On March 14, 2022, Regeneron Pharmaceuticals Inc. (“Regeneron”) filed a statutory disclaimer under 37 CFR § 1.321 disclaiming all claims of U.S. Patent No. 10,857,231 B2 (the “’231 patent”) in response to a petition for a post-grant review submitted by Celltrion Inc. (“Celltrion”). On September 7, 2021, Celltrion submitted a petition for post-grant review of the ’231 patent, requesting a review of claims 1-11, 17-21, 27-32, 41-53, and 58-67 (the “Challenged Claims”) of the ’231 patent. In response, Regeneron submitted a Preliminary response, and later, a Sur-reply to Celltrion’s reply to Regeneron’s Preliminary response.
Prior to issuance of an institution decision by the Patent Trial and Appeal Board (the “Board”), however, Regeneron submitted an unopposed Motion to Withdraw its preliminary response and sur-reply. In an email to the Board accompanying the motion, Regeneron stated that it has reason to question whether the data presented in Table 7 of the ’231 patent corresponds to the formulation described in Example 4 at column 10, lines 27–38. Further, one day before the statutory date for the Board’s Decision on Institution, Regeneron notified the Board, via an email, that it intended that day to file a Notice of Disclaimer with the U.S. Patent and Trademark Office, disclaiming all claims of the ‘231 patent. Upon disclaimer of all claims, the Board denied institution of the requested post-grant review. See 37 C.F.R. § 42.207(e) (“No post-grant review will be instituted based on disclaimed claims”).
The Challenged Claims were broadly directed to formulations comprising 10-50 mg/ml aflibercept (or VEGF antagonist fusion proteins more generally); a stabilizing agent comprising a sugar, an amino acid, or both; an organic co-solvent comprising polysorbate; and a histidine buffer. In its petition, Celltrion asserted that the challenged claims were unpatentable on a number of grounds, including lack of written description, lack of enablement, indefiniteness, and obviousness.
At this time, it is unclear what the broader impact of Regeneron’s disclaimer will be on other patents in the family of the ‘231 patent and its priority application, PCT/US2006/010600 (WO2006104852; the “Dix family”). The Dix family includes nine issued U.S. patents and four pending U.S. applications, most of them directed to formulations of VEGF antagonist fusion proteins. The patents and applications in the Dix family claim priority to March 25, 2005, and are expected to expire on March 25, 2025, absent patent term adjustments or further disclaimers or invalidity determinations.
 Celltrion, Inc. v. Regeneron Pharmaceuticals, Inc., PGR2021-00117, Paper 1 at 1 (PTAB Sept. 7, 2021)
 Celltrion, Inc. v. Regeneron Pharmaceuticals, Inc., PGR2021-00117, Paper 6 (PTAB Dec. 15, 2021); Celltrion, Inc. v. Regeneron Pharmaceuticals, Inc., PGR2021-00117, Paper 11 (PTAB Jan. 25, 2022)
 Celltrion, Inc. v. Regeneron Pharmaceuticals, Inc., PGR2021-00117, Paper 13 (PTAB Mar. 3, 2022)
 Id. at 1
 Celltrion, Inc. v. Regeneron Pharmaceuticals, Inc., PGR2021-00117, Paper 16 at 2 (PTAB Mar. 15, 2022)