FDA Breakthrough Rescission on Protagonist’s Rusfertide

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FDA has told Protagonist Therapeutics that it intends to rescind the company’s breakthrough therapy designation for rusfertide and its use in treating polycythemia vera. In an updated company slide presentation, the agency attributed its rescission decision to “observed malignancies, in follow-up to the FDA clinical hold imposed on 9/16/2021,” according to the company.

 

The clinical hold was quickly lifted on 10/11/2021 (see earlier story). The hold followed notification to FDA about a recent non-clinical finding in a 26-week rasH2 transgenic mouse model study, the company said at the time. “The rasH2 model is designed to detect signals related to tumorigenicity, and benign and malignant subcutaneous skin tumors were observed in this study,” it said.

The company says it has submitted a response on the breakthrough rescission and requested a meeting. It notes that its orphan drug and fast track designations remain in place. Protagonist anticipates no changes to its development plans for rusfertide, including no anticipated changes to timelines for the Phase 3 VERIFY study in polycythemia vera.

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