US 12077791

I'll search for authoritative information on this patent number.

Let me dig into the claims and the specific PTAB challenge for this patent.

Let me try to locate the exact claim language for this specific patent.

US Patent 12,077,791 — Summary

Note on scope: I was able to pull the authoritative full text of this patent (Google Patents mirror of the USPTO grant) and to find PTAB/PGR and district‑court filings naming it. I was not able to retrieve a verbatim copy of the claims section (the mirrored text I obtained contains the specification/definitions but not the numbered claims), so the claim overview below is derived from the specification, the patent's title, and the family's litigation record, and is flagged accordingly.

Identification (literal, not normalized)

Family/continuity recited in the specification: the application is a continuation tracing through 17/327,586, 16/824,572 (issued as US 11,041,149 on 2021‑06‑22), 15/226,489 (issued as US 10,865,400 on 2020‑12‑15), and 13/694,731 (issued as US 9,447,401 on 2016‑09‑20), all to the same four inventors.

Abstract (verbatim)

"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."

Substance of the disclosure

The patent describes engineered variants of PH20 hyaluronidase (a neutral‑active, sperm‑associated hyaluronidase; PH‑20) bearing one or more amino acid replacements, with the position numbering referenced to the soluble human PH20 sequence SEQ ID NO:3. The stated goals are (a) increased stability under protein‑denaturing conditions — elevated temperature (≥30 °C), agitation, low/no salt (e.g., <100 mM NaCl), and denaturing excipients such as phenolic preservatives (phenol, m‑cresol, benzyl alcohol, parabens) — and (b) increased hyaluronidase activity. The specification reports a full positional scan of the 447‑residue SEQ ID NO:3 sequence (each residue replaced by, on average, ~13 other amino acids), giving residue‑by‑residue structure/function information, and lists position 309 among the positions whose substitution alters activity/stability. Variants generally must retain ≥40% of the unmodified enzyme's activity and are defined relative to reference sequences SEQ ID NOs:3, 7, 32–66, 69 and 72, or sequences at least 91% identical thereto.

Independent claims — plain‑language overview (with uncertainty flagged)

⚠️ Uncertainty: I could not verify the exact numbered claim text from an authoritative source. Based on the title, specification, and the claim structure of the sibling patents in this family, the independent claims most plausibly read as follows — but treat this as a characterization, not a quotation:

1. Composition‑of‑matter claim (modified PH20 polypeptide). A modified PH20 polypeptide comprising an amino acid sequence that is at least 91% identical to a reference PH20 sequence (e.g., SEQ ID NO:3, 7, 32–66, 69 or 72), with the proviso that the residue at the position corresponding to position 309 of SEQ ID NO:3 is substituted with one or more specified amino acids (from the specification, the tolerated/active 309 substitutions include but are not limited to E, G, H, L, M, N, Q, R, S, V and T at that position), wherein the polypeptide exhibits hyaluronidase activity (and, in some claims, increased stability and/or activity relative to the unmodified PH20).
2. Method claim (method of making). A method of producing such a modified PH20 polypeptide, comprising culturing a host cell (typically a mammalian cell, e.g., CHO) containing a nucleic acid/vector encoding the variant under conditions in which the polypeptide is expressed and secreted, and recovering the expressed polypeptide.
3. Possibly nucleic acid / vector / host cell and pharmaceutical composition claims (the specification expressly provides nucleic acids, prokaryotic and eukaryotic vectors, host cells, and compositions optionally containing a phenolic preservative and/or a fast‑acting insulin).

Important caveat / potential source of confusion: the searches surfaced PTAB filings in the same Halozyme family that argue about variants at position 307 and position 312 (with 91% identity), e.g., in Merck Sharp & Dohme LLC v. Halozyme, Inc., PGR2025‑00009. Those positions do not match this patent's title (position 309), and I could not confirm whether those excerpts relate to the '791 patent or to sibling patents in the same family. I am reporting the 309 numbering as it appears in the patent title and specification and am not auto‑correcting it to 307 or 312.

Litigation and docket status

• PTAB: PGR2025‑00050 was filed against the '791 patent and is listed as instituted / pending. The petitioner in this family of challenges is Merck Sharp & Dohme (MSD). Google Patents' "family has litigation" panel for this patent links: https://portal.unifiedpatents.com/ptab/case/PGR2025-00050
• PTAB papers for the '791 patent include Halozyme's patent‑owner preliminary response (petition file 1557844), which expressly names "Case PGR2025‑00050 U.S. Patent No. 12,077,791," and a declaration exhibit referencing the '791 patent's HTML text at https://ppubs.uspto.gov/external/patents/html/12077791?source=USPAT.
• Third‑party IP reporting states MSD filed petitions for post‑grant review against 14 Halozyme US patents, all instituted, with the list including US 12077791 (alongside US 11952600, US 12018298, US 12152262, US 12123035, US 12110520, US 12054758, US 12060590, US 12049652, US 12104185, US 12037618, US 12091692, US 12195773 and US 12264345). Source: https://www.pearceip.law/2025/11/19/msds-subcutaneous-keytruda-approved-in-europe/
• District court: a co‑pending litigation is Halozyme, Inc. v. Merck (Merck Sharp & Dohme) in the District of New Jersey, case 2:25‑cv‑03179‑(ES‑JRA) (filed 2025‑04‑24), concerning Merck's subcutaneous KEYTRUDA® (pembrolizumab) product. Google Patents links: https://portal.unifiedpatents.com/litigation/New%20Jersey%20District%20Court/case/2%3A25-cv-03179
• CAFC (2026): I searched specifically for a Federal Circuit 2026 docket for patent 12077791 and found none. As of the date of my searches, the '791 dispute appears to be at the PTAB (PGR) and district‑court stage only. I cannot rule out a subsequently docketed appeal that is not yet indexed; if a CAFC appeal exists, I do not have authoritative information on it.

What I could not verify

• The verbatim text of claims 1–N of US 12,077,791 (I only had the specification and the abstract).
• Whether the asserted/claimed position is exclusively 309 in every independent claim, or whether some claims cover multi‑substitution variants/other positions in addition.
• The current disposition of PGR2025‑00050 (instituted; I have no final written decision date in hand) and any CAFC appeal activity.
• The patent's actual, current expiration (2032‑12‑28 is an algorithmic estimate from Google Patents, not a legal conclusion; PTA/terminal disclaimer effects are not reflected).

I'll research litigation involving US 12,077,791 across patent‑litigation trackers, PTAB, district court, and the Federal Circuit.

Strong results. Let me now pin down the details: whether the '791 patent is among the asserted patents in the district‑court case, the current PTAB posture, and any Federal Circuit activity.

Litigation involving US 12,077,791 ("the '791 patent")

Bottom line: The '791 patent is the subject of two live proceedings — one PTAB post‑grant review and one district‑court infringement action — both stemming from the same dispute between Halozyme, Inc. (patent owner/plaintiff) and Merck Sharp & Dohme (petitioner/defendant) over subcutaneous KEYTRUDA® / berahyaluronidase alfa. I found no Federal Circuit appeal naming this patent, and no other defendants or jurisdictions. The '791 patent is one of fifteen related Halozyme patents asserted in the district court case; it is the sole patent at issue in the PGR.

1. PTAB — Merck Sharp & Dohme LLC v. Halozyme, Inc., PGR2025‑00050 (US 12,077,791)

• Petitioner: Merck Sharp & Dohme LLC (counsel: Jeffrey P. Kushan, Sidley Austin LLP).
• Patent Owner: Halozyme, Inc. (counsel: Sterne Kessler / Cravath / in‑house).
• Petition filed: May 7, 2025. The petition challenges only the '791 patent. Exhibit 1001 is "U.S. Patent No. 12,077,791."
• Grounds: The Patent Owner's Response is organized around Ground 1 (written description, § 112(a)) and Ground 2 (enablement) — i.e., Merck's challenge to the '791 patent is a § 112 attack on a large claimed genus of modified PH20 polypeptides, not an obviousness attack. The challenged variants are recited as "I309" substitutions (EX2182–EX2200: "I309L Swiss Model," "I309N Swiss Model," "I309E," "I309G," "I309H," "I309M," "I309Q," "I309R," "I309S," "I309T," plus combinations such as "I309N, N47A, N131A, N219A").
• Institution: Granted. A "DECISION Granting Institution of Post-Grant Review" appears on the docket, with a "Director Discretionary Decision: Refer" (Sept 26, 2025) and an Order Granting Petitioner's Motion to Seal. Venable's PTAB tracker confirms the USPTO Director denied Halozyme's requests for discretionary denial and referred the institution decisions to the panel in PGR2025‑00024, ‑00030, ‑00042, ‑00046, ‑00050, and ‑00052.
• Current posture (as of my sources, late 2025 / early 2026): Merits phase. Patent Owner's Response filed Jan 16, 2026; Petitioner's Opposition to Patent Owner's Motion for Additional Discovery filed Jan 19, 2026. In the parallel proceedings, Halozyme has filed a Motion to Terminate arguing that Merck & Co., Inc. ("MCI," the parent) is an unnamed real party‑in‑interest; Petitioner opposed (opposition filed Feb 24, 2026 in PGR2025‑00009), and the Board already denied Halozyme's motion for additional discovery on that theory in the related PGR2025‑00003.
• No final written decision is in hand.
• Sources: https://ipverse.greyb.com/ptab-web/cases/case-details/PGR2025-00050 ; https://biologicshq.com/ptab-grants-institution-of-three-pgrs-related-to-mercks-keytruda-qlex/ ; 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 ; https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1557844](/patent/1557844)/download-documents

2. District court — Halozyme, Inc. v. Merck Sharp & Dohme Corp., No. 2:25‑cv‑03179‑ES‑JRA (D.N.J.)

• Plaintiff: Halozyme, Inc. Defendants: Merck Sharp & Dohme Corp. and Merck Sharp & Dohme LLC (the docket and later filings render the defendant as Merck Sharp & Dohme LLC f/k/a Merck Sharp & Dohme Corp.; a stipulation substituted the correct Merck entity, and Merck's response deadline was set for July 14, 2025).
• Filed: April 24, 2025. Assigned to: U.S. District Judge Esther Salas ("ES"); Magistrate Judge Jose R. Almonte ("JRA").
• Cause of action: Patent infringement (35 U.S.C. § 271(a), (b), (c)) and declaratory judgment of patent infringement, plus willfulness, injunctive relief, and an exceptional‑case/attorneys'‑fees demand. The accused product is SC KEYTRUDA® (subcutaneous pembrolizumab), which uses berahyaluronidase alfa ("BHA"), described in the complaint as "a modified PH20 that makes rapid subcutaneous administration of KEYTRUDA possible."
• The '791 patent is expressly asserted: The complaint pleads it as Count 9 ("INFRINGEMENT OF U.S. PATENT NO. 12,077,791"), ¶¶ 187–200. ¶ 188 states the '791 patent issued September 3, 2024 and "has not yet expired"; ¶ 191–197 plead direct, induced, and contributory infringement.
• Fifteen patents in suit (single family): U.S. Patent Nos. 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; and 12,264,345. The complaint states the '400, '656, '618, and '791 patents "have claims directed to modified PH20s with modifications to residue 309."
• Current status: Pending; no substantive merits ruling found. No stay was granted on the filings I located (Petitioner's briefs in the parallel PGRs argued the DNJ case "likely" would be stayed if more PGRs instituted, and noted the DNJ trial would not occur before ~May 2030 under time‑to‑trial statistics). The only procedural events I found: pro hac vice admissions and orders (Aug 2025), the Rule 16.1 letter order and initial scheduling conference (Oct 20, 2025), and an Oct 14, 2025 extension order.
• Sources: https://dockets.justia.com/docket/new-jersey/njdce/2:2025cv03179/[566903](/patent/566903) ; https://www.law.com/radar/card/halozyme-inc-v-merck-sharp--dohme-corp-57770840-1/ ; complaint text at https://www.statnews.com/wp-content/uploads/2025/06/halozyme-v-merck-re-keytruda-patents.pdf ; https://www.docketalarm.com/cases/PTAB/PGR2025-00009/Merck_Sharp_%26_Dohme_LLC_v._Halozyme_Inc/docs/04-28-2025-Patent_Owner/Exhibit-2058-EX2058___District_Court_Complaint.pdf

3. Federal Circuit — none found

I found no appeal at the U.S. Court of Appeals for the Federal Circuit naming US 12,077,791. This is expected: the only PTAB proceeding on this patent (PGR2025‑00050) is still in merits briefing and has not reached a final written decision, and the district‑court case remains pre‑trial. No CAFC docket for the '791 patent appeared in any source I searched. (I note the limitation that a very recently docketed appeal may not yet be indexed.)

Related / adjacent proceedings that do NOT involve the '791 patent

For completeness, the same Merck–Halozyme campaign includes 14 PGRs (Nov 2024 – Jun 2025) against Halozyme patents, of which the '791 is one (PGR2025‑00050), and IPR2026‑00312/‑00313/‑00314 (filed Mar 23, 2026) against the '791 patent's parent/related patents US 10,865,400, 11,041,149, and 11,066,656. Those proceedings do not name the '791 patent.

Flags and corrections to the previously generated section

Per the instruction not to auto‑correct identifiers, and to flag contradictions:

1. Prior section's open question resolved — position 309 is correct. The prior analysis was uncertain whether the claimed position was 309 (per the title) or 307/312 (from sibling‑patent briefing). The complaint confirms: the '791 patent has claims directed to modified PH20s with modifications to residue 309, and Merck's PGR exhibits are all "I309" models. The 307/312 material belongs to other patents in the family, not the '791.
2. Petitioner identity. The prior section noted Google Patents displayed "Petitioner: Unified Patents PTAB Data." That is a data‑attribution label, not the petitioner. The actual petitioner is Merck Sharp & Dohme LLC.
3. Filing date confirmed. The prior section listed PGR2025‑00050 without a filing date; it was filed May 7, 2025.
4. Prior section's "position 307/312" aside (attributed to Merck Sharp & Dohme LLC v. Halozyme, PGR2025‑00009) is inconsistent with the docket: PGR2025‑00009 concerns US 12,123,035, not the '791 patent. I am reporting this as a discrepancy rather than correcting it.
5. Prior section said "I could not verify the verbatim text of claims 1–N." Still true for me; however Merck's briefing characterizes independent claim 1 as reciting 91% sequence identity and a genus exceeding 10^112 distinct modified PH20 polypeptides, consistent with the prior section's "≥91% identity" characterization. Also notable: Halozyme filed statutory disclaimers cancelling claims in several sibling patents in response to Merck's § 112 challenges (e.g., claims 3‑5, 16, 31‑35 of the '520 patent).

What I could not verify

• Any substantive ruling, stay, or settlement in 2:25‑cv‑03179 (only scheduling/procedural orders surfaced).
• The final outcome of PGR2025‑00050 (no final written decision found) or the disposition of Halozyme's Motion to Terminate.
• Whether Halozyme's disclaimer practice extended to the '791 patent's claims (the Exhibit 2003 disclaimer I saw relates to application 18/659,215, a different matter).
• Any additional litigation beyond these two proceedings (none found in the Unified Patents, Docket Alarm, Justia, Law.com or Darts‑ip records surfaced; the Darts‑ip entry on the patent page is the same family litigation).

I'll verify the structured block against live sources, since the prior section flagged a possible PGR on this patent.

Search results contradict the structured block — there is a PGR on this patent. Let me pin down the details.

Let me nail down the institution decision specifics and claims at issue.

⚠️ Data conflict at the outset — read this first

The structured "PTAB proceedings on file" block in my instructions states that "the USPTO ODP API returns no AIA trial proceedings for this patent" and defaults to "no PTAB activity on file."

That is wrong for US 12,077,791. Multiple primary-source and secondary documents — including USPTO P-TACTS petition/filing documents, a Director decision, and the Board's institution decision — establish an instituted post-grant review on this patent. Per your operating rules, I am preferring the live sources over the structured block and flagging the contradiction explicitly rather than treating the block as canonical. The ODP ingest for this patent is stale or incomplete.

I therefore do not report "no PTAB activity." Reported below is one real proceeding, sourced to USPTO P-TACTS and corroborating reporting.

Proceedings overview

There is one AIA trial proceeding on US 12,077,791: PGR2025-00050, Merck Sharp & Dohme LLC v. Halozyme, Inc. — status active (trial instituted 2025-11-19, no Final Written Decision yet); breakdown = 1 active / 0 claims canceled / 0 claims sustained / 0 settled / 0 institution-denied.

Bottom-line defensive posture for a defendant: the patent is under live, instituted § 112(a) attack and is not yet adjudicated — this is a "hold your breath" posture, not a "hardened" or "dead" one. Unlike several sibling Halozyme patents in the same campaign (which already have Final Written Decisions invalidating all challenged claims), the '791 patent has survived only to the institution stage. A defendant should expect the FWD in roughly late 2026, should not assume validity, and should not treat the office action history as dispositive — the Board has already found Merck's written-description/enablement theory strong enough to institute.

PGR2025-00050 — Merck Sharp & Dohme LLC v. Halozyme, Inc.

• Type: Post-Grant Review (35 U.S.C. §§ 321–329; patent is PGR-eligible — filed within 9 months of the 2024-09-03 grant)
• Filed: 2025-05-07
• Status: "Trial Instituted" (verbatim from PTAB docket aggregators), institution granted 2025-11-19 under 35 U.S.C. § 324. Plain-English gloss: the Board found it more likely than not that at least one challenged claim is unpatentable, and trial is running. No Final Written Decision as of the latest available update (Pearce IP status table dated 2026-09-09 still lists "Instituted 19 Nov 2025").
• Judge panel: Jeffrey N. Fredman, Susan L. C. Mitchell, Cynthia M. Hardman (with Michael A. Valek also listed on one aggregator). Tech Center 1600, Art Unit 1649. ⚠️ Panel composition is reported by third-party docket mirrors, not confirmed from the face of the institution decision; treat the fourth name as uncertain.
• Petition grounds: At minimum § 112(a) written description and § 112(a) enablement of the claimed genus of modified PH20 polypeptides, plus a § 103 obviousness challenge. The § 112 theories turn on:
  • claim 1 encompassing a genus of modified PH20 polypeptides defined by at least 95% sequence identity to SEQ ID NO:35 and a modification at position 309 (E, G, H, L, M, N, Q, R, S, or T) and "increased hyaluronidase activity";
  • Petitioner's expert (Dr. Michael Hecht, with Dr. Park on enablement) calculating the claimed genus at ~10⁴⁹ to 10⁶⁰ distinct polypeptides, that ~57% of the single substitutions disclosed in the '791 specification are inactive, and that the specification offers only a "prophetic, iterative make-and-test" path;
  • Prosecution-history estoppel-adjacent argument by Halozyme that the Examiner already considered and resolved these same written-description/enablement issues (the Examiner had rejected then-pending claims 1–10 and 14–17 for lack of written description, then allowed after an "increased hyaluronidase activity" limitation was added).
  • ⚠️ I could not confirm from the excerpted record whether the § 103 obviousness ground was instituted or denied at institution. In the parallel PGRs on sibling patents, the Board declined to institute on obviousness but instituted on § 112. Do not assume the '791 institution reached the same split without reading the decision.
• Institution decision: Instituted 2025-11-19 (35 U.S.C. § 324). Procedural predicate: the Director (Coke Morgan Stewart, Deputy Under Secretary/Deputy Director) denied Halozyme's request for discretionary denial and referred the petition to the Board (decision on file; the aggregator timeline shows the referral docketed 2025-09-26, and Venable reports Director denials/referrals across PGR2025-00024, -00030, -00042, -00046, -00050 and -00052 in August–September 2025). The Director's referral decision declined to exercise § 324(a)/Fintiv-style discretion, incorporating the reasoning from PGR2025-00006, Paper 29 (Director 2025-06-12), and expressly instructed that no rehearing/Director-Review request be filed until the Board ruled on institution.
• Final Written Decision: None issued as of this writing. Statutory deadline is within 12 months of institution — i.e., ~2026-11-19 — extendable up to 6 months for good cause (up to ~2027-05-19). A FWD may therefore issue very close to or after this report.
• Key procedural events (2026) — these are unusual and worth flagging:
  • 2026-02-09: Board grants Patent Owner's unopposed motion to seal (PO's Motion for Additional Discovery, Paper 63, and Exhibits 2401–2406, 2426–2444) and enters the default protective order; the sealed material concerns Petitioner's law-firm engagement letters and billing/payment records.
  • 2026-02-12: Board conference call on Halozyme's request for authorization to file a motion to terminate for failure to name all real parties-in-interest (RPI).
  • 2026-02-24: Petitioner's opposition to Patent Owner's motion to terminate (this paper is captioned in the multi-case PGR2025-00009 docket but addresses the group, including PGR2025-00050). Merck's position: Merck & Co., Inc. (MCI), the parent, is not an RPI; MCI did not direct, control or fund the PGRs; Halozyme waived the RPI issue by delay; estoppel-circumvention theory "unfounded."
  • 2026-03-11: Halozyme's motion to terminate (public, redacted) — argues Merck & Co.'s 2025-11-05 SEC Form 10-Q tells investors that "the Company" "began filing a series of post grant review (PGR) petitions before the PTAB," that executive leadership and boards overlap, and that MSD is attempting to circumvent estoppel. If Halozyme won this, termination would be a major defensive event for the patent.
  • 2026-04-02: PO paper granting a motion to seal (per aggregator docket).
  • ⚠️ I could not verify the Board's ruling on the RPI motion to terminate. Motion practice was live as of March 2026; no disposition is reflected in the sources I could retrieve.
• Settlement / termination: No settlement, no termination. The RPI motion to terminate is a merits/procedural motion, not a settlement, and its outcome is unconfirmed.
• Appeal: No Federal Circuit appeal — none is possible yet, because no FWD has issued. I searched specifically for a CAFC docket for 12,077,791 and found none.
• Defensive value: This is the only PTAB proceeding touching the '791 patent, it is live, and the Board already found the § 112 challenge sufficient to institute. For a defendant, that means (a) an IPR/PGR-based invalidity defense is available and already teed up, but (b) it is not yet a judgment you can rely on — there is no canceled claim to point to. Watch the FWD (~2026-11-19 statutory target). Separately, the RPI/estoppel fight matters to you: if the Board finds Merck & Co. should have been named, privity-based estoppel arguments could ripple across all 14–15 Merck PGRs.

Strategic summary

Claim-by-claim status: everything is UNTESTED; nothing is canceled and nothing is sustained.

• The only claims I can identify as claim-level subject matter are claim 1 (a modified PH20 polypeptide with ≥95% identity to SEQ ID NO:35, a position-309 substitution selected from E, G, H, L, M, N, Q, R, S, or T, and increased hyaluronidase activity) and its dependents. ⚠️ I could not verify the exact challenged claim set from the institution decision text. The prosecution history referenced then-pending and ultimately allowed claims 1–3, 6–10, 14, and 23 — but I will not assert that Merck challenged exactly those claims without the decision in hand.
• No claim of 12,077,791 has been canceled, disclaimed, or held unpatentable. If a demand letter cites the '791 patent today, you cannot yet respond "that claim is dead." You can respond that the patent faces an instituted PGR with a § 112(a) theory the Board credited, and that its sibling patents in the same campaign are dropping.

Estoppel landscape.

• PGR estoppel runs under 35 U.S.C. § 325(e)(2) (the PGR analogue of § 315(e)(2)) and attaches only after a final written decision. Since no FWD exists, no estoppel has attached yet — including none against Merck.
• When it does attach, § 325(e)(2)'s PGR estoppel is the broadest of the AIA estoppels: it bars the petitioner and its privies from asserting in a civil action or before the Office that a claim is invalid on any ground the petitioner raised or reasonably could have raised in the PGR — which, in a PGR, sweeps in § 101 and § 112 grounds, not just §§ 102/103 printed publications. That makes a final judgment against Merck on § 112 potentially decisive, in Halozyme's favor or against it.
• For a non-Merck defendant currently being asserted against: nothing is estopped as to you. All prior-art grounds under §§ 102/103 remain available, subject only to the ordinary IPR eligibility limits. Note one hard statutory constraint on your side: the '791 patent issued 2024-09-03, so its 9-month PGR window closed ~2025-06-03. If you want a § 112 or § 101 attack, you cannot get it at the PTAB in a PGR; you'd need to raise it in district court or an ex parte reexam-adjacent vehicle. The PTAB route now available to you is IPR, and IPR is limited to §§ 102/103 on patents and printed publications.
• Watch the RPI motion: if MSD is found to have failed to name Merck & Co. as an RPI, privity arguments could expose Merck entities to estoppel. If it is denied (as Merck argues it should be), MSD remains the sole RPI and estoppel stays confined to MSD LLC.

Pattern signals.

• Same petitioner, coordinated campaign: Merck (MSD LLC) filed 14–15 PGRs against Halozyme's modified-PH20 portfolio, with PGR2025-00050 being the one aimed at the '791 patent. This is a coordinated multi-patent, multi-police force on a single technology (subcutaneous KEYTRUDA Qlex™ / berahyaluronidase alfa-pmph).
• Patent owner fights hard: Halozyme (Sterne Kessler; in-house counsel Aubrey Haddach) litigated Director-review discretionary denial requests, additional discovery into Petitioner's counsel/RPI structure, and motions to terminate for RPI across the campaign. It has NOT settled.
• The campaign is going badly for Halozyme so far on siblings: PTAB FWDs have invalidated all challenged claims of several sibling patents (e.g., US 11,952,600 on 2026-05-12; the '298 patent in PGR2025-00004, oral hearing 2026-03-02; the '520 patent in PGR2025-00017 per the Sept 2026 FWD posted by Venable). Roughly four Halozyme patents had all challenged claims invalidated as of the 2026-09-09 Pearce IP update. The '791 patent is in the same family/specification and faces the same § 112(a) genus theory — the family-level trend is adverse to the patent.
• No defensive aggregator (e.g., Unified Patents) is in the chain; this is brand-vs-brand litigation, not a troll scenario. Google Patents links the proceeding through Unified Patents' PTAB portal, but Unified is a data source there, not a party.

Recommended next steps

1. Pull the institution decision (Paper likely dated 2025-11-19) from PTAB E2E / P-TACTS and confirm two things I could not verify: (a) the exact challenged claim list, and (b) which grounds were instituted (§ 112(a) written description, § 112(a) enablement, and/or § 103). Start at the proceeding's P-TACTS entry (https://ptacts.uspto.gov/ptacts/public-informations/petitions/1557844/... for the '791 record) and the Board's E2E portal: https://ptacts.uspto.gov/ ; the aggregator mirrors are https://ipverse.greyb.com/ptab-web/cases/case-details/PGR2025-00050 and https://www.docketalarm.com/cases/PTAB/PGR2025-00050/Merck_Sharp_%26_Dohme_LLC_v._Halozyme_Inc/ .
2. Mark the FWD deadline: ~2026-11-19 (12 months from institution), extendable to ~2027-05-19. If a FWD invalidates all challenged claims, Halozyme's appeal clock to the Federal Circuit (35 U.S.C. § 329; Fed. Cir. R. 15) starts, and the FWD becomes citable against you immediately. There is no appeal to cite today.
3. Track the RPI motion to terminate. It is the single biggest near-term swing factor. A grant would terminate the '791 PGR outright — the strongest defensive outcome available short of a favorable FWD — and would also undercut the other 13 proceedings. Check the docket for a Board decision (the motion was filed 2026-03-11; the Board authorized it on/around 2026-02-12).
4. Confirm the district-court stay posture. Co-pending is Halozyme, Inc. v. Merck Sharp & Dohme Corp., 2:25-cv-03179 (D.N.J.), in which the '791 patent is one of the asserted patents. In the parallel PGRs the Petitioner argued the Board's decisions "will significantly streamline the district court litigation," and the Board noted the U.S. RPI/estoppel interplay. If you are a co-defendant, a stay motion calibrated to the PGR institution is worth evaluating.
5. Do not over-rely on the '791 office action history. Halozyme's central rebuttal is that the Examiner already resolved written description/enablement in its favor. The Board nonetheless instituted — meaning it did not treat the prosecution record as dispositive at the § 324 stage. If you are building a § 112 theory, use the same Hecht/Park-style quantitative record (genus size ~10⁴⁹–10⁶⁰; ~57% of disclosed single mutants inactive; no structural correlation for multiply-substituted variants).
6. Fix the intake record. If your internal ODP-derived docket says "no PTAB activity" for 12,077,791, correct it — that data gap caused the contradiction flagged at the top of this report.

Caveats and unverified items (stated plainly)

• Panel composition: reported by third-party mirrors; not read from the decision itself.
• Challenged claims: claim 1 is confirmed as the focal claim; the full challenged set is not verified.
• Grounds instituted: § 112(a) grounds are evidenced by substantial record excerpts; whether § 103 was instituted for the '791 patent is unconfirmed.
• RPI-termination disposition: unconfirmed (last observed activity: PO motion to terminate 2026-03-11, Petitioner opposition 2026-02-24).
• No FWD, no settlement, no CAFC appeal as of the most recent status source (2026-09-09).
• I found no second PTAB proceeding on the '791 patent. In particular, PGR2025-00009 concerns a different Halozyme patent in the same family (its briefing references the '791 patent only as a related matter). This corrects the cross-reference in the earlier summary section, which associated the "position 307/312" argument with this patent — that numbering belongs to a different patent in the family, not to the '791 patent's position-309 claims.

I'll research the assignment record for this patent. Let me start with several searches.

Let me search for the specific assignment records and reel/frame data.

Ownership-chain reconstruction — US 12,077,791 B2

Access note (read first). I was not able to query the USPTO Assignment Center directly for this patent (my tooling for this pass was web search only, not a live Assignment Center/ODP session). What I can state is drawn from (a) the Google Patents legal-events mirror of the USPTO assignment record captured in the authoritative full text supplied to me, and (b) assorted secondary sources. Reel and frame numbers were not retrievable and are therefore omitted rather than estimated. Verify at: https://assignmentcenter.uspto.gov/ (search "12077791") or https://assignment.uspto.gov/patent/index.html

Inventors

Sources: ADS data reproduced in the prosecution record (PGR2025‑00009, Ex. 1002‑2 file history; and the Norwegian Patent Gazette printing of the sibling case, which lists all four with the same San Diego / Oceanside addresses and assignee Halozyme, Inc., 11388 Sorrento Valley Road, San Diego, CA 92121).

Unusual patterns.

• Three of four inventors live within a few miles of Halozyme's San Diego campus; Shepard's Oregon residence is the outlier. His residence tracks with founder/CSO‑emeritus status rather than active bench work. This is not evidence of a 12‑month departure — but it does mean the named inventive group is not a normal same‑site team.
• No inventor departed within 12 months of the 2023‑06‑22 filing on the face of the assignment record. The chain runs into the company, not out of it. The mirror-image warning sign (mass inventor departure preceding a portfolio fire‑sale) is absent.
• All four are repeat inventors across the PH20/MDASE family (the "LinkedIn profiles of Michael Shepard, Robert Connor, Ge (Gina) Wei, and Qiping Zhao" exhibit in PGR2025‑00017 confirms they were Halozyme personnel). A long-lived, stable inventor group on a single corporate family is the opposite of the NPE precursor pattern.

Original assignee

Halozyme, Inc., San Diego, California — name printed as assignee on the face of the grant ("HALOZYME, INC., San Diego, California has been assigned a patent (No. US 12077791 B2…)"; Google Patents: Original Assignee = Halozyme Inc; Current Assignee listed as Halozyme Inc and Halozyme Therapeutics Inc).

• Primary business: commercial biopharmaceutical company built on its recombinant human hyaluronidase PH20 (rHuPH20) franchise — the ENHANZE® drug‑delivery platform — plus proprietary products Hylenex® and XYOSTED®.
• Does it ship a product embodying the claims? Yes, at the platform level: rHuPH20 is the enzyme in a large set of FDA‑approved subcutaneous co‑formulations (Phesgo, Tecentriq Hybreza, Ocrevus Zunovo, Opdivo Qvantig, HyQvia, Vyvgart Hytrulo, etc.). Halozyme is also asserting this patent family, which is the dispositive fact for the verdict below.
• Current status: operating and profitable. Halozyme Therapeutics, Inc. is SEC‑registered (CIK 0001159036) and publicly traded (NASDAQ: HALO). FY2025 guidance reported at $1.3–1.375 billion revenue, with ~$850–880M of that from partner‑product royalties. Halozyme, Inc. functions as the group's IP‑holding/operating subsidiary; Halozyme Therapeutics, Inc. is the public parent.
• Not acquired, not dissolved, not in bankruptcy.

Contradiction flagged vs. the earlier summary: the earlier section listed the assignee as "Halozyme, Inc.; assignment records also name Halozyme Therapeutics, Inc." That is corroborated, and the assignment chain now explains why both names appear — see the documentary inconsistency at entry 2 below.

Assignment timeline

The Google Patents legal‑events record contains three reassignment entries, all recorded 2023‑06‑27 — five days after the 2023‑06‑22 filing. No reel/frame was exposed in any source I could reach; the entries are listed in the order the mirror presents them.

• Executed date not stated in the source / recorded 2023‑06‑27 — Reel not retrieved

  • Conveyance: Assignment ("ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS)")
  • Assignor: Connor, Robert James; Wei, Ge; Zhao, Qiping (3 of 4 inventors)
  • Assignee: Halozyme Therapeutics, Inc.
  • Correspondent: not retrievable from available sources. Flag: the family's prosecution firm of record is Dentons US LLP (attorney/agent of record on sibling US 11,066,656 in this same PH20 family), and the family uses docket series "33320.03xxx.US…". This is a prosecution correspondent, not a confirmed assignment correspondent — I could not confirm recurrence across assignment records, so no repeat‑correspondent finding is made.
  • Context: internal reorg / confirmatory filing — perfecting the inventor→company chain for a newly filed continuation of a 2011‑priority family.

• Executed date not stated / recorded 2023‑06‑27 — Reel not retrieved

  • Conveyance: Assignment
  • Assignor: Shepard, H. Michael (the 4th inventor)
  • Assignee: Halozyme, Inc. (note: not Halozyme Therapeutics, Inc., unlike his three co‑inventors)
  • Correspondent: not retrievable
  • Context: internal reorg / artefact of separate inventor agreement. The documentary inconsistency — one inventor assigning directly to the operating entity while the other three assign to the parent — is worth a note; it is consistent with Shepard having executed under an older founder/consultant agreement.

• Executed date not stated / recorded 2023‑06‑27 — Reel not retrieved

  • Conveyance: Assignment
  • Assignor: Halozyme Therapeutics, Inc.
  • Assignee: Halozyme, Inc.
  • Correspondent: not retrievable
  • Context: internal reorg — upstream parent transfers the collected rights down to the entity that holds and asserts the patents (Halozyme, Inc. is named as assignee on the printed grant).

No further assignments appear of record. Specifically, I found no evidence of: a security interest, a standalone recorded licence, a merger/change‑of‑name filing against this patent, or any transfer to a third party. The chain begins and ends inside the Halozyme corporate family.

Timeline diagram

timeline
    title Ownership of US 12077791
    2011 : PH20 family priority date
    2023 : Application 18339829 filed by Halozyme
         : Inventors assign to Halozyme Therapeutics
         : Shepard assigns to Halozyme Inc
         : Halozyme Therapeutics assigns to Halozyme Inc
    2024 : Patent US 12077791 B2 granted
    2025 : Halozyme sues Merck in New Jersey
         : Merck petition PGR2025-00050 filed
         : PGR instituted by PTAB

NPE / troll-pattern signals

1. Shell-entity transfer — not present.
The only transferees are Halozyme Therapeutics, Inc. and Halozyme, Inc. (recorded 2023‑06‑27). Neither carries an "IP / Patents / Licensing / Holdings / Ventures" suffix. Both are addressed at Halozyme's own corporate campuses (11388 Sorrento Valley Road / 12390 El Camino Real, San Diego, CA 92121/92130) — not a registered‑agent service. Halozyme, Inc. ships the claimed technology inside marketed drugs.

2. Known asserter in the chain — not present.
Neither current nor prior assignee matches any published NPE list. I found no Acacia, Marathon Patent Group, Intellectual Ventures, IPNav, Wi‑LAN, Conversant/Mosaid, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Document Generation Corp, or Spangenberg‑affiliated entity anywhere in the chain. The asserters on this patent are Merck (as PGR petitioner) and Halozyme (as plaintiff) — both operating pharmaceutical manufacturers.

3. Repeat correspondent across the chain — unclear.
I could not retrieve the assignment correspondent of record for any of the three 2023‑06‑27 recordings, so I explicitly decline to make this finding. For completeness (and clearly labelled as not the assignment correspondent): family prosecution firm = Dentons US LLP; PGR2025‑00050 counsel are Jeffrey P. Kushan / Sidley Austin LLP for petitioner Merck and Eldora Ellison for patent owner Halozyme; lead district‑court counsel of record — none of these are NPE‑associated names. No recurrence finding.

4. Cascading transfers — not present.
Three recordings, one date (2023‑06‑27), zero third‑party LLC hops, all inside one corporate family, over a 0‑day window. No chain of LLCs, no shared‑address assignees, no common‑principal pattern.

5. Pre-litigation transfer — not present.
The only assignment block is 2023‑06‑27. The first infringement suit naming this patent is Halozyme, Inc. v. Merck Sharp & Dohme LLC, 2:25‑cv‑03179 (D.N.J.), filed 2025‑04‑24 — roughly 22 months later, well outside the 6‑month window. (The grant date, 2024‑09‑03, is ~8 months pre‑suit, but a grant is not a transfer.)

6. Bankruptcy fire‑sale — not present.
No Chapter 7/11 activity by Halozyme. The assignee is a going concern guiding to $1.3–1.375B FY2025 revenue.

7. Privateering — not present.
Halozyme asserts in its own name, on its own patents, against a direct commercial competitor (Merck's subcutaneous KEYTRUDA®). There is no intermediary NPE asserting on Halozyme's behalf. Reported context: Halozyme offered MSD a licence in March 2025 and sued on 2025‑04‑24 after MSD declined — the classic operating‑company licensing‑then‑suit posture, not privateering.

8. Defensive aggregator — not present.
No RPX, Allied Security Trust, LOT Network, Unified Patents, or OIN entity appears in the chain. The patent is live and being actively asserted, not neutralised.

Adjacent pattern worth recording (not an NPE signal)

Although no NPE hallmark is present, this patent sits inside an assertion‑oriented continuation strategy that a portfolio analyst should log separately:

• Late‑filed continuations: application 18/339,829 was filed 2023‑06‑22 on a 2011‑12‑30 priority claim — ~11.5 years into the term — and granted 2024‑09‑03, with anticipated expiration around 2032‑12‑28/29 (Google Patents estimates 2032‑12‑28; a Korean sell‑side table lists 2032.12.29 — flagging the one‑day discrepancy, which is an artifact of PTA/terminal‑disclaimer treatment and should be confirmed in PAIR).
• Thicket formation: at least 14 Halozyme US patents from this family were challenged by MSD in PGRs filed Nov 2024–Jun 2025, all instituted (US 11952600, 12018298, 12152262, 12123035, 12110520, 12054758, 12060590, 12049652, 12104185, 12037618, 12091692, 12077791, 12195773, 12264345).
• Claim scope now confirmed (correcting the earlier "could not verify claims" caveat): independent claim language for this patent is reported verbatim as "position 309 is a replacement selected from among E, G, H, L, M, N, Q, R, S, and T." This is consistent with — and slightly narrower than — the earlier summary's guess of "E, G, H, L, M, N, Q, R, S, V and T" (the V is not in the quoted claim; the native residue at 309 is I). This also resolves the earlier 307/312 caveat: PGR2025‑00050 concerns 309 specifically (its exhibit list includes Swiss‑Model structures for I309L, I309N, I309E, I309G, I309H, I309M, I309Q, I309R, I309S and I309T; instituted 2025‑11‑19).
• Assertion cascade: the PGR2025‑00050 record shows an unusual patent‑owner motion to terminate (Feb 2026) plus litigation‑integrity discovery fight — i.e., the dispute has moved into a conduct‑based attack rather than pure merits.

Verdict

Operating-company assertion.

Justification: the complete recorded chain consists of three 2023‑06‑27 inventor/parent→Halozyme, Inc. assignments (no reel/frame retrievable), all inside the Halozyme corporate family, with zero third‑party or LLC transfers and zero recorded security or licence interests. The current owner, Halozyme, Inc., is the operating arm of publicly traded Halozyme Therapeutics, Inc. (CIK 0001159036, FY2025 revenue guidance $1.3–1.375B), ships the claimed rHuPH20 technology inside marketed subcutaneous drug products, and is suing Merck — an actual competitor — in Halozyme, Inc. v. Merck Sharp & Dohme LLC, No. 2:25‑cv‑03179 (D.N.J., filed 2025‑04‑24), with the patent under instituted post‑grant review in PGR2025‑00050 (instituted 2025‑11‑19). No NPE signal is present; the only concern is aggressive continuation‑thicket portfolio strategy by an operating company, which is not an NPE pattern.

Verification links:

• USPTO Assignment Center: https://assignmentcenter.uspto.gov/
• USPTO Patent Assignment Search: https://assignment.uspto.gov/patent/index.html (query "12077791")
• Google Patents legal events: https://patents.google.com/patent/US12077791/en
• PTAB PGR2025‑00050: https://portal.unifiedpatents.com/ptab/case/PGR2025-00050 · https://ipverse.greyb.com/ptab-web/cases/case-details/PGR2025-00050
• District court: https://portal.unifiedpatents.com/litigation/New%20Jersey%20District%20Court/case/2%3A25-cv-03179

Explicit gaps (not inferred): reel/frame numbers for the three 2023‑06‑27 recordings; the assignment correspondent of record; the executed (as opposed to recorded) dates of those assignments; and any post‑issuance assignment, licence, or security interest not surfaced by the Google Patents legal‑events mirror. If Assignment Center is queried directly and a fourth entry appears, the verdict is unlikely to change — but the reel/frame citations above should be back‑filled.

I'll search for the USPTO records and cited prior art for this specific patent number.

Key finding: the patent-owner filings reference an "L307" discussion, while the '791 title says 309 — I'll flag that later. First, let me try to pull the actual front-page "References Cited" for 12,077,791.

Let me try to locate the granted patent's front-page reference list directly.

Bottom line up front

I could not retrieve a verbatim copy of the front-page "(56) References Cited" list for US 12,077,791 B2 from the USPTO/Google Patents record. The mirrored full text I have contains the specification and definitions but omits the front page and the numbered claims. What I was able to retrieve and verify are the reference lists that appear in the PTAB/PGR record for this patent family (including exhibits in the MSD challenges, one of which — IPR2026‑00312 — charts prior art against the sibling US 10,865,400 using a reference the petitioner labels "US‑275"), plus the art expressly acknowledged in the '791 specification itself.

So the list below is "references of record in the '791 family/PTAB record + applicant-acknowledged art," not a certified transcription of the '791 front page. Each entry is tagged with how it was verified. I have not invented any citation: every item below appeared in a search result I can point to, and anything I inferred (as opposed to read) is flagged as an inference.

⚠️ I cannot map any reference to a numbered claim with confidence, because I do not have the verbatim claim text of US 12,077,791 (a limitation also flagged in the previously generated summary). The § 102 mapping below is therefore given at the claim-category level and is expressly provisional.

1. What the record actually returned (audit trail)

Not retrieved: the actual examiner-cited U.S. patent documents and foreign documents on the '791 front page (i.e., the numbered items under "(56)"), and the verbatim claims.

2. Patent-document references (of record in the '791 family / PTAB record)

3. Non-patent literature (verified from the family's PTAB/EPO reference lists)

4. How the § 102 analysis actually hangs together

1. The whole § 102 question reduces to priority. US 12,077,791 was filed 2023‑06‑22 as a continuation chain reaching back to 13/694,731 (filed 2012‑12‑28) and provisional 61/631,313 (2011‑12‑30). If every claim is fully supported by that 2011 disclosure, then pre‑AIA § 102 applies and the only usable art predates 2011‑12‑30 — which excludes P1, P2, P8, N14, and probably P3/P7.
2. If any claim is not entitled to 2011‑12‑30, the AIA applies (application contained a claim with an effective filing date on/after 2013‑03‑16), and the family's own 2013 publications (P1, P2) become § 102(a)(1) prior art notwithstanding the shared inventorship. That is precisely the posture in which Petitioner's use of "US‑275" makes sense — the same reference is being used against sibling claim 4 of US 10,865,400 in IPR2026‑00312 (Ex. 1003).
3. The single most dangerous reference for the '791 title position is therefore P1 ("US‑275")/P2 (WO 2013/102144), because the claim chart I retrieved states that the reference expressly discloses a single-substitution I309N PH20₁₋₄₄₇ variant with 311 % relative activity — i.e., literally a "PH20 polypeptide with a modification at position 309" that is more active than wild type. If the claim language covers I309N (or a genus including N at 309), and if priority fails, this is a § 102(a)(1) anticipation rather than a § 103 combination.
4. Everything else in the list (P3–P6, N3–N13) is, on the record I can see, § 103 art at best — it supplies the soluble/truncated PH20 scaffold, the assay formats, the salt effect (N10), and the phenolic-preservative denaturation rationale (N9), but none of it discloses the distinguishing 309 substitution.
5. References cited in an IDS are not the same as references applied in a rejection. I can confirm the family/PTAB record lists them; I cannot confirm which of them the examiner actually cited on the '791 front page.

5. Contradictions and unresolved items I am flagging rather than correcting

• 309 vs. 307 — unresolved and material. The '791 title says "modification at position 309," and the PTAB claim chart I retrieved confirms a disclosed I309N variant. However, the patent-owner response text I retrieved (PTAB petition file 1557268) argues about "the L307 mutation and 91 % identity" and "nine L307 variants." Those two positions (307, 309) do not match. My working read is that file 1557268 belongs to a different, sibling Halozyme patent in the 14‑patent MSD group (the group includes US 12,104,185, US 12,104,184, US 12,110,520, US 12,123,035, US 12,152,262, US 12,195,773, US 12,264,345, etc.), while PGR2025‑00050 paper file 1557844 is the one that expressly names US 12,077,791. I have not resolved this, and I am not renumbering 309 to 307 or vice versa.
• "US‑275" is not verified. I am reporting the petitioner's literal shorthand. My identification of it with a …/0302275 U.S. publication is an inference, not a verified citation. Treat the P1 row as "content verified, document number unverified."
• Claims still unverified. As in the earlier section, I do not have the verbatim text of claims 1–N of US 12,077,791. Every "potentially anticipates claim X" statement above is therefore a claim-category statement, not a limitation-by-limitation § 102 mapping.
• Two different "today" dates appear in my instructions (2026‑09‑28 in the system context, 2026‑04‑26 in the task). I have not resolved that; all docket statements are "as of the date of these searches." The most recent item I retrieved is IPR2026‑00312 (filed 2026‑03‑23) and PGR2025‑00050 exhibits dated into 2026, all of which are consistent with a 2026 current date.

6. What I could not verify (explicit)

• The verbatim (56) "References Cited" list as printed on the face of US 12,077,791 B2 (U.S. patents, foreign patent documents, and the examiner's initialed citations).
• The verbatim claims, and hence which specific substitution(s) at 309 are recited (candidate residues from the specification for 309 include E, G, H, L, M, N, Q, R, S, V, T — but I cannot confirm which appear in the claims).
• Whether P1 ("US‑275") is the same document as US 2013/0302275 A1 or another …-275 document.
• Whether US 2015/0010529 A1 (thermally stable PH20 variants) is actually a cited reference on the '791.
• Whether any U.S. patent/application listed on the '791 front page was applied in a § 102 rejection during prosecution (as opposed to merely being cited in an IDS).
• Any CAFC 2026 appeal activity for this patent (searched, none found earlier).

I'll gather the prior-art references cited on the '791 patent and the PGR challenge grounds before analyzing.

Let me pull the specific prior-art references cited on the '791 patent and the PGR2025-00050 grounds.

Let me confirm the primary reference and the '791 claim language.

Obviousness Analysis — U.S. Patent 12,077,791 B2 under 35 U.S.C. § 103

Prepared: April 26, 2026 (note: the session clock reports 2026‑09‑28; I flag this discrepancy rather than silently reconciling it)
Patent: US 12,077,791 B2, "PH20 Polypeptide Variants with a Modification at Position 309 of the PH20 Polypeptide and a Method of Making Thereof"
Assignee: Halozyme, Inc. | Priority: 2011‑12‑30 | Granted: 2024‑09‑03 | Challenged in: PGR2025‑00050 (Merck Sharp & Dohme LLC v. Halozyme, Inc.), instituted

1. Evidence base and caveats

What I am building on. The previously generated sections identified the patent, its family, its priority chain, and the PGR/litigation posture. Those are treated as authoritative here and are not repeated. Two corrections/refinements from the new evidence base:

1. The earlier section flagged uncertainty about "position 307 and 312" references appearing in the PGR record. That is now resolved: position 307 is claimed in a different family member (the sibling that the parties call the "'590 patent"; Merck's PGR2025‑00030/‑00024 briefing refers to "the nine L307 variants and their active subvariants"), while position 309 is specific to the '791 patent. Merck's exhibit list for PGR2025‑00050 contains SWISS‑MODEL structures for I309L, I309N, I309E, I309G, I309H, I309M, I309Q, I309R, I309S, I309T, plus combinations with N47A/N131A/N219A and ortholog (orangutan/chimpanzee/gibbon) I309N models (https://ipverse.greyb.com/[ptab](/ptab)-web/cases/case-details/PGR2025-00050). There is no evidence of a 309→307/312 error in the patent.
2. The earlier section's plain‑language claim overview can now be sharpened. Per the Board's preliminary record: claim 1 "allows up to 21 changes, with each additional change (except at position 309) being to any of 19 alternative amino acids. But the up to 21 changes also can be at any of 433 different positions," and the claim encompasses "modified PH20 polypeptides with 'increased activity' that have 433 residues (SEQ ID NO:35) … and up to 17 or 21 additional substitutions" (https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1557844](/patent/1557844)/download-documents?artifactId=ivZep5Ai02mB5V5bcvpWGIxqIuX3bbeITbp3X4qF1LILTuEJPuruMdw).

⚠️ Unverified: the verbatim numbering and numeric limits (91% vs. 95% identity; "up to 17" vs. "up to 21" differences) of claims 1–N. The composition of the claim (mandatory 309 substitution + a small number of additional differences + retained hyaluronidase activity) is well corroborated; the numerals are not. Any inference that turns on an exact numeral is flagged below.

The prior art on the face of this page. The front‑page prior‑art field gives a critical date of 2011‑12‑30 and keyword set "position corresponding / polypeptide / modified / amino acid / seq." The citation lists available for this family (FreePatentsOnline listing for co‑pending US 2025/0154488, https://www.freepatentsonline.com/y2025/0154488.html) name US 7,767,429 and Chao et al., Biochemistry 2007;46:6911‑6920, alongside the family's own members. The PGR record adds the references Merck has actually asserted: the '429 patent (EX1005), Chao (EX1006), Stern (EX1008), Zhang (EX1010), Arming (EX1011), and US 2010/0143457 (the "Wei '457 publication"), with Guo et al. appearing in the Examiner's written‑description rejection as teaching additivity of mutation effects (EX1002, 513).

2. The claim to be invalidated, anatomized

For § 103 purposes, claim 1 reduces to three elements:

This anatomy controls the entire analysis. Elements (a) and (c)‑structure are squarely in the prior art. Element (b) — a substitution at one specific, non‑catalytic, non‑conserved position — is where the case is won or lost, and the patent's own data (57.13% of 6,753 single substitutions inactive) cuts both ways.

3. The prior art

3.1 US 7,767,429 (Frost et al., Halozyme; filed 2003‑2004; issued 2010‑08‑03) — the primary reference

The '429 patent claims and exemplifies the soluble, neutral‑active human PH20 glycoprotein ("sHASEGP") truncated at residue 447 (PH20₁₋₄₄₇; residues 36–482 of SEQ ID NO:1) and its C‑terminal truncation series. Critically, it teaches in express terms:

"Those of skill in this art recognize that, in general, single amino acid substitutions in non‑essential regions of a polypeptide do not substantially alter biological activity," and that "other substitutions are also permissible and can be determined empirically or in accord with known conservative substitutions," with a Table 1 of conservative replacements (quoted in the PGR briefing; e.g. https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1557626](/patent/1557626)/download-documents; see also the petition digest at http://www.pearceip.law/wp-content/uploads/2025/03/MSD-v-Halozyme-[IPR](/resources/cost-of-inter-partes-review)-Petitions-Filed-Nov-2024-to-Feb-2025.pdf).

§ 102 status. The '429 issued 2010‑08‑03, more than one year before the earliest priority date (2011‑12‑30), and its pre‑grant publication likewise predates the critical date by years. It is therefore § 102(b) prior art, and the common‑ownership exception (pre‑AIA § 103(c); AIA § 102(b)(2)(C)) does not reach it — common ownership only disqualifies art that is prior art solely under § 102(e)/(f)/(g) (pre‑AIA) or § 102(a)(2) (AIA). Halozyme cannot insulate its own earlier patent on that basis, and the inventors of record differ (Frost et al. vs. Wei et al.), so the "same inventive entity" route is also closed.

3.2 Chao et al., Biochemistry 2007;46:6911‑6920 — the structural teaching

Chao reports the experimentally determined structure of human HYAL‑1, its superposition on bee‑venom hyaluronidase, the conserved catalytic residues, invariant positions, conserved disulfide‑forming cysteines, conserved N‑glycosylation sites, and a C‑terminal EGF‑like domain in PH20 (reported at 337–409). This is the reference that converts the '429 patent's general invitation into a specific structural map from which non‑essential positions can be read off.

3.3 Secondary/corroborating references

• US 2010/0143457 (Wei et al., pub. 2010‑06‑10) — the C‑terminal truncation series of PH20 with activity data for truncations running from position 465 down to 430; supplies the 433‑residue species and shows truncated soluble PH20 retains hyaluronidase activity.
• Arming et al., Eur. J. Biochem. 1997;247:810‑814 — PH20 site‑directed mutagenesis: E113Q and E249Q abolish activity; D111N retains ~3%. Establishes which residues are essential — and, by exclusion, that residues like 309 are not.
• Zhang et al. — Hyal‑1 point mutants; N216A and N350 mutations behave differently, underlining that not every position is essential.
• Stern et al. — hyaluronidases share a common "elongated cleft" active site.
• Guo et al. — mutation effects on protein function are "largely additive" (relied on by the Examiner).

4. Grounds of rejection

Ground 1 (strongest): '429 in view of Chao — single substitution at position 309

Rationale. Substitution of one known element for another to obtain a predictable result (KSR). The '429 patent expressly identifies the modification (single amino‑acid substitution), the locus (non‑essential regions of PH20), the scaffold (PH20₁₋₄₄₇ / soluble truncated PH20), and the expected result (no substantial alteration of activity). Chao supplies the structural information needed to identify which residues sit in non‑essential regions, including the boundaries of the HyalEGF domain and the invariant catalytic set. A POSA executing this two‑reference recipe arrives at position 309.

Motivation, articulated. (i) The '429 patent's express assurance of success; (ii) PH20₁₋₄₄₇ was an FDA‑approved therapeutic (Hylenex®, 2005), giving a concrete commercial driver; (iii) the co‑pending subcutaneous‑delivery field created reason to optimize a known enzyme; (iv) the art taught that single conservative substitutions in non‑essential regions are a routine tool.

Expectation of success. Reasonable for this position if the petitioner shows 309 lies outside the catalytic/structural core and that homologous hyaluronidases tolerate variation there. The strongest form of this showing is a multiple‑sequence alignment of PH20 orthologs and homologs (Merck's Dr. Park performed precisely this exercise on 88 homologous sequences in the sibling proceedings): if position 309 shows a distribution of amino acids across species — rather than invariance — the alignment itself supplies the "finite number of identified, predictable solutions" that KSR treats as obvious to try. Merck's own exhibit list in PGR2025‑00050 models I309N in orangutan, chimpanzee, and gibbon PH20, which suggests the ortholog data are being used to argue that position 309 varies naturally.

Ground 2: Ground 1 + Wei '457 publication — the truncated ‑species element

Because claim 1's species include a 433‑residue soluble PH20 (SEQ ID NO:35), a petitioner should pair the '429's truncation teaching with the '457 publication's explicit activity data across the 430–465 truncation range. Together they make the "soluble truncated PH20 scaffold" element plainly obvious and pre‑empt the argument that a 433‑residue backbone is a separate inventive contribution.

Ground 3: Ground 1 + Guo — the multiple‑substitution element

If claim 1 permits up to ~17–21 differences, the petitioner needs a teaching of predictability for combinations. Guo's additivity teaching (already in the prosecution file) supplies it: mutation effects are largely additive, so a POSA would expect the retained‑activity property to survive the stacking of a small number of tolerated changes. This is the weakest of the grounds — see § 5.

Ground 4: Ground 1 + Arming/Zhang — "309 is not essential"

Arming and Zhang define the essential residues (E113, E249, D111 in PH20; the Hyal‑1 catalytic cluster). A POSA reading those references alongside Chao's invariant‑residue map would conclude that position 309 is a permissible site of substitution, not a protected one. This ground is best pleaded as evidence supporting the expectation of success for Grounds 1–3 rather than as a standalone combination.

Ground 5 (method claim): '429 + Chao + conventional CHO expression

Any "method of making" claim (culturing a host cell expressing a nucleic‑acid encoding the variant; recovering the secreted polypeptide) is obvious a fortiori if the polypeptide is obvious: the '429 patent itself teaches expression of sHASEGP in mammalian (CHO) cells with a heterologous or native signal sequence. The method adds no independent inventive weight.

5. Where the § 103 case is vulnerable (and what Halozyme will say)

This is not a straightforward win, for reasons that the Board has already surfaced on the record:

1. The patent's own data cut against a broad expectation of success. The '791 patent reports 6,753 single substitutions across residues 1–447; 3,380 (~57.13%) were inactive, fewer than 10% had increased activity. Halozyme will argue this is the antithesis of predictability and that "over 600 increased‑activity mutants out of 6,753" is the opposite of a finite, predictable set (POPR/Board record at petition 1557844 and the '791 preliminary-decision excerpts).
2. The multi‑substitution element is materially harder. Merck's own witness conceded that SWISS‑MODEL "doesn't tell you anything about the energetics" and that modeling combinations "was not a solved problem back in 2011" (deposition excerpts appearing in the sibling PGR record, e.g. https://www.alteogen.com/upload/board/최종결정_ffedf.pdf). Where a claim covers a genus ranging over 10⁴⁹–10⁶⁰ species, the Federal Circuit's admonition in In re Stepan/In re Vaeck — that "general guidance" is not a reasonable expectation of success — is available to the patentee.
3. Teaching away on truncation. The '429 patent is itself cited by Merck for the proposition that "PH20 polypeptides terminating at or below position 442 have significantly reduced or no hyaluronidase activity" (petition 1557268). That same passage is a teaching‑away arrow pointed at the 433‑residue species (SEQ ID NO:35) if the claim scope requires it.
4. Institution‑stage reality. In the sibling PGRs where institution decisions issued (the '520, '652, and '185 patents), the PTAB instituted on the § 112 grounds but "found that Petitioner had not shown it was more likely than not to establish that the patents are obvious in light of the prior art" (https://biologicshq.com/ptab-grants-institution-of-three-pgrs-related-to-mercks-keytruda-qlex/; https://www.lexology.com/library/detail.aspx?g=12e547c3-5cea-4251-837a-e07ff5fa2a19). The publicly posted Final Written Decision in PGR2025‑00017 (US 12,110,520) is captioned "Unpatentable," but its substantive discussion is directed to written description/enablement and the position‑324/317 theories, and the decision recites both parties' § 103 arguments — consistent with a § 112‑driven outcome rather than a § 103 win. An obviousness challenge to this family is, on the current record, materially weaker than the enablement/written‑description challenge.
5. Functional limitations with no nexus. If any claim requires "increased stability in the presence of a phenolic preservative" (phenol, m‑cresol), the petitioner must contend with the fact that the pre‑2011 art treated phenolics as denaturing excipients; there is no obvious pre‑2011 reason to expect a PH20 point mutant to be phenol‑stable. Conversely, if claim 1 is limited to "hyaluronidase activity," this limitation disappears and Grounds 1–3 strengthen considerably.
6. Secondary considerations (to be assessed if reached): Halozyme's commercial licensing success (ENHANZE®), the FDA approvals, and the ~25‑year research narrative are available, but the nexus requirement (In re Kao; Rambus) is a serious obstacle — Halozyme itself has told investors the challenged patents are "of no consequence" to its ENHANZE revenue, which undercuts any nexus theory built on licensing revenue.

6. Bottom line

The single most defensible § 103 theory is: the '429 patent expressly instructs making single substitutions in non‑essential regions of PH20₁₋₄₄₇ without substantially altering activity; Chao maps which regions and residues are non‑essential; a sequence alignment across PH20 homologs shows that position 309 tolerates a variety of residues across species; therefore at least the single‑substitution 309 species of claim 1 is obvious. That theory will not, on the record as it stands, carry the multi‑substitution scope of the claim, and it has already failed to persuade the Board at the institution stage in companion cases.

Confidence: High on the identity and content of the prior art and on the '429 patent's express teaching. Moderate on the claim's exact numeric boundaries. Moderate‑to‑low on the ultimate § 103 outcome, which turns on evidence (the 309‑position alignment and the 57% inactivity datum) that I have seen only through party briefing, not from the primary exhibits.

Citations used: https://patents.google.com/patent/US12077791/en · https://ipverse.greyb.com/ptab-web/cases/case-details/PGR2025-00050 · https://ptacts.uspto.gov/ptacts/public-informations/petitions/1557844 · https://ptacts.uspto.gov/ptacts/public-informations/petitions/1557626 · https://ptacts.uspto.gov/ptacts/public-informations/petitions/1557268 · https://www.freepatentsonline.com/y2025/0154488.html · https://biologicshq.com/ptab-grants-institution-of-three-pgrs-related-to-mercks-keytruda-qlex/ · https://www.lexology.com/library/detail.aspx?g=12e547c3-5cea-4251-837a-e07ff5fa2a19 · https://www.pearceip.law/2025/11/19/msds-subcutaneous-keytruda-approved-in-europe/ · http://www.pearceip.law/wp-content/uploads/2025/03/MSD-v-Halozyme-IPR-Petitions-Filed-Nov-2024-to-Feb-2025.pdf · https://biologicshq.com/wp-content/uploads/2026/09/PTAB-PGR2025-00017-Merck-v.-Halozyme-Keytruda-Qlex-Final-Written-Decision-Unpatentable.pdf · https://www.alteogen.com/upload/board/최종결정_ffedf.pdf · https://www.docketalarm.com/cases/PTAB/PGR2025-00017/