby controlling red blood cell production and preventing excessively high hematocrit levels.

The drug is administered as a weekly subcutaneous injection and its most common side effects include injection site reactions in 56% of patients and anemia in 16% of patients. Protagonist discovered the drug and took primary responsibility for its development through Phase 3, while Takeda handled regulatory submission and commercialization after Protagonist opted out in April 2026.

This is Protagonist's second FDA approval in 2026, and the company will host an investor call on Monday at 8:30 a.m. ET.