Untitled case

This patent infringement litigation, Case No. 2:25-cv-03179, is taking place in the New Jersey District Court and involves two significant players in the pharmaceutical industry: plaintiff Halozyme, Inc. and defendant Merck Sharp & Dohme LLC. Halozyme, Inc. is a biotechnology company specializing in oncology therapies and innovative drug delivery solutions, particularly its proprietary ENHANZE® technology, which employs a recombinant human hyaluronidase enzyme (rHuPH20) to facilitate the subcutaneous administration of injectable biologics. Merck Sharp & Dohme LLC, a multinational pharmaceutical giant headquartered in Rahway, New Jersey, develops and markets prescription medicines, vaccines, biologic therapies, and animal health products, with its blockbuster cancer immunotherapy, KEYTRUDA, being a major revenue driver. The dispute centers on Merck's newly developed subcutaneous (SC) version of KEYTRUDA, known as SC KEYTRUDA, which allegedly utilizes Halozyme's patented hyaluronidase enzyme technology for its subcutaneous delivery.

The patents asserted by Halozyme in this action, including US Patent 12264345, are part of a larger family of patents that stem from Halozyme's extensive research into modifications of human hyaluronidase (PH20) to enhance drug delivery. US Patent 12264345 specifically describes "PH20 polypeptide variants, formulations and uses thereof," encompassing modified PH20 hyaluronidase polypeptides designed for increased stability and/or activity, particularly mentioning modifications to amino acid residue 313. The case is being heard by District Judge Esther Salas and Magistrate Judge James B. Clark, III, in the District of New Jersey. This venue is highly significant for pharmaceutical patent litigation, as the District of New Jersey, along with Delaware, historically handles a vast majority of such disputes, especially those under the Hatch-Waxman Act and BPCIA, due to the presence of many pharmaceutical companies' operational headquarters in the state, offering a natural nexus for jurisdiction and judges with specialized expertise.

This litigation is particularly notable given the substantial market implications surrounding Merck's KEYTRUDA, one of the world's top-selling drugs, which faces a patent expiry (often referred to as a "patent cliff") for its intravenous formulation in 2028. The development of SC KEYTRUDA is a critical lifecycle management strategy for Merck to maintain market exclusivity and revenue against the impending entry of biosimilar competitors. The involvement of Halozyme's core ENHANZE® technology in this subcutaneous formulation makes this a high-stakes licensing and infringement battle between two major operating companies rather than a non-practicing entity (NPE) assertion, despite the patent being listed by Unified Patents. Furthermore, the case is linked to multiple parallel Post-Grant Review (PGR) proceedings filed by Merck against Halozyme's patents at the Patent Trial and Appeal Board (PTAB), a common strategy to challenge patent validity alongside district court litigation.

Here's a chronological overview of the key legal developments and outcomes in the patent infringement litigation, Halozyme, Inc. v. Merck Sharp & Dohme LLC, Case No. 2:25-cv-03179:

Key Legal Developments and Outcome:

• Complaint Filing (2025-04-24): Halozyme, Inc. filed a patent infringement lawsuit against Merck Sharp & Dohme Corp. in the U.S. District Court for the District of New Jersey. Halozyme alleged that Merck's subcutaneous formulation of Keytruda (SC KEYTRUDA), intended for launch in 2025, infringes multiple patents related to Halozyme's MDASE subcutaneous delivery technology, including U.S. Patent 12264345. Halozyme sought damages and injunctive relief, asserting willful infringement.
• Defendant Name Substitution & Answer Deadline (2025-05-15): The original complaint named "Merck Sharp & Dohme Corp." as the defendant. However, Merck Sharp & Dohme Corp. had merged into Merck Sharp & Dohme LLC in the spring of 2022. The parties stipulated to substitute Merck Sharp & Dohme LLC as the proper defendant, and the court ordered this substitution on May 15, 2025. Merck Sharp & Dohme LLC was given sixty days from this date to answer or otherwise respond to the complaint.
• Proposed Discovery Confidentiality Order (pre-2026-02-19): An early discovery milestone occurred with the enclosure of a proposed Discovery Confidentiality Order to Magistrate Judge Jose R. Almonte.
• Merck Files Multiple Post-Grant Reviews (PGRs) (2024-11 - 2025-06): Beginning in November 2024, and continuing through mid-2025, Merck Sharp & Dohme LLC initiated numerous Post-Grant Review (PGR) petitions against Halozyme's patents at the Patent Trial and Appeal Board (PTAB). These petitions challenged patents from the family asserted in the district court litigation. By June 27, 2025, at least thirteen PGR petitions had been filed. Specific PGRs targeting patents related to the litigation include:
  • PGR2025-00033 filed March 7, 2025.
  • PGR2025-00039 filed March 28, 2025.
  • PGR2025-00042 filed April 15, 2025.
  • PGR2025-00046 filed April 29, 2025.
  • PGR2025-00050 filed May 7, 2025.
  • PGR2025-00052 filed June 27, 2025, specifically challenging U.S. Patent No. 12,264,345, the primary patent at issue in this district court case.
• PTAB Institutes Multiple PGRs (2025-10): The PTAB instituted trial in several of Merck's PGR petitions. Prior to some institution decisions, Halozyme disclaimed certain claims:
  • PGR2025-00046 (U.S. Patent No. 12,091,692) was instituted on October 10, 2025. Halozyme disclaimed claims 3-4, 6, and 27-28 prior to this decision.
  • PGR2025-00052 (U.S. Patent No. 12,264,345) was instituted on October 16, 2025. The PGR challenged claims 1-17 for obviousness, lack of written description, enablement, and indefiniteness. This PGR is currently "Instituted, Pending".
  • PGR2025-00024 (U.S. Patent No. 12,060,590) was instituted on October 16, 2025. Halozyme disclaimed claims 3-5, 16, and 31-35 beforehand.
  • PGR2025-00030 (U.S. Patent No. 12,054,758) was instituted on October 16, 2025. Halozyme disclaimed claims 3-5 and 31-40 beforehand.
• German Preliminary Injunction (2025-12-04): In a related international development, a German court granted Halozyme's request for a preliminary injunction against Merck, ordering it to refrain from distributing and offering Keytruda SC in Germany. The Munich Regional Court found imminent infringement of Halozyme's European Patent No. 2 797 622 (EP 622), part of Halozyme's global enforcement of its MDASE patents.
• Litigation Stayed Pending IPRs (Current Posture): As of April 2026, the district court litigation (2:25-cv-03179) is ongoing but has been stayed pending the outcome of the parallel PTAB IPR proceedings. Halozyme had previously argued against discretionary denial of institution by the PTAB based on the Fintiv factors, contending that the district court litigation would proceed regardless of the PGR outcomes, but the PTAB still instituted reviews.

Halozyme, Inc. is represented by a team of attorneys from several firms, including both lead and local counsel, as well as in-house counsel.

Here is a breakdown of the counsel of record for Halozyme, Inc.:

Lead Counsel:

• David A. Nelson
  • Role: Of Counsel (pro hac vice forthcoming)
  • Firm: Quinn Emanuel Urquhart & Sullivan, LLP, Chicago, Illinois office
  • Note: Quinn Emanuel is a prominent firm in patent litigation, and David Nelson has been identified as counsel for Halozyme in this case and related PTAB proceedings.
• Jeffrey S. Gerchick
  • Role: Of Counsel (pro hac vice forthcoming)
  • Firm: Quinn Emanuel Urquhart & Sullivan, LLP, Washington, D.C. office
• Zachariah B. Summers
  • Role: Of Counsel (pro hac vice forthcoming)
  • Firm: Quinn Emanuel Urquhart & Sullivan, LLP, Los Angeles, California office
• Lauren Martin
  • Role: Of Counsel (pro hac vice forthcoming)
  • Firm: Quinn Emanuel Urquhart & Sullivan, LLP, Boston, Massachusetts office
• Nancy L. Zhang
  • Role: Counsel (not admitted to USDC - NJ Bar)
  • Firm: Quinn Emanuel Urquhart & Sullivan LLP
  • Note: Nancy Zhang has experience in various patent litigation practice areas, including biotechnology.

Local Counsel:

• Liza M. Walsh
  • Role: Counsel
  • Firm: Walsh Pizzi O'Reilly Falanga LLP, Newark, New Jersey office
  • Note: Liza Walsh is a named attorney on documents related to the case, including a proposed Discovery Confidentiality Order.
• Lauren R. Malakoff
  • Role: Counsel
  • Firm: Walsh Pizzi O'Reilly Falanga LLP, Newark, New Jersey office
• Katelyn O'Reilly
  • Role: Counsel
  • Firm: Walsh Pizzi O'Reilly Falanga LLP, Newark, New Jersey office

In-House Counsel:

• Josh Mack
  • Role: Executive Director, Patent Litigation Counsel
  • Firm: Halozyme, Inc.
  • Note: Josh Mack leads all litigation matters for Halozyme and has prior experience in intellectual property litigation at firms like Wilson Sonsini Goodrich & Rosati and as Senior Counsel at Amgen.
• Mark Snyder
  • Role: Senior Vice President, General Counsel, Chief Compliance Officer and Corporate Secretary
  • Firm: Halozyme Therapeutics, Inc.
  • Note: Mark Snyder oversees IP strategy development and prosecution, and previously led litigation strategy for Qualcomm Incorporated.

Defendant Merck Sharp & Dohme LLC is represented by a team of attorneys from several law firms, as well as in-house counsel.

Here's a breakdown of the counsel of record for Merck:

Local Counsel:

• Charles H. Chevalier (Local Counsel)
  • Firm: Gibbons P.C., Newark, New Jersey
  • Note: Chevalier is listed on the Corporate Disclosure Statement for Merck in this case, filed July 14, 2025.
• Michael V. Caracappa (Local Counsel)
  • Firm: Gibbons P.C., Newark, New Jersey
  • Note: Caracappa is also listed on the Corporate Disclosure Statement for Merck in this case.

Of Counsel:

• Katherine A. Helm (Of Counsel)
  • Firm: Dechert LLP, New York, New York
  • Note: Helm has been added to receive Notices of Electronic Filing as of May 29, 2025.
• Blaine Hackman (Of Counsel)
  • Firm: Dechert LLP, New York, New York
  • Note: Hackman has also been added to receive Notices of Electronic Filing as of May 29, 2025.
• Brian M. Goldberg (Of Counsel)
  • Firm: Dechert LLP, Philadelphia, Pennsylvania
  • Note: Goldberg is listed as an attorney for Merck in a May 2025 court document in this case.
• Daniel Roberts (Of Counsel)
  • Firm: Dechert LLP, Philadelphia, Pennsylvania
  • Note: Roberts has been added to receive Notices of Electronic Filing as of May 29, 2025.
• Shyam Shanker (Of Counsel)
  • Firm: Dechert LLP, Charlotte, North Carolina
  • Note: Shanker has been added to receive Notices of Electronic Filing as of May 29, 2025.

In-House Counsel:

• Mark Stewart (In-House Counsel, Vice President - Head of Global IP Litigation)
  • Firm: Merck Sharp & Dohme LLC, Rahway, New Jersey
  • Note: Stewart has over 30 years of experience as in-house counsel in the pharmaceutical industry, focusing on global IP litigation, and also coordinates the battle with Halozyme in-house at MSD in parallel international proceedings. He is also listed as counsel for Merck in related PTAB proceedings.
• Aaron Clay (In-House Counsel, Director of Global Intellectual Property Litigation & Patents)
  • Firm: Merck Sharp & Dohme LLC, Rahway, New Jersey
  • Note: Clay specializes in patent litigation, post-grant proceedings, and appeals related to pharmaceuticals and biologics. He is also listed as counsel for Merck in related PTAB proceedings.

It is worth noting that while Quinn Emanuel Urquhart & Sullivan, LLP has represented Merck in other pharmaceutical patent litigation matters, the provided documents for this specific case (2:25-cv-03179) indicate Dechert LLP and Gibbons P.C. as the primary external counsel for Merck. However, some documents related to this case in PTAB proceedings list O'Melveny & Myers LLP attorneys as counsel for Merck. Jeff Kushan from Sidley Austin is noted as leading the US cases for MSD in broader litigation against Halozyme.