Regeneron Pharmaceuticals, Inc. v. Amgen Inc.

This patent infringement litigation pits two major American biopharmaceutical companies against each other: Plaintiff Regeneron Pharmaceuticals, Inc., the innovator of the blockbuster eye drug Eylea (aflibercept), and Defendant Amgen Inc., a developer of biosimilar therapeutics. Regeneron alleges that Amgen's biosimilar version of Eylea, marketed as Pavblu™ (ABP 938), infringes U.S. Patent 11084865. This patent broadly claims ophthalmic formulations of a vascular endothelial growth factor (VEGF) antagonist, specifically aflibercept, that are suitable for intravitreal administration and include a VEGF antagonist, an organic co-solvent, a buffer, and a stabilizing agent.

The case, initially filed in the U.S. District Court for the Central District of California (2:24-cv-00264) on January 10, 2024, was subsequently transferred and consolidated into a multi-district litigation (MDL No. 1:24-md-3103) in the U.S. District Court for the Northern District of West Virginia, under Chief Judge Thomas S. Kleeh. This venue became the hub for Regeneron's extensive efforts to protect its Eylea franchise against numerous biosimilar challengers. A critical procedural development occurred when the district court denied Regeneron's request for a preliminary injunction against Amgen. This decision was notably upheld by the U.S. Court of Appeals for the Federal Circuit (CAFC Appeal No. 24-2351) on March 14, 2025, which found that Regeneron had not established a likelihood of success on infringement because Amgen's biosimilar utilized a "self-buffering" formulation, distinguishing it from the '865 patent's claims, which were construed to require a separate buffer component.

This case is highly notable within the pharmaceutical industry due to the substantial market value of Eylea, generating approximately $6 billion in annual sales. The Federal Circuit's decision allowed Amgen to launch Pavblu™ in October 2024, making it the first and, for a period, the only Eylea biosimilar available, in stark contrast to other biosimilar developers (e.g., Samsung Bioepis, Formycon, Celltrion) whose launches were blocked by preliminary injunctions on the same '865 patent. The outcome highlights the critical role of claim construction in biosimilar litigation and the effectiveness of design-around strategies, setting a significant precedent for future Biologics Price Competition and Innovation Act (BPCIA) disputes. Furthermore, the '865 patent has been the subject of multiple inter partes review (IPR) petitions at the Patent Trial and Appeal Board (PTAB) by other biosimilar applicants, although these were often denied institution on discretionary grounds due to ongoing district court litigation.

Here's a chronological summary of the key legal developments and outcome for the patent infringement litigation involving U.S. Patent 11084865 between Regeneron Pharmaceuticals, Inc. and Amgen Inc.:

Filing & Initial Pleadings:

• 2024-01-10: Regeneron Pharmaceuticals, Inc. filed a complaint against Amgen Inc. in the U.S. District Court for the Central District of California (Case No. 2:24-cv-00264). The complaint asserted 32 patents, including U.S. Patent No. 11,084,865, alleging infringement by Amgen's proposed aflibercept biosimilar, ABP 938 (later marketed as PAVBLU).
• 2024-01-11: Regeneron filed a motion to transfer the case to the Northern District of West Virginia.
• 2024-02-07: Amgen filed its Answer to the Complaint and asserted Counterclaims.
• 2024-02-23: Amgen provided Regeneron with its 180-day notice of commercial marketing for ABP 938, as required by the Biologics Price Competition and Innovation Act (BPCIA).
• 2024-02-23: Regeneron filed its Answer to Amgen's Counterclaims.

Pre-trial Motions of Substance — Transfer & Preliminary Injunction:

• 2024-01-23: The Central District of California granted Regeneron's request to set a preliminary injunction (PI) schedule but determined that this case should follow the schedule of other related cases already pending.
• 2024-04-11: The Judicial Panel on Multidistrict Litigation (JPML) centralized several aflibercept biosimilar actions, including Regeneron v. Amgen, in the U.S. District Court for the Northern District of West Virginia (Case No. 1:24-md-03103, with the Amgen action docketed as 1:24-cv-00039). The cases were assigned to Chief District Judge Thomas S. Kleeh for coordinated or consolidated pretrial proceedings.
• 2024-06-07: Regeneron filed its motion for a preliminary injunction against Amgen, focusing on U.S. Patent No. 11,084,865.
• 2024-08-23: The FDA approved Amgen's biosimilar, PAVBLU (aflibercept-ayyh).
• 2024-10-01: The District Court for the Northern District of West Virginia denied Regeneron's motion for a preliminary injunction against Amgen. The court concluded that Regeneron failed to establish a likelihood of success in proving infringement of the '865 patent, based on a claim construction finding that Amgen's product lacked a "separate buffer" component as required by the asserted claims.
• 2024-10 (approx.): Amgen launched its biosimilar PAVBLU at-risk.

Appeal of Preliminary Injunction Denial:

• 2024-10 (approx.): Regeneron appealed the district court's denial of the preliminary injunction to the U.S. Court of Appeals for the Federal Circuit (CAFC Appeal No. 24-2351).
• 2024-10-22: The Federal Circuit denied Regeneron's request for an emergency injunction pending appeal but granted expedited briefing and placed the case on its January 2025 oral argument calendar.
• 2025-01-14: Oral argument on Regeneron's appeal was held before a Federal Circuit panel.
• 2025-03-14: The Federal Circuit affirmed the district court's denial of the preliminary injunction. The CAFC agreed with the district court's claim construction and application of the presumption that separately listed elements (VEGF antagonist and buffer) in a claim are distinct components, meaning Regeneron did not show a likelihood of success on infringement of the '865 patent.

Parallel PTAB IPR Proceedings:

• 2024-11 to 2025-01: Samsung Bioepis (IPR2025-00176), Formycon (IPR2025-00233), and Celltrion (IPR2025-0456) filed separate inter partes review (IPR) petitions challenging the validity of U.S. Patent No. 11,084,865.
• 2025-06-02: The Patent Trial and Appeal Board (PTAB) denied institution of Samsung Bioepis' and Formycon's IPR petitions against the '865 patent. The PTAB exercised its discretion under the Fintiv factors, citing the advanced stage of parallel BPCIA litigation, including a 9-day trial in a related Mylan case and preliminary injunction proceedings focused on the '865 patent.
• 2025-06-26: The PTAB also denied institution of Celltrion's IPR petition for similar discretionary reasons under the Fintiv factors.
• 2025-07-14: Fresenius Kabi filed IPR petitions against U.S. Patent No. 11,084,865 (and another patent), asserting new anticipation grounds. Notably, Fresenius Kabi was not a party to BPCIA litigation with Regeneron at the time.

Claim Construction (Markman) & Current Posture:

• 2025-09-29: A Scheduling Order was issued in the MDL, setting a Markman (claim construction) hearing for November 23, 2026.
• The litigation remains active within the MDL proceedings in the Northern District of West Virginia.

Regeneron Pharmaceuticals, Inc. is represented by a team of external counsel, primarily from Williams & Connolly LLP, in this patent infringement case (2:24-cv-00264), which has been transferred to the Northern District of West Virginia and consolidated into MDL No. 3103, In Re: Aflibercept Patent Litigation.

The following counsel have appeared for Regeneron:

• David I. Berl

  • Role: Lead Counsel (Liaison Counsel in MDL)
  • Firm: Williams & Connolly LLP, Washington, D.C.
  • Experience Note: Mr. Berl is a prominent patent litigator, frequently representing clients in biotechnology, pharmaceutical, and energy patent disputes, including Hatch-Waxman and BPCIA litigation, and has PTAB expertise.

• Shannon Gibson

  • Role: Liaison Counsel (in MDL)
  • Firm: Williams & Connolly LLP, Washington, D.C.
  • Experience Note: Ms. Gibson is named as Liaison Counsel for Regeneron in the MDL proceedings, indicating her active role in coordinating the litigation.

• Adam Pan

  • Role: Counsel
  • Firm: Williams & Connolly LLP, Washington, D.C. (Admitted in D.C. and California)
  • Experience Note: Mr. Pan clerked for Judge Timothy B. Dyk of the U.S. Court of Appeals for the Federal Circuit and has a Ph.D. from MIT for research on computational X-ray phase contrast imaging of human atherosclerotic disease, providing a strong technical background in patent litigation.

• Matthew Donald Umhofer

  • Role: Local Counsel (initially in C.D. Cal.)
  • Firm: Umhofer, Mitchell & King LLP, Los Angeles, California
  • Experience Note: Mr. Umhofer has extensive experience in complex civil litigation, white-collar criminal defense, and government investigations, including acting as local counsel in multi-district cases involving patent infringement.

• Anthony R. Bisconti

  • Role: Local Counsel (initially in C.D. Cal.)
  • Firm: Bienert Katzman Littrell Williams LLP, San Clemente, California
  • Experience Note: Mr. Bisconti is part of a firm specializing in complex civil litigation, white-collar criminal defense, and whistleblower claims, with experience in a wide range of high-stakes legal matters.

Other attorneys from Williams & Connolly LLP listed in early filings as "pro hac vice forthcoming" or appearing with David I. Berl include Ellen E. Oberwetter, Thomas S. Fletcher, Andrew V. Trask, Teagan J. Gregory, Shaun P. Mahaffy, Kathryn S. Kayali, Arthur J. Argall III, Rebecca A. Carter, Haylee N. Bernal Anderson, and Jennalee Beazley.

There is no specific in-house counsel for Regeneron Pharmaceuticals, Inc. listed as counsel of record appearing on the public docket for this particular patent infringement case. Regeneron does employ in-house patent attorneys and corporate counsel who manage intellectual property and advise on legal matters related to product development and commercialization.

I'll research the defense counsel for Amgen Inc. in this litigation.

Let me gather more specific details on Amgen's defense team and confirm roles.

Let me verify the appellate representation and in-house counsel details.

Defense Counsel of Record — Amgen Inc.

Regeneron Pharmaceuticals, Inc. v. Amgen Inc., originally C.D. Cal. No. 2:24-cv-00264, now N.D. W. Va. member case No. 1:24-cv-00039-TSK-JPM within MDL No. 1:24-md-03103-TSK-JPM (Chief Judge Thomas S. Kleeh; Magistrate Judge James P. Mazzone).

Amgen is represented by a multi-firm team: a Chicago IP boutique as lead trial/MDL liaison counsel, a D.C. patent boutique, a national litigation firm handling West Virginia local-counsel work, a Big-Law antitrust/litigation firm added for the counterclaims, and Amgen's own in-house litigation group. Amgen's counsel are publicly listed across the JPML service lists, the MDL liaison-counsel order, the Dec. 2025 stipulation signature block, and the Federal Circuit's counsel listing in the PI appeal.

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1. Lead Trial / Liaison Counsel

Marshall, Gerstein & Borun LLP — 233 S. Wacker Dr., 6300 Willis Tower, Chicago, IL 60606 (312-474-6300)

The firm also operates the MDL service mailbox MGB-Amgen-ABP938@marshallip.com.

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2. Appellate Counsel

MoloLamken LLP — Washington, D.C.

(Names and firm appear in the Federal Circuit panel opinion's counsel listing for defendant-appellee Amgen in the appeal from the PI denial.)

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3. D.C. Patent Boutique (Trial / IPR-side counsel)

Rothwell, Figg, Ernst & Manbeck, P.C. — 901 New York Ave., NW, Suite 900 East, Washington, D.C. 20001 (202-783-6040)

The firm maintains the Amgen service mailbox ABP938@rothwellfigg.com.

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4. Antitrust / Counterclaim Counsel

Cravath, Swaine & Moore LLP — Two Manhattan West, 375 Ninth Ave., New York, NY 10001 (212-474-1000)

These two firms (Cravath) appear to have been brought in around the filing of Amgen's Sherman Act § 2, California UCL, inequitable-conduct, and prosecution-laches counterclaims — Amgen's offensive posture in the MDL, which sits alongside the patent defenses.

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5. West Virginia Local Counsel (N.D. W. Va.)

Bowles Rice LLP — 600 Quarrier St., Charleston, WV 25301 (304-347-1110); 125 Granville Square, Morgantown, WV 26505

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6. California Local Counsel (initial C.D. Cal. forum, pre-transfer)

Proskauer Rose LLP — 2029 Century Park East, Suite 2400, Los Angeles, CA 90067-3010

(These two are listed as "Counsel for Defendant Amgen Inc." on the JPML/MDL service lists tied to C.D. Cal. No. 2:24-cv-00264.)

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7. Amgen In-House Counsel

Amgen Inc. — One Amgen Center Drive, Thousand Oaks, CA 91320 (805-447-1000)

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8. Intervenor (separate but related Amgen entity)

Amgen USA, Inc. (intervenor in the MDL) is represented by:

• John H. Tinney, Jr. — Hendrickson & Long, PLLC, 214 Capitol St., P.O. Box 11070, Charleston, WV 25301.

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Notes, caveats, and a flagged inconsistency

1. Counsel of record is public; underlying filings often are not. Several Amgen briefs in the MDL have been filed under seal (e.g., Amgen's reply in support of its motion to compel, Dkt. 773, and the exhibits to its PI opposition). The identities of counsel of record are drawn from public signature blocks, service lists, and court opinions, not from sealed material.

2. Team structure is evolving, not fixed. The composition differs by phase: Proskauer (C.D. Cal. local) appears on the earliest JPML lists, Bowles Rice became the N.D. W. Va. local counsel of record after transfer, and Cravath appears only in the 2025–2026 counterclaim phase. Amgen has therefore had at least three firms file in a "local counsel" capacity across the life of the case.

3. Possible caption/citation discrepancy worth flagging. The prior case summary states the PI affirmance was in CAFC Appeal No. 24-2351, and the CourtListener docket for No. 24-2351 is captioned "Regeneron Pharmaceuticals, Inc. v. Mylan Pharmaceuticals Inc." — listing Amgen Inc. as defendant-appellee. Separately, Amgen's own counterclaim pleading cites the affirmance as Regeneron Pharms., Inc. v. Mylan Pharms. Inc., 130 F.4th 1372 (Fed. Cir. 2025). This suggests the published opinion may carry the Mylan-captioned lead case (with the Amgen appeal consolidated into the same panel disposition) rather than an Amgen-captioned opinion. If precision matters for citation purposes, the exact reporter caption of the March 14, 2025 decision should be confirmed directly against the Federal Circuit docket before being relied on. The substance — affirmance of the PI denial on the "separate buffer" construction — is well corroborated (district court Dkt. 343; Fed. Cir. affirmance; Amgen's counterclaims quote both).

4. Not verified: individual attorney bar numbers, current titles (e.g., whether Ms. Whiteford holds a specific "Chief IP Counsel" title), and whether any of the listed attorneys have since withdrawn. Only Arthur J. Argall III (Regeneron side) and Priyata Patel (Regeneron side) are shown on the docket as having withdrawn (orders entered Apr. 1, 2026 and Mar. 24, 2026 respectively) — I found no comparable withdrawal entries for Amgen's team as of the latest docket entries reviewed.