Determination of Regulatory Review Period for Purposes of Patent Extension; HYMPAVZI
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The FDA has calculated the regulatory review period for the biologic drug HYMPAVZI (marstacimab-hncq), used to prevent bleeding episodes in patients with hemophilia A or B. The total review period is 2,858 days, consisting of a 2,491-day testing phase that began on December 16, 2016, when the IND became effective, and a 367-day approval phase from the BLA submission on October 11, 2023, until approval on October 11, 2024. This determination sets the maximum possible patent term extension for U.S. Patent No. 10,550,200 held by Pfizer. The applicant is seeking 462 days of extension. Comments challenging the dates must be submitted by June 2, 2026, and petitions regarding due diligence by September 30, 2026.
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Key Changes
- Regulatory review period for HYMPAVZI determined as 2,858 days total
- Testing phase: 2,491 days from December 16, 2016 to October 11, 2023
- Approval phase: 367 days from October 11, 2023 to October 11, 2024
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Obligations
What this law requires
Submit comments challenging the published dates for the regulatory review period by June 2, 2026, via electronic submission to https://www.regulations.gov or written submission to FDA Dockets Management Staff
Include Docket No. FDA-2025-E-0158 in all submissions regarding the HYMPAVZI regulatory review period determination
Submit petitions regarding whether the applicant acted with due diligence during the regulatory review period by September 30, 2026
Ensure electronic comments submitted to https://www.regulations.gov do not contain confidential information, medical information, Social Security numbers, or confidential business information, as such submissions will be made publicly available
Submit comments containing confidential information only as written/paper submissions in two copies—one with confidential information marked and one with information redacted—to FDA Dockets Management Staff