Unified Patents LLC v. Halozyme Inc

This case, Unified Patents LLC v. Halozyme Inc (PGR2025-00003), involves a post-grant review (PGR) proceeding before the Patent Trial and Appeal Board (PTAB) concerning U.S. Patent No. 11,952,600. The petitioner, Unified Patents LLC, is a member-based organization focused on deterring frivolous patent litigation by non-practicing entities (NPEs) and improving patent quality through challenges like IPRs and PGRs, acting independently of its members. The patent owner, Halozyme Inc., is an American biotechnology company that develops oncology therapies and proprietary drug delivery technologies. Halozyme is particularly known for its ENHANZE® technology, which utilizes recombinant human hyaluronidase (rHuPH20) to enable the subcutaneous administration of intravenously delivered drugs, enhancing patient convenience and absorption. The PGR did not involve an "accused product" in the traditional infringement sense, but rather challenged the fundamental validity of Halozyme's patent, which underpins aspects of its core drug delivery platform.

The sole patent at issue is U.S. Patent No. 11,952,600, titled "PH20 polypeptide variants, formulations and uses thereof." This patent broadly covers modified PH20 hyaluronidase polypeptides designed to exhibit increased stability and/or activity, along with compositions, formulations, and their uses. The procedural posture of this case is a Post-Grant Review (PGR) filed at the Patent Trial and Appeal Board (PTAB), a specialized administrative court within the U.S. Patent and Trademark Office (USPTO). The petition for PGR2025-00003 was filed within nine months of the patent's issuance, a statutory requirement for PGR eligibility. The case has reached a Final Written Decision by the PTAB.

This case is notable due to its significant market context and the industry players involved. Halozyme's ENHANZE® technology is a critical platform for the pharmaceutical industry, enabling the conversion of blockbuster intravenous drugs to more patient-friendly subcutaneous formulations, such as Merck Sharp & Dohme's (MSD) Keytruda SC. The validity of patents like US 11952600 is crucial to Halozyme's business model, which relies heavily on licensing agreements with major pharmaceutical companies. The PGR is part of a broader series of challenges against Halozyme's patents, and the PTAB's Final Written Decision in PGR2025-00003, issued on May 12, 2026, found the challenged claims of the '600 patent to be unpatentable, representing a significant outcome for the competitive landscape of subcutaneous drug delivery. This PTAB decision has substantial implications, particularly as related district court infringement litigation involving these patents has been temporarily stayed pending the PTAB's validity determinations.

The post-grant review (PGR) case of Unified Patents LLC v. Halozyme Inc, PGR2025-00003, concerning U.S. Patent 11,952,600, has reached a Final Written Decision. Notably, the petitioner for PGR2025-00003 was Merck Sharp & Dohme LLC, not Unified Patents LLC, although Unified Patents LLC is active in other PTAB proceedings.

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

• Patent Issuance (2024-04-09): U.S. Patent No. 11,952,600, titled "PH20 polypeptide variants, formulations and uses thereof," was issued to Halozyme Inc.
• PGR Petition Filing (2024-11-12): Merck Sharp & Dohme LLC (Merck) filed a petition for post-grant review (PGR2025-00003) challenging the patentability of U.S. Patent 11,952,600. The petition was filed within the statutory nine-month window for PGR eligibility. Merck challenged the patent on grounds including lack of written description, enablement, and obviousness.
• Institution Decision (2025-06-02): The Patent Trial and Appeal Board (PTAB) instituted the post-grant review. Halozyme Inc. had requested discretionary denial of institution, which the Director of the USPTO denied on June 12, 2025. The Director reasoned that a Final Written Decision was projected for July 14, 2026, which would likely precede a district court trial by several years, making discretionary denial inappropriate.
• Claim Construction: In its institution decision, the Board made a preliminary claim construction, finding that the claims, while not expressly reciting a function, required hyaluronidase activity.
• Discovery Milestone (Real Party-in-Interest Dispute) (2026-02-09): Halozyme Inc. filed a motion for additional discovery, arguing that Merck & Co., Inc., the corporate parent of Merck Sharp & Dohme LLC, should also be named as a real party-in-interest. The PTAB ordered Merck to produce certain unredacted documents for in camera review by February 11, 2026, to assess the RPI issue. Halozyme also sought leave to file a motion to terminate the petition based on this RPI dispute.
• Final Written Decision (2026-05-12): The PTAB issued its Final Written Decision in PGR2025-00003, finding all challenged claims (claims 1-4 and 8-21) of U.S. Patent 11,952,600 unpatentable. The Board concluded that Merck had demonstrated by a preponderance of the evidence that these claims were unpatentable due to lack of written description and enablement under 35 U.S.C. § 112. The Board found that the claims defined an "enormous genera" of modified PH20 polypeptides, but the patent specification failed to provide adequate written description or enablement for the full scope of these claims. However, the claims were found not to be unpatentable as obvious.
• Parallel PTAB and District Court Proceedings:
  • Merck filed numerous other PGRs against Halozyme's PH20 hyaluronidase patent portfolio, including PGR2025-00004 (US 12,018,298), PGR2025-00006 (US 12,152,262), and several others.
  • In a related case, PGR2025-00006, the PTAB also issued a Final Written Decision on May 18, 2026, finding claims 1-4 and 8-13 of U.S. Patent 12,152,262 unpatentable for lack of written description and enablement.
  • Another related case, PGR2025-00004, saw a Final Written Decision on June 8, 2026, invalidating all claims of U.S. Patent 12,018,298.
  • Conversely, institution was denied for PGR2025-00087 (U.S. Patent 12,371,685) on May 15, 2026, based on discretionary and non-merits considerations.
  • Halozyme has a patent infringement lawsuit filed in the District of New Jersey against Merck Sharp & Dohme Corp. (e.g., case 2:25-cv-03179), alleging infringement of its patents, including the '600 patent. This district court litigation was temporarily suspended by the court, awaiting the PTAB's validity determinations.
• Appeal: As of today's date (2026-06-16), the search results do not indicate that the Final Written Decision for PGR2025-00003 has been appealed to the Federal Circuit. However, an appeal period would typically be active following the May 12, 2026, decision.

It appears there was an error in the initial case metadata provided. The plaintiff (Petitioner) in PGR2025-00003, Unified Patents LLC v. Halozyme Inc, is actually Merck Sharp & Dohme LLC, not Unified Patents LLC. The case caption for PGR2025-00003 is "Merck Sharp & Dohme LLC v. Halozyme Inc".

Based on the available information, the following attorneys represent Merck Sharp & Dohme LLC (Petitioner) in PGR2025-00003:

• Sue Wang

  • Role: Counsel (Pro Hac Vice)
  • Firm and Office Location: Not explicitly stated in the provided snippets, but likely associated with one of the firms listed for Merck Sharp & Dohme LLC.
  • Note: Granted pro hac vice admission in this and related proceedings, indicating sufficient qualifications and litigation experience.

• Brian M. Goldberg

  • Role: Counsel (Pro Hac Vice)
  • Firm and Office Location: Not explicitly stated in the provided snippets, but likely associated with one of the firms listed for Merck Sharp & Dohme LLC.
  • Note: Granted pro hac vice admission in this and related proceedings, indicating sufficient qualifications and litigation experience.

Other firms and attorneys mentioned in connection with Merck Sharp & Dohme LLC in related PTAB cases or as representing the Petitioner in PGR2025-00003 include:

• Sidley Austin LLP
  • Jeffrey Kushan
  • Lauren E. Peterson
• Dechert LLP
  • Blaine M. Hackman
• Merck Sharp & Dohme (in-house)
  • Mark J. Stewart

While these individuals and firms are listed as attorneys for Merck Sharp & Dohme LLC in relation to PGR2025-00003, the specific roles (e.g., lead counsel, of counsel) for all of them are not detailed in the provided search results beyond the pro hac vice admissions for Ms. Wang and Mr. Goldberg. Merck Sharp & Dohme also has in-house counsel, such as Mark J. Stewart.

It appears there is a discrepancy in the plaintiff's name for PGR2025-00003. While the case metadata in the prompt identifies "Unified Patents LLC" as the plaintiff, docket information and other search results consistently name "Merck Sharp & Dohme LLC" as the petitioner (plaintiff) in PGR2025-00003 against Halozyme Inc. concerning US Patent 11952600. This analysis will proceed based on the public record showing Merck Sharp & Dohme LLC as the petitioner, and identify counsel representing the patent owner, Halozyme Inc.

The counsel of record representing Halozyme Inc. (Patent Owner/Defendant) in PGR2025-00003 includes attorneys from Sterne Kessler Goldstein & Fox P.L.L.C., in-house counsel from Halozyme Inc., and potentially others.

Here are the identified attorneys:

Sterne Kessler Goldstein & Fox P.L.L.C. (Washington, D.C.)

• Ralph W. Powers, III
  • Role: Likely lead or significant counsel.
  • Firm & Office: Sterne Kessler Goldstein & Fox P.L.L.C., Washington, D.C.
  • Experience Note: Powers is listed as counsel for Halozyme in multiple related PGR proceedings.
• Eldora L. Ellison
  • Role: Likely lead or significant counsel.
  • Firm & Office: Sterne Kessler Goldstein & Fox P.L.L.C., Washington, D.C.
  • Experience Note: Ellison is a prominent attorney at Sterne Kessler with extensive experience in PTAB proceedings, particularly post-grant reviews and inter partes reviews. She is listed as counsel for Halozyme in multiple related PGR proceedings.
• David H. Holman
  • Role: Counsel
  • Firm & Office: Sterne Kessler Goldstein & Fox P.L.L.C., Washington, D.C.
  • Experience Note: Holman is listed as counsel for Halozyme in PGR2025-00003.
• Jennifer Meyer Chagnon
  • Role: Counsel
  • Firm & Office: Sterne Kessler Goldstein & Fox P.L.L.C., Washington, D.C.
  • Experience Note: Chagnon is listed as counsel for Halozyme in PGR2025-00003.
• Tyler C. Liu
  • Role: Counsel
  • Firm & Office: Sterne Kessler Goldstein & Fox P.L.L.C., Washington, D.C.
  • Experience Note: Liu is listed as counsel for Halozyme in PGR2025-00003.
• Louis P. Panzica, Jr.
  • Role: Counsel
  • Firm & Office: Sterne Kessler Goldstein & Fox P.L.L.C., Washington, D.C.
  • Experience Note: Panzica is listed as counsel for Halozyme in PGR2025-00003.

Halozyme Inc. (In-house Counsel)

• Aubrey Haddach
  • Role: In-house Counsel
  • Firm & Office: Halozyme Inc.
  • Experience Note: Haddach is listed as in-house counsel for Halozyme in PGR2025-00003.
• Joshua A. Mack
  • Role: In-house Counsel
  • Firm & Office: Halozyme Inc.
  • Experience Note: Mack is listed as in-house counsel for Halozyme in PGR2025-00003.
• Mark H. Snyder
  • Role: In-house Counsel
  • Firm & Office: Halozyme Inc.
  • Experience Note: Snyder is listed as in-house counsel for Halozyme in PGR2025-00003.

Other Counsel Mentioned

• David J. Kappos
  • Role: Counsel (appears to be "of counsel" or consulting)
  • Firm & Office: Cravath, Swaine & Moore LLP.
  • Experience Note: Former Under Secretary of Commerce for Intellectual Property and Director of the USPTO. He is listed in the service list for PGR2025-00003.
• Lauren N. Martin
  • Role: Counsel
  • Firm & Office: Quinn Emanuel Urquhart & Sullivan, LLP.
  • Experience Note: Martin is listed in the service list for PGR2025-00003. Quinn Emanuel is also listed in PTAB cases for Halozyme Inc. as Patent Owner's Counsel.