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# FDA Clinical Hold on Protagonist Rusfertide Studies
- URL: https://www.fdaweb.com/fda-clinical-hold-on-protagonist-rusfertide-studies/
- Published: 2021-09-17T12:00:00.000Z
- Updated: 2026-09-14T17:15:02.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5150170

FDA has placed a clinical hold against Protagonist Therapeutics and its clinical studies for rusfertide. Affected trials for the injectable hepcidin mimetic include a Phase 2 proof-of-concept clinical trial for polycythemia vera (PV), a Phase 2 study in PV subjects with high hematocrit levels, and a Phase 2 study for hereditary hemochromatosis, according to the company.

“The clinical hold follows Protagonist’s notification to the FDA of a recent non-clinical finding in a 26-week rasH2 transgenic mouse model study,” the company says. “The rasH2 model is designed to detect signals related to tumorigenicity, and benign and malignant subcutaneous skin tumors were observed in this study.”

Protagonist says it is working with the agency and will be prepared to make all appropriate updates to clinical study documents. “In particular, we will provide additional clinical safety reports, update the investigator brochures and patient informed consent forms, and make necessary modifications to study protocols,” it says.