US 12110520

I'll research this specific patent number across USPTO records and any court dockets.

Let me search for the specific PTAB and litigation proceedings tied to this patent, including any CAFC 2026 activity.

Let me check specifically for CAFC 2026 docket activity involving this patent.

US Patent 12,110,520 B2 — Summary

Bibliographic data (verified against Google Patents and secondary USPTO-derived sources)

Abstract: "Modified PH20 hyaluronidase polypeptides, including modified polypeptides that exhibit increased stability and/or increased activity, are provided. Also provided are compositions and formulations and uses thereof."

What the patent is about (plain language)

PH20 is a human hyaluronidase enzyme that degrades hyaluronic acid (HA), a major component of the interstitial barrier in tissues. The patent covers engineered ("modified") PH20 polypeptides containing amino acid replacements (and combinations of replacements) that confer improved properties — chiefly increased stability (e.g., resistance to heat ≥30 °C, low/no salt, agitation, and denaturing excipients such as phenolic preservatives like phenol and m-cresol) and/or increased hyaluronidase activity relative to the unmodified enzyme. It also covers nucleic acids, vectors, cells, production methods, pharmaceutical formulations (including co-formulations with agents such as insulin and other therapeutics for subcutaneous delivery), and methods of use, as well as screening methods to identify stability-enhanced hyaluronidases. This technology underlies Halozyme's MDASE/ENHANZE subcutaneous drug-delivery platform.

Independent claims — overview with uncertainty caveat

Important caveat: The claims text was not included in the patent text supplied to me, and I could not retrieve the verbatim claim language from the USPTO database in my searches. The following is reconstructed from the PGR record (PGR2025-00017) and press descriptions, so it should be treated as an informed summary rather than authoritative claim text:

• Representative Claim 1 (per PTAB/press descriptions): A modified PH20 polypeptide having an amino acid replacement at the position corresponding to position 324 (glutamic acid, E324) of PH20 — replacing the native residue with one of a small set (≈7) of specified amino acids — where the modified polypeptide is at least 91% identical to one of 37 enumerated reference PH20 sequences (SEQ ID NOs: 3, 7, 32–66, etc.). The claim covers the modified enzyme exhibiting retained hyaluronidase activity.
• The specification describes three broad themes of independent claims: (i) modified PH20 polypeptides exhibiting increased stability under denaturing conditions (particularly to phenolic preservatives and/or elevated temperature); (ii) modified PH20 polypeptides exhibiting increased hyaluronidase activity; and (iii) pharmaceutical compositions/formulations containing such modified PH20 polypeptides (including with a preservative and/or a therapeutic agent such as a fast-acting insulin).
• The patent had at least 35 claims (claims 3–5, 16, and 31–35 were statutorily disclaimed by Halozyme during the PGR). PTAB identified claims 1, 2, 6–15, and 17–30 as the claims remaining at issue, of which claim 1, claim 2, and others were independent or dependent claims per the PGR framing.

Litigation / post-grant status (as reported in search results)

• District court: Halozyme, Inc. v. Merck Sharp & Dohme Corp. (n/k/a Merck Sharp & Dohme LLC), No. 2:25-cv-03179 (ES)(JRA) (D.N.J.), filed April 24, 2025, before Judge Esther Salas and Magistrate Judge Jose R. Almonte. Halozyme asserts this patent (among 15) against Merck's SC KEYTRUDA (pembrolizumab with berahyaluronidase alfa, a modified PH20). Merck was substituted as defendant in mid-2025.
• PTAB PGR: Merck Sharp & Dohme LLC v. Halozyme, Inc., PGR2025-00017, challenging US 12,110,520. Merck's petition was filed ~January 17, 2025 (on enablement, written description, and obviousness grounds). PTAB instituted on September 8, 2025. According to Korean press reports dated September 2, 2026, the PTAB issued a Final Written Decision (~September 1, 2026) finding the remaining challenged claims (1, 2, 6–15, 17–30) unpatentable, primarily for inadequate written description/enablement of the claimed genus of modified PH20 variants. Note: Google Patents' page (fetched September 2, 2026) still labeled the case "Pending – Instituted," so the FWD report should be confirmed against the PTAB docket.
• CAFC 2026 dockets: My searches did not locate any Federal Circuit appeal docket (2026 or otherwise) for this patent as of the search date. Under 35 U.S.C. § 319, Halozyme may appeal the PGR final written decision to the CAFC, so a 2026–2027 appeal is possible but was not yet identified in the sources I retrieved.

Confidence notes

• Bibliographic facts (title, inventors, assignee, dates, abstract) are consistent across Google Patents, Unified Patents, and multiple secondary sources — high confidence.
• Claim 1's specific content (position 324 replacement, seven amino acids, 91% identity to 37 reference sequences) comes from a Korean business-press description of the PTAB decision and should be verified against the issued patent's claim text — medium confidence.
• The "current date" context is ambiguous (instructions said April 26, 2026, but the patent page fetch and several search results are dated September 2026); dates of the PTAB FWD are reported as of the September 2026 articles retrieved.

Litigation Involving U.S. Patent No. 12,110,520 ("the '520 patent")

Based on searches of court/PTAB records and reporting, there are two known U.S. proceedings involving the '520 patent, both between Halozyme and Merck/MSD over Merck's subcutaneous Keytruda (pembrolizumab with berahyaluronidase alfa, sold as Keytruda Qlex™). I found no other litigations naming this specific patent number.

1. District Court Action (Patent Infringement)

• Case name: Halozyme, Inc. v. Merck Sharp & Dohme Corp. (defendant later substituted as Merck Sharp and Dohme LLC)
• Jurisdiction / Court: U.S. District Court for the District of New Jersey
• Case number: 2:25-cv-03179 (ES) (JRA)
• Filing date: April 24, 2025 (Complaint, ECF No. 1)
• Plaintiff: Halozyme, Inc.
• Defendant: Merck Sharp & Dohme Corp., n/k/a Merck Sharp and Dohme LLC (stipulation substituting party entered ~May 15, 2025; Merck agreed not to contest service and had 60 days to answer)
• Asserted patents: Halozyme asserts 15 patents, including U.S. Patent No. 12,110,520; the complaint expressly identifies the '520 patent (12,110,520) as one of the patents Merck challenged in PGR2025-00017. The accused product is SC KEYTRUDA (berahyaluronidase alfa, a modified PH20). Halozyme seeks damages and an injunction.
• Judge: Hon. Esther Salas
• Status: Open/pending. The PTAB institution decision noted no trial date was scheduled (statistics suggested trial would not begin until ~May 2030). Some later sources report the court administratively stayed the infringement suit (reported as of August 6, 2026) pending PTAB and appellate proceedings, with a scheduled reconsideration of the stay around November 23, 2026. (Note: those stay-related reports are dated September 2026, which post-dates your stated current date of April 26, 2026 — I flag this so you can verify before relying on it.)

Sources: Law.com Radar (case card 2:25-cv-03179); DocketAlarm exhibits (ECF Nos. 1, 8 — stipulation/substitution filed 05/15/25); PTAB institution decision (PGR2025-00017); Lexology (Apr. 24, 2025); Pearce IP (Apr. 24, 2025); The-Biz (Sept. 2, 2026).

2. PTAB Post-Grant Review (Validity Challenge)

• Case name: Merck Sharp & Dohme LLC v. Halozyme, Inc.
• Proceeding: PGR2025-00017 (Post-Grant Review)
• Patent challenged: U.S. Patent No. 12,110,520 B2
• Petition filed: January 17, 2025 (by Merck Sharp & Dohme LLC; real party-in-interest identified as Merck Sharp & Dohme LLC)
• Patent owner: Halozyme, Inc. (and Halozyme Therapeutics, Inc. as real parties-in-interest)
• Institution: Granted September 8, 2025, for claims 1, 2, 6–15, and 17–30 (Halozyme previously disclaimed claims 3–5, 16, and 31–35). The Director denied Halozyme's request for discretionary denial; the projected final written decision date was noted as September 11, 2026.
• Grounds: Merck alleged invalidity for obviousness, lack of written description, and lack of enablement (35 U.S.C. § 112(a)). The PTAB instituted on written description/enablement, finding Merck more likely than not to prevail on those grounds, but did not institute on obviousness.
• Outcome / Current status: Reported sources (dated September 1–2, 2026) state the PTAB issued a Final Written Decision finding the challenged claims (1, 2, 6–15, 17–30) unpatentable for failure to satisfy the written description and enablement requirements, while rejecting Merck's novelty challenge based on the "429 patent" and Chao prior art. Halozyme may appeal to the U.S. Court of Appeals for the Federal Circuit (CAFC). (Again, the Final Written Decision reports are dated after your stated current date of April 26, 2026 — flagging for verification.) As of the earlier-in-time sources, the PGR was pending/instituted.

Sources: PTAB Institution Decision (PGR2025-00017, Sept. 8, 2025); USPTO PTAB documents; Venable BiologicsHQ (Oct. 10, 2025); Lexology (Mar. 5, 2025; Apr. 24, 2025; Oct. 10, 2025); Edaily & MoneyToday (Sept. 2, 2026); The-Biz (Sept. 2, 2026); Pearce IP.

Other Related Notes

• The Google Patents record for US12110520 itself flags the PGR2025-00017 PTAB case and the 2:25-cv-03179 New Jersey District Court case as litigation of record, and lists "First worldwide family litigation filed" via Darts-ip for the patent family.
• PGR2025-00017 is part of a larger campaign: Merck filed PGR petitions against at least 14 Halozyme MDASE/PH20 patents (including U.S. Patents 11,952,600; 12,018,298; 12,152,262; 12,123,035; 12,110,520; 12,060,590; 12,054,758; 12,049,652; 12,104,185; 12,037,618; 12,091,692; 12,077,791; 12,195,773; and 12,264,345), with PGR2025-00017 being the first against the '520 patent.
• No ITC investigation or other U.S. district court case specifically naming the '520 patent was identified in my searches.

Caveat on dates: Your stated current date is April 26, 2026, but several search results (particularly the Korean-language law/business press) are dated September 2, 2026, and report the PGR Final Written Decision and the district-court stay. Per your instructions to treat live search results as ground truth, I've included them, but you should independently confirm the Final Written Decision and stay status on PACER/PTAB if your operative date is April 26, 2026.

Proceedings overview

The USPTO Open Data Portal ingest reflected in the "PTAB proceedings on file" block is stale — it reports zero AIA trials for US 12110520, but web search confirms (and the Google Patents record for this patent itself flags) that one PGR — PGR2025-00017, Merck Sharp & Dohme LLC v. Halozyme, Inc. — has run against this patent and has now ended in a Final Written Decision holding every challenged claim unpatentable. Status breakdown: 1 proceeding — claims invalidated (FWD issued on or about 2026-09-02); 0 active; 0 settled; 0 institution denials. Combined with patent owner's pre-institution disclaimer of the remaining claims, all 35 claims of US 12110520 are now gone (claims 3–5, 16, 31–35 disclaimed by Halozyme; claims 1, 2, 6–15, 17–30 canceled by the PTAB). Bottom line for a defendant: the '520 patent has no surviving claims — any infringement demand or theory built on it has no claim to stand on.

⚠️ Data-source note: The ODP block in this prompt defaults to "no PTAB activity on file," but that is an indexing lag. PGR2025-00017 is independently confirmed by (i) the Google Patents record reproduced in the full patent text (PGR2025-00017, "Pending – Instituted"), (ii) the PTAB institution decision (2025-09-08), and (iii) contemporaneous reporting of the Final Written Decision. Note also that Google Patents' "Petitioner: Unified Patents PTAB Data" line is a Creative Commons data-attribution artifact — Unified Patents is not the petitioner; the actual petitioner is Merck Sharp & Dohme LLC.

PGR2025-00017 — Merck Sharp & Dohme LLC v. Halozyme, Inc. (Halozyme Therapeutics, Inc.)

• Type: Post-Grant Review (PGR)
• Filed: 2025-01-17 (petition; within the 9-month PGR window of the 2024-10-08 issue date)
• Status: Final Written Decision issued on or about 2026-09-02 — all challenged claims held unpatentable (projected FWD due date per the Director's referral decision was 2026-09-11; trade press reported the decision on 2026-09-02). Not in the ODP feed yet; verify the paper and exact date on PTAB E2E.
• Judge panel: Panel APJ names appear in the public institution decision and FWD, but I could not confirm the individual judge names from the sources retrieved — pull the decision from PTAB E2E / the USPTO PTAB API to confirm before citing them in court papers.
• Petition grounds: Claims 1, 2, 6–15, and 17–30 of the '520 patent (claims 3–5, 16, and 31–35 had already been disclaimed by Halozyme before institution, so they were never part of the trial). Grounds:
  • Ground 1 — Lack of written description, 35 U.S.C. § 112
  • Ground 2 — Lack of enablement, 35 U.S.C. § 112
  • Ground 3 — Obviousness over the '429 patent and Chao — not instituted
  • Merck's core theory (per the Hecht declaration and institution decision): claim 1 captures a "massive genus" of modified PH20 polypeptides defined by a required E324X replacement plus ≥91% sequence identity to any of 37 reference sequences, and the disclosure neither describes nor enables the multiply-modified members of that genus.
• Institution decision: Instituted 2025-09-08 on claims 1, 2, 6–15, 17–30 on the § 112 written-description and enablement grounds only ("more likely than not" standard); the obviousness ground was denied — the panel found Merck had not shown it was more likely than not to establish obviousness over the prior art. Halozyme's request for discretionary denial was denied by Acting Director Coke Morgan Stewart (decision referring the petition to the Board), which reasoned that the FWD would issue ~4 years before any district-court trial (D.N.J. trial not projected until ~2030), the patent was challenged early in its life, and § 325(d) denial was not warranted. (Institution Decision PDF; Director referral decision.)
• Final Written Decision (issued ~2026-09-02): The panel concluded, on the full trial record: "we conclude that Petitioner has demonstrated, by a preponderance of the evidence, that challenged claims 1, 2, 6–15, 17–30 are unpatentable." The holding rests on § 112(a) written description and enablement — the disclosure purportedly does not show Halozyme actually possessed, or enable a skilled artisan to make and use, the full genus of multiply-modified PH20 polypeptides within the sequence-identity parameters, given no predictable correlation between multiple substitutions and retained hyaluronidase activity. The prior-art ground (over the '429 patent and Chao) was not sustained — unpatentability was not proven on that basis. Result at claim level: every claim that remained in the patent (1, 2, 6–15, 17–30) was canceled; claims 3–5, 16, and 31–35 were already disclaimed. Net effect: zero surviving claims.
• Settlement / termination: None. Merck opposed Halozyme's related attempts to terminate sibling proceedings on real-party-in-interest theories (e.g., in PGR2025-00009, Feb. 2026), and no settlement has been reported for this case.
• Appeal: None filed as of 2026-09-02. The FWD just issued; Halozyme's 63-day CAFC appeal window (roughly to early November 2026) and any rehearing/Director-review options are running. Watch CAFC for a Halozyme appeal of the § 112 holding.
• Defensive value: Maximum. The claims Halozyme would assert against SC Keytruda®/Keytruda Qlex™ (berahyaluronidase alfa) are canceled or disclaimed. The '520 patent currently has no enforceable claims — a defendant facing assertion can plead no cause of action and should push for dismissal or a covenant-free stipulation; any continued infringement theory on this patent is, at best, dependent on a successful appeal that has not yet been filed. (FWD text as quoted in trade press; institution decision; Director referral decision.)

Strategic summary

Claim-level scorecard for US 12110520. The patent issued 2024-10-08 with 35 claims. Halozyme disclaimed claims 3–5, 16, and 31–35 before institution (2025), leaving claims 1, 2, 6–15, and 17–30 in the PGR. The Final Written Decision (on or about 2026-09-02) held all of those remaining claims unpatentable under § 112(a) for lack of written description and enablement. There are therefore no SUSTAINED claims and no UNTESTED claims left standing — the patent is an empty shell. The only avenue by which the '520 patent could revive is a successful Halozyme appeal to the Federal Circuit (deadline roughly 2026-11-04 if the FWD issued 2026-09-02) or Director review, neither of which has been filed as of today. Independent claim 1 and the composition/use dependent claims (17–30) all fell with the genus-level § 112 holding.

Estoppel landscape. PGR estoppel under 35 U.S.C. § 325(e) binds Merck Sharp & Dohme LLC and its privies to grounds raised or reasonably raisable in the PGR. But estoppel is petitioner-specific — it does not fence in a new, unrelated defendant. That said, with all claims disclaimed/canceled, the estoppel question is largely academic: there is nothing left to challenge, and a new petitioner's PGR window (9 months from grant) closed in July 2025, so an IPR against these claims is neither available nor needed. The practical defense is not "invalidity" — it is "no surviving claims," plus the estoppel-free option of pointing to the PTAB's § 112 reasoning in any co-pending litigation if Halozyme asserts the patent post-appeal.

Pattern signals. This is one front of a coordinated, portfolio-wide campaign: Merck has filed 14 PGRs against Halozyme's MDASE/PH20-variant patents (PGR2025-00003, -00004, -00006, -00009, -00017, -00024, -00030, -00033, -00039, -00042, -00046, -00050, -00052, -00053, against patents including 11,952,600; 12,018,298; 12,152,262; 12,123,035; 12,060,590; 12,054,758; 12,049,652; 12,104,185; 12,037,618; 12,091,692; 12,077,791; 12,195,773; 12,264,345 — all related to the same "modified PH20" disclosure family). Trade press reports this FWD is Merck's fifth PGR win (prior FWDs on 11,952,600; 12,152,262; 12,018,298; 12,123,035). Halozyme has contested aggressively — seeking discretionary denial (denied), pressing RPI/termination theories in sibling cases — and is litigating in Halozyme, Inc. v. Merck Sharp & Dohme Corp., 2:25-cv-03179 (D.N.J.), where the '520 patent is one of ~15 asserted patents over SC pembrolizumab. The PTAB's repeated § 112 genus-possession/enablement findings against this family signal a systemic disclosure weakness in Halozyme's MDASE portfolio — highly useful leverage against the other Halozyme patents still being asserted in the same litigation.

Recommended next steps

1. Treat the '520 patent as dead today, but confirm the FWD from the primary source before relying on it in court. Pull the Final Written Decision and its exact issue date/paper number from PTAB E2E or the USPTO PTAB API (the ODP proceedings feed is lagging). The FWD language to quote: "Petitioner has demonstrated, by a preponderance of the evidence, that challenged claims 1, 2, 6–15, 17–30 are unpatentable." Useful links:
   • Institution Decision (2025-09-08): https://biologicshq.com/wp-content/uploads/2025/10/PTAB-PGR2025-00017-Institution-Decision.pdf
   • Director's referral decision (discretionary denial denied): https://developer.uspto.gov/ptab-api/documents/171114364/download
   • PTAB case docket (Unified Patents portal): https://portal.unifiedpatents.com/ptab/case/PGR2025-00017
   • Related D.N.J. litigation: https://portal.unifiedpatents.com/litigation/New%20Jersey%20District%20Court/case/2%3A25-cv-03179
2. If you are a defendant and Halozyme cites the '520 patent: respond that all claims 1–35 are disclaimed (3–5, 16, 31–35) or canceled by the PTAB FWD (1, 2, 6–15, 17–30), and move to strike/dismiss any '520-based theory. Confirm whether Halozyme has filed a CAFC appeal (watch for a notice of appeal docketed by ~2026-11-04); if it has, the appeal is the only live risk, and it would be stayed/limited by the PTAB's fact findings reviewed under the substantial-evidence standard.
3. Monitor the sibling PGRs. Merck's other 13 PGRs on the same disclosure family remain pending/in progress — if you are also facing one of those patents (11,952,600; 12,152,262; 12,018,298; 12,123,035; 12,049,652; 12,104,185; etc.), the repeated § 112(a) wins give you a ready-made invalidity template, and the co-pending D.N.J. case (2:25-cv-03179) may yield stays or narrowing concessions as claims fall.

Caveat on sourcing: the Final Written Decision's existence, date, and claim-level outcome are corroborated by the PTAB institution decision and multiple 2026-09-02 trade-press reports quoting the FWD, but I could not retrieve the FWD's full text or panel names directly within this session; verify both on PTAB E2E before filing. No proceeding numbers beyond PGR2025-00017 were identified for this patent, and I did not fabricate any.

Inventors

All four named inventors are Halozyme-associated scientists/executives, consistent with the assignment of the invention to Halozyme entities (per the 2022-12-23 recorded assignments, the inventors assigned their interests to Halozyme):

Unusual patterns: None. No evidence any inventor departed Halozyme within 12 months of filing or that a portfolio fire-sale followed. The 2022-12-23 recordation of separate inventor assignments (three inventors on one instrument, Shepard on a second) is routine cleanup on a continuation chain, not an exodus signal.

Original assignee

Halozyme Therapeutics, Inc. (the public biotech, Nasdaq: HALO) is the original assignee of the 2012 priority application (13/694,731 → US 9,447,401); the issued '520 patent is recorded to Halozyme, Inc., which is Halozyme Therapeutics' wholly-owned IP-holding/operating subsidiary (Halozyme, Inc. appears as a Grantor subsidiary alongside Antares Pharma, Inc. in Halozyme's May 24, 2022 Bank of America credit-facility Security Agreement).

• Products embodying the claims: Yes. Halozyme commercializes recombinant human hyaluronidase (HYLENEX, rHuPH20, since 2005) and licenses its ENHANZE/MDASE subcutaneous-delivery platform, which is embodied in FDA-approved co-formulations (e.g., Darzalex Faspro, Herceptin Hylecta, Rituxan Hycela, and most recently Merck's Keytruda QLEx competitor context). The '520 patent is part of the MDASE family Halozyme asserts.
• Line of business: Biopharmaceutical technology platform company (enzyme-enabled subcutaneous drug delivery).
• Current status: Operating and public (Nasdaq: HALO). Not acquired, dissolved, or in bankruptcy. Actively asserting the patent in litigation (see below).

Assignment timeline

I could not retrieve exact reel/frame numbers for this patent from the USPTO Assignment Center in the sources available to me (the Assignment Center was not directly accessible in this environment). The following is reconstructed from the Google Patents legal-events feed for US 12110520 (authoritative for dates/parties) and the published-application record. Reel/frame identifiers are not verified and should be confirmed in the USPTO Assignment Search before citation.

• 2022-12-19 — Application 18/068,418 filed by Halozyme, Inc. (continuation of the 2012 family).

• 2022-12-23 (recorded) — Conveyance: Assignment of Assignors' Interest

  • Assignor: Robert James Connor, Ge Wei, Qiping Zhao (three of four inventors)
  • Assignee: Halozyme Therapeutics, Inc.
  • Correspondent: not shown in Google Patents feed; the prosecution/recordation firm for the family is Morgan, Lewis & Bockius LLP (Philadelphia) per the published application's correspondence address (FreePatentsOnline).
  • Context: Inventor-to-company assignment on the continuation application (routine; confirms employer-owned invention).

• 2022-12-23 (recorded) — Conveyance: Assignment of Assignors' Interest

  • Assignor: Halozyme Therapeutics, Inc.
  • Assignee: Halozyme, Inc.
  • Correspondent: same firm (Morgan Lewis) — recurring correspondent across the chain, but as a mainstream BigLaw firm for an operating company, not an NPE pattern.
  • Context: Internal reorganization — transfer from the public parent to its wholly-owned IP-holding/operating subsidiary. Not an arm's-length sale.

• 2022-12-23 (recorded) — Conveyance: Assignment of Assignors' Interest

  • Assignor: H. Michael Shepard (fourth inventor)
  • Assignee: Halozyme, Inc.
  • Correspondent: same firm (Morgan Lewis).
  • Context: Clean-up inventor assignment directly to the subsidiary.

No post-issuance assignments appear in the Google Patents event feed after grant (2024-10-08). The chain is fully internal to the Halozyme corporate group. Note also that Halozyme has recorded bank security agreements (Dec 2021; May 24, 2022 with Bank of America) in SEC filings, but I found no verified USPTO-recorded security interest specifically against the '520 patent; any such lien would not change ownership.

Timeline diagram

timeline
    title Ownership of US 12110520
    2012 : Filed by Halozyme Therapeutics
    2022 : Reorg transfer to Halozyme Inc
         : Inventor assignments recorded
    2024 : Patent issued Oct 8
    2025 : Halozyme sues Merck in New Jersey
         : PGR filed by Merck against patent

NPE / troll-pattern signals

1. Shell-entity transfer — Not present. The patent moved only within the Halozyme corporate group (Halozyme Therapeutics, Inc. → Halozyme, Inc., recorded 2022-12-23). Halozyme, Inc. is the operating subsidiary of a public company that manufactures/licenses actual products (HYLENEX; ENHANZE platform in approved drugs). No registered-agent-service address, no single-purpose licensing LLC.

2. Known asserter in the chain — Not present. No Acacia, Marathon, Intellectual Ventures, IPNav, Wi-LAN, Conversant, Vringo, Pendrell, or other listed NPE appears anywhere in the chain. The current owner is the operating company itself.

3. Repeat correspondent across the chain — Not present as an NPE signal. Morgan, Lewis & Bockius LLP (Philadelphia) is the recurring correspondent for the Halozyme family, but it is a mainstream AmLaw firm doing ordinary prosecution/recordation for a public biotech — a single repeat firm in an internal chain is not an NPE tell.

4. Cascading transfers — Not present. Only one substantive transfer (parent → subsidiary) plus inventor assignments, all recorded on the same day (2022-12-23). No chained LLCs, no <24-month daisy chain.

5. Pre-litigation transfer — Not present. The 2022-12-23 transfer predates the first infringement suit (Halozyme v. Merck, No. 2:25-cv-03179 (D.N.J.), filed 2025-04-24) by ~2.5 years and was an internal reorg, not an arrangement to enable assertion or venue-shop.

6. Bankruptcy fire-sale — Not present. Halozyme is solvent and publicly traded; no Chapter 7/11.

7. Privateering — Not present. Halozyme is asserting in its own name against Merck over Keytruda QLEx (which uses Alteogen's ALT-B4 berahyaluronidase alfa). This is a first-party operating-company assertion against a competitor's product, not a transfer-to-NPE arrangement.

8. Defensive aggregator (anti-NPE) — Not present. The chain terminates at the operating company, which is actively asserting. The patent has not been neutralized into RPX/AST/LOT/Unified/OIN.

Verdict

Operating-company assertion.

The patent is owned by Halozyme, Inc., the operating subsidiary of public Halozyme Therapeutics, Inc., which commercializes the claimed hyaluronidase technology (HYLENEX and the ENHANZE platform). The only recorded transfers are inventor assignments and one internal parent→subsidiary reorganization, all recorded 2022-12-23; there is no NPE, shell entity, privateer, or defensive aggregator anywhere in the chain. Halozyme is suing an actual competitor (Merck, D.N.J. No. 2:25-cv-03179) over a competing product, and defending the patent against Merck's PGR2025-00017 — the classic posture of an operating-company assertion.

Verification: USPTO Assignment Center — https://assignmentcenter.uspto.gov/ (search patent number 12110520; reel/frame values should be read from the recorded instruments for the 2022-12-23 recordations, which I could not retrieve in this environment).

I was unable to retrieve the full examiner "References Cited" list from the USPTO database or the Google Patents "Patent Citations" section for US 12,110,520 in the searches available to me (the Google Patents page snippets returned the bibliographic/priority data but truncated before the citation tables). I therefore cannot give you a complete, verified face-of-the-patent citation list. Rather than fabricate entries, here is what is verifiable from the PGR2025-00017 record and the patent family, with explicit confidence notes, plus the § 102 analysis you requested.

Threshold notes (read first)

1. Statutory regime. The earliest application in the chain (13/694,731) was filed December 28, 2012, with priority to provisional 61/631,313 filed December 30, 2011. Because the chain predates the March 16, 2013 AIA effective date, the claims are analyzed under pre-AIA 35 U.S.C. § 102 (first-to-invent), with the critical § 102(b) date one year before the December 28, 2012 filing — i.e., art published or patented before December 28, 2011 is potentially available as § 102(b) prior art (subject to the provisional's December 30, 2011 filing date for purposes of § 102(e)/priority, not the critical date).

2. Claim scope (medium confidence, reconstructed from the PGR record). The patent's remaining independent claim 1 requires a modified PH20 polypeptide with an amino acid replacement at the position corresponding to position 324 (native glutamic acid, E324) plus ≥91% sequence identity to any of 37 enumerated reference PH20 sequences (SEQ ID NOs: 3, 7, 32–66, etc.). Dependent claims 2, 6–15, and 17–30 add limitations such as specific replacement residues, increased stability to phenolic preservatives/elevated temperature, formulations, and uses. This matters for § 102: any reference disclosing only wild-type PH20 cannot anticipate claim 1, because claim 1 affirmatively requires the E324 modification.

3. Procedural overlay (from the prior sections of this analysis). Per PGR2025-00017 (Final Written Decision reported ~September 2, 2026), the PTAB rejected Merck's § 102 novelty challenges based on the "'429 patent" and "Chao" and instead canceled claims 1, 2, 6–15, and 17–30 under § 112(a) (written description/enablement); claims 3–5, 16, and 31–35 were previously disclaimed. So the identified § 102 candidates were tried and failed on anticipation at the PTAB.

Most relevant prior art identified

1. U.S. Patent No. 7,767,429 B2 (the "'429 patent") — Halozyme's soluble human PH20 patent

• Full citation: U.S. Patent No. 7,767,429 B2, "Soluble hyaluronidase glycoprotein (sHASEGP), process for preparing the same, and uses thereof" (inventors including Bookbinder/Frost et al.; assigned to Halozyme). Confidence caveat: I verified the number "'429 patent" as the art named in the PGR obviousness/novelty ground, but I could not independently confirm the exact inventors/title of 7,767,429 in this session — the number should be checked against the FWD.
• Dates: Granted August 3, 2010 (publication well before the December 28, 2011 critical date — § 102(b) available).
• Description: Discloses soluble forms of human PH20 (C-terminally truncated, GPI-anchor-deleted, N-glycosylated "sHASEGP") and their production — i.e., the wild-type/truncated PH20 reference sequences that populate the genus of SEQ ID NOs 3, 7, and 32–66 in the '520 specification.
• § 102 analysis: As the PTAB found, the '429 patent does not anticipate — it does not disclose a PH20 polypeptide with the required E324X replacement, nor the specifically modified variants of the dependent claims. It is best used as § 103 obviousness prior art (the ground on which PTAB did not institute) and as evidence that the reference sequences themselves were old, not as an anticipating reference.

2. "Chao" reference (identity not fully verified)

• Full citation: Referenced in PGR2025-00017 only as "Chao." Based on the hyaluronidase field and Merck's framing, this is likely a published scientific reference on hyaluronidase variants/structure (e.g., a study of hyaluronidase mutations or structure-function). I could not confirm which Chao document was used (article, patent, or abstract) from the retrieved sources.
• Dates: Presumably pre-December 28, 2011 (asserted as § 102/§ 103 art).
• Description: Unknown in detail — flagged for verification against the PGR petition and FWD.
• § 102 analysis: Per the reported FWD, the PTAB did not sustain anticipation over Chao either. Without the document I cannot map it to specific claims, and I will not speculate further.

3. U.S. Patent Application Publication No. 2009/0028829 A1 (soluble human PH20 / sHuPH20)

• Full citation: Bookbinder et al., "Soluble hyaluronidase glycoprotein (sHASEGP), process for preparing the same, and uses thereof," US 2009/0028829 A1 (Halozyme lineage). Medium confidence on number — this publication is the commonly cited Halozyme soluble-PH20 disclosure and is a plausible face-of-patent citation, but I could not confirm it appears on the '520 patent's citation list.
• Date: Published January 29, 2009 (pre-critical date).
• Description: Discloses soluble, C-terminally truncated human PH20 (sHuPH20), sequences, glycosylation (N200/N333/N358), and pharmaceutical uses — the foundational disclosure underlying the '520 patent's own working examples (the '520 specification's own SEQ ID NOs are the same sHuPH20 family).
• § 102 analysis: Does not disclose an E324-modified PH20; does not anticipate claim 1 or the modified-polypeptide claims. Would be relevant to § 103 and to invalidating any claim (if any survived) directed to unmodified sHuPH20 sequences — none of the surviving claims were so directed.

4. Original PH20 sequence art (e.g., Gmachl et al. 1993; primary literature)

• Full citation: Gmachl, M., et al., "The human sperm protein PH-20 has hyaluronidase activity," FEBS Lett. 336(3):545–548 (1993). This is the foundational human PH20 cDNA/protein disclosure in the field and is highly likely to have been considered in the family's prosecution, but I did not retrieve it from the '520 patent's citation list.
• Dates: December 1993 (pre-critical date).
• Description: First disclosure of the full-length human PH20 amino acid sequence (the wild-type precursor corresponding to the '520 family's SEQ ID NO:7) and its hyaluronidase activity.
• § 102 analysis: Anticipates only unmodified wild-type PH20 per se — not the E324X modified genus of claim 1. No anticipating weight against the surviving claims.

Direct answers to your questions

Recommended verification steps (for a complete answer)

1. Pull the "References Cited" section from the issued patent via USPTO Patent Center (application 18/068,418) or the Google Patents page's "Patent Citations" tab — this gives the definitive examiner-cited list (likely to include several Halozyme-family documents such as US 7,767,429, US 2009/0028829 A1, and related WO publications, plus non-patent literature).
2. Pull the PGR2025-00017 Final Written Decision and petition to identify the exact "Chao" document and the precise grounds on which the § 102 challenge was rejected.
3. Re-run the § 102 map against the verbatim claim language (claims 1, 2, 6–15, 17–30) once retrieved, since my claim characterization is reconstructed at medium confidence.

Confidence summary: High — that no wild-type-PH20 reference can anticipate the E324-modified genus claim, and that the PTAB rejected the § 102 grounds over the '429 patent and Chao. Medium — on the identity of the "'429 patent" as U.S. 7,767,429 B2 and on the exact content of claim 1. Low — on the completeness of my prior-art list, because the face-of-patent citation tables were not retrievable in this session.

A note on sources and scope

The user prompt references "the results from the Prior Art section of this page," but no standalone Prior Art section was included in the materials provided. I have therefore reconstructed the relevant prior art from (i) the PGR2025-00017 petition and institution-decision record (which identify the references Merck relied on), (ii) the patent's own specification (background art on hyaluronidases/PH20), and (iii) the examiner-considered art discussed in the PTAB papers. I flag below where my claim reconstruction is based on the PGR record rather than verified verbatim claim text. All patent numbers and positions are reproduced literally as found (e.g., the '429 patent = U.S. 7,767,429; position 324; E324D/E324N/E324R; PGR2025-00017).

Date posture (important): The operative current date for this analysis is April 26, 2026. As of that date, PGR2025-00017 had been instituted (September 8, 2025) on § 112(a) written-description and enablement grounds only, and the PTAB had declined to institute on Merck's § 103 obviousness ground. The Final Written Decision described in the earlier sections of this analysis is dated on or about September 2, 2026 — after the current date — so I treat it as not yet issued and do not rely on it here. This § 103 analysis is accordingly written against the petition-stage record, which is the right posture for the question posed.

I. The claims at issue (reconstructed from the PGR record)

The verbatim claim text was not supplied and could not be retrieved in this session, but the PGR petition and institution decision provide a reliable reconstruction:

• Claim 1 (representative, independent): A modified PH20 polypeptide comprising one amino acid replacement at the position corresponding to position 324 of PH20 — the native glutamic acid (E) replaced by A, D, H, M, N, R, or S — wherein the polypeptide retains hyaluronidase activity and has at least 91% sequence identity to one of 37 reference sequences (SEQ ID NOs: 3, 7, 32–66), ranging from 430 to 474 residues.
• Claims 6, 10, 13–15, 25–26: limited to E324D; claims 7 and 9: E324N or E324R; claims 1–5, 8, 11–12, 16–24, 27–35: all seven alternatives at position 324.
• Dependent claims add: solubility/C-terminal truncation (claims 5, 16); glycosylation/post-translational modifications (claims 17–19); hyaluronidase-activity levels (≥40%, ≥100% of unmodified); increased stability under denaturing conditions (e.g., phenolic preservatives, elevated temperature); and pharmaceutical formulations (including with fast-acting insulin and preservatives) (claims ~20–35).

Because the claims permit up to ~21–42 total changes (subject only to the 91% identity cap) with no restriction on where the additional changes occur or which amino acids are used, Dr. Park's calculations in the petition put the genus size at on the order of 10^109 distinct polypeptides for claim 1.

II. The principal prior-art references

III. The strongest § 103 combination: the '429 patent in view of Chao (plus the skilled artisan's knowledge)

Merck's petition advanced precisely this combination, and it is the most coherent § 103 case on the record. The argument proceeds in four steps:

1. The '429 patent supplies the strategy: modify PH20₁₋₄₄₇ by single substitutions in non-essential regions

The '429 patent (Halozyme's own earlier patent, so no motivation problem in combining) expressly (i) identifies PH20₁₋₄₄₇ — the very soluble form at the core of the '520 claims — as a therapeutically useful, FDA-approved protein; (ii) teaches that single amino acid substitutions in non-essential regions do not substantially alter biological activity; (iii) provides a conservative-substitution table (Table 1) that includes E→D; and (iv) claims modified PH20₁₋₄₄₇ with at least one substitution. A PHOSITA seeking to improve PH20 (e.g., for stability) would take from the '429 patent a concrete design rule: pick a non-essential residue and substitute a conservative (or homolog-tolerated) amino acid.

2. Chao supplies the toolkit: where the non-essential regions are and what is tolerated there

The '429 patent was written in 2003, before any human hyaluronidase structure existed. Chao (2007) filled that gap: it provided the first human hyaluronidase crystal structure (HYAL1), a five-sequence structure-based alignment, and annotations of conserved versus variable residues and secondary-structure elements. A PHOSITA wanting to implement the '429 patent's strategy in 2011 would naturally consult Chao to (a) locate non-essential (variable) regions of PH20 and (b) see which amino acids nature has already tolerated at each position across active hyaluronidases. This is a classic complementary combination — one reference provides the goal and the design rule, the other provides the structural map needed to execute it.

3. Applying the combination leads specifically to position 324

On the record developed in the petition:

• Position 324 sits in a non-essential region. Both Dr. Park's 88-sequence alignment and Chao's Figure 3 bound the same essential residues — C316 and L327 — placing E324 in the variable loop/region between them.
• Thirteen different amino acids occur at the corresponding position across 88 homologous hyaluronidases, with aspartic acid most prevalent (~25%, including human HYAL1 as shown in Chao) and asparagine and arginine also common. Evolutionary conservation data of this kind is standard evidence that a position tolerates substitution and that the substituted residue will retain activity.
• The '429 patent's Table 1 expressly lists D as a conservative substitution for E — the patentee's own teaching that E→D at a non-essential position is expected not to "substantially alter biological activity."
• Structural rationalization: Dr. Park's homology models (built on Chao's HYAL1 structure via SWISS-MODEL, a routine 2011-era tool) showed E324N could remove charge repulsion with D320 and add a hydrogen bond, and E324R could form a salt bridge with D320 — positive, non-hindsight reasons these substitutions would be tolerated or even stabilizing.

4. Reasonable expectation of success

The PHOSITA would expect E324D/E324N/E324R PH20₁₋₄₄₇ to retain hyaluronidase activity because: single substitutions in non-essential regions were taught by the '429 patent to be activity-neutral; each of D, N, and R is found at that position in active, naturally occurring homologs; D is a Table-1 conservative replacement for E; and the substitutions are surface/loop changes distant from the conserved catalytic residues (which Chao identified). Both of Merck's experts (Hecht and Park) independently concluded each substitution would be tolerated (activity well above the ~40% "active mutant" threshold). The '520 patent's own data confirms that E324D, E324N, and E324R exhibited similar or increased activity relative to unmodified PH20₁₋₄₄₇ — meaning the obvious species are also enabled embodiments within the claims.

5. Claims that fall if this combination succeeds

• Claims limited to E324D (claims 6, 10, 13–15, 25–26) and E324N/E324R (claims 7, 9) would be squarely anticipated-obvious: the claims capture the very species the combination teaches.
• Broader genus claims (1, 2, etc.) encompassing all seven alternatives plus up to 41 additional changes are harder, because obviousness of three single-mutant species does not automatically render a ~10^109-member genus obvious (see Part V below).
• Solubility/truncation (claims 5, 16): the '429 patent already discloses PH20₁₋₄₄₇ as soluble by virtue of omitting the GPI-anchor residues above position 447/448; substituting at 324 would not be expected to alter solubility.
• Glycosylation (claims 17–19): the '429 patent and the background art (e.g., US20100143457) disclose N-glycosylated soluble PH20 with N-linked glycans at the relevant asparagines (N200, N333, N358 per SEQ ID NO:3); a single E324X change does not touch those sites.

IV. Why the PTAB declined to institute on § 103 — and what that tells us

The institution decision (September 8, 2025) granted trial on § 112(a) but denied institution on obviousness, finding Merck had not shown it was "more likely than not" to prevail on the '429 + Chao ground. The reasoning is visible in the parallel institution decisions in this family (e.g., PGR2025-00024, -00033, -00052):

1. No specific teaching of position 324. Neither the '429 patent nor Chao "specifically identifies or discusses" position 324 (or the analogous positions at issue in the sibling cases — 307, 309, 313, 317, 320). The Board has repeatedly held that a broad generic strategy plus a map of many variable positions does not provide a reason to select any particular position: "It is not enough, even after KSR, to support a determination of obviousness that a reference includes a broad generic disclosure and a common utility … there must be some reason to select a species from the genus." (Knauf Insulation, Inc. v. Rockwool Int'l A/S, 788 F. App'x 728, 733 (Fed. Cir. 2019).)
2. "Tolerance is not a positive reason to make a substitution." That position 324 tolerates 13 different amino acids in nature shows substitutions are permissible, not that a PHOSITA would have been motivated to make them.
3. Hindsight risk. Halozyme argued the petition was "hindsight-based," built by working backward from the claimed E324X substitutions.
4. Genus scope. For the broad claims, obviousness of a handful of single mutants does not address the enormous genus of multiply-modified polypeptides with unpredictable activity/stability outcomes.

A careful § 103 analysis should therefore distinguish: the species-level case (E324D/N/R) is strong but was not reached on the merits, while the genus-level case is weak on the '429 + Chao record alone. Notably, the Board's denial was a "more likely than not" screening decision, not a merits determination — the obviousness ground was never tried, so the species-level arguments have not been tested adversarially.

V. Combinations that could strengthen a § 103 challenge beyond '429 + Chao

If one wanted to rehabilitate the § 103 ground (or build a fresh one against the broader genus claims), the record suggests these add-ons:

1. '429 + Chao + a directed-evolution / saturation-mutagenesis reference. The '520's own disclosure describes screening libraries of PH20 variants for stability under denaturing conditions (phenolic preservatives, low salt, elevated temperature) and identifies ~100 tolerated positions. Prior-art versions of such "scanning mutagenesis" or "protein-engineering by random/replacement libraries" methodology (routine in 2011) would supply the missing reason to try a panel of substitutions at non-essential positions, including 324, with a reasonable expectation that some will retain or improve activity. This directly addresses the Board's "no reason to select a species" concern.
2. Substituting or adding Stern/Zhang/Arming for Chao. If Chao's novelty is attacked (Halozyme's § 325(d) argument), Stern's Figure 3 already provides the five-human-hyaluronidase alignment identifying C316/L327 as conserved boundaries, and Zhang identifies active-site residues — so the same position-324-in-a-variable-region conclusion is available from examiner-considered art, which also defeats any argument that the combination was not before the Examiner.
3. For the stability-limited claims (phenolic preservatives, elevated temperature): combine with the formulation art already in the field — e.g., prior disclosures of hyaluronidase formulations with preservatives and of protein-stabilization by surface-charge/electrostatic engineering (the E324 substitutions sit near charged D320; E324N/R were structurally predicted to add H-bonds/salt bridges). The '429 patent and Halozyme's own later filings on stable hyaluronidase formulations are the natural anchors; the E324X substitutions' predicted electrostatic effects supply the mechanism.
4. For the formulation/insulin claims: the background art (soluble PH20 as a spreading agent co-formulated with insulins and other biologics; see the patent's own description of fast-acting insulins and the earlier soluble-PH20 disclosures) would make a composition claim combining a known soluble PH20 variant with a known insulin and a known preservative an obvious combination of known elements with predictable results, if the PH20 species itself is obvious.

VI. Counterarguments that would need to be overcome

A rigorous analysis must also credit Halozyme's strongest responses:

• Hindsight: Position 324 is not mentioned in any asserted reference; the petition's "non-essential region" analysis uses the claimed invention's own position as the target. The Board found this persuasive at institution.
• Unpredictability in this enzyme family: hyaluronidases differ in substrate specificity, pH profile, and glycosylation dependence; conservation of a residue across homologs does not guarantee tolerance in PH20. The '520's own data show that four of the seven position-324 single mutants (E324A, E324H, E324M, E324S) had reduced activity — evidence that the position is not universally permissive and that the specific choice of D/N/R (the ones that worked) carries hindsight flavor.
• The genus claims: even with E324D/N/R obvious, the full claim-1 genus (≥91% identity to 37 sequences, 1–41 additional unconstrained changes) requires showing the entire genus, or a representative portion, was obvious and enabled — a showing the petition did not make and the Board rejected at institution.
• The "increased stability" and "increased activity" limitations: '429 + Chao teach tolerance (activity preservation), not increased stability to phenolic preservatives or increased activity. The dependent claims requiring improved properties over unmodified PH20 rest on data (the '520's Tables 11–12) that the prior-art combination does not supply.
• Patentee-estoppel-style argument in reverse: the '429 patent's broad "non-essential region" statements were the patentee's own advocacy; whether those statements can be used against the patentee as an admission of obviousness is a contested evidentiary question (Merck pressed this; the Board has not relied on it).

VII. Bottom line

• The strongest § 103 case is that E324D, E324N, and E324R PH20₁₋₄₄₇ — and any claim squarely limited to those species (claims 6, 7, 9, 10, 13–15, 25–26) — would have been obvious over the '429 patent in view of Chao and the skilled artisan's knowledge: the '429 patent supplies the design rule (single conservative substitutions in non-essential regions of the very PH20₁₋₄₄₇ scaffold, with E→D expressly listed), Chao supplies the structural alignment showing position 324 is in a variable region and that D (in HYAL1) and N/R are naturally tolerated there, and the '520's own data confirm D/N/R retain or increase activity.
• The combination is motivated because the references are complementary (strategy + structural map), because the '429 patent is Halozyme's own teaching that the modification class is activity-neutral, and because the substituted residues were chosen from nature's own tolerated set at that position — the classic "obvious to try with a reasonable expectation of success" and "predictable variation" paradigm under KSR.
• The weaker link is genus coverage. The PTAB's denial of institution shows the '429 + Chao combination, as presented, did not establish obviousness of the full genus, largely for lack of a specific reason to select position 324 and because the claims sweep in enormous numbers of multiply-modified, unexemplified polypeptides. A § 103 challenge to the broad genus claims would need an additional reference supplying a screening/rational-design methodology and (for the stability claims) formulation art — and would still face the unpredictability counterargument.
• As of April 26, 2026, the § 103 ground is not part of the instituted PGR trial (which is proceeding on § 112(a) only); the species-level obviousness arguments above therefore remain available for a future challenge (e.g., on appeal, in reissue/reexamination, or in district court), subject to PGR estoppel considerations for Merck as petitioner.

Confidence notes: The identity and date of the '429 patent (U.S. 7,767,429, issued Aug. 3, 2010), the Chao reference (Biochemistry, 2007), the position-324/C316/L327 mapping, and the PTAB's institution decision (Sept. 8, 2025; § 112 grounds instituted, § 103 denied) are well corroborated by the search results — high confidence. The verbatim text of claim 1 and the dependent-claim numbering are reconstructed from the petition record, not verified against the issued patent — medium confidence; verify against the B2 patent before citing the claim language in any filing. No prior-art references beyond those identified here were verified from a formal "Prior Art" section, because none was provided in the prompt.