SUPPLEMENTARY INFORMATION:

I. Background

The Drug Price Competition and Patent Term Restoration Act of 1984 (Pub. L. 98-417) and the Generic Animal Drug and Patent Term Restoration Act (Pub. L. 100-670) generally provide that a patent may be extended for a period of up to 5 years so long as the patented item (human drug or biological product, animal drug product, medical device, food additive, or color additive) was subject to regulatory review by FDA before the item was marketed. Under these acts, a product's regulatory review period forms the basis for determining the amount of extension an applicant may receive.

A regulatory review period consists of two periods of time: a testing phase and an approval phase. For human biological products, the testing phase begins when the exemption to permit the clinical investigations of the biological product becomes effective and runs until the approval phase begins. The approval phase starts with the initial submission of an application to market the human biological product and continues until FDA grants permission to market the biological product. Although only a portion of a regulatory review period may count toward the actual amount of extension that the Director of USPTO may award (for example, half the testing phase must be subtracted as well as any time that may have occurred before the patent was issued), FDA's determination of the length of a regulatory review period for a human biological product will include all of the testing phase and approval phase as specified in 35 U.S.C. 156(g)(1)(B).

FDA has approved for marketing the human biological product, ANDEMBRY (garadacimab-gxii). ANDEMBRY is indicated for prophylaxis to prevent attacks of hereditary angioedema in adult and pediatric patients aged 12 years and older. Subsequent to this approval, the USPTO received a patent term restoration application for ANDEMBRY (U.S. Patent Nos. 9,518,127 and 11,174,321) from CSL Behring GmbH and CSL Ltd., and the USPTO requested FDA's assistance in determining the patents' eligibility for patent term restoration. In a letter dated October 15, 2025, FDA advised the USPTO that this human biological product had undergone a regulatory review period and that the approval of ANDEMBRY represented the first permitted commercial marketing or use of the product. Thereafter, the USPTO requested that FDA determine the product's regulatory review period.

II. Determination of Regulatory Review Period

FDA has determined that the applicable regulatory review period for ANDEMBRY is 2,528 days. Of this time, 1,916 days occurred during the testing phase of the regulatory review period, while 612 days occurred during the approval phase. These periods of time were derived from the following dates:

1. The date an exemption under section 505(i) of the Federal Food, Drug, and Cosmetic Act (21 U.S.C. 355(i)) became effective: July 14, 2018. The applicant claims July 13, 2018, as the date the investigational new drug application (IND) became effective. However, FDA records indicate that the IND effective date was July 14, 2018, which was 30 days after FDA receipt of the IND.

2. The date the application was initially submitted with respect to the human biological product under section 351 of the Public Health Service Act (42 U.S.C. 262): October 13, 2023. The applicant claims June 29, 2023, as the date the biologics license application (BLA) for ANDEMBRY (BLA 761367) was initially submitted. However, FDA records indicate that BLA 761367, submitted on June 29, 2023, was incomplete. FDA refused this application and notified the applicant of this fact by letter dated August 28, 2023. The complete BLA was then submitted on October 13, 2023, which is considered to be the initially submitted date.

3. The date the application was approved: June 16, 2025. FDA has verified the applicant's claim that BLA 761367 was approved on June 16, 2025.

This determination of the regulatory review period establishes the maximum potential length of a patent extension. However, the USPTO applies several statutory limitations in its calculations of the actual period for patent extension. In its applications for patent extension, this applicant seeks 1,626 and 610 days of patent term extension.

III. Petitions

Anyone with knowledge that any of the dates as published are incorrect may submit either electronic or written comments and, under 21 CFR 60.24, ask ( printed page 57358) for a redetermination (see DATES ). Furthermore, as specified in § 60.30 (21 CFR 60.30), any interested person may petition FDA for a determination regarding whether the applicant for extension acted with due diligence during the regulatory review period. To meet its burden, the petition must comply with all the requirements of § 60.30, including but not limited to: must be timely (see DATES ), must be filed in accordance with § 10.20, must contain sufficient facts to merit an FDA investigation, and must certify that a true and complete copy of the petition has been served upon the patent applicant. (See H. Rept. 857, part 1, 98th Cong., 2d sess., pp. 41-42, 1984.) Petitions should be in the format specified in 21 CFR 10.30.

Submit petitions electronically to https://www.regulations.gov at Docket No. FDA-2013-S-0610. Submit written petitions (two copies are required) to the Dockets Management Staff (HFA-305), Food and Drug Administration, 5630 Fishers Lane, Rm. 1061, Rockville, MD 20852.