Protagonist Therapeutics is a clinical-stage biopharmaceutical company that discovers and develops peptide-based drugs, then partners them with large pharma companies in exchange for milestone payments and royalties. Protagonist's core capability is a proprietary peptide technology platform that produces molecules small enough to be taken orally but capable of blocking targets — like cytokine receptors — that typically require injectable biologics. Its two most advanced assets are both partnered and approaching potential commercial launch: icotyde (icotrokinra), an oral IL-23 receptor blocker licensed to J&J for moderate-to-severe plaque psoriasis, with an NDA filed in mid-2025 and a potential U.S. launch in 2026; and rusfertide, an injectable hepcidin mimetic partnered with Takeda for polycythemia vera, a rare blood disorder, with an NDA filed in late 2025 and a potential launch in the second half of 2026. Protagonist expects to opt out of its 50/50 U.S. profit-share with Takeda in Q2 2026, converting to a tiered global royalty on rusfertide. Earlier-stage wholly-owned programs include PN-881, an oral IL-17 antagonist in Phase 1 for inflammatory diseases, and two obesity assets — PN-477, a triple GLP-1/GIP/glucagon agonist, and PN-458, a dual GLP-1/GIP agonist — both in pre-IND studies. Protagonist does not manufacture drugs; J&J and Takeda handle manufacturing for partnered assets, while Protagonist uses CMOs for its own pipeline.