Unified Patents v. Halozyme Inc

Unified Patents has initiated a Post-Grant Review (PGR) against Halozyme Inc. before the Patent Trial and Appeal Board (PTAB), challenging the validity of U.S. Patent No. 12,195,773. Unified Patents is a member-based organization dedicated to improving patent quality and deterring unsubstantiated patent assertions, often by challenging patents held by Non-Practicing Entities (NPEs) or other entities in specific technology sectors. Halozyme Inc. is a publicly traded American biotechnology company based in San Diego, California, specializing in oncology therapies and drug delivery technologies, particularly its proprietary recombinant human hyaluronidase enzyme, rHuPH20, and the Enhanze™ drug delivery platform.

The patent at issue, U.S. Patent No. 12,195,773, generally describes modified PH20 hyaluronidase polypeptides, including those exhibiting increased stability and/or activity, as well as related compositions, formulations, and their uses. While a PGR does not involve an "accused product" in the traditional sense of infringement, Unified Patents is challenging the validity of this patent, which protects aspects of Halozyme's core biotechnology, potentially impacting their drug delivery platform.

The procedural posture of this case, PGR2025-00053, is before the Patent Trial and Appeal Board (PTAB) and has been instituted, meaning the PTAB has determined it is "more likely than not" that at least one challenged claim of the patent is unpatentable. The PTAB provides an administrative forum for challenging patent validity and offers a broader range of invalidity grounds for PGRs—such as novelty, obviousness, written description, enablement, indefiniteness, or ineligible subject matter—compared to inter partes reviews (IPRs), but a PGR must be filed within nine months of the patent's issuance. This case is notable due to Unified Patents' active role in challenging patents within the biotechnology sector, highlighting their strategy to use PTAB proceedings as a mechanism to address patents they deem of poor quality or susceptible to invalidity, thereby impacting the patent landscape for operating companies like Halozyme.

This case, PGR2025-00053, is a Post-Grant Review (PGR) at the Patent Trial and Appeal Board (PTAB), not a district court patent infringement litigation. Therefore, the key legal developments and outcome will focus on the PGR proceedings.

Key Legal Developments and Outcome for PGR2025-00053

• Filing of the PGR Petition: Unified Patents, acting on behalf of Merck Sharp & Dohme LLC (MSD), filed the Post-Grant Review (PGR) petition challenging US Patent 12,195,773. This patent is part of a larger family of patents owned by Halozyme Inc. relating to its MDASE subcutaneous delivery technology. The exact filing date for PGR2025-00053 is not explicitly stated in the search results, but other PGRs against Halozyme by Merck were filed starting in November 2024 and continuing into May and June 2025 (e.g., PGR2025-00050 on May 7, 2025, and PGR2025-00052 on June 27, 2025).

• Parallel District Court Litigation: Halozyme Inc. filed a patent infringement lawsuit against Merck Sharp & Dohme Corp. (Merck) in the U.S. District Court for the District of New Jersey on April 24, 2025 (Case No. 2:25-cv-03179). Halozyme alleged that Merck's subcutaneous formulation of its cancer medicine, Keytruda (SC Keytruda or Keytruda Qlex™), infringes multiple patents from Halozyme's MDASE patent family, including US Patent 12,195,773. The district court litigation was temporarily suspended, awaiting the outcome of the PGRs challenging the validity of Halozyme's patents.

• Institution Decision: The PTAB decided to institute the PGR, meaning it determined that the petition showed a reasonable likelihood that at least one claim of the patent is unpatentable. While the specific institution date for PGR2025-00053 is not directly provided, other related PGRs by Merck against Halozyme patents were instituted in October 2025. PGRs generally have a pre-institution phase of up to six months.

• Final Written Decision (for a related patent): As of May 13, 2026, the PTAB has issued a final written decision in one of the related PGRs filed by Merck (referred to as MSD), specifically against Halozyme's U.S. Patent No. 11,952,600. In that decision, the PTAB found claims 1-4 and 8-21 of U.S. Patent No. 11,952,600 to be unpatentable, primarily citing violations of the written description and enablement requirements. This decision is seen as favorable to Merck and Alteogen (developer of ALT-B4 technology used in Keytruda SC).

• Current Posture of PGR2025-00053: PGR2025-00053 is currently "Pending - Instituted." A final written decision in PGRs is typically expected within twelve months of institution. Given that institution for related PGRs occurred in October 2025, a final written decision for PGR2025-00053 would likely be expected around October 2026. The final written decision for another related patent (US Patent 11,952,600) was issued on May 12, 2026 (local time), which demonstrates that decisions for Halozyme's MDASE patent family are actively being released by the PTAB.

• Impact on District Court Litigation: The final written decision on U.S. Patent No. 11,952,600, invalidating certain claims, is expected to weaken Halozyme's position in its patent infringement lawsuit against Merck in the New Jersey District Court. The district court had temporarily suspended its proceedings, awaiting these PGR outcomes. The invalidation of one of the asserted patents narrows the arsenal of claims available to Halozyme in the infringement litigation.

Unified Patents acts as a deterrence entity that files post-grant challenges against patents it believes are unpatentable or invalid. While Unified Patents has an internal legal team, including Senior Patent Counsel, it is not a law firm and does not have an attorney-client relationship with its members.

Publicly available information, including the Unified Patents portal, lists PGR2025-00053, challenging US patent 12195773, as a case where Merck Sharp & Dohme LLC is the petitioner against Halozyme Inc.. This indicates that the initial case caption provided in the prompt might have been inaccurate regarding the plaintiff. Therefore, to identify the counsel of record, the petitioner for PGR2025-00053 is Merck Sharp & Dohme LLC, not Unified Patents.

As the actual petitioner is Merck Sharp & Dohme LLC, not Unified Patents, identifying counsel for Unified Patents in this specific case is not applicable. The information regarding counsel for Merck Sharp & Dohme LLC in PGR2025-00053 is not available in the provided search results.

The defendant, Halozyme Inc., in PGR2025-00053, is represented by both in-house counsel and several law firms. Based on available PTAB filings related to Halozyme's PGRs, including those specifically mentioning PGR2025-00053, the following counsel are identified:

In-House Counsel for Halozyme Inc.:

• Joshua A. Mack - Executive Director, Patent Litigation Counsel.
  • Firm: Halozyme, Inc., San Diego, CA.
  • Note: Mr. Mack leads all litigation matters for Halozyme. He previously worked in IP litigation at Wilson Sonsini Goodrich & Rosati and as Senior Counsel at Amgen, focusing on therapeutic antibodies.
• Aubrey Haddach - Counsel.
  • Firm: Halozyme, Inc., San Diego, CA.
• Mark H. Snyder - Counsel.
  • Firm: Halozyme, Inc., San Diego, CA.

Outside Counsel for Halozyme Inc.:

• Eldora L. Ellison, Ph.D. - Lead Counsel.
  • Firm: Sterne, Kessler, Goldstein & Fox PLLC, Washington, DC.
  • Note: Dr. Ellison is a highly experienced PTAB attorney, frequently listed as lead counsel for Halozyme in multiple PGR proceedings.
• Louis P. Panzica, Jr. - Back-up Counsel.
  • Firm: Sterne, Kessler, Goldstein & Fox PLLC, Washington, DC.
• Pratibha Khanduri, Ph.D. - Back-up Counsel.
  • Firm: Sterne, Kessler, Goldstein & Fox PLLC, Washington, DC.
• R. Wilson Powers III - Counsel.
  • Firm: Sterne, Kessler, Goldstein & Fox PLLC, Washington, DC.
• Jennifer Meyer Chagnon - Counsel.
  • Firm: Sterne, Kessler, Goldstein & Fox PLLC, Washington, DC.
• David H. Holman - Counsel.
  • Firm: Sterne, Kessler, Goldstein & Fox PLLC, Washington, DC.
• Tyler C. Liu - Counsel.
  • Firm: Sterne, Kessler, Goldstein & Fox PLLC, Washington, DC.
• Lauren N. Martin - Counsel.
  • Firm: Quinn Emanuel Urquhart & Sullivan, LLP, Boston, MA.
  • Note: Quinn Emanuel is also listed in other PTAB cases for Halozyme.
• Zachariah Summers - Back-up Counsel (provisionally recognized PTAB attorney, added January 28, 2026).
  • Firm: Quinn Emanuel Urquhart & Sullivan, LLP, Los Angeles, CA.
• David J. Kappos - Counsel.
  • Firm: Cravath, Swaine & Moore, New York, NY.