Protagonist Therapeutics

Protagonist Therapeutics is a Newark, California clinical-stage biopharmaceutical company that turns peptides - short chains of amino acids long dismissed as too fragile to be drugs - into stable, often orally available medicines. Its proprietary peptide discovery and engineering platform powers a pipeline spanning hematology, inflammation/immunology and metabolic disease, anchored by rusfertide (a hepcidin mimetic for polycythemia vera under FDA Priority Review) and icotrokinra, an oral IL-23 receptor blocker partnered with Johnson & Johnson that reached the U.S. market in 2026. Publicly traded on Nasdaq as PTGX, the company pairs internal discovery with high-value pharma partnerships.