FDA Approves MIMRYLO (Rusfertide), First Hepcidin Mimetic Peptide for Polycythemia Vera

The FDA has approved MIMRYLO (rusfertide), a subcutaneously delivered first-in-class hepcidin mimetic peptide, for the treatment of erythrocytosis in adults with polycythemia vera. The approval was announced on August 28, 2026, by Protagonist Therapeutics, which developed rusfertide with Takeda.

Polycythemia vera is a blood cancer defined by the overproduction of red blood cells. Rusfertide mimics hepcidin, the body’s master regulator of iron metabolism, restricting iron availability for red blood cell production. It is the first hepcidin mimetic to complete FDA review, establishing a new peptide drug class.

As with every FDA approval, the agency’s decision applies to the specific product - MIMRYLO - and the specific indication on its label. The approval does not extend to compounded formulations, research compounds, or any other use of the molecule.

For researchers, the approval is a landmark data point: a peptide discovered through hepcidin biology has now cleared the full FDA review process, joining GLP-1 agonists and other peptide classes with validated regulatory pathways.