US 11959109

US Patent 11,959,109 — Analyst Summary

Important caveat up front: I could not directly fetch the full patent text from the USPTO or Google Patents before hitting the search-step limit, so some bibliographic fields below are sourced from secondary metadata and the PGR record rather than the patent document itself. I flag confidence levels accordingly.

Confirmed bibliographic data (high confidence)

The patent is currently (as of late 2025 / into 2026) the subject of a post-grant review: Charles River Laboratories, Inc. v. Seikagaku Corporation, PGR2025-00023, challenging claims 1–10 under 35 U.S.C. § 112 (written description and enablement). Note that a statutory disclaimer of claim 10 has been filed (Ex. 2001 in the PGR record). The PGR petition identifies prosecution history at App. No. 18/346,420, and priority back to a "'767 Application" and a "'840 JP priority application." These identifiers are reproduced literally as they appear in the PGR papers; I did not independently verify their full contents.

Title

Medium confidence. Google Patents metadata for US11959109B2 lists the title as:

"Recombinant Factor C and method for producing the same, and method for measuring endotoxin"

This is the same title Google lists for sibling patent US 10,982,202 (Seikagaku, priority 2012-12-10), so I cannot fully rule out metadata carryover. A related European divisional in the Seikagaku family (EP4745235A2, originating from an Oct. 18, 2017 filing) is titled "Recombinant proteins derived from genus Limulus, and DNA molecules encoding same," with an abstract covering "methods for producing an endotoxin detecting agent … and methods for detecting endotoxin in a specimen." The PGR petition describes the '109 claims in those same terms. Verify the exact title against the patent front page if precision is needed.

Inventors

Low-to-medium confidence. I did not find a page explicitly listing the named inventors of the '109 patent itself. The closely related Seikagaku EP family (EP4745235A2 / EP3530670, same subject matter and priority chain) names:

• Mizumura, Hikaru
• Kobayashi, Yuki
• Oda, Toshio

These are plausibly (but not confirmed to be) the inventors of the '109 patent. Do not treat as authoritative without checking the USPTO front page.

Filing date

Not confirmed. The issue date is April 16, 2024 (Google Patents), and the application is No. 18/346,420, which suggests a mid-2023 filing; the PGR record shows an "Opposition" exhibit referencing a European counterpart (EP 3 530 670). I could not retrieve the exact US filing date.

Abstract

I could not retrieve the verbatim USPTO abstract. Based on the family counterpart (EP4745235A2 abstract) and the PGR petition's overview, the invention relates to:

• methods for producing an endotoxin detection agent (assay) by recombinantly producing the horseshoe-crab clotting-cascade proteins — Factor C, Factor B, and pro-clotting enzyme (zymogen proteins) — and
• methods for detecting/measuring endotoxin in a specimen using the resulting agent, where the three recombinant proteins assemble into a functioning enzymatic cascade that reacts to endotoxin.

Independent claims — plain-language overview

Per the PGR petition (which reproduces the challenged-claim substance), the claims are method/genus claims built around a recombinant alternative to animal-derived Limulus amebocyte lysate (LAL). There are 10 claims; claim 10 has been disclaimed. The petition states the challenged claims "define a genus of endotoxin detection assays and methods for making the same requiring the recombinant production of all three" proteins, with claim 1 as the primary independent claim and the set including method-of-making and method-of-measuring embodiments.

Independent claim 1 (plain language, inferred from the PGR record):
A method of producing an endotoxin detection assay in which:

1. Factor C is produced recombinantly (expressed from a host cell programmed with horseshoe-crab Factor C genetic information);
2. Factor B is produced recombinantly and, critically, is expressed in a mammalian cell as the host cell;
3. Pro-clotting enzyme is produced recombinantly, also expressed in a mammalian cell as the host cell;
4. the three recombinant proteins are recovered and combined into an assay that performs the endotoxin-triggered clotting cascade, so that endotoxin in a test sample can be detected.

The genus language allows options/variation in (a) the species of horseshoe crab providing the sequence information, (b) the recombinant expression systems used, and (c) the recovery means — with the components permitted to come from different expression systems/species and still be combined. Petitioner conservatively counts the claim-1 genus as ~3,456 combinations.

Other claims (dependent, and possibly additional independents): per the petition, dependent claims 2–9 narrow the genus (e.g., by fixing expression systems, recovery steps, or sequence sources), and the claim set also covers methods for measuring/quantifying endotoxin in a specimen using the produced assay (the basis of the "method for measuring endotoxin" portion of the title). The exact wording, dependency structure, and any second independent claim were not retrievable in full within my search limits.

Ongoing proceeding context (grounds asserted)

• PGR2025-00023, filed by Charles River Laboratories, Inc. against Seikagaku Corporation (petition dated ~Sept. 2025).
• Ground 1: claims 1–10 lack written description (§ 112) — the priority disclosure allegedly describes only insect-cell (Sf9) production of Factor B and pro-clotting enzyme, not the claimed mammalian-cell expression across the full genus.
• Ground 2: claims 1–10 are not enabled (§ 112) across the full genus.
• Patent Owner has filed a preliminary response arguing (inter alia) that the claims are supported by the JP priority application and seeking discretionary denial; a disclaimer of claim 10 was also filed, narrowing the case.

Key references

• USPTO PTAB PGR2025-00023 papers (ptacts.uspto.gov), including petition text describing claims 1–10 of the '109 patent.
• Google Patents metadata for US11959109B2 (issue date 2024-04-16; assignee Seikagaku Corporation; listed title "Recombinant Factor C and method for producing the same, and method for measuring endotoxin").
• Seikagaku EP family documents (EP4745235A2 / EP3530670) for the subject-matter abstract and probable inventors.

Bottom line: US 11,959,109 (Seikagaku Corporation; issued April 16, 2024) covers recombinant horseshoe-crab endotoxin-detection reagents/methods built from recombinantly produced Factor C, Factor B, and pro-clotting enzyme, with Factor B and pro-clotting enzyme expressed in mammalian host cells. Title and inventor fields carry moderate uncertainty and should be verified against the USPTO full-text record before formal citation.

Result: No district-court litigation identified for US Patent 11,959,109

Based on the searches I could complete, I did not find any federal district court litigation naming US Patent 11,959,109 as an asserted patent. The only adversarial proceeding I located involving that exact patent number is a PTAB post-grant review (an administrative proceeding, not a district-court case).

Administrative proceeding found (not district-court litigation)

Under PGR procedure, Charles River Laboratories is the moving/challenging party (analogous to a plaintiff) and Seikagaku Corporation is the patent owner (analogous to a defendant). Trial was instituted on September 9, 2025, meaning the PTAB found it reasonably likely that at least one challenged claim would be found unpatentable.

Important exclusions (to avoid confusion with similar numbers)

• I deliberately excluded University of British Columbia v. Caption Health, Inc. et al., No. 5:24-cv-03200 (N.D. Cal., filed May 28, 2024). Although that case discusses a "'591 patent," the patent at issue there is US Patent 11,129,591 (echocardiography image quality), which is a different patent number from 11,959,109. Per your instruction not to auto-correct or conflate identifiers, that case does not involve the patent you asked about.
• A chemical-supplier catalog hit for "EVT-11959109" and a Japanese real-estate listing using "11959109" as a property reference are unrelated and were disregarded.

Caveats

• My search results did not disclose whether the PGR was filed in the shadow of a related district-court case (e.g., a pre-suit challenge) or whether Seikagaku has separately asserted this patent in litigation. The searches were also rate-limited, so I could not exhaustively query PACER/Unified Patents/CAFC dockets for this patent number.
• If you want a complete confirmation of "no district court case," I'd recommend running the patent number through:
  • Unified Patents Portal (https://portal.unifiedpatents.com/litigation/caselist),
  • RPX Insight (https://litigation.rpxcorp.com), and
  • PACER nationwide case searches.

Bottom line: As of the information retrievable today, the only known adversarial matter involving US Patent 11,959,109 is PTAB proceeding PGR2025-00023 (Charles River Laboratories, Inc. v. Seikagaku Corporation), filed January 15, 2025, with trial instituted September 9, 2025 — no district-court litigation was found.

I'll start by verifying the current state of PTAB activity for US Patent 11,959,109, since there's a tension between the ODP block (no proceedings on file) and the prior litigation summary (PGR2025-00023). Let me search for current information.

I have good initial data. The ODP block says "no proceedings on file" but the record clearly shows PGR2025-00023 is active (instituted 2025-09-09). Let me dig into the docket, institution decision, panel, and any final decision or settlement.

The picture is forming: PGR2025-00023 challenges claims 1–10 (claim 10 disclaimed, leaving 1–9), with § 112 and priority-date grounds. Let me pin down the institution decision panel/reasoning, the claims actually instituted, and whether any final decision or settlement has occurred as of today (2026-09-09).

Proceedings overview

One AIA trial proceeding is pending on US Patent 11,959,109 — PGR2025-00023, status "Trial Instituted" (active). No Final Written Decision, no settlement, and no institution denial has occurred; no claims have been canceled by the Board yet. Bottom-line defensive posture: the patent has not been "hardened" or "gutted" — it is mid-stress-test. Trial was instituted on 2025-09-09, meaning the Board found it reasonably likely that at least one challenged claim is unpatentable, but all challenged claims (1–9, after patent owner's disclaimer of claim 10) remain in force until a FWD issues. A defendant facing assertion today gets a credible stay-application (parallel PTAB review of the very claims being asserted) and, if the FWD comes down against Seikagaku, claim-cancellation ammunition — but cannot yet tell a demand-letter troll that any claim is dead.

⚠️ Data conflict flagged: the structured "PTAB proceedings on file" block (USPTO Open Data Portal) reports no AIA trial proceedings for this patent. That is stale/incomplete — the public PTAB record (ipverse, DocketAlarm, PTACTS filings) confirms PGR2025-00023 was filed 2025-01-15 and instituted 2025-09-09. Treat the ODP block as an ingest gap, not as the truth.

PGR2025-00023 — Charles River Laboratories, Inc. v. Seikagaku Corporation

• Type: Post-Grant Review (PGR)
• Filed: 2025-01-15 (PTAB docket; the Acting Director's referral decision recites the petition as filed 2025-01-16 — one-day discrepancy in the sources)
• Status: "Trial Instituted" — active merits phase; no Final Written Decision as of the latest retrievable data (ipverse snapshot updated 2026-08-31 still lists "Trial Instituted" / "Decision pending")
• Judge panel: APJs Michael J. Fitzpatrick, Susan L. C. Mitchell, and Tawen Chang (current panel). APJ Mitchell replaced APJ James A. Worth "due to unavailability" per a Panel Change Order issued by Vice Chief APJ Michael W. Kim; the order states all prior decisions remain in effect. I could not confirm from available sources whether the 2025-09-09 Institution Decision was authored by the pre- or post-change panel.
• Petition grounds: The petition challenges claims 1–10 of the '109 patent (petitioner's expert, Dr. Siddhartha Jain, declared on claims 1–10; patent owner subsequently disclaimed claim 10, leaving claims 1–9 as the live challenged set). Based on the Patent Owner's Preliminary Response (dated 2025-06-11), the grounds are:
  • Ground 1 — § 112 written description / enablement of claim 1's genus as of the asserted 2013-12-10 priority date (patent owner argued petitioner improperly imports specification components into claim 1 and inflates the genus calculation);
  • Ground 2 — § 112 enablement (patent owner argued the Wands factors cut against institution);
  • Ground 3 — § 102/§ 103 anticipation/obviousness over the '629 publication, expressly contingent on the claims being entitled only to a 2023-07-03 priority date rather than the 2013 priority date.
  • Subject matter: recombinant horseshoe-crab coagulation factors (Factor C, Factor B, pro-clotting enzyme) for endotoxin detection, where mammalian-cell-expressed Factor C retains activity in salt-containing pharmaceutical formulations.
• Pre-institution skirmishes: Patent owner sought discretionary denial (Paper 6; opposed Paper 8). Acting Director Coke Morgan Stewart declined to exercise discretion to deny and referred the petitions to the Board (2025), reasoning there was no parallel litigation, the patent had issued recently, and an early challenge weighs against discretionary denial (also addressing § 325(d)). Patent owner's request to compel discovery for discretionary-denial purposes was denied by the Director (email ruling 2025-07-02), with leave to renew before the panel on merits.
• Institution decision: Instituted 2025-09-09. I could not retrieve the decision's text from the available search results, so I cannot state claim-by-claim which claims/grounds were instituted; verify on PTAB E2E before relying on scope.
• Final Written Decision: None yet. Statutory deadline for the FWD is one year from institution — 2026-09-09 (today) — with possible extension for good cause, so a decision may issue imminently. Last public snapshot (2026-08-31) still showed trial pending.
• Settlement / termination: None identified. The docket is adversarial, not cooperative: Patent Owner's Response was filed 2025-12-01 (Paper 26); Patent Owner's unopposed motion for additional discovery was granted 2025-11-13 (Paper 22); that dispute was declared moot 2025-12-19 after petitioner produced discovery confirming it was the party behind parallel European Patent Office oppositions (EP '466 and EP '670, same family) — conduct patent owner says contradicts petitioner's PGR positions (PGR2025-00023, Paper 26 at 80–90).
• Appeal: None — no FWD exists to appeal to the Federal Circuit.
• Defensive value: For a defendant facing assertion of the '109 patent today: the patent owner has already surrendered claim 10 by disclaimer (one claim down, for free), and trial is instituted — under 35 U.S.C. § 324 the Board found a reasonable likelihood the challenger prevails on at least one claim. That supports a stay of any co-pending district-court case. But until the FWD issues, claims 1–9 are presumed valid and enforceable; do not advise a client that the patent is dead.

Sources: ipverse case page · DocketAlarm docket · Acting Director's referral decision and Panel Change Order (USPTO PTACTS petition files 1557244/1557243) · Patent Owner's Preliminary Response (2025-06-11, via PTACTS).

Strategic summary

Claim status of the '109 patent today — CANCELED vs. SUSTAINED vs. UNTESTED:

• CANCELED (by patent owner's own action): claim 10 was disclaimed (per the deposition record), removing it from the patent regardless of PGR outcome.
• SUSTAINED (so far): claims 1–9 remain in force — none canceled, because no FWD has issued. They are the claims under active challenge in the PGR.
• UNTESTED: any claims beyond the challenged 1–10 set (if the patent contains more) and, pending the FWD, everything not yet ruled upon. I could not confirm from available sources whether the issued patent contains claims beyond 10 — verify the issued claim set before advising.

Estoppel landscape: Because this is a PGR, the relevant bar is 35 U.S.C. § 325(e), and it attaches only when a final written decision issues. Today there is no FWD, so no estoppel has attached — neither Charles River nor Seikagaku is estopped yet, and a new defendant is not estopped at all. Once the FWD issues, Charles River (and its privies) will be barred from re-raising in district court or another AIA proceeding any ground it raised or reasonably could have raised in the PGR — which would cover its § 112 written-description/enablement theories and its '629-publication anticipation/obviousness ground. A defendant who is not in privity with Charles River retains full freedom to run those art theories in district court regardless. Note the practical caveat: the '109 patent is a post-AIA patent (PGR-eligible), so § 101/§ 112 and any prior art are all on the table for future challengers until the PGR estoppel clock runs against Charles River only.

Pattern signals: This is a coordinated, well-resourced campaign by a single life-sciences competitor — not a shell/aggregator play. Charles River Laboratories (counsel: Scott McKeown/Flora Luo, Wolf Greenfield) filed PGR2025-00023 on the '109 patent in parallel with IPR2025-00440 on the related US 11,236,318 patent (same parties, same lead counsel, same expert), and is simultaneously running EPO oppositions against Seikagaku's European family members (EP '466, EP '670) — the EPO connection became a heated discovery fight in the PGR, with Seikagaku (Morgan Lewis: Alexander Stein/Christopher Betti) moving to compel and petitioner finally conceding it was behind the European oppositions. There is no Unified Patents / defensive aggregator in the chain — this is an organic commercial dispute (recombinant endotoxin-detection reagents), with Seikagaku defending aggressively (discretionary-denial papers, discovery motions, inconsistency arguments). No repeat IPR filer pattern against this specific patent beyond Charles River's two-family attack.

Recommended next steps

1. Check PTAB E2E today for the FWD. Trial was instituted 2025-09-09, so the FWD is statutorily due 2026-09-09 (today) and may already be docketed or imminent. Retrieve the decision at PTAB E2E / PTAB decisions portal and read the claim-by-claim disposition — if claims 1–9 (or any subset) are canceled, quote the disposition verbatim to any asserting party and demand dismissal of infringement theories resting on those claims.

2. If you are being sued today: move to stay the district-court case pending the PGR — institution already found a reasonable likelihood of unpatentability, and the district court has no reason to duplicate the Board's work. If the FWD lands against the patent owner, cancellation is binding on everyone (35 U.S.C. § 318), not just Charles River, and your infringement exposure on the canceled claims ends.

3. Watch the EPO-connection thread. The Board has already seen evidence that Charles River's PGR positions allegedly contradict its European opposition positions (PGR Paper 26 at 80–90). If a FWD goes against Seikagaku, expect a Federal Circuit appeal; if it goes for Seikagaku, Charles River faces a difficult path given it has already burned its primary grounds in this PGR (with § 325(e) estoppel attaching at FWD).

4. If no PGR existed (per the ODP block), that absence would itself be a signal — but it does exist, and it is active. Do not rely on the ODP "no proceedings" ingest; the authoritative docket shows a live, instituted PGR.

Correction flag on earlier content (per instruction to flag contradictions): The earlier Patent summary reconstructed claim 1 as a three-protein cascade method (recombinant Factor C + Factor B + pro-clotting enzyme, with Factor B and pro-clotting enzyme expressed in mammalian cells). The bibliographic/abstract data I was able to retrieve in this pass does not fully corroborate that reading: the metadata abstract for US11959109B2 (PatentGuru, mirrored by ipqwery) describes a horseshoe crab Factor C protein expressed from CHO DG44 or HEK cells — and the cited prosecution history (App. 14/650,767 line) argues claims reciting "Factor C produced through being expressed from a CHO DG44 cell." The retrieved data is consistent with the '109 patent centering on Factor C product/method-of-production claims (and a method of measuring endotoxin), but I could not retrieve verbatim claim 1 of the issued patent, so the earlier plain-language claim reconstruction should be treated as unverified and the actual claim text confirmed against the patent before formal use. This ownership analysis below does not depend on resolving that discrepancy.

Inventors

Per the retrieval-verified metadata for US11959109B2 (PatentGuru; supported by ipqwery's Seikagaku family index), the named inventors are:

1. Mizumura, Hikaru — employer at filing not confirmed from a primary record. He is a recurring named inventor across the Seikagaku family filings (US2018/0259527, CN-104919046-A, EP3663400) naming Seikagaku Corporation / Seikagaku Kogyo KK as assignee, so Seikagaku staff researcher is the strong inference (medium confidence).
2. Oda, Toshio — same profile: recurring Seikagaku-family inventor with Seikagaku assigned; employer inferred as Seikagaku Corporation (medium confidence).
3. Kawabata, Shun-ichiro — public academic record identifies a Shun-ichiro Kawabata as a longtime horseshoe-crab clotting-cascade researcher at Kyushu University (Japan); his appearance alongside Seikagaku staff on this family is consistent with a normal industry–university collaboration (medium confidence; not verified against the USPTO front page).

Unusual patterns: none detected. There is no evidence of inventor mass-departure within 12 months of filing or of a post-filing portfolio fire-sale; all three names recur across the Seikagaku family filings from 2012–2023, which is the opposite of the classic pre-sale churn pattern. (Earlier summary's "low-to-medium confidence" inventor note is now upgraded to names confirmed by secondary metadata; employers remain inferred.)

Original assignee

The entity named on the issued patent (per Google Patents / PatentGuru / ipqwery and the PGR record) is Seikagaku Corporation (Tokyo, Japan; TSE code 4548; corporate predecessor Seikagaku Kogyo Kabushiki Kaisha).

• Line of business: publicly traded Japanese biopharmaceutical and diagnostics company (hyaluronic-acid products, glycosaminoglycan biochemistry, and in vitro diagnostics). The endotoxin-reagent space is commercially relevant to it — it owns an "ENDOMEASURE"-family trademark and has multiple granted/issued family patents on recombinant horseshoe-crab Factor C and endotoxin assay agents.
• Product embodiment: the company is an operating company that markets diagnostics/pharmaceuticals; whether it currently ships a product literally embodying the '109 claims is not confirmed from my sources (secondary family materials describe assay agents rather than a named marketed product).
• Current status: operating — a going-concern TSE-listed company. It is also the patent owner/respondent defending the patent in PGR2025-00023, which is consistent with continued self-ownership.

Assignment timeline

No recorded assignment records were retrievable for US 11959109 in this analysis. I could not execute a direct query of the USPTO Assignment Center database (interactive/JS-gated), and targeted web searches returned no reel/frame, conveyance, execution-date, or correspondent data for this patent number. Per your operating constraints, I will not fabricate entries.

That absence is itself informative, combined with two corroborating facts:

1. The patent issued to Seikagaku Corporation (April 16, 2024), and
2. Seikagaku Corporation appears as the patent owner / respondent in PGR2025-00023 (filed Jan. 15, 2025; trial instituted Sept. 9, 2025) — i.e., the original assignee is the party still controlling the patent through 2025–2026.

No Google Patents legal-event listing surfaced in my searches showing a post-issuance assignment, security agreement, merger, or license for this patent. (An initial inventors→corporation assignment almost certainly exists in the file history of the priority chain but its reel/frame could not be verified.)

Verification path (please run before treating "no assignments" as final):

• USPTO Patent Assignment Search — https://assignmentcenter.uspto.gov/ (search patent no. 11959109; also https://assignment.uspto.gov/patent/index.html)
• Google Patents legal events — https://patents.google.com/patent/US11959109B2/en
• PGR record confirming Seikagaku as patent owner — https://ipverse.greyb.com/[ptab](/ptab)-web/cases/case-details/PGR2025-00023

Timeline diagram

timeline
    title Ownership of US 11959109
    2012 : JP priority filed
    2023 : US continuation filed
    2024 : Patent issued to Seikagaku
    2025 : PGR2025-00023 filed by Charles River
         : Trial instituted Sep 2025

Note: this diagram reflects dates confirmed via secondary metadata (priority 2012-12-10; US application filed 2023-07-03; issue 2024-04-16; PGR filed 2025-01-15; institution 2025-09-09). Because no assignment records were found, no ownership-transfer events appear — the chain is a straight line at Seikagaku Corporation.

NPE / troll-pattern signals

1. Shell-entity transfer — not present. No transfer of this patent to any LLC / "IP Holdings" / licensing vehicle is recorded or evidenced in any retrieved source. The owner of record is a TSE-listed operating company.
2. Known asserter in the chain — not present. Neither the current nor any prior assignee matches Acacia, Marathon, Intellectual Ventures, IPNav, Wi-LAN, Conversant/Mosaid, Vringo, Pendrell, Innovatio, MPHJ, Round Rock, Spangenberg entities, or any RPX/Unified Patents high-frequency-plaintiff list surfaced. The only adversarial posture is Seikagaku defending against Charles River Laboratories in a PGR.
3. Repeat correspondent across the chain — unclear / no data. The recorded US prosecution representative for the family is Sughrue Mion, PLLC (per PatentGuru bibliographic data for the '109 patent) — a large mainstream firm that does extensive operating-company work; a single appearance is expressly not a finding per your rubric. No post-issuance recordings exist to evaluate correspondent recurrence across links, so no NPE-correspondent pattern can be shown.
4. Cascading transfers — not present. No consecutive chained-LLC assignments were found in any window, let alone <24 months.
5. Pre-litigation transfer — not present. The only proceeding is a PGR brought against the owner; no transfer occurred in the six months before it, and there is no infringement suit by the patent owner to enable.
6. Bankruptcy fire-sale — not present. Seikagaku Corporation is operating and solvent on all available evidence; no Ch. 7/11 sale appears.
7. Privateering — not present. No operating-company-to-NPE transfer and no evidence of assertion against competitors on Seikagaku's behalf.
8. Defensive aggregator (anti-NPE) — not present. The chain does not terminate at RPX, AST, LOT Network, Unified Patents, or OIN; it remains at the original corporate owner.

Verdict

Insufficient data — no recorded assignments were retrievable, and the available records show only the original-assignee state (patent issued to, and apparently still held by, Seikagaku Corporation).

That said, every NPE signal that could be evaluated is negative, and the affirmative evidence (TSE-listed operating company as assignee/patent owner; no transfers of any kind; Seikagaku defending rather than asserting in PGR2025-00023) points firmly away from a troll pattern. The verdict is driven by the absence of verifiable Assignment Center reel/frame data, not by any indicia of NPE behavior — a direct query at https://assignmentcenter.uspto.gov/ (patent no. 11959109) is the one remaining step needed to upgrade this to "Operating-company / non-asserting" with full confidence.

I'll research the prior art cited against US Patent 11,959,109. Let me start by retrieving the patent's citation data from USPTO and Google Patents.

The searches surfaced useful metadata. Now let me retrieve the Google Patents page for US11959109B2 itself to see its citations and claim text.

Let me try to retrieve the full patent record with citations from alternate databases.

I reached the search-step limit before I could pull the front-page "References Cited" list directly off the USPTO/Google Patents record for the '109 patent. Below is my best-supported analysis, with explicit confidence flags so you can tell exactly what is verified against the '109 record versus reconstructed from the patent's own priority family.

Corrections/updates to the earlier summary (flagging a contradiction)

The prior "Patent summary" section carried low-to-medium confidence on bibliographic fields and suggested inventors "Mizumura, Kobayashi, Oda." A database record keyed to US11959109B2 itself now confirms and corrects those fields:

The '109 patent's pre-grant publication is US 2023/0357742 A1 ("Novel recombinant Factor C and method for producing the same, and method for measuring endotoxin"; freepatentsonline record), whose specification confirms the invention narrative: recombinant horseshoe-crab Factor C produced in human (HEK) or Chinese-hamster (CHO) cells, with a stated object of providing a reconstituted cascade reaction system not inhibited by salts — directly relevant to the PGR's § 112 challenges described in the earlier sections.

Important verification caveat on the citation list

I could not verify the exact front-page "References Cited" of US 11,959,109 within my search limit. What I did verify:

• The specification of the '109 family (as reproduced in US 2023/0357742 A1) explicitly names only two patent documents as prior art — Patent Document 1: WO 2008/004674 and Patent Document 2: WO 2012/118226 — plus four non-patent documents (Iwanaga 1993; Nakamura et al., J. Biochem. 99:847–57 (1986); Dwarakanath et al., Biotechnol. Lett. 19(4):357–361 (1997); Wang et al., Biotechnol. Lett. 23:71–76 (2001)).
• A citation list was retrievable from sibling documents in the same priority family (the WO 2014/092079 A1 publication claiming the same 2012-12-10 priority, and the US-family member US 10,144,923 B2 page on Google Patents). These two lists heavily overlap and almost certainly overlap the '109's own examiner citation list, but I did not obtain the '109's own list, so treat each item below as "cited on the '109 family (high confidence) / cited on the '109 front page (probable, unverified)."

Prior art most relevant to US 11,959,109

Ranked by likely relevance to the claim scope (claim 1, per the abstract, is a composition/product claim: a horseshoe-crab Factor C protein (from Tachypleus tridentatus, Limulus polyphemus, or Carcinoscorpius rotundicauda) having Factor C activity, produced by recombinant expression in CHO DG44 or HEK cells; per the PGR petition, the full claim set also covers methods of producing an endotoxin-detection assay and methods of measuring endotoxin, with Factor B and pro-clotting enzyme expressed in mammalian host cells).

1. WO 2008/004674 A1 — "Pro-clotting enzyme, and method for detection of endotoxin or (1→3)-β-D-glucan using the same"

• Full citation: Seikagaku Corporation, WO 2008/004674 A1, published January 10, 2008 (filed July 7, 2006).
• Description: The '109 specification's own "Patent Document 1." Discloses the reconstituted horseshoe-crab clotting-cascade endotoxin assay built from Factor C, Factor B, and pro-clotting enzyme, and production of these components by recombinant expression — the specification notes it used insect cells as hosts and that the cascade is suppressed by sodium chloride, magnesium sulfate, and calcium chloride in the reaction system (the problem the '109 family addresses with mammalian-cell expression).
• § 102 anticipation potential: The closest single reference to the method-of-producing-an-assay claims (PGR-paraphrased claims requiring recombinantly produced Factor C + Factor B + pro-clotting enzyme combined into a cascade assay). It discloses every element of such a claim except the mammalian (CHO DG44/HEK) host-cell limitation for Factor B/pro-clotting enzyme (it uses insect cells). Accordingly, it would not anticipate claims containing the mammalian-host limitation, but it is the primary candidate to anticipate any claim lacking host-cell specificity, and the lead § 103 base reference against the method claims.

2. WO 2012/118226 A1 — "An agent for measuring endotoxin"

• Full citation: Seikagaku Corporation, WO 2012/118226 A1, published September 7, 2012 (priority February 28, 2011).
• Description: The '109 specification's own "Patent Document 2." Discloses an endotoxin-measuring agent comprising recombinant Factor C (His-tag-free), recombinant Factor B, and recombinant pro-clotting enzyme — each expressed using insect cells as a host — plus methods for producing the agent and methods for measuring endotoxin therewith. This is the most complete antecedent disclosure of the three-protein cascade as a recombinant product.
• § 102 anticipation potential: Same analysis as WO 2008/004674: anticipates the "three recombinant proteins combined into an endotoxin-measuring agent/method" theme but teaches insect-cell expression, not mammalian cells. Potentially anticipates any claim in the '109 set that does not require the mammalian host-cell limitation; cannot anticipate claims limited to CHO DG44/HEK or mammalian-cell Factor B/pro-clotting enzyme expression. Central § 103 reference for the genus claims the PGR challenges.

3. US 5,858,706 A — "Expression of Carcinoscorpius rotundicauda factor C in eukaryotes"

• Full citation: National University of Singapore, US 5,858,706 A, granted January 12, 1999 (filed August 19, 1994).
• Description: Discloses cloning and eukaryotic expression of Carcinoscorpius rotundicauda Factor C, including expression attempts in mammalian COS-1 (African green monkey kidney) cells — which, per the '109 family's own specification (and the Wang 2001 / Dwarakanath 1997 non-patent documents), produced insoluble Factor C. This reference is the one the specification distinguishes.
• § 102 anticipation potential: Directly relevant to claim 1's genus of "recombinant horseshoe-crab Factor C having Factor C activity," since it discloses recombinant CrFC in eukaryotes. It does not disclose expression in CHO DG44 or HEK cells (only COS-1, and reportedly non-functional/insoluble), so it would not anticipate a claim limited to CHO DG44/HEK expression; it is a prime § 102 candidate only against any broader claim reciting recombinant Factor C without the specific host-cell limitation, and a lead § 103 reference otherwise.

4. WO 99/15676 A1 — "A novel generation of cloned horseshoe crab recombinant factor C for detection and removal of endotoxin"

• Full citation: National University of Singapore, WO 99/15676 A1, published April 1, 1999 (filed September 19, 1997).
• Description: Recombinant Carcinoscorpius rotundicauda Factor C expressed in eukaryotic systems, used for detection and removal of endotoxin — i.e., the rFC assay concept that the '109's mammalian-cell Factor C builds on.
• § 102 anticipation potential: Anticipates a broad "recombinant Factor C for endotoxin detection" theme; like US 5,858,706, does not disclose CHO DG44/HEK host expression. Relevant to the method-of-measuring-endotoxin claims only if those claims lack the specific CHO/HEK or mammalian-host limitations.

5. SG 94673 A1 — "Expression of Carcinoscorpius rotundicauda factor C in eukaryotes"

• Full citation: National University of Singapore, SG 94673 A1, published March 18, 2003 (filed February 3, 1996).
• Description: Singapore counterpart of US 5,858,706 — eukaryotic (including COS-1 mammalian cell) expression of CrFC.
• § 102 anticipation potential: Same as US 5,858,706; under pre-AIA § 102(a)/(b)/e analysis its effective prior-art date must be checked against the '109's 2012-12-10 JP priority date. It predates it comfortably, so it is citable prior art; it does not disclose CHO DG44/HEK.

6. US 5,712,144 A — "Cloned factor C cDNA of the Singapore Horseshoe Crab, Carcinoscorpius rotundicauda and purification of Factor C proenzyme"

• Full citation: National University of Singapore, US 5,712,144 A, granted January 27, 1998 (filed August 19, 1994).
• Description: The foundational clone-and-purify disclosure of Carcinoscorpius rotundicauda Factor C cDNA and its proenzyme — the structural basis for the Factor C sequences the '109 family uses from that species.
• § 102 anticipation potential: Anticipates any claim to native-sequence CrFC or its recombinant production that lacks the specific CHO DG44/HEK expression step; not anticipatory of the host-cell-limited claims.

7. JP 2005-500520 A — "Methods and reagents for detecting endotoxins" (Cambrex)

• Full citation: Cambrex Bio Science Walkersville, Inc., JP 2005-500520 A (Japanese national phase), published January 6, 2005 (priority 2001-06-28); the underlying PCT is WO 03/… in the same family.
• Description: Commercial recombinant Factor C (rFC)-based endotoxin detection reagents/methods — the LAL-replacement product space the '109 patent occupies.
• § 102 anticipation potential: Relevant to the method-of-measuring-endotoxin claims as a disclosure of rFC-based endotoxin measurement; does not disclose the specific CHO DG44/HEK expression of Factor C or mammalian-cell Factor B/pro-clotting enzyme.

8. JP 2006-087435 A — "Novel polypeptide and DNA encoding the same" (Seikagaku)

• Full citation: Seikagaku Kogyo Co., Ltd., JP 2006-087435 A, published April 6, 2006 (priority June 29, 1993).
• Description: Seikagaku's earlier horseshoe-crab clotting-factor polypeptide/DNA disclosure from the same corporate family — background art on the cascade components.
• § 102 anticipation potential: Low. Background on horseshoe-crab clotting proteins; not a focused anticipation candidate for the CHO DG44/HEK Factor C or the mammalian-cell cascade claims.

9. US 5,795,962 A — "Horseshoe crab amebocyte lysate factor G subunit A"

• Full citation: Seikagaku Kogyo Kabushiki Kaisha, US 5,795,962 A, granted August 18, 1998 (filed June 29, 1993).
• Description: Factor G subunit A of the horseshoe-crab lysate (the (1→3)-β-D-glucan pathway), not the Factor C/endotoxin pathway. Appears in the family citation list as background.
• § 102 anticipation potential: Low/none for Factor C or endotoxin-cascade claims — different (β-glucan) branch of the clotting cascade.

Bottom-line § 102 read

• No reference located in the retrievable family citation lists discloses the claim 1 combination in full — i.e., a Tachypleus/Limulus/Carcinoscorpius Factor C recombinantly expressed in CHO DG44 or HEK cells. The Singapore-school references (US 5,858,706; SG 94673; WO 99/15676; US 5,712,144) actually teach that mammalian (COS-1) expression of CrFC was insoluble — the very problem the '109 solves.
• The strongest potential § 102 anticipations are against broader, host-cell-unlimited genus claims: (a) WO 2008/004674 and WO 2012/118226 for the three-protein cascade assay/method claims as PGR-paraphrased, and (b) the Singapore Factor C references for recombinant-Factor-C product claims shorn of the CHO DG44/HEK limitation.
• If the claims are read to require the mammalian host cell / CHO DG44 / HEK elements (as the abstract of claim 1 and the PGR petition both suggest), none of these references is a clean § 102 anticipation; the realistic attack posture is § 103 combinations — which is consistent with the actual PGR being brought on § 112 written-description/enablement grounds rather than § 102/103.

Confidence flags: (1) Bibliographic fields in the table above — high (patentguru record keyed to the '109). (2) Identity of the '109's own front-page citations — unverified; the list above is reconstructed from the '109 family specification's Patent Documents 1–2 and from citation lists on WO 2014/092079 A1 / US 10,144,923 B2, which share the 2012-12-10 priority. (3) Claim-to-reference anticipation mapping — reasoned inference, because I could not retrieve the verbatim '109 claim text within the search limit. For a definitive citation map, pull the patent's front page from the USPTO Patent Center (application 18/346,420) or Google Patents "Citations" tab, and confirm whether the examiner added any later-filed references (e.g., US 10,982,202 B2 or US 2018/0258414 A1) not present in the older family records I retrieved.

I have good leads. Note the PGR petition reproduces the examiner's original §103 rejections (Ding-1/Tamura and Ding-2/Tamura), and the issued claims were amended after those rejections. I need the issued claim text and the cited-art list. Let me pull the granted claims and the exhibit list.

§103 Obviousness Analysis — US Patent 11,959,109 (Seikagaku Corporation)

0. Preliminary flags (read before relying on anything below)

1. No "Prior Art section" was actually present on this page. The two sections supplied (Patent Summary; Litigation Summary) contain no prior-art compilation, and the Current Task refers to "the results from the Prior Art section of this page." That section is missing. Rather than fabricate it, I reconstructed the operative prior-art record from live searches of (i) the PGR2025-00023 petition and Patent Owner's Preliminary Response (POPR) on PTAB's site, (ii) the prosecution history as quoted in the petition, and (iii) the Seikagaku patent family publications. Treat my "prior-art section" below as reconstructed, with each item source-flagged.

2. The pending PGR does not plead § 103. PGR2025-00023 grounds are § 112 written description/enablement only (Petition Grounds 1–2; claims 1–10 in the petition header, claims 1–9 after the disclaimer of claim 10 and per the expert declaration quoted in the POPR). So this § 103 memo is an independent technical-legal analysis, not a summary of pending grounds. It borrows heavily from the § 103 rejections the Examiner actually made in prosecution, which the petition quotes verbatim and which are the best-documented obviousness positions against this patent.

3. Priority-date sensitivity. The '109 patent claims an effective filing date of December 10, 2013 (JP priority application No. 2013-254767, the "'767 Application," itself claiming JP 2012-269840 of Dec. 10, 2012). The PGR is contesting entitlement to that 2013 date on § 112 grounds. Which references are § 103 prior art therefore bifurcates:

   • Scenario A (claims keep the Dec. 10, 2013 date): only art published ≤ Dec. 10, 2013 counts.
   • Scenario B (priority defeated): art published between Dec. 2013 and July 3, 2023 (filing of App. 18/346,420) — including Seikagaku's own later "‘629 publication" and Charles River-related disclosures — becomes available. The § 103 case is materially stronger in Scenario B. I analyze both.

4. Inventor list now confirmed by PatentGuru/CNPA data for US11959109B2: Mizumura, Hikaru; Oda, Toshio; Kawabata, Shun-ichiro (assignee Seikagaku Corporation; filed 2023-07-03; issued 2024-04-16). This upgrades the prior low-confidence note.

1. The claims to be analyzed

The issued claim 1, as reproduced in the PGR expert declaration (EX2006-type exhibit, PTAB document, comparison of claims 1 and 10), reads:

A method for producing an endotoxin assay agent comprising a horseshoe crab Factor C, a horseshoe crab Factor B, and a horseshoe crab Pro-clotting enzyme, the method comprising:

• expressing the horseshoe crab Factor C in a Chinese Hamster Ovary cell or a Human Embryonic Kidney cell as a host cell, secreting the horseshoe crab Factor C into an extracellular culture supernatant, and recovering the horseshoe crab Factor C in the culture supernatant, wherein the recovered Factor C has activity of Factor C, and wherein the horseshoe crab Factor C is a Tachypleus tridentatus Factor C or a Limulus polyphemus Factor C;
• expressing the horseshoe crab Factor B having activity of Factor B in a mammalian cell as a host cell;
• expressing the horseshoe crab Pro-clotting enzyme having activity of Pro-clotting enzyme in a mammalian cell as a host cell; and
• producing an endotoxin assay agent comprising the horseshoe crab Factor C, Factor B, and Pro-clotting enzyme,
• wherein the host cell for Factor C, the host cell for Factor B, and the host cell for Pro-clotting enzyme may be the same or different.

Caveats: The reproduction above may omit dependent-claim recovery/filtration limitations (prosecution history describes claim 7 as adding "filtration of a supernatant," ¶42 of the petition), and I could not retrieve the full issued claims 2–10 verbatim within search limits. Claim 10 (measuring endotoxin by mixing the agent with a specimen and measuring progress of a cascade reaction) has been statutorily disclaimed, so it is not part of an actionable obviousness analysis.

The claim family is therefore a method-of-production genus: co-produce three active horseshoe-crab clotting-cascade zymogens, with the distinguishing technical choices being (a) CHO or HEK293 (not other mammalian, not insect) as the Factor C host and secretion into, and recovery from, the extracellular supernatant; (b) "mammalian cell" hosts for Factor B and pro-clotting enzyme; (c) Factor C from T. tridentatus or L. polyphemus; and (d) mix-and-match host cells.

2. Reconstructed Prior Art Section

2A. Pre-2013 references (Scenario A — valid in all events)

2B. Post-2013 references (Scenario B — only if the Dec. 10, 2013 priority date is defeated)

Note on the exhibit list: the PGR petition's exhibit list (as retrieved) begins EX1001 ('109 patent), EX1002 (prosecution history), EX1003/1004 (Jain declaration + CV), EX1005 (WO 2018/074498), EX1006 (Higdon 2010 protein-function-prediction paper), EX1007 (Kobayashi 2015), EX1008 (JP 2012-269840 certified translation), EX1009 et seq. — the remainder of the list and the § 103-relevant items (Ding-1, Ding-2, Tamura) live inside the prosecution history (EX1002) rather than as separate petition exhibits, consistent with the PGR's § 112-only grounds.

3. Primary § 103 combination — the Examiner's actual grounds (best-documented)

The prosecution history (quoted at ¶¶41–42 of the PGR petition) records two formal § 103 rejections of all original claims 1–10, dated September 15, 2023:

Ground A: claims 1–10 obvious over Ding-1 (US 5,858,706) in view of Tamura (US 2009/0208995).
Ground B: claims 1–10 obvious over Ding-2 (US 5,716,834) in view of Tamura (US 2009/0208995).

The Examiner's findings, as summarized in the petition:

• Ding-1 taught: (i) the desirability of recombinant Factor C for endotoxin detection assays; (ii) a mammalian host cell transformed with a recombinant vector encoding Factor C cDNA; (iii) recombinant production of Factor C in, e.g., CHO cells, including purification/recovery. (Ding's own working examples used COS-1 with recovery from cell lysate.)
• Ding-1 did not teach: recombinant Factor B or pro-clotting enzyme, or filtration of supernatant (claim 7).
• Tamura supplied those missing elements — the Factor B and pro-clotting enzyme components of the cascade and the reconstituted three-protein detection method.

Why a POSA would combine Ding + Tamura (motivation analysis):

1. Same field, same problem, complementary disclosures. Both references address replacing animal-derived Limulus amebocyte lysate with recombinantly produced clotting factors for endotoxin testing — a problem the '109's own background concedes was longstanding (horseshoe-crab conservation; inexhaustible supply; reproducible reagents). Ding supplies the upstream protease (Factor C) and its recombinant/mammalian expression; Tamura supplies the downstream zymogens (Factor B, pro-clotting enzyme) that Ding lacked and the three-component reconstitution that makes detection possible. The combination is the textbook case of filling each other's gaps in a known biochemical cascade (FC → activated FC → FB → activated FB → PCE → clotting enzyme → substrate cleavage), whose order and substrate specificity were documented since the 1980s (Morita et al. 1981; Nakamura et al. 1983, cited throughout the family).
2. Express suggestion in the art. Tamura expressly states the detection method uses "limulus-derived Factor C and/or recombinant factor C" and "limulus-derived factor B and/or recombinant factor B" with the Pro-CE — i.e., it points the skilled artisan directly at the Ding-type recombinant Factor C to complete its system. Ding, for its part, is directed to making rFC for endotoxin assays, which is meaningless without the rest of the cascade.
3. Known, finite design space / obvious-to-try. By 2013 the art knew the three zymogens had each been cloned (Tachypleus/Carcinoscorpius Factor C in the 1990s; Pro-CE cloned per Tamura and Non-Patent Document 2 of the family background; Factor B per the WO2008/004674 lineage), and knew that insect-cell-expressed versions assembled into a working assay (WO 2008/004674, WO 2012/118226). The only knob left was the expression host, and CHO/HEK293 were the default mammalian production platforms for secreted, glycosylated pharmaceutical proteins by 2013. A POSA seeking a manufacturing-scale, animal-free reagent would have routine motivation to port the known cascade from insect cells (Tamura; WO2008/004674) and/or from Ding's COS-1 cells to CHO/HEK293 for secreted production.
4. No new principle claimed. Nothing in claim 1 rests on a newly discovered cascade member or a newly discovered mechanism; the claim is a production-method genus over known proteins and a known reaction. That structural conservatism is what § 103 is aimed at.

Gap analysis against the issued claim 1 (why the Examiner's rejections did not stick as-filed):

Patent Owner overcame the rejections by amendment, not by a merits decision that the combination was non-obvious. The Nov. 24, 2023 amendments added: (i) secreting Factor C into an extracellular culture supernatant and recovering the secreted protein (as opposed to Ding's lysate/supernatant-from-lysed-cells recovery); (ii) Factor C species limited to T. tridentatus or L. polyphemus; (iii) "having activity of" qualifiers for each protein; (iv) the "host cells may be the same or different" clause. Patent Owner supported these amendments with the Mizumura declaration, which asserted that Ding-1/Ding-2's COS-1-expressed Factor C showed no activity in the culture supernatant and that "excellent" activity was only observed in the inventors' own secreted CHO/HEK material (petition ¶¶45–46).

For a post-amendment § 103 analysis, the honest reading is:

• The Examiner's combination still supplies the three-protein assay agent, the mammalian-cell hosts (broadly), the known Tachypleus factor C (via WO2008/004674 if added), and the measurement context.
• It does not squarely supply (a) extracellular secretion + supernatant recovery of active Factor C (Ding's reported teaching is the opposite — intracellular/insoluble COS-1 material), nor (b) CHO/HEK293 as the Factor C host with secreted activity (CHO appears in Ding only as a generic suggestion, not as a demonstrated secreted-expression host), nor (c) L. polyphemus Factor C sequence information, which the record says was not publicly available as of Dec. 2013 (Petition ¶66 citing EX1011 and EX1015 ¶¶0004–0013; the '629 publication states that no complete structural/functional identification of L. polyphemus clotting proteins existed even 20+ years after the Tachypleus reports).
• The "same or different host cells" clause is largely a claim-drafting artifact — with one expression plasmid per protein (as PO itself argues: pCI-neo/pCA7 vectors are host-agnostic), mixing host cells adds no inventive content.

Conclusion on Grounds A/B: Ding-1 (or Ding-2) + Tamura is a prima facie § 103 combination that the Examiner found persuasive over the original claims, but on the issued claims it fails at the "secretion into extracellular supernatant" and, for the L. polyphemus arm, at the "possession of the species' sequences" level — unless the challenger layers in the additional references below. Patent Owner's own declaration concedes the decisive factual premise (activity only after secretion from CHO/HEK-type cells) — which cuts against obviousness on the 2013 record, because it evidences an unexpected/inoperative result from the closest prior-art host (COS-1).

4. Strengthened combinations

Combination 1 (Scenario A): Ding-1 or Ding-2 + Tamura + WO 2008/004674 (and/or WO 2012/118226)

What it adds: WO 2008/004674 supplies (i) the T. tridentatus Factor C and Factor B and pro-clotting enzyme genes (Tamura alone arguably gives only Pro-CE plus generic rFC/rFB preferences), (ii) proof that all three recombinant proteins assemble into a functioning, endotoxin-triggered cascade in a recombinant system, and (iii) the assay-agent formulation (three factors + Boc-LGR-pNA chromogenic substrate) that mirrors the "endotoxin assay agent" and (via claim 10, now disclaimed) the measuring method. It is Seikagaku's own earlier work, cited in the '109's background — an admission that the full three-protein cascade and the goal of a recombinant assay agent were already in the art.

Motivation to combine: Identical field and identical problem; the cascade proteins are species homologs across horseshoe crabs with known functional interchangeability in mixed-species systems (the art already mixed C. rotundicauda rFC with T. tridentatus rFB/rPCE — per the US 2018/0259527 family background quoting WO2008/004674). A POSA wanting to move from insect cells (WO2008/004674's Sf9 platform) or from COS-1 (Ding) to the standard CHO/HEK293 secreted-protein platform would be combining routine manufacturing knowledge with the known cascade, for an obvious reason: secretion into conditioned medium simplifies recovery, scale-up, and GMP production of an injectable-safety assay reagent — the dominant reasons the industry moved recombinant therapeutic proteins to CHO.

Residual weakness: The record evidence (PO's declaration; the '109 background itself reporting that COS-1-expressed Factor C was insoluble) means a challenger must still show a reasonable expectation that Factor B and pro-clotting enzyme — which per the PGR record had never been reported in mammalian cells as of 2013 — would express as active, secreted proteins in CHO/HEK, and that L. polyphemus Factor C (sequence unavailable in 2013) was obtainable without undue effort. That is precisely the terrain of the pending § 112 enablement/written-description fight, and a § 103 challenger inherits the same factual burden. On the 2013-era art alone, this is a realistic but not certain § 103 case.

Combination 2 (Scenario B — priority defeated): post-2013 references + Combination 1

If the '109 claims are not entitled to the Dec. 10, 2013 date (the PGR's live question), a § 103 challenger gains decisive pieces that were missing in 2013:

• '629 Publication (US 2019/0241629 A1) discloses the complete L. polyphemus Factor C/Factor B/pro-clotting enzyme sequences and mammalian (CHO/HEK) expression with secreted, active product — eliminating the L. polyphemus gap that is the single biggest factual obstacle in Scenario A.
• CN-104919046-A and its US/EP family members (the inventors' own earlier publications) expressly teach horseshoe-crab Factor C recombinantly expressed in CHO DG44 and HEK293 — squarely covering the issued Factor C host/secretion limitations.
• Kobayashi 2015 (EX1007) completes the Factor B picture.
• WO 2018/074498 (EX1005) and other post-2013 recombinant-amebocyte-factor filings corroborate that assembling rFC + rFB + rPCE in mammalian cells was being pursued and achieved independently, evidence of obviousness and contemporaneous independent development (a secondary consideration working against patentability here).

Under Scenario B, the claim limitations that survived prosecution (secretion/supernatant recovery; CHO/HEK; L. polyphemus; activity qualifiers; same-or-different hosts) are all either explicitly disclosed or routine design choices in the combined post-2013 art, and the motivation story is unchanged and stronger (industry convergence on CHO/HEK-expressed recombinant cascade reagents is documented in the '629 publication's own background: PyroGene/EndoZyme/PyroSmart already on the market, all Tachypleus-based, all recombinant). A § 103 challenger would here have a strong case.

5. Motivation-to-combine synthesis (applicable to all combinations)

A POSA of the type defined in the PGR (PhD-level protein biochemist/molecular biologist, ~2+ years in recombinant protein production and endotoxin assays) would combine these references because:

1. Recognized, unsolved problem with an obvious solution architecture. The art's background (echoed verbatim in the '109 family) states the goals: avoid harvesting horseshoe crabs, produce the cascade proteins recombinantly, reconstitute the assay. Every combination above simply executes that stated program with known components.
2. Homology and cross-species interchangeability were established. The cascade had been reconstituted with native proteins (Non-Patent Document 2 of the family background) and with mixed-species recombinants (WO2008/004674 combining Carcinoscorpius or Tachypleus rFC with Tachypleus rFB/rPCE). Given that, selecting T. tridentatus or L. polyphemus Factor C was an ordinary species choice among the four known horseshoe-crab species (the '109 family's own documents list all four as interchangeable sources).
3. The expression-system step was a routine platform migration. By 2013 CHO and HEK293 were the industry-standard hosts for secreted, disulfide-rich, glycosylated zymogens/proteases; moving an insect-cell or COS-1 expression system to CHO/HEK for secretion, with signal peptides and codon optimization, was within the ordinary skill the parties agree the POSA possessed. Where the record shows genuine unpredictability (COS-1 insolubility; no prior mammalian FB/PCE expression; missing L. polyphemus sequences), that is where the obviousness case weakens — and where Scenario B art rescues it.
4. No blocking secondary considerations cut the other way — except the ones already described. (No long-felt-need argument favoring Seikagaku, since the '629 publication itself concedes commercial recombinant products pre-existed; the "unexpected" secretion result asserted by PO is the only serious rebuttal, and it is confined to the narrow COS-1-vs-CHO/HEK supernatant point.)

6. Bottom line

• Documented § 103 position: Claims 1–10 (as originally filed) were rejected by the Examiner as obvious over Ding-1 (US 5,858,706) + Tamura (US 2009/0208995) and over Ding-2 (US 5,716,834) + Tamura — the strongest evidence that a prima facie obviousness case exists. Patent Owner escaped by amending to add (i) secretion into and recovery from the extracellular culture supernatant, (ii) CHO/HEK293 as the Factor C host, (iii) T. tridentatus/L. polyphemus Factor C, and (iv) activity and same-or-different-host qualifiers, backed by the Mizumura declaration.
• Against the issued claims on pre-2013 art only, the best challenger case is Ding-1/Ding-2 + Tamura + WO 2008/004674 (and/or WO 2012/118226). It renders most of claim 1's elements obvious, but a genuine dispute remains on reasonable expectation of success for secreted, active Factor C in CHO/HEK and for mammalian-cell Factor B/pro-clotting enzyme, and on access to L. polyphemus sequences — the same factual fault lines the pending PGR exposes on § 112.
• If the Dec. 10, 2013 priority is defeated (PGR Scenario B), the § 103 case becomes strong, because the '629 Publication (US 2019/0241629 A1), the inventors' own CHO/HEK Factor C publications (e.g., CN-104919046-A family), Kobayashi 2015, and WO 2018/074498 collectively supply every element the 2013 art lacked, with clear motivation to combine.
• Caveat on completeness: I could not retrieve (within search limits) the full issued claims 2–9, the complete PGR exhibit list beyond EX1009, or a full face-of-patent "References Cited" page; dependent-claim recovery/filtration limitations (e.g., claim 7's supernatant filtration) and any second independent claim should be mapped element-by-element before a final § 103 verdict is written. I also note the earlier summary's "claims 1–10" PGR description versus the "claims 1–9" language in the later expert declaration — consistent with the claim 10 disclaimer, but worth verifying against the Institution Decision (issued Sept. 9, 2025; final decision pending as of April 2026).

Key sources: PGR2025-00023 petition and POPR documents on ptacts.uspto.gov (incl. quoted prosecution history ¶¶40–46 and exhibit list EX1001–1009+); US 2019/0241629 A1 (Justia); US 2009/0208995 A1 and US 5,681,710-family background (Patents-Review/Justia); WO2008004674 (Google Patents, EP family); CN-104919046-A (PubChem/patentguru.com.cn, confirming inventors and CHO DG44/HEK293 Factor C); freepatentsonline.com US2023/0357742 A1 (published application of the '109 patent).