Fresenius Kabi SwissBioSim GmbH v. Regeneron Pharmaceuticals, Inc.

This case involves an Inter Partes Review (IPR) petition, IPR2025-01268, filed by Fresenius Kabi SwissBioSim GmbH against Regeneron Pharmaceuticals, Inc. concerning U.S. Patent No. 11,084,865. Fresenius Kabi SwissBioSim GmbH is a global healthcare company that provides medicines, medical devices, and clinical nutrition, with a strategic focus on biosimilar development. Regeneron Pharmaceuticals, Inc. is an American biotechnology company renowned for discovering, developing, and commercializing life-transforming medicines, particularly for eye diseases, cancer, and inflammatory conditions. Although Fresenius Kabi SwissBioSim is not currently a direct defendant in a patent infringement lawsuit brought by Regeneron concerning aflibercept, it has entered into a licensing agreement for a biosimilar version of Regeneron's Eylea® (aflibercept), which is the implied accused product or technology at the heart of this challenge.

The patent at issue, U.S. Patent No. 11,084,865, titled "VEGF antagonist formulations suitable for intravitreal administration," broadly covers ophthalmic formulations of a vascular endothelial growth factor (VEGF)-specific fusion protein antagonist, specifically designed for injection into the eye. The claims often focus on stable liquid formulations, detailing specific concentrations of the VEGF antagonist (such as 40 mg/ml), along with various excipients like buffers, organic co-solvents (e.g., polysorbate), and stabilizing agents. This patent is central to Regeneron's intellectual property protecting its blockbuster drug Eylea® (aflibercept), used to treat various angiogenic eye disorders.

The procedural posture for IPR2025-01268 is before the Patent Trial and Appeal Board (PTAB) of the U.S. Patent and Trademark Office. The petition was "Not Instituted" on procedural grounds, specifically through a discretionary denial by the PTAB. This denial is notable and stems from the PTAB's application of discretionary factors, often referred to as Fintiv factors, which consider the existence and advanced stage of parallel district court litigation involving the same patent. The '865 patent has been the subject of multiple Biologics Price Competition and Innovation Act (BPCIA) litigations against other biosimilar manufacturers, including Mylan, Samsung Bioepis, Celltrion, Formycon, and Amgen. The PTAB previously denied institution for IPRs challenging the '865 patent filed by Samsung Bioepis, Formycon, and Celltrion for similar discretionary reasons, highlighting the PTAB's inclination to defer to ongoing district court proceedings when significant investment has already been made in those parallel litigations. This IPR's denial underscores the strategic interplay between IPR challenges and BPCIA litigation in the biosimilar space, particularly concerning high-value biologics like aflibercept.

Regeneron's Aflibercept Patent 11,084,865 Sees IPR Denial and Subsequent Settlement with Fresenius Kabi

Fresenius Kabi SwissBioSim GmbH's attempt to challenge Regeneron Pharmaceuticals, Inc.'s U.S. Patent No. 11,084,865 at the Patent Trial and Appeal Board (PTAB) through IPR2025-01268 was denied institution on procedural grounds on November 20, 2025. This denial, and the subsequent settlement between the parties in February 2026, constitute the key legal developments directly involving Fresenius Kabi and this specific patent.

Parallel PTAB IPR Proceedings and District Court Litigation Landscape

U.S. Patent No. 11,084,865, directed to ophthalmic formulations of the vascular endothelial growth factor (VEGF) antagonist aflibercept (marketed by Regeneron as Eylea®), has been a central focus of extensive Biologics Price Competition and Innovation Act (BPCIA) litigation and numerous IPR challenges by various biosimilar manufacturers.

Prior to Fresenius Kabi's petition, the '865 patent was challenged in IPRs by Samsung Bioepis (IPR2025-00176), Formycon (IPR2025-00233), and Celltrion (IPR2025-00456). All three of these petitions were discretionarily denied institution by the Acting PTO Director in June 2025, primarily due to ongoing BPCIA litigation between Regeneron and those parties.

Regeneron had initiated BPCIA litigation against multiple biosimilar applicants, including Amgen, Samsung Bioepis, Formycon, Celltrion, Sandoz, and Mylan/Biocon, with many of these cases consolidated into multidistrict litigation (MDL No. 1:24-md-3103) in the U.S. District Court for the Northern District of West Virginia.

In the litigation involving Amgen, the U.S. District Court for the Northern District of West Virginia denied Regeneron's motion for a preliminary injunction against Amgen's biosimilar, Pavblu®, concerning the '865 patent. This decision was affirmed by the Federal Circuit on March 14, 2025. A key aspect of this appeal involved claim construction, with the Federal Circuit affirming the district court's interpretation that the claims of the '865 patent require the VEGF antagonist (aflibercept) and the buffer to be separate components. This claim construction was crucial for Amgen's "self-buffering" formulation, which does not contain a separate buffer component.

In contrast, preliminary injunctions were granted against Samsung Bioepis and Formycon, and later Celltrion, preventing the launch of their biosimilars, with these injunctions upheld on appeal by the Federal Circuit in January and March 2025. Regeneron also reached settlements with Biocon (April 2025), Sandoz, Formycon, Celltrion (October 2025), and Alvotech/Teva (December 2025), outlining agreed-upon launch dates for their respective aflibercept biosimilars in 2026.

Fresenius Kabi's IPR and Subsequent Settlement

Filing of IPR (2025-07-14): Fresenius Kabi SwissBioSim GmbH filed IPR2025-01268 on July 14, 2025, challenging claims 1-5, 7-30, and 32-50 of U.S. Patent No. 11,084,865. At the time of filing, Fresenius was noted as not being a party to any BPCIA litigation brought by Regeneron concerning aflibercept, unlike other petitioners whose IPRs were discretionarily denied. Fresenius's petition primarily argued invalidity based on anticipation by the "Dix '226" prior art reference, which had not been a primary basis in previous IPRs against the '865 patent.

PTAB Institution Decision (2025-11-20): The PTAB denied institution of IPR2025-01268 on November 20, 2025, on "Discretionary Denial" grounds. While the exact details of the procedural denial for this specific IPR are not explicitly detailed in the search results beyond its "discretionary denial" status, it aligns with a period where the USPTO Director implemented new policies and reviewed discretionary denial factors for IPR and PGR proceedings. These policies often consider factors such as the existence of parallel district court litigation, timing, and whether a petitioner is also a party to such litigation. Despite Fresenius not having a direct BPCIA lawsuit from Regeneron at the time of the IPR filing, the PTAB's discretionary denial likely stemmed from the broader context of ongoing, extensive litigation surrounding the '865 patent and the Director's efforts to manage the PTAB's resources and avoid duplicative efforts.

Settlement (2026-02-24): On February 24, 2026, Fresenius Kabi and its partner Sam Chun Dang (SCD) announced a settlement with Regeneron regarding their aflibercept biosimilar, SCD411 (Vygenfree™). The terms of the confidential settlement permit SCD/Fresenius to launch their biosimilar in the U.S. at an undisclosed future date. This settlement effectively resolved the patent dispute between the parties, including the issues raised in the IPR petition. No full-blown patent infringement litigation, with extensive pre-trial motions, claim construction, discovery, and trial, appears to have transpired directly between Fresenius Kabi and Regeneron concerning U.S. Patent No. 11,084,865 before this settlement.

I'll research counsel for the Petitioner (Fresenius Kabi SwissBioSim GmbH) in IPR2025-01268.

Let me dig deeper into the Petitioner's counsel roster and the companion IPR.

Let me pull the full petition counsel section and check for additional attorneys and the power of attorney.

Counsel of Record for the Petitioner / "Plaintiff-Side" (Fresenius Kabi SwissBioSim GmbH)

Labeling note: IPR2025-01268 is an inter partes review, not a district court infringement action. The metadata's "Plaintiff" maps onto the Petitioner, Fresenius Kabi SwissBioSim GmbH, and "Defendant" onto the Patent Owner/Respondent, Regeneron. The "plaintiff-side" counsel below are therefore Petitioner's PTAB counsel. There is no PACER docket sheet or "local counsel" concept here — service and appearances run through PTACTS — so this section is grounded in the petition, the power-of-attorney/counsel designations under 37 C.F.R. § 42.8(b)(3)–(4), and the papers and PTAB emails in this proceeding.

Petitioner's representation is handled by a single firm — ArentFox Schiff LLP (formerly Arent Fox, merged with Schiff Hardin in 2022) — which has served as Fresenius Kabi's principal patent litigation firm in the U.S. for years.

Identified attorneys

Service/correspondence alias used in this proceeding: AFS-Fresenius-aflibercept865IPR@afslaw.com (the parallel '345 case used AFS-Fresenius-aflibercept345IPR@afslaw.com).

PTAB correspondence routing (Dec. 19–22, 2025 Director-Review emails): the Board copied Petitioner at jaly@schiffhardin.com (an apparent legacy Schiff Hardin address for Aly) and sailesh.patel@afslaw.com, with the case alias. The Dec. 19, 2025 email from Director_PTABDecision_Review went to dberl@wc.com, jaly@schiffhardin.com, atrask@wc.com, aargall@wc.com, and sailesh.patel@afslaw.com — confirming Aly and Patel as the live Petitioner contacts at the Director-Review stage.

In-house counsel

• No in-house Fresenius Kabi attorney appears on the public record in IPR2025-01268. Corporate documents in unconnected Fresenius Kabi matters name regulatory/signatory personnel (e.g., Nicole Biehl, Director Regulatory Affairs & Post Market Surveillance, Fresenius Kabi AG, on an unrelated 2025 letter of authorization), but nothing places an in-house lawyer on this IPR record. Fresenius Kabi has not publicly identified an in-house IP litigation lead for the aflibercept biosimilar program that I could verify.

Other names seen on the papers (not counsel of record)

• Nicole S. Lynch — signed the certificates of service on both Fresenius petitions (July 14, 2025) and on the Oct. 23, 2025 opposition and Feb. 26, 2026 refund request. She is not listed on the § 42.8(b)(3) counsel table as lead or back-up counsel; the filings suggest firm support staff (paralegal/legal assistant) rather than an attorney of record. I could not confirm her bar/registration status — flagging as unverified.

Party/real-party-in-interest note (context for who is being represented)

The caption names only Fresenius Kabi SwissBioSim GmbH, but third-party trackers (Venable's BiologicsHQ; IPVerse's "et al.") list the petitioner side as Fresenius Kabi SwissBioSim GmbH, Fresenius Kabi AG, Fresenius Kabi USA, LLC, and Sam Chun Dang Pharm Co., Ltd. — consistent with the companion petition's use of "Petitioners" and plural power-of-attorney forms. I could not retrieve the § 42.8(b)(1) real-party-in-interest statement in -1268 itself, so treat that roster as likely but not confirmed from the primary record.

Sourcing and caveats

• Primary support: the IPR2025-01268 Petition (served July 14, 2025; public copy at pearceip.law and the PTACTS artifact for the Feb. 26, 2026 Request for Refund of Post-Institution Fees, artifactId for petition 1558189); the Oct. 23, 2025 "Opposition to Patent Owner's Request for Discretionary Denial" (signed /Imron T. Aly/, both attorneys "Attorneys for Petitioner"); and the Dec. 19 / Dec. 22, 2025 Director-Review emails in PTACTS listing Petitioner's email contacts.
• Confirmed continuity: Aly and Patel remained Petitioner's counsel of record through the last public paper I could access (the Feb. 26, 2026 refund request following the Nov. 20, 2025 discretionary denial and the pending Director Review request). The Director Review request (Dec. 19, 2025) is a Petitioner filing; I did not locate its signature page, but the Board's responsive emails route to Aly and Patel.
• Not located: the Petitioner Power of Attorney in -1268 (the petition states one was filed concurrently under §§ 41.10(b)/42.10(b)); the -1268 mandatory notices/RPI section; any motion for pro hac vice admission or order for Riaz in -1268; and any withdrawal/substitution papers after Feb. 26, 2026. Because Fresenius and Regeneron settled in February 2026 (per the existing case summary), no further counsel activity is expected in this proceeding absent a Director Review ruling.
• No district court appearances to report: Fresenius Kabi SwissBioSim was not a defendant in Regeneron's aflibercept BPCIA litigation (it expressly argued it was not a party to the MDL, 1:24-md-3103 (N.D. W. Va.)), so there is no separate district-court counsel roster for the same client on this patent. ArentFox Schiff is also Fresenius Kabi's counsel in the companion IPR2025-01269 against U.S. Pat. 10,828,345.
• One consistency check against the prior section: the Respondent-side identification (Williams & Connolly — Berl, Trask, Argall) is corroborated by the certificates of service on Petitioner's papers, which list exactly those three attorneys plus the Eylea@wc.com alias. No contradiction.

Bottom line: Petitioner's counsel of record in IPR2025-01268 are Imron T. Aly (lead) and Sailesh K. Patel (back-up), both of ArentFox Schiff LLP, Chicago. Bradford Frese and Ahmed M.T. Riaz are documented on the companion '-345 petition but are unverified on the -1268 record, and no in-house Fresenius Kabi attorney is publicly identified.

I'll research the counsel representing Regeneron (the patent owner / respondent in this IPR).

Strong signals that Williams & Connolly represents Regeneron. Let me confirm the full counsel roster and lead counsel designation.

Let me try to pin down the formal lead/back-up counsel designation for Regeneron in this specific IPR and check for in-house counsel.

Counsel of Record for the Respondent / Patent Owner (Regeneron Pharmaceuticals, Inc.)

Labeling note: IPR2025-01268 is an inter partes review, so the party alignment in the case metadata ("Plaintiff"/"Defendant") maps onto Petitioner (Fresenius Kabi SwissBioSim) and Patent Owner / Respondent (Regeneron). The "defendant-side" counsel here are therefore Regeneron's patent-owner representatives. Regeneron's defense is handled by a single firm — Williams & Connolly LLP, Washington, D.C. — the same firm that has represented Regeneron across the Eylea® BPCIA litigation and the prior '865-patent IPRs.

Identified attorneys

Contact-of-record address used in this proceeding: dberl@wc.com, atrask@wc.com, aargall@wc.com, and the team alias Eylea@wc.com (the same service alias used in Regeneron's other aflibercept proceedings).

In-house counsel (named, but not formally appearing in this IPR on the record)

• Gilbert Voy — Head of Global Patent Litigation, Regeneron Pharmaceuticals, Inc. He executed Regeneron's powers of attorney in the related aflibercept PTAB matters (e.g., IPR2025-00176 on the '865 patent, dated Dec. 31, 2024, and PGR2025-00085 on U.S. Pat. 12,168,036, dated Oct. 5, 2025). He is the appropriate in-house contact, but the public PTAB correspondence I retrieved for IPR2025-01268 itself does not show him as an attorney of record.

Possibly involved firm (unconfirmed for this IPR)

• Regeneron's power of attorney in IPR2025-00176 (Samsung Bioepis v. Regeneron, same '865 patent) also listed Elizabeth S. Weiswasser (Reg. No. 55,721) and Priyata Y. Patel (Reg. No. 76,861) of Paul, Weiss, Rifkind, Wharton & Garrison LLP, and service certificates in the '865 proceedings copy Paul Weiss at eweiswasser@paulweiss.com / ppatel@paulweiss.com / GRP-PW-EYLEA-Biosimilars@paulweiss.com. I did not find a Paul Weiss entry on the IPR2025-01268 papers I could access, so treat Paul Weiss's participation here as unverified.

Sourcing and caveats

• Regeneron's counsel identification is grounded in PTAB P-TACTS correspondence in IPR2025-01268 (petition artifactId 1558189), including the Oct. 30, 2025 discretionary-denial-reply authorization and the Dec. 19–22, 2025 Director-Review emails (Trask signing "Counsel for Patent Owner"; Argall's signature block identifying him as a Williams & Connolly associate at 680 Maine Ave. SW), plus the third-party docket aggregators (GreyB/IPVerse and Ex Parte AI-Lab), which list "Respondent Counsel: Berl, David et al."
• I could not retrieve the Patent Owner's power of attorney or mandatory notices filed in IPR2025-01268 itself. The Reg. Nos. above are taken from Regeneron's substantively identical power of attorney in IPR2025-00176 (same '865 patent) and PGR2025-00085. Because the same three attorneys (Berl, Trask, Argall) appear on the IPR2025-01268 record, the designations are reliable, but I am flagging that the case-specific § 42.8(b)(3) lead/back-up designation paper was not located in the accessible public set.
• No distinct "local counsel" appears — PTAB practice does not require one, and none is shown.
• One consistency check against the existing case summary: the summary states institution was denied on Nov. 20, 2025. The docket correspondence confirms that date and further shows Fresenius filed a request for Director Review (Dec. 19, 2025) with Regeneron authorized to respond (deadline extended to Jan. 6, 2026). This is consistent with — and adds detail to — the "not instituted / discretionary denial" posture already described, not a contradiction.