Merck Sharp & Dohme LLC v. Halozyme, Inc. et al.

I'll research this case before drafting. Note upfront: the metadata describes a PTAB post-grant review, not a district court infringement suit — I'll verify the parallel litigation landscape too.

Good material. Now let me verify the parallel D.N.J. case, the judge, and the latest PTAB status (given today is Nov 2026, a final written decision may have issued).

Important: a final written decision appears to have issued October 15, 2026. Let me confirm in English sources and check the D.N.J. case status.

Case Overview & Background

A threshold clarification on the caption. Despite the "infringement litigation" framing, PGR2025-00030 is not an infringement suit — it is a post-grant review at the USPTO Patent Trial and Appeal Board, captioned Merck Sharp & Dohme LLC v. Halozyme, Inc., in which the accused infringer is the petitioner. The corresponding infringement action is the mirror-image case Halozyme, Inc. v. Merck Sharp & Dohme Corp., No. 2:25-cv-03179 (D.N.J.), filed April 24, 2025 — i.e., Halozyme sued Merck, and Merck counter-punched at the PTAB. Both are part of one global dispute. (Institution Decision, PGR2025-00030, Paper __, at § III (P.T.A.B. Oct. 16, 2025); Venable BiologicsHQ copy.)

The parties. Halozyme, Inc. and Halozyme Therapeutics, Inc. (San Diego) are operating companies, not an NPE/PAE — a drug-delivery biotech whose ENHANZE® platform (recombinant human hyaluronidase, rHuPH20) enables subcutaneous administration of large-molecule biologics, and whose ~6,000-mutant PH20 research program produced the "MDASE™" patent family at issue. Halozyme sells Hylenex® and licenses ENHANZE to Roche (Ocrevus), J&J (Darzalex), BMS (Opdivo Qvantig) and argenx; Merck's briefs put its ENHANZE-derived revenue at "more than a billion dollars every year" (Petitioner's Sur-reply/Opposition to Discretionary Denial Br., Sept. 12, 2025). Merck Sharp & Dohme LLC is an operating subsidiary of Merck & Co., Inc. (Rahway, NJ) and the entity that markets KEYTRUDA® (pembrolizumab). Note the identity fight this created: Halozyme moved to terminate the PGR family in early 2026 on the theory that Merck & Co., Inc. is an unnamed real party-in-interest, attempting to trigger § 325(e) estoppel — a motion Merck opposed with corporate-separateness evidence (see, e.g., PGR2025-00009, Paper 89; Grez Decl., EX1224-2 (Mar. 12, 2026)). This is a contested, unresolved-in-part procedural front, and I did not locate a public, fully sourced disposition of the motion.

The accused product and technology. The accused product is KEYTRUDA Qlex™ (pembrolizumab + berahyaluronidase alfa-pmph), Merck's subcutaneous formulation of its ~$30B/year cancer franchise, FDA-approved in September 2025. Its enabling enzyme, berahyaluronidase alfa ("BHA"), is ALT-B4, licensed from Korea's Alteogen — a multiply-modified PH20 with 30+ changes from wild-type Hylenex, which Merck says was "developed independently" of Halozyme. Halozyme's D.N.J. complaint alleges BHA "includes the amino acid modifications first identified by Halozyme's inventors and covered by the asserted patents," and asserts fifteen patents from a single family (US 10,865,400; 11,041,149; 11,066,656; 11,952,600; 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; 12,264,345) (D.N.J. Compl. ¶¶ 1–6). US 12,054,758 B2 ("Modified Human Hyaluronidase (PH20) Polypeptides," issued Aug. 6, 2024) claims structurally altered PH20 polypeptides that (i) contain at least one specified substitution at residue 317, (ii) may bear numerous other modifications, and (iii) must retain enzymatic activity — a genus Merck's petition pegged at 10⁵⁹ or more distinct species supported only by singly-modified working examples. Merck's two grounds were (1) § 112(a) written description and enablement across all claims 1–40, and (2) obviousness of claims 1–2, 5–6, 8, 10–40 over Halozyme's own US 7,767,429 patent in view of Chao (2007 Biochemistry), targeting the single L317Q mutant (Petition, Feb. 4, 2025; see Petition summary).

Procedural posture and venue significance. Merck filed 14 PGRs against Halozyme's PH20 portfolio between November 2024 and February 2025 (17 challenges total per Alteogen-adjacent reporting), all within PGR's nine-month post-issuance window. PGR eligibility for the '758 patent hinged on at least one claim lacking § 112(a) support in the sole pre-March 16, 2013 application (the '731 application) — a threshold Halozyme contested and the Board accepted. The Board instituted on October 16, 2025, on claims 1, 2, and 6–30 only, after Halozyme disclaimed claims 3–5 and 31–40; the panel is APJs Susan L. C. Mitchell, Cynthia M. Hardman, and Michael A. Valek, with oral argument reset to July 23, 2026 (Amended Scheduling Order, PGR2025-00024/-00030/-00052). The Board construed "modified PH20 polypeptide" broadly (encompassing active molecules), rejecting Halozyme's structure-only reading, and instituted on § 112 while declining the obviousness ground. Because the PGR statute permits full § 112 challenges — unavailable in IPR — the PTAB, not the district court, became the primary venue for the merits. That mattered: Halozyme's chosen forum is D.N.J. (Judge Esther Salas, per the "-ES" docket suffix — I could not independently confirm the assignment via PACER, so treat as provisional), where Merck's own Fintiv briefing projected a trial date around May 2030, four years after the PGR rulings.

Why the case is notable. Several reasons. First, it is the leading post-Amgen v. Sanofi (598 U.S. 594 (2023)) test of genus-claim enablement and written description in the biologics/drug-delivery space, applied at scale to a patent family. Second, it exemplifies a "reverse" PGR strategy: an accused infringer using PGR's § 112 tools offensively, pre-launch, to clear a patent thicket rather than waiting to defend in district court — and doing so before the patentee sued. Third, it produced a sustained discretionary-denial and Director-review battleground: the Director refused Halozyme's § 325(d) and Fintiv-based denial requests in August–September 2025 and remanded to the panels, repeatedly reasoning that a PTAB decision would land years before any D.N.J. trial. Fourth, the outcomes now diverge sharply by jurisdiction: on October 15, 2026 the Board issued a final written decision in both PGR2025-00030 and PGR2025-00024 ('590 patent) holding every instituted claim unpatentable on written description and enablement — 27 claims of the '758 patent and 26 of the '590 (reported by TheBioNews, Oct. 16, 2026 and an Akros/KBIOTT event note). I could not locate the FWD itself or English-language legal press coverage to confirm the precise claim count and ground, so that figure should be verified against the PTAB docket. Meanwhile Europe went the other way: a German preliminary injunction (Dec. 2025) and a Dutch decision of October 7, 2026 upholding Halozyme's EP 2,797,622 and barring Keytruda SC in eight countries (Belgium, Denmark, France, Ireland, Italy, Netherlands, Sweden, Switzerland), with Halozyme consenting to UK revocation in May 2026 (BioSpace; ECLI:NL:RBDHA:2026:29643). Fifth, the market stakes are enormous: Keytruda is the world's top-selling drug at roughly $30B annually with loss of exclusivity looming in 2028, and the subcutaneous formulation — $463M in Q2 2026 versus $7.9B for IV — is Merck's principal lifecycle-extension play because it sits outside the biosimilar path; Halozyme's stock and analyst commentary (TD Cowen's Brendan Smith) treat the litigation as leverage toward "a future license or other economic resolution." Finally, the case is a bellwether for the PTAB's § 112 jurisprudence across 14 parallel proceedings: reporting indicates 11 of 14 instituted PGRs have now invalidated all instituted claims, meaning Halozyme's MDASE U.S. portfolio has been substantially eroded even as its European counterpart patent survives — an asymmetry worth tracking through any Federal Circuit appeal, which Halozyme has signaled it is considering.

I'll research this case and its parallel proceedings carefully. Note upfront: the metadata identifies this as a PTAB post-grant review, not a district court infringement action — so I'll verify whether a parallel district court suit exists and cover both.

Now let me dig into the parallel D.N.J. litigation docket and the PGR2025-00030 trial-stage docket.

Threshold correction: the metadata describes a PTAB proceeding, not an infringement suit

Before the chronology, one important framing point, because it changes what "filing," "Markman," "verdict," and "settlement" mean here:

• PGR2025-00030 (the case in your metadata) is a post-grant review before the PTAB, captioned Merck Sharp & Dohme LLC v. Halozyme, Inc. Merck is the petitioner; Halozyme is the patent owner. There is no complaint, answer, Markman, or verdict in a PGR.
• The actual infringement litigation you are asking about is the mirror-image case: Halozyme, Inc. v. Merck Sharp & Dohme Corp., No. 2:25-cv-03179-ES (D.N.J.), filed 2025-04-24, assigned to Judge Esther Salas (Magistrate Judge Jose R. Almonte), in which Halozyme is plaintiff and Merck is defendant. (Law.com Radar card; Justia docket)
• Note: several secondary sources (Pearce IP, Lexology, Reed Smith) state the complaint was filed "24 April 2024." That is a typo; the complaint's own header stamp reads "Case 2:25-cv-03179-ES Document 1 Filed 04/24/25." I use 2025-04-24 throughout.

So below I run two parallel tracks in one chronology: Track A = PGR2025-00030; Track B = the D.N.J. infringement action, with the European enforcement campaign noted where it materially bears on the U.S. posture.

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Chronology

2024-11 → 2025-02-04 — Merck opens the PTAB front (Track A begins)

Merck began filing PGR petitions against Halozyme's MDASE/PH20 portfolio in November 2024 — ultimately 14 PGR petitions against 14 patents, plus (in March 2026) 3 IPR petitions. PGR2025-00030 was the seventh-in-time, filed 2025-02-04, challenging claims 1–40 of US 12,054,758 B2 ("Modified Human Hyaluronidase (PH20) Polypeptides," issued 2024-08-06).

Grounds (per the petition, Paper 1, and the institution decision):

I'll research the counsel of record in this PTAB post-grant review.

I found strong initial leads. Let me pin down the specific counsel in this PGR and their roles.

Now let me verify the Dechert LLP involvement and check for updated mandatory notices naming additional counsel in this specific PGR.

Threshold clarification on the caption

PGR2025-00030 is not a district-court infringement action: it is a post-grant review before the USPTO Patent Trial and Appeal Board, in which Merck Sharp & Dohme LLC is the petitioner (the functional "plaintiff" side) and Halozyme, Inc./Halozyme Therapeutics, Inc. are the patent owner(s). Accordingly, there is no "local counsel" in the Rule 83 / L. Civ. R. sense; PTAB practice uses lead counsel / back-up counsel, all of record before the Board.

One important nuance: the only true infringement suit between these parties is Halozyme, Inc. v. Merck Sharp & Dohme Corp., No. 2:25-cv-03179 (D.N.J.), noted as a related matter in the institution decision. In that case Halozyme is the plaintiff and Merck is the defendant — so the "plaintiff's counsel" in the D.N.J. case would be Sterne Kessler/Quinn Emanuel/Cravath for Halozyme, not the attorneys below. This memo addresses counsel for Merck, the petitioner/claimant-side party in the PTAB case you identified.

Counsel of record for Petitioner Merck Sharp & Dohme LLC in PGR2025-00030

Service address for Petitioner (all PGRs): HalozymePGRs@sidley.com, plus the individual addresses above.

Sourcing and confidence

• High confidence (primary docket documents): Kushan as lead; Peterson and Stewart as back-up. These come from the PGR2025-00030 Petition itself (Feb. 4, 2025, § "Counsel and Service Information" and signature block, /Jeffrey P. Kushan/), and from Petitioner's Updates to Mandatory Notices filed in the family (e.g., PGR2025-00017, Paper 13, Apr. 16, 2025; PGR2025-00039, Paper 15, June 30, 2025), both of which list PGR2025-00030 as a related proceeding and identify the same three attorneys with the same addresses. The Rule 42.10(a) designation is also reflected in the institution decision of Oct. 16, 2025 (biologicshq.com PDF of PTAB-PGR2025-00030).
• Medium confidence: Dechert/Helm. Dechert's role as Merck's counsel in the Halozyme matters is well corroborated (Chambers USA, Legal 500, IAM Patent 1000 profiles; Merck's own PTAB email correspondence listing "Sidley Austin LLP and Dechert LLP" as counsel of record whose invoices MSD pays). However, I could not locate a Helm Notice of Intent to Designate filed in PGR2025-00030 specifically — the equivalent filings I verified are in PGR2025-00039 (Papers 32 and the companion Sue Wang notice, Paper 30, both Nov. 11, 2025). It is likely the same designations were filed across the family, but I would not state that as docket-confirmed for -00030.
• Unconfirmed: Christine Engen's firm, and whether any additional Dechert or Sidley attorneys (e.g., Sue Wang, designated in PGR2025-00039) have entered in -00030.

What I did not find

• No withdrawal or substitution of counsel appears in the record I could retrieve; the trial-phase papers (Patent Owner's RPI additional-discovery motion, the Feb. 2026 request for leave to file a motion to terminate on real-party-in-interest grounds) continue to run through Kushan at Sidley.
• Nothing is sealed as to counsel identity — PTAB mandatory notices and powers of attorney are public. (Sealing in this family goes to the RPI discovery dispute, not to counsel.)
• I found no local counsel designation, which is expected: there is no such role at the PTAB.

One practical note

The live strategic dispute in this family is Halozyme's real-party-in-interest challenge — it argues Merck & Co., Inc. (MCI) should have been named alongside MSD LLC, based on the Director's Oct. 28, 2025 precedential designation of Corning Optical Communications RF, LLC v. PPC Broadband, Inc., IPR2014-00440. Merck's counsel of record have represented that all in-house counsel directing the PGRs are MSD LLC employees (e.g., Merck's PTAB conference-call request re additional discovery; Kelly Grez deposition in the December 2025 discovery). That is the theory most likely to affect whether these instituted trials survive to a final written decision.

I'll research this. Note the case is a PTAB post-grant review, not a district court infringement suit — I'll look for Halozyme's PTAB counsel and any parallel district court/ITC counsel.

I have strong leads. Let me verify the specific PGR2025-00030 docket entries, power of attorney, and attorney backgrounds.

Now let me check whether Quinn Emanuel and Cravath attorneys appear in PGR2025-00030 specifically, and confirm the D.N.J. parallel case counsel.

Threshold point on framing

PGR2025‑00030 is not a patent infringement case — it is a USPTO Patent Trial and Appeal Board post‑grant review, Merck Sharp & Dohme LLC v. Halozyme, Inc., on U.S. Patent 12,054,758. The "defendant‑side" party is therefore the Patent Owner, Halozyme (Halozyme, Inc. and Halozyme Therapeutics, Inc. are named as real parties‑in‑interest). Halozyme is, however, the plaintiff in the parallel infringement action, Halozyme, Inc. v. Merck Sharp & Dohme Corp., No. 2:25‑cv‑03179 (D.N.J.). I've covered the PTAB counsel of record first (that is what the question literally asks), then the D.N.J. roster and opposing counsel for completeness.

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1. Counsel of record for Halozyme in PGR2025‑00030 (verified)

The Oct. 16, 2025 institution decision in PGR2025‑00030 lists the following under "For PATENT OWNER," and this matches Halozyme's mandatory notices practice across the 15 related Merck PGRs:

Sources: PGR2025‑00030 Institution Decision, caption block (https://biologicshq.com/wp-content/uploads/2025/10/PTAB-PGR2025-00030-Institution-Decision.pdf); Halozyme's Updated Mandatory Notices under 37 C.F.R. § 42.8(a)(3), e.g. PGR2025‑00017 (listing Ellison as lead and Powers, Chagnon, Liu, Haddach as back‑up) (https://www.docketalarm.com/cases/PTAB/PGR2025-00017/Merck_Sharp_%26_Dohme_LLC_v._Halozyme_Inc/docs/05-21-2025-Patent_Owner/Notice__Updated_Mandatory_Notice-19-Patent_Owners_Updated_Mandatory_Notices.pdf).

Nothing in this proceeding is sealed as to counsel — the PTAB docket, institution decision, and mandatory notices are public and identify counsel by name, registration number, firm, and address.

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2. Wider Halozyme trial team appearing in the Merck PGR series (not confirmed on the '030 caption)

Because the 15 Merck PGRs are run as one consolidated defense, the following attorneys have appeared for Halozyme in sibling proceedings. I could not independently confirm from the PGR2025‑00030 docket itself that they were added to the '030 mandatory notices, so treat these as "team members in the related PGRs" rather than verified '030 counsel of record:

• David H. Holman (Reg. No. 61,205) — Sterne Kessler, Washington, DC. Added as back‑up counsel in later updated mandatory notices; listed "For Patent Owner" in the Director's referral decision in PGR2025‑00017.
• David J. Kappos (Reg. No. 34,357) — Cravath, Swaine & Moore LLP, 375 Ninth Ave., New York, NY. Former USPTO Director; added as back‑up counsel in Halozyme's updated mandatory notices and appears in the caption block of the Director's decision in PGR2025‑00017.
• Lauren N. Martin; Zach Summers; Zhen Cui; Nancy Zhang — Quinn Emanuel Urquhart & Sullivan LLP, 111 Huntington Ave., Suite 520, Boston, MA (Zhang also appears with the firm). Martin, Summers, Cui and Zhang appear "on behalf of the Patent Owner" at Halozyme expert depositions in the Merck PGRs. Quinn Emanuel is the natural candidate for Halozyme's D.N.J. infringement team, but I did not confirm their appearance in the D.N.J. docket.

Source: deposition transcript of Michael Hecht, Ph.D. (Aug. 26, 2025, PGR2025‑00003/‑00004/‑00006/‑00009), appearances page (https://www.docketalarm.com/cases/PTAB/PGR2025-00017/Merck_Sharp_%26_Dohme_LLC_v._Halozyme_Inc/docs/01-06-2026-Patent_Owner/Exhibit-2076-EX2076___Hecht_Deposition_Transcript.pdf); Cherr deposition transcript (PGR2025‑00009, Ex. 1129).

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3. Opposing side (for context) — Merck, the petitioner

• Jeffrey P. Kushan (Reg. No. 43,401), Sidley Austin LLP, 1501 K St. NW, Washington, DC — lead counsel for Petitioner.
• Back‑up: Leif Peterson (Sidley, Chicago), Sue Wang, Amy Mahan, Christine M. Engen, Amit Bhatla (Sidley), Katherine A. Helm, Ph.D. and Blaine Hackman and Brian M. Goldberg (all Dechert LLP — Helm in New York, Goldberg in Philadelphia), and Mark Stewart (Merck in‑house, Rahway, NJ).
• Helm and Goldberg are also Merck's defense counsel in the D.N.J. action; Goldberg's Nov. 3, 2025 pro hac vice declaration states he is "counsel of record for the Defendant in … Halozyme Inc. v. Merck Sharp and Dohme LLC, C.A. No. 2:25‑03179 (D.N.J.)." (https://www.docketalarm.com/cases/PTAB/PGR2025-00009/Merck_Sharp_%26_Dohme_LLC_v._Halozyme_Inc/docs/11-03-2025-Petitioner/Exhibit-1114-Declaration_of_Brian_M_Goldberg.pdf)

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4. Parallel D.N.J. action — what I could and could not verify

• Merck's petition certificates of service in this PGR family list, as Halozyme's service addresses, Robert Smyth, Morgan, Lewis & Bockius LLP (1111 Pennsylvania Ave. NW, Washington, DC) and Mark Snyder, Senior Vice President, General Counsel, CCO & Secretary, Halozyme Therapeutics (San Diego) — indicating Morgan Lewis was Halozyme's outside counsel address of record for service at petition filing (Feb. 2025). (http://www.pearceip.law/wp-content/uploads/2025/03/MSD-v-Halozyme-IPR-Petitions-Filed-Nov-2024-to-Feb-2025.pdf — Petition, Certificate of Service, PGR2025‑00030.)
• I could not obtain the D.N.J. docket sheet or the signature block of Halozyme's complaint through open web sources here; PACER and the Quinn Emanuel/Morris Nichols appearance filings were not accessible in this session. I am therefore not naming local D.N.J. counsel (the Rule 101.1 local‑counsel designation) for Halozyme — that would require pulling the 2:25‑cv‑03179 docket.

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5. Current posture note bearing on counsel activity

As of the most recent public record, Halozyme's counsel team (Ellison/Powers at Sterne Kessler) is litigating a real‑party‑in‑interest discovery dispute across all 15 Merck PGRs — a motion for additional discovery (filed Jan. 6, 2026) and a request for leave to file a motion to dismiss each petition for failure to name Merck & Co., Inc. as an RPI (Feb. 5, 2026 letter to the Board), following the Director's designation of Corning and de‑designation of Adello/Proppant. Merck's opposition is led by Kushan. This is the live contested issue alongside the merits; the Board instituted review in the '030 case on a subset of the challenged claims in its Oct. 16, 2025 decision.

Caveats: all counsel identifications above are drawn from public PTAB filings and transcripts; I did not invent any name or firm. Where I could not verify (Quinn Emanuel/Cravath's formal status on the '030 caption; Halozyme's D.N.J. local counsel of record), I have said so explicitly.