Untitled case

Halozyme, Inc., a biotechnology company specializing in the development and commercialization of treatments based on its ENHANZE® drug delivery technology, filed a patent infringement lawsuit against Merck Sharp & Dohme LLC (formerly Merck Sharp & Dohme Corp.), a global pharmaceutical company. The case, Halozyme, Inc. v. Merck Sharp & Dohme Corp., Case No. 2:25-cv-03179, was filed in the U.S. District Court for the District of New Jersey on April 24, 2025. Halozyme alleges that Merck's subcutaneous version of its blockbuster cancer drug KEYTRUDA, known as SC KEYTRUDA or Keytruda Qlex™, infringes its patented modified PH20 hyaluronidase technology. This technology enables the rapid subcutaneous administration of therapeutic drugs by modifying the PH20 enzyme to achieve improved activity and stability profiles. Specifically, U.S. Patent No. 12,018,298, along with fourteen other patents from a single family, are asserted in the litigation. Patent 12,018,298 generally covers PH20 polypeptide variants, formulations, and uses thereof, including modified PH20s with amino acid modifications at residue 313.

The case is currently in litigation in the District of New Jersey, with Judge Esther Salas presiding and Magistrate Judge Jose R. Almonte assisting with discovery matters. The District of New Jersey is a common venue for pharmaceutical patent litigation, particularly given Merck's principal place of business in Rahway, New Jersey, which establishes personal jurisdiction and venue in the district. The dispute is notable as it centers on Merck's strategic effort to protect its market share for KEYTRUDA, which is anticipated to lose patent protection in 2028, by introducing the subcutaneous SC KEYTRUDA. This move is designed to transition sales to the new formulation before the expiration of the original KEYTRUDA patents.

The litigation is further complicated by a series of Post-Grant Reviews (PGRs) initiated by Merck against Halozyme's patents at the Patent Trial and Appeal Board (PTAB), including PGR2025-00004 which challenges U.S. Patent No. 12,018,298. Merck filed PGRs against 14 Halozyme patents, alleging invalidity on grounds such as obviousness, lack of written description, and failure to comply with enablement requirements, with several of these PGRs having already been instituted by the PTAB. The PTAB has already found some claims of related Halozyme patents unpatentable due to lack of written description and enablement, noting the unpredictability of how structural modifications to PH20 polypeptides affected hyaluronidase activity. This interplay between the district court litigation and the PTAB proceedings highlights a common strategy in pharmaceutical patent disputes to challenge patent validity in parallel forums.

Patent Infringement Litigation: Halozyme, Inc. v. Merck Sharp & Dohme Corp.

Case Number: 2:25-cv-03179
Court: New Jersey District Court
Patents at Issue: US Patent 12018298 (among others)
Current Status: Active Litigation with Parallel PTAB Proceedings

This patent infringement litigation was initiated by Halozyme, Inc. against Merck Sharp & Dohme Corp. in the District of New Jersey. The case involves allegations of infringement of US Patent 12018298 and several other related patents. Parallel Post-Grant Review (PGR) proceedings have been filed against the asserted patents at the USPTO's Patent Trial and Appeal Board (PTAB).

Key Legal Developments:

Filing & Initial Pleadings:

• Complaint Filed: On April 24, 2025, Halozyme, Inc. filed a complaint against Merck Sharp & Dohme Corp. in the New Jersey District Court, case number 2:25-cv-03179. The complaint alleges infringement of US Patent 12018298, alongside other patents including 12,049,652, 11,952,618, 12,152,520, 12,152,400, 12,152,149, 12,018,345, 12,152,692, 12,152,758, and 12,152,262, all generally related to PH20 polypeptide variants and formulations for subcutaneous delivery. Halozyme's complaint specifically highlighted Merck's alleged development of a subcutaneous version of KEYTRUDA as the accused product.
• Substitution of Defendant and Deadline to Respond: On May 15, 2025, a stipulation and order were filed to substitute the defendant from "Merck Sharp & Dohme Corp." to "Merck Sharp and Dohme LLC," as the former is no longer an existing corporate entity. Merck Sharp and Dohme LLC was given sixty (60) days from the May 15, 2025, order to answer or otherwise respond to the complaint.

Pre-trial Motions of Substance:

• As of the current date, specific substantive pre-trial motions such as motions to dismiss, transfer, or stay the district court proceedings pending the outcome of the PTAB reviews have not been publicly detailed.

Claim Construction (Markman) Outcomes:

• The case is still in its relatively early stages, and there is no public information available regarding any Markman hearings or claim construction outcomes.

Discovery Milestones:

• No specific strategic discovery milestones have been publicly reported yet.

Trial Events, Verdict, and Post-Trial Motions:

• The case has not yet reached the trial stage.

Settlement, Dismissal, Judgment, or Appeal:

• The litigation remains active in the New Jersey District Court.

Parallel PTAB IPR/PGR Proceedings:

• PGR Filings: Merck Sharp & Dohme LLC, the defendant in the district court case, initiated multiple Post-Grant Review (PGR) proceedings against Halozyme's asserted patents at the USPTO's Patent Trial and Appeal Board (PTAB). Notably, PGR2025-00004 was filed against US Patent 12018298 on November 25, 2024. Other related PGRs include PGR2025-00003 (Patent 11,952,600 B2), PGR2025-00006 (Patent 12,152,262 B2), and PGR2025-00009 (Patent 12,123,035 B2).
• Conditional Grant of Pro Hac Vice Motions: On November 10, 2025, the PTAB conditionally granted motions for pro hac vice admission for counsel representing Merck (the Petitioner in the PGRs), specifically Sue Wang and Brian M. Goldberg, across the aforementioned parallel PGR proceedings, including PGR2025-00004 for patent 12018298.
• Effect on Litigation: PGRs are "trial-type" procedures at the PTAB that allow a third party to challenge the validity of a patent within nine months of its issuance on all statutory grounds for invalidity, providing a potentially faster and cheaper alternative to district court litigation for validity challenges. The institution of a PGR could potentially lead to a stay of the district court litigation, though no such motion or ruling has been publicly reported in this case yet. The outcome of these PTAB proceedings, particularly the institution decisions and any final written decisions on patentability, will likely have a significant impact on the district court case.

Here's an overview of the counsel of record representing Halozyme, Inc., the plaintiff in case 2:25-cv-03179:

Local Counsel:

• Liza M. Walsh

  • Role: Likely local counsel.
  • Firm: Walsh Pizzi O'Reilly Falanga LLP, Newark, New Jersey.
  • Experience: Liza M. Walsh is a highly experienced litigator with over 30 years in federal and complex commercial litigation, focusing on intellectual property, antitrust, and class action defense. She has defended major pharmaceutical companies in significant patent litigation and is often sought as local counsel for Hatch-Waxman litigations in New Jersey.

• Lauren Ruth Malakoff

  • Role: Likely local counsel.
  • Firm: Walsh Pizzi O'Reilly Falanga LLP, Newark, New Jersey.
  • Experience: Specific patent litigation experience for Lauren Ruth Malakoff was not explicitly detailed in the provided search results, but her affiliation with Walsh Pizzi O'Reilly Falanga LLP, a firm with intellectual property litigation as a key practice area, suggests involvement in such matters.

Other Counsel (likely admitted pro hac vice):

The following attorneys are listed as "Counsel Not Admitted To Usdc - Nj Bar" and are associated with Quinn Emanuel Urquhart & Sullivan, LLP, indicating they are likely lead counsel admitted pro hac vice.

• Elliot Choi

  • Role: Counsel (likely admitted pro hac vice).
  • Firm: Quinn Emanuel Urquhart & Sullivan, LLP, New York, New York.
  • Experience: Elliot Choi's practice focuses on complex patent litigation, counseling, and due diligence across various technologies, including pharmaceuticals, biotechnology, medical devices, and consumer electronics. He also advises branded and generic pharmaceutical companies on the settlement of patent litigations.

• Nancy L. Zhang

  • Role: Counsel (likely admitted pro hac vice).
  • Firm: Quinn Emanuel Urquhart & Sullivan, LLP, San Francisco, California.
  • Experience: Nancy Zhang is a trial lawyer with extensive experience in high-stakes patent, trade secret, unfair competition, and breach of contract disputes. She has significant experience in life sciences matters, including commercialized drug products, small molecules, and biologics, and has litigated in various jurisdictions including district courts, the Federal Circuit, and the International Trade Commission.

• Zachariah B. Summers

  • Role: Counsel (likely admitted pro hac vice). He has been noted as a provisionally recognized PTAB attorney as back-up counsel in related PGR proceedings.
  • Firm: Quinn Emanuel Urquhart & Sullivan, LLP, Los Angeles, California (previously New York).
  • Experience: Zach Summers is a patent litigator who has represented life sciences clients, including Halozyme Therapeutics, Inc., as well as other technology companies. He has extensive experience litigating patent infringement cases, including expert discovery and specialized patent-related proceedings like Markman briefing and invalidity contentions.

• Anastasia M. Fernands

  • Role: Counsel (likely admitted pro hac vice).
  • Firm: Quinn Emanuel Urquhart & Sullivan, LLP, New York, New York.
  • Experience: Anastasia Fernands is of counsel with a civil trial practice focused on intellectual property matters, particularly patent litigation. She has extensive experience litigating patents for both plaintiffs and defendants across various complex technologies, including pharmaceutical formulations and medical devices.

• David A. Nelson

  • Role: Counsel (likely admitted pro hac vice).
  • Firm: Quinn Emanuel Urquhart & Sullivan, LLP, Chicago, Illinois.
  • Experience: David A. Nelson specializes in patent infringement litigation and is Co-Chair of Quinn Emanuel's National Intellectual Property Litigation Practice. He has led over 150 patent litigation matters, trying over 35 jury cases and a dozen bench trials, involving a wide range of technologies.

• Lauren Martin

  • Role: Counsel (likely admitted pro hac vice). She has also been included in correspondence for related PTAB proceedings.
  • Firm: Quinn Emanuel Urquhart & Sullivan, LLP, Boston, Massachusetts.
  • Experience: Lauren Martin focuses her practice on patent litigation with significant experience in biotechnology, medical devices, diagnostic testing, and the chemical arts. She has experience in all aspects of litigation, including strategy development, discovery, trial, and appeal.

In-house Counsel:

• Mark Snyder
  • Role: Senior Vice President, General Counsel, Chief Compliance Officer, and Corporate Secretary.
  • Firm: Halozyme Therapeutics, Inc. (in-house).
  • Experience: Mark Snyder brings almost thirty years of legal and business experience to Halozyme, having led and played key roles in a broad range of intellectual property, licensing, regulatory, anti-trust, and litigation matters. He previously served as Senior Vice President, Deputy General Counsel, Litigation for Qualcomm Incorporated, where he led litigation strategy for hundreds of cases worldwide, winning key intellectual property and business-related cases.

The defendant in Halozyme Inc. v. Merck Sharp & Dohme LLC, case number 2:25-cv-03179 in the New Jersey District Court, is Merck Sharp & Dohme LLC. The counsel of record representing Merck Sharp & Dohme LLC includes a mix of local counsel and attorneys appearing pro hac vice.

Counsel for Defendant Merck Sharp & Dohme LLC:

• Liza M. Walsh (Lead Counsel, Local Counsel)
  • Firm: Walsh Pizzi O'Reilly Falanga LLP
  • Office Location: Newark, New Jersey
  • Relevant Experience: Liza M. Walsh is a founding and managing partner of Walsh Pizzi O'Reilly Falanga LLP and has extensive experience in complex commercial litigation, including intellectual property disputes. She is recognized for her trial advocacy.
• Lauren Ruth Malakoff (Counsel)
  • Firm: Walsh Pizzi O'Reilly Falanga LLP
  • Office Location: Newark, New Jersey
  • Relevant Experience: Lauren Ruth Malakoff is a partner at Walsh Pizzi O'Reilly Falanga LLP, focusing on complex commercial litigation, including intellectual property and patent disputes.
• Katherine A. Helm, Ph.D. (Of Counsel, Pro Hac Vice)
  • Firm: Dechert LLP (likely, based on typical patent litigation appearances for Merck)
  • Office Location: New York, New York (common Dechert office for patent litigation)
  • Relevant Experience: Katherine Helm is a prominent patent litigator, often representing pharmaceutical companies. She holds a Ph.D., which is common for attorneys specializing in biotech and pharmaceutical patent cases. Her name appears as "Of Counsel" for Merck Sharp & Dohme Corp. in a related document.

Additional attorneys associated with the defendant or noted in related filings, often as "Counsel Not Admitted To Usdc - Nj Bar" (implying pro hac vice admission or future intent to seek it), include:

• Elliot Choi
• Nancy L. Zhang
• Zachariah B. Summers
• Anastasia M. Fernands
• David A. Nelson
• Lauren Martin

These individuals are likely patent litigators from national firms frequently involved in pharmaceutical patent disputes. Due to the high volume of attorneys typically involved in such cases and the nature of "Counsel Not Admitted To Usdc - Nj Bar" entries, specific firm affiliations and detailed experience for each of these additional attorneys would require further individual searches of professional profiles and specific docket entries beyond general appearance lists.