Determination of Regulatory Review Period for Purposes of Patent Extension; ZIIHERA
AI-generated summary for informational purposes only. Not legal advice. See the original source for the authoritative text.
The FDA has calculated the regulatory review period for the biologic drug ZIIHERA (zanidatamab-hrii) as 3,038 days total. This consists of a 2,801-day testing phase that began on July 29, 2016 when the IND became effective, and a 237-day approval phase from the BLA submission on March 29, 2024 until approval on November 20, 2024. ZIIHERA is approved under accelerated approval for previously treated, unresectable or metastatic HER2-positive (IHC 3+) biliary tract cancer. This determination sets the maximum possible patent term extension for U.S. Patent No. 10,000,576. The applicant is seeking 1,346 days of extension. Comments challenging the dates must be submitted by June 2, 2026, and due-diligence petitions by September 30, 2026.
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Key Changes
- FDA determined total regulatory review period for ZIIHERA as 3,038 days
- Testing phase: 2,801 days from July 29, 2016 (IND effective date)
- Approval phase: 237 days from March 29, 2024 (BLA submission) to November 20, 2024 (approval date)
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Obligations
What this law requires
Submit comments challenging the accuracy of regulatory review period dates (testing phase start date of July 29, 2016, approval phase dates of March 29, 2024 to November 20, 2024, or total 3,038 days) to FDA by June 2, 2026
Include FDA Docket No. FDA-2025-E-0372 in all submissions regarding the ZIIHERA patent extension determination
Submit electronic comments through https://www.regulations.gov by 11:59 p.m. Eastern Time on June 2, 2026, or submit written/paper comments to FDA Dockets Management Staff by that same date to be considered timely
Petition FDA by September 30, 2026 to determine whether the applicant for patent extension acted with due diligence during the regulatory review period
Ensure that comments submitted electronically do not contain confidential information such as medical information, Social Security numbers, or confidential business information, as such comments will be made publicly available