Protagonist Therapeutics, Inc., a biopharmaceutical company, develops peptide-based drugs for hematology and blood disorders, and inflammatory and immunomodulatory diseases.

It is developing Rusfertide (PTG-300), an injectable hepcidin mimetic that is in Phase II clinical trials for the treatment of erythrocytosis, iron overload, and other blood disorders; and JNJ-2113, an orally delivered investigational drug to block biological pathways that is in Phase II clinical trials for the treatment of moderate-to-severe plaque psoriasis; and PN-943, an orally delivered, gut-restricted alpha 4 beta 7 specific integrin antagonist, which is in Phase II clinical trials for inflammatory bowel disease.

The company has a license and collaboration agreement with Janssen Biotech, Inc. Protagonist Therapeutics, Inc. was incorporated in 2006 and is headquartered in Newark, California.