Untitled case

Halozyme, Inc. initiated a patent infringement lawsuit against Merck Sharp & Dohme Corp. (now Merck Sharp and Dohme LLC) in the District of New Jersey, alleging infringement of US Patent 11952600 and several related patents. Halozyme, an operating biopharmaceutical company, specializes in drug delivery technology, particularly through its proprietary ENHANZE® platform which utilizes modified PH20 hyaluronidase. Merck, a global pharmaceutical operating company, is accused of infringing these patents with its development and commercialization of "SC KEYTRUDA," a subcutaneous version of its blockbuster cancer immunotherapy drug, KEYTRUDA. The asserted patents, including US Patent 11952600, broadly cover "PH20 polypeptide variants, formulations and uses thereof," which are modified PH20 hyaluronidase polypeptides designed to exhibit increased stability and/or activity, facilitating the rapid subcutaneous administration of therapeutic drugs.

The case, assigned civil action number 2:25-cv-03179, was filed on April 24, 2025, in the United States District Court for the District of New Jersey. While Magistrate Judge Jose R. Almonte has presided over various discovery and confidentiality matters, the complaint indicates District Judge Esther Salas as the assigned district judge. The District of New Jersey is a prominent venue for pharmaceutical patent litigation, especially in cases related to Abbreviated New Drug Applications (ANDA) and Biologics Price Competition and Innovation Act (BPCIA). The district has recently become a more favored forum for patentees over the District of Delaware, partly due to its full judicial bench, specialized local rules, and a perceived increase in patentee-favorable outcomes.

This litigation is particularly notable due to the high commercial stakes involved. Merck's existing KEYTRUDA patent protection is set to expire in 2028, and the development of SC KEYTRUDA is seen as a strategic move to preserve market share. Halozyme alleges that Merck's subcutaneous formulation relies on its patented MDASE™ technology. The dispute has also extended to the Patent Trial and Appeal Board (PTAB), where Merck Sharp & Dohme LLC has filed multiple Post-Grant Review (PGR) petitions challenging the validity of several of Halozyme's asserted patents, including related patents US 12,049,652 and US 12,104,185. The PTAB has granted institution for some of these PGRs, signaling a multi-front legal battle over critical biopharmaceutical technology.

This case, Halozyme, Inc. v. Merck Sharp & Dohme Corp., Case No. 2:25-cv-03179, filed in the New Jersey District Court, is an active patent infringement litigation asserting US Patent 11,952,600, among others. The litigation has seen significant developments, particularly in parallel Post-Grant Review (PGR) proceedings at the Patent Trial and Appeal Board (PTAB).

Here's a chronological summary of the key legal developments and current posture:

1. Filing & Initial Pleadings

• Complaint Filed (2025-04-24): Halozyme, Inc. filed a patent infringement complaint against Merck Sharp & Dohme Corp. in the U.S. District Court for the District of New Jersey. The complaint asserted infringement of US Patent 11,952,600, along with numerous other related patents including 10,865,400, 11,041,149, 11,066,656, 12,018,298, 12,037,618, 12,049,652, 12,054,758, 12,077,791, 12,091,692, 12,104,185, 12,110,520, 12,152,262, 12,195,773, and 12,264,345, all belonging to a single patent family related to modified PH20 polypeptides for subcutaneous drug delivery.
• Substitution of Defendant (2025-05-15): The parties stipulated, and the Court ordered, the substitution of "Merck Sharp & Dohme Corp." with "Merck Sharp and Dohme LLC," as the former was no longer an existing corporate entity. Merck Sharp and Dohme LLC was granted 60 days from this date to answer or otherwise respond to the complaint.
• (Information regarding the filing of Merck's Answer and any Counterclaims is not available in the provided search results.)

2. Pre-trial Motions of Substance

• Motion for Issuance of Letters Rogatory (2026-01-07): The Court granted a motion for the issuance of Letters Rogatory, indicating active international discovery efforts.
• Discovery Confidentiality Order Disputes (2026-01-07 - 2026-02-18): The Court noted ongoing disputes between the parties regarding a Discovery Confidentiality Order (DCO) in joint letters filed in January 2026. The parties were ordered to meet and confer, and deadlines for submitting a proposed DCO or a joint letter outlining disputes were extended multiple times, ultimately until February 18, 2026.
• Status Conferences (2026-01-28): An in-person status conference was scheduled for January 28, 2026, to address unresolved disputes.
• Status Update on PTAB Decisions (2026-02-05): The Court ordered the parties to submit a joint letter by June 9, 2026, to advise on the status of the matter following the Patent Trial and Appeal Board's (PTAB) Final Written Decision.

3. Claim Construction (Markman) Outcomes

• (No specific Markman hearing or claim construction order has been identified in the district court docket for this case based on the provided search results. However, claim construction was part of the PTAB's analysis in the parallel PGR proceedings.)

4. Discovery Milestones with Strategic Significance

• The granting of Letters Rogatory and the ongoing discussions and orders concerning a Discovery Confidentiality Order indicate that discovery is actively proceeding in the case.

5. Trial Events, Verdict, and Post-Trial Motions

• (The case is still in the pre-trial phase, and no information regarding trial events, verdict, or post-trial motions is available.)

6. Final Disposition or Present Posture

• Active Litigation with PTAB Influence (Present): The case remains active. The district court explicitly signaled that the outcome of the parallel PTAB proceedings, particularly the Final Written Decisions, would impact the status of the litigation, requesting a joint status letter by June 9, 2026.

7. Parallel PTAB IPR/PGR Proceedings

Merck Sharp & Dohme LLC has challenged several of Halozyme's asserted patents, including 11,952,600, through Post-Grant Review (PGR) proceedings at the PTAB.

• PGR2025-00003 (U.S. Patent 11,952,600):
  • Petition Filed: Merck Sharp & Dohme LLC filed a PGR petition against U.S. Patent 11,952,600.
  • Claims Disclaimed: Halozyme disclaimed claims 5-7, leaving claims 1-4 and 8-21 at issue.
  • Institution Granted (2025-06-02): The PTAB instituted a trial on claims 1-4 and 8-21, determining that Merck was more likely than not to prevail on challenges under 35 U.S.C. § 112 for lack of written description and enablement.
  • Final Written Decision (2026-05-12): The PTAB issued a Final Written Decision, finding all challenged claims (1-4 and 8-21) of US Patent 11,952,600 unpatentable for failing to comply with the written description and enablement requirements. The Board, however, found the claims not unpatentable as obvious.
• Other Related PGR Proceedings: Merck has filed numerous other PGR petitions against patents asserted in the district court litigation, including:
  • PGR2025-00006 (U.S. Patent 12,152,262): A Final Written Decision was issued on May 18, 2026, finding all challenged claims unpatentable for lack of written description and enablement.
  • PGR2025-00087 (U.S. Patent 12,371,685): The Director of the USPTO denied institution of this PGR on May 15, 2026, based on discretionary and non-merits considerations, without reaching the merits of the invalidity grounds.
  • Other PGRs were instituted, including against patents 12,018,298 (PGR2025-00004), 12,123,035 (PGR2025-00009), 12,110,520 (PGR2025-00017), 12,060,590 (PGR2025-00024), 12,054,758 (PGR2025-00030), 12,049,652 (PGR2025-00033), 12,104,185 (PGR2025-00039), 12,037,618 (PGR2025-00042), 12,091,692 (PGR2025-00046), 12,077,791 (PGR2025-00050), 12,264,345 (PGR2025-00052), and 12,195,773 (PGR2025-00053).
• Effect on Litigation: The PTAB's finding that claims of US Patent 11,952,600 and other related patents are unpatentable is a significant development that will likely have a substantial impact on the ongoing district court infringement case. The court's order for a status update following the FWDs directly reflects this influence.

Halozyme, Inc. is represented by the following counsel in Halozyme, Inc. v. Merck Sharp & Dohme Corp. (2:25-cv-03179) in the New Jersey District Court:

• Liza M. Walsh

  • Role: Likely local counsel.
  • Firm: Walsh Pizzi O'Reilly Falanga LLP, Newark, NJ.
  • Experience Note: As a founding partner, Ms. Walsh has extensive experience in complex commercial litigation, including in federal courts.

• Lauren Ruth Malakoff

  • Role: Likely local counsel.
  • Firm: Walsh Pizzi O'Reilly Falanga LLP, Newark, NJ.
  • Experience Note: Ms. Malakoff is a partner at the firm and focuses on complex commercial litigation.

The following attorneys are also listed as counsel but are noted as "Counsel Not Admitted To Usdc - Nj Bar," indicating they are likely out-of-state counsel who will seek admission pro hac vice, with Walsh Pizzi O'Reilly Falanga LLP serving as local counsel:

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

To provide a one-line note on relevant patent litigation experience or notable past cases for these attorneys, further investigation into their specific practices and firm affiliations (which are not immediately clear from the PacerMonitor snippet for those not admitted to the NJ Bar) would be required. The initial search indicates Halozyme, Inc. as the plaintiff and the case involves multiple patents related to PH20 polypeptide variants.

In the patent infringement case Halozyme Inc v. Merck Sharp & Dohme Corp, case number 2:25-cv-03179, filed in the New Jersey District Court, the defendant, Merck Sharp & Dohme Corp. (now known as Merck Sharp and Dohme LLC), is represented by the following counsel:

• Liza M. Walsh

  • Role: Likely local counsel.
  • Firm: Walsh Pizzi O'Reilly Falanga LLP.
  • Office Location: Newark, New Jersey.
  • Experience Note: Liza M. Walsh is a co-founding partner of Walsh Pizzi O'Reilly Falanga LLP and has extensive experience in complex litigation, including pharmaceutical and patent litigation, often serving as local counsel in New Jersey. She is a former federal prosecutor and has served as lead counsel in numerous high-stakes cases.

• Lauren Ruth Malakoff

  • Role: Likely local counsel.
  • Firm: Walsh Pizzi O'Reilly Falanga LLP.
  • Office Location: Newark, New Jersey.
  • Experience Note: Lauren Ruth Malakoff is a partner at Walsh Pizzi O'Reilly Falanga LLP, focusing on complex commercial litigation, including intellectual property disputes and pharmaceutical litigation.

Other attorneys, including Elliot Choi, Nancy L. Zhang, Zachariah B. Summers, Anastasia M. Fernands, and David A. Nelson, are also listed in relation to the defendant, but are noted as "Counsel Not Admitted To Usdc - Nj Bar". This suggests they are likely lead or national counsel from firms outside New Jersey, working in conjunction with local counsel. Further details on their firms and specific roles are not explicitly stated in the provided search results.