Protagonist Therapeutics, Inc

Protagonist Therapeutics, Inc. is an integrated discovery and development company focused on medicines for inflammation and immunology, hematology, and metabolic diseases. The company aims to develop differentiated therapies for validated biological and commercial targets. Its development products include Icotyde™ (icotrokinra), an investigational targeted oral peptide that selectively blocks the Interleukin-23 receptor (IL-23R). Icotyde is licensed to Janssen Biotech, Inc. (JNJ) under a 2017 agreement. Protagonist was responsible for Icotyde's development through Phase 1, with JNJ taking over for Phase 2 and beyond. In July 2025, JNJ submitted a New Drug Application (NDA) to the U.S. Food and Drug Administration (FDA), and in September 2025, an application to the European Medicines Agency (EMA), for Icotyde to treat moderate-to-severe plaque psoriasis in adults and pediatric patients 12 years and older. Another key product is Rusfertide, an investigational injectable mimetic of the natural hormone hepcidin. Rusfertide is in development for the rare blood disorder polycythemia vera (PV). Protagonist discovered rusfertide and advanced it to Phase 3. In January 2024, the company entered a co-development and co-commercialization agreement with Takeda Pharmaceuticals, Inc. (Takeda). Protagonist remained primarily responsible for clinical development activities through rusfertide's NDA filing for erythrocytosis in PV patients, which Protagonist and Takeda submitted in December 2025. Rusfertide has received Orphan Drug status, Fast Track designation, and Breakthrough Therapy designation (BTD) in August 2025.