Fujirebio Diagnostics, Inc. v. Quanterix Corp.

Fujirebio Diagnostics, Inc. ("Fujirebio") initiated an Inter Partes Review (IPR) against Quanterix Corp. ("Quanterix") before the Patent Trial and Appeal Board (PTAB), challenging claims of U.S. Patent No. 11,275,092. Fujirebio, a global leader in in vitro diagnostics, develops, manufactures, and markets high-quality diagnostic solutions and biomarker assays with a focus on areas like neurodegeneration, infectious diseases, and oncology. Quanterix, the patent owner, is a life sciences company founded in 2007, known for its ultra-sensitive digital immunoassay platforms, particularly the Simoa (Single Molecule Array) technology. This technology enables the detection of protein biomarkers at extremely low concentrations, driving advancements in neurology, oncology, cardiology, and infectious disease research.

The asserted patent, U.S. Patent No. 11,275,092, is titled "Methods of determining a treatment protocol for and/or a prognosis of a patient's recovery from a brain injury." Broadly, it describes methods for quantifying tau protein levels in a patient's bodily fluid sample (such as blood or a blood component) using a highly sensitive assay (with a limit of quantification less than 0.2 pg/ml) to provide a prognostic indication or inform a treatment protocol for brain injury. While no specific "accused product" is at issue in an IPR, the underlying technology relates to Quanterix's Simoa platform, which is utilized for highly sensitive biomarker detection, including tau protein measurements relevant to neurological conditions. Quanterix has also been actively asserting its tau-related patent claims as the market for Alzheimer's disease testing expands.

The procedural posture of this case is at the Patent Trial and Appeal Board, where Fujirebio's petition for IPR2025-01060 was "Not Instituted - Procedural" on March 7, 2025. This indicates a discretionary denial by the PTAB rather than a decision on the merits of unpatentability. The case is notable because it exemplifies the increasing trend of discretionary denials at the PTAB, often influenced by factors such as parallel district court litigation. Indeed, a related patent infringement lawsuit, Fujirebio Diagnostics, Inc. v. Quanterix Corporation, Case No. 1:25-cv-00659, was filed in the District of Delaware on May 28, 2025, which likely contributed to the PTAB's decision to deny institution. The PTAB's use of discretionary denials, which can consider "settled expectations" or other policy considerations from the USPTO Director, highlights the evolving and often unpredictable landscape of post-grant proceedings for life sciences patents.

I. Parallel District Court Patent Infringement Litigation

Fujirebio Diagnostics, Inc. initiated a patent infringement lawsuit against Quanterix Corp. on May 28, 2025, in the U.S. District Court for the District of Delaware, case number 1:25-cv-00659. The complaint alleged infringement of U.S. Patent No. 11,275,092. Quanterix Corp. subsequently filed counterclaims, with Fujirebio Diagnostics, Inc. and Fujirebio Europe N.V. named as counter-defendants. The case was presided over by Judge Gregory B. Williams.

The district court litigation was terminated on April 10, 2026. The specific nature of the termination (e.g., settlement, dismissal, judgment) is not detailed in the available information.

II. Parallel PTAB IPR Proceeding

Filing and Initial Pleadings:
On May 28, 2025, the same day the district court complaint was filed, Fujirebio Diagnostics, Inc. filed a petition for Inter Partes Review (IPR) against U.S. Patent No. 11,275,092, owned by Quanterix Corp., with the Patent Trial and Appeal Board (PTAB). The IPR petition was assigned number IPR2025-01060. Fujirebio challenged claims 1 and 6-21 of the patent, arguing they were unpatentable under 35 U.S.C. § 103. Quanterix Corp. filed a preliminary response on September 19, 2025.

Institution Decision:
The PTAB, under the authority of Director John Squires, issued a decision on institution on October 17, 2025. The petition was not instituted, with the status recorded as "Discretionary Denial." This discretionary denial occurred as part of a broader shift in 2025 where the PTAB adopted a more restrictive, policy-driven approach to IPR institution, with Director Squires consolidating control over all institution determinations and often issuing summary notices for routine decisions without detailed reasoning. The exact specific reason for the discretionary denial in IPR2025-01060 is not explicitly stated in the provided records, though such denials often relate to considerations of parallel district court litigation (known as Fintiv factors) or other policy-based considerations for efficient resource allocation by the USPTO. Given that a parallel district court case was filed on the exact same day, it is highly probable the IPR was discretionarily denied due to the ongoing litigation.

Effect on Litigation:
The discretionary denial of the IPR petition meant that the validity challenge to patent 11,275,092 continued solely in the Delaware district court. The district court case, 1:25-cv-00659, subsequently terminated on April 10, 2026.

Here is the counsel of record representing Fujirebio Diagnostics, Inc. in IPR2025-01060:

• Patrick D. McPherson

  • Role: Attorney for Petitioner
  • Firm: Duane Morris LLP, Washington, D.C.
  • Note: Mr. McPherson is registered with USPTO (Reg. No. 46,255) and is listed on the Petitioner's Power of Attorney for this IPR.

• Thomas J. Kowalski

  • Role: Attorney for Petitioner
  • Firm: Duane Morris LLP, New York, NY
  • Note: Mr. Kowalski is registered with USPTO (Reg. No. 32,147) and is listed on the Petitioner's Power of Attorney for this IPR.

• Christopher S. Kroon

  • Role: Attorney for Petitioner
  • Firm: Duane Morris LLP, Boston, MA
  • Note: Mr. Kroon is registered with USPTO (Reg. No. 54,241) and is listed on the Petitioner's Power of Attorney for this IPR.

• John D'Amelio Jr., Esq.

  • Role: Corporate Counsel (in-house) for Fujirebio Diagnostics, Inc.
  • Firm: Fujirebio Diagnostics, Inc.
  • Note: Signed the Petitioner's Power of Attorney on behalf of Fujirebio Diagnostics, Inc.

I'll research counsel for the defendant in this matter. First, let me establish which "patent infringement case" is at issue and its docket.

Now let me pin down counsel for the defendant (Quanterix) in the Delaware action, including local Delaware counsel and their appearances.

Let me confirm the full slate of defense-side appearances, including any additional Cooley attorneys admitted pro hac vice, and verify local counsel roles.

Defense-side counsel of record — Fujirebio Diagnostics, Inc. v. Quanterix Corp., C.A. No. 1:25-cv-00659-GBW (D. Del.)

Scope note (which "case" this is): IPR2025-01060 is an ex parte-style adversarial PTAB proceeding in which Quanterix is Patent Owner, not a defendant. The only "patent infringement case" in this dispute is the parallel Delaware action, C.A. No. 1:25-cv-00659-GBW (D. Del., Judge Gregory B. Williams), in which Quanterix Corporation is the Defendant and Counter-Plaintiff (CourtListener docket). Counsel for Quanterix in that case are set out below, with the overlapping PTAB representation noted separately. Two structural facts matter up front:

• This began as a declaratory-judgment action filed by Fujirebio (Compl., D.I. 1, filed 5/28/2025); Quanterix then answered and counterclaimed for infringement of the '092 patent (D.I. 12, 6/23/2025; Amended Counterclaim, D.I. 20, 7/14/2025). So Quanterix's counsel of record act as both defense counsel (DJ counts) and plaintiff's counsel (infringement counterclaim).
• The case is closed (civil case terminated 4/10/2026, following a stipulation to stay pending finalization of a settlement agreement, D.I. 48, and a joint status report, D.I. 51). The roster below is therefore historical, not an active appearance list.

---

1. Counsel of record for Quanterix Corporation (D. Del.)

Elizabeth M. ("Betsy") Flanagan — Cooley LLP (Minneapolis/Edina, MN) — trial/lead counsel; counsel of record

• Firm office: Cooley LLP, 30 S. 9th Street, 7th Floor, Minneapolis, MN 55402 (also listed with a Chicago direct line, +1 312 881 6383); Law360 lists her as Edina, MN.
• Docket basis: Notice of Appearance of Elizabeth M. Flanagan entered for Quanterix on 6/23–6/24/2025 (filed on her behalf by local counsel); her name appears in the Cooley "OF COUNSEL" signature block on Quanterix's filings (e.g., D.I. 19, stipulation filed 7/11/2025, listing "Elizabeth M. Flanagan (No. 5891), Cooley LLP, 30 S. 9th Street…").
• Note: Life-sciences patent trial lawyer; former managing partner of Fish & Richardson's Minneapolis office; per her Cooley profile, admitted in the D. Del. and Federal Circuit, with Hatch-Waxman, method-of-treatment and PTAB experience, including a § 101 dismissal for a diagnostics client (Cooley profile PDF).

Orion Armon — Cooley LLP (Denver, CO; IPR notices list Washington, D.C.) — counsel of record (admitted pro hac vice)

• Firm office: Cooley LLP, 1144 15th Street, Suite 2300, Denver, CO 80202 (Cooley's PTAB mandatory notice uses 1299 Pennsylvania Ave., NW, Suite 700, Washington, D.C. 20004); USPTO Reg. No. 65,421.
• Docket basis: Motion for Pro Hac Vice Appearance of Attorney Orion Armon filed by Quanterix (D.I. 15, 6/23/2025; PHV fee paid same day, receipt ADEDC-4717121); he signs as "Admitted Pro Hac Vice" on Quanterix filings (D.I. 19) and his name appears on the Rule 4 service letter transmitting the counterclaim to Fujirebio Europe N.V. (D.I. 18-1, 7/3/2025).
• Note: Registered patent attorney who serves as lead counsel for Quanterix in IPR2025-01060 (Patent Owner's mandatory notices), i.e., the same Cooley team is running both tracks.

Jeremy A. Tigan — Morris, Nichols, Arsht & Tunnell LLP (Wilmington, DE) — Delaware local counsel; principal docket filer

• Delaware Bar No. 5239; 1201 North Market Street, P.O. Box 1347, Wilmington, DE 19899; (302) 658-9200.
• Docket basis: E-filed Quanterix's Answer & Counterclaim (D.I. 12), Amended Counterclaim/Answer (D.I. 20), the PHV motion for Armon (D.I. 15), and the Rule 7.1 disclosure; the original summons directed service responses to "Jeremy A. Tigan, Morris, Nichols, Arsht & Tunnell LLP" as Quanterix's attorney (D.I. 18-1).
• Note: Longtime D. Del. patent litigator; regularly appears as Delaware counsel in ANDA and life-sciences patent cases (see, e.g., his appearances in Beckman Coulter v. Cytek Biosciences and Pfizer/BMS matters).

Cameron P. Clark — Morris, Nichols, Arsht & Tunnell LLP (Wilmington, DE) — Delaware local counsel

• Delaware Bar No. 6647; same Wilmington address.
• Docket basis: Signed/e-filed defense-side papers, including the 9/12/2025 stipulation extending Quanterix's opposition and Fujirebio's reply deadlines (D.I. 27, filed by "Clark, Cameron"); listed in Quanterix's signature blocks; appears in UniCourt's list of "Defendant and Counter-Claimant Attorneys."

Ben Yenerall — Morris, Nichols, Arsht & Tunnell LLP (Wilmington, DE) — Delaware local counsel

• Delaware Bar No. 7132; same Wilmington address; included in the Morris Nichols signature block on Quanterix filings (e.g., D.I. 27, 9/12/2025).
• Caveat: Yenerall appears in signature blocks but I did not find him separately listed among "Defendant and Counter-Claimant Attorneys" in the third-party docket aggregator (UniCourt lists only Flanagan, Clark, and Tigan). Treat his formal entry of appearance as unconfirmed from the sources retrieved.

2. Overlapping PTAB representation (IPR2025-01060, Patent Owner Quanterix Corp.)

Quanterix's Updated Mandatory Notice under 37 C.F.R. § 42.8(b)(3) (dated 8/20/2025) lists a Cooley team that substantially overlaps the Delaware defense team (PTAB document):

• Orion Armon — Lead counsel (Reg. No. 65,421), Cooley LLP, Washington, D.C. office.
• Elizabeth Flanagan — back-up counsel (PHV admission to be requested), Cooley LLP, Chicago/Minneapolis.
• **Joseph E. Van