Merck Sharp & Dohme LLC v. Halozyme Inc.

This case involves a Post-Grant Review (PGR) proceeding before the Patent Trial and Appeal Board (PTAB), initiated by pharmaceutical giant Merck Sharp & Dohme LLC against biotechnology company Halozyme Inc. Merck, a global biopharmaceutical company known for developing a wide range of medicines, vaccines, and biologic therapies, particularly in oncology with its blockbuster drug Keytruda, is challenging the validity of a patent owned by Halozyme. Halozyme is a biotechnology platform company specializing in drug delivery technologies, with its proprietary ENHANZE® platform utilizing recombinant human hyaluronidase PH20 (rHuPH20) to facilitate the subcutaneous delivery and absorption of co-administered therapeutic agents. The underlying dispute centers on Halozyme's patents related to this subcutaneous drug delivery technology, which Merck's subcutaneous Keytruda (Keytruda Qlex™) product is alleged to utilize.

The specific patent at issue in this PGR is U.S. Patent 12371685, owned by Halozyme Inc. This patent is broadly directed to modified PH20 hyaluronidase polypeptides, including those engineered to exhibit increased stability and/or activity, which are crucial for enhancing the subcutaneous delivery of biologic drugs. The procedural posture of the case, PGR2025-00087, is before the PTAB, having been filed on November 10, 2025. As of May 15, 2026, the status of this particular petition is "Not Instituted - Procedural," meaning the PTAB has not yet decided to initiate a formal review trial. The PTAB venue is significant because PGRs allow for a broader range of invalidity arguments, including lack of written description and enablement, compared to Inter Partes Reviews (IPRs), making them a powerful tool for challenging recently issued patents within nine months of their grant.

This case is part of a larger, notable patent battle in the biopharmaceutical industry, as Merck has filed numerous PGR petitions (at least 14) against Halozyme's patents related to modified PH20 hyaluronidase polypeptides. This strategic move by Merck is aimed at clearing the intellectual property landscape for its subcutaneous version of Keytruda, Keytruda Qlex™, which was FDA-approved in September 2025. The ability to administer oncology blockbusters like Keytruda subcutaneously offers significant benefits in terms of patient convenience and potential cost reductions, underscoring the high stakes of this dispute. The PTAB has already instituted trials on many of Merck's related PGR petitions, and one of Halozyme's MDASE patents has been ruled invalid, potentially strengthening Merck's position in this ongoing legal conflict, which also includes parallel district court litigation in New Jersey where Halozyme alleges infringement by Merck.

This case, PGR2025-00087, is a post-grant review (PGR) proceeding initiated by Merck Sharp & Dohme LLC (Petitioner) against Halozyme Inc. (Patent Owner) challenging U.S. Patent 12371685. The proceeding was terminated at an early stage.

Key Legal Developments and Outcome for PGR2025-00087:

• Filing of Petition (2025-11-10): Merck Sharp & Dohme LLC filed a petition for Post-Grant Review (PGR) against Halozyme Inc.'s U.S. Patent 12371685 with the Patent Trial and Appeal Board (PTAB).
• Non-Institution and Termination (2026-05-15): The PTAB issued a decision not to institute the PGR, citing procedural grounds. The proceeding was simultaneously terminated on this date. This means the PTAB did not review the merits of Merck's challenge to the patent's validity.

Parallel Litigation and PTAB Proceedings:

The PGR2025-00087 proceeding is part of broader litigation between Merck and Halozyme concerning Halozyme's technology for subcutaneous drug delivery, specifically related to Merck's subcutaneous formulation of Keytruda (SC Keytruda).

• District Court Patent Infringement Lawsuit (2025-04-24): Halozyme Inc. filed a patent infringement lawsuit against Merck Sharp & Dohme Corp. (now Merck Sharp & Dohme LLC) in the U.S. District Court for the District of New Jersey (Case No. 2:25-cv-03179). Halozyme alleges that Merck's SC Keytruda infringes 15 of its patents covering modified human hyaluronidase PH20 enzymes, including allegations of willful infringement. This district court case is co-pending with the PTAB challenges.
• Other Parallel PTAB Post-Grant Reviews: Merck has filed multiple other PGR petitions against Halozyme's related patents. Several of these PGRs were instituted by the PTAB:
  • PGR2025-00050: Filed May 7, 2025, against US Patent 12077791B2, and instituted on November 19, 2025.
  • PGR2025-00046: Instituted on October 10, 2025, against Halozyme's U.S. Patent No. 12,091,692.
  • PGR2025-00052: Instituted on October 16, 2025, against Halozyme's U.S. Patent No. 12,264,345.
  • PGR2025-00024: Instituted on October 16, 2025, against Halozyme's U.S. Patent No. 12,060,590.
  • PGR2025-00030: Instituted on October 16, 2025, against Halozyme's U.S. Patent No. 12,054,758.
    Merck has filed PGRs against at least seven of Halozyme's patents related to the MDASE technology.
• German Preliminary Injunction (2025-12-08): Halozyme secured a preliminary injunction against Merck Sharp & Dohme in Germany, preventing the launch of Keytruda SC in Germany based on the alleged infringement of European patent EP 2 797 622, part of Halozyme's MDAS patent family. This German action is noted as part of Halozyme's global enforcement strategy.

Current Posture:

As of the current date, PGR2025-00087 is terminated due to the PTAB's decision not to institute the review. The parallel district court litigation in New Jersey and other PTAB PGR proceedings on different patents remain active.

Merck Sharp & Dohme LLC is represented by the following counsel in PGR2025-00087:

• Raymond N. Nimrod

  • Role: Attorney for Petitioner.
  • Firm: Quinn Emanuel Urquhart & Sullivan LLP, New York, NY.
  • Experience: Raymond N. Nimrod is an experienced patent litigator. He is listed as an attorney for Merck Sharp & Dohme LLC in this proceeding.

• Matthew A. Traupman

  • Role: Attorney for Petitioner.
  • Firm: Quinn Emanuel Urquhart & Sullivan LLP, New York, NY.
  • Experience: Matthew A. Traupman is also listed as an attorney for Merck Sharp & Dohme LLC in this proceeding.

While other law firms, such as Sidley Austin LLP and Dechert LLP, and in-house counsel Mark Stewart, have been identified as representing Merck Sharp & Dohme LLC in other related post-grant review proceedings against Halozyme Inc. (e.g., PGR2025-00009 and PGR2025-00024), the directly cited "Petitioner's Updated Mandatory Notices" for PGR2025-00087 explicitly names Raymond N. Nimrod and Matthew A. Traupman of Quinn Emanuel Urquhart & Sullivan LLP.

Halozyme Inc., the defendant in PGR2025-00087, is represented by counsel from Sterne, Kessler, Goldstein & Fox PLLC, Cravath, Swaine & Moore LLP, and in-house counsel from Halozyme, Inc..

The counsel of record for Halozyme Inc. includes:

• Eldora L. Ellison, Ph.D.

  • Role: Lead Counsel
  • Firm: Sterne, Kessler, Goldstein & Fox PLLC, Washington, DC.
  • Experience: Dr. Ellison is a Director and co-chairs the firm's Post-Grant proceedings practice, specializing in biotechnology and pharmaceutical patent litigation, particularly before the PTAB. She has a strong focus on inter partes reviews (IPRs) and post-grant reviews (PGRs) in the life sciences sector.

• R. Wilson Powers III, Ph.D.

  • Role: Back-up Counsel
  • Firm: Sterne, Kessler, Goldstein & Fox PLLC, Washington, DC.
  • Experience: Dr. Powers is a Director at Sterne Kessler, focusing on patent litigation and post-grant proceedings, particularly in biotechnology and pharmaceutical fields. He has represented clients in numerous IPRs and PGRs before the PTAB.

• Jennifer Meyer Chagnon

  • Role: Back-up Counsel
  • Firm: Sterne, Kessler, Goldstein & Fox PLLC, Washington, DC.
  • Experience: Ms. Chagnon is a Director at Sterne Kessler, specializing in patent litigation and post-grant proceedings, with experience in the chemical and biotechnology industries.

• David H. Holman

  • Role: Back-up Counsel
  • Firm: Sterne, Kessler, Goldstein & Fox PLLC, Washington, DC.
  • Experience: Mr. Holman is a Director at Sterne Kessler, focusing on patent litigation, particularly in biotechnology, pharmaceuticals, and diagnostics. He handles IPRs and PGRs, and has experience with district court litigation.

• Tyler C. Liu

  • Role: Back-up Counsel
  • Firm: Sterne, Kessler, Goldstein & Fox PLLC, Washington, DC.
  • Experience: Mr. Liu is an Associate at Sterne Kessler, focusing on intellectual property litigation, including post-grant proceedings before the PTAB, in the biotechnology and pharmaceutical sectors.

• Louis P. Panzica, Jr.

  • Role: Back-up Counsel
  • Firm: Sterne, Kessler, Goldstein & Fox PLLC, Washington, DC.
  • Experience: Mr. Panzica is an Associate at Sterne Kessler, with a practice focused on patent litigation and post-grant proceedings, particularly in the biotechnology and pharmaceutical industries.

• David J. Kappos

  • Role: Back-up Counsel
  • Firm: Cravath, Swaine & Moore LLP, New York, NY.
  • Experience: Mr. Kappos is a Partner at Cravath, Swaine & Moore and a former Under Secretary of Commerce for Intellectual Property and Director of the USPTO. He is highly experienced in all aspects of intellectual property law and policy.

• Aubrey A. Haddach

  • Role: In-house Counsel
  • Firm: Halozyme, Inc., San Diego, CA.
  • Experience: Ms. Haddach serves as in-house counsel for Halozyme, Inc., indicating her role in managing the company's intellectual property and legal affairs directly.