The FDA approved Takeda’s Mimrylo (rusfertide) for polycythemia vera, giving Protagonist Therapeutics a second approval and adding a potentially large revenue opportunity for Takeda as it seeks to broaden beyond pipeline pressures. The approval clears Mimrylo for adults with polycythemia vera who require treatment for erythrocytosis, using a weekly injection approach. Multiple reports described broader-than-expected label expansion and analysts’ expectations for sales potential that could reach or exceed $2 billion. For Protagonist, Mimrylo represents continued momentum from earlier clinical development and reinforces the company’s ability to partner its peptide platform through commercialization. In rare hematology, new approved options matter because managing erythrocytosis drives reduction in thrombotic risk—an area where dosing and patient selection can be decisive.