PTAB

IPR2025-01060

FujireBio Diagnostics Inc v. Quanterix Corp

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Methods of determining a treatment protocol for and/or a prognosis of a patient's recovery from a brain injury
  • Brief Description: The ’092 patent discloses methods for producing a bodily fluid sample from a patient with a suspected neurological condition, wherein the sample contains an analytically quantified amount of endogenous tau protein. The method involves obtaining and diluting a blood sample and then quantifying the tau protein using a highly sensitive assay capable of detecting concentrations below 5 pg/mL with a limit of quantification below 0.2 pg/mL.

3. Grounds for Unpatentability

Ground 1: Claims 1, 6-21 are obvious over Rissin in view of Todd

  • Prior Art Relied Upon: Rissin (a 2010 journal article entitled "Single-molecule enzyme-linked immunosorbent assay detects serum proteins at subfemtomolar concentrations") and Todd (a 2008 journal article entitled "How Low Can You Go? Next generation immunoassay systems and the revival of protein biomarkers").
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Rissin taught the core method of the challenged claims, including a single-molecule array (SMA) or "digital ELISA" for detecting very low concentrations of proteins in diluted serum samples. Rissin’s method achieved sub-picogram sensitivity, meeting the claimed limits of quantification (<0.2 pg/mL) and detection (<5 pg/mL). While Rissin focused on biomarkers like PSA and TNF-α, Todd explicitly taught that ultra-sensitive immunoassays like SMAs were the solution for diagnosing neurological disorders such as Alzheimer’s Disease (AD) and identified tau proteins as a primary biomarker candidate for detection in blood. The combination of Rissin's method with Todd's specific target analyte (tau) and disease context (neurological disorders) renders the claims obvious.
    • Motivation to Combine: Petitioner contended that a person of ordinary skill in the art (POSITA) would combine Rissin’s advanced, simplified SMA technique with Todd’s teachings to create a sensitive blood test for tau. Todd identified the need for ultra-sensitive detection of biomarkers like tau for AD diagnosis, and Rissin provided a superior method for achieving it. Rissin itself cited related work and discussed the importance of measuring proteins related to neurological disorders, providing a clear rationale to apply its improved assay to a well-known biomarker like tau.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success because Rissin successfully used its SMA to quantify other low-concentration proteins, including some also studied by Todd. Applying this proven, highly sensitive technology to another known protein biomarker (tau), which Todd identified as a key target, was a straightforward application of a known tool to a known problem.

Ground 2: Claims 1, 6-21 are obvious over Rissin in view of Voorheis

  • Prior Art Relied Upon: Rissin (the 2010 journal article) and Voorheis (Patent 5,492,812).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground again relied on Rissin for its high-sensitivity digital ELISA method capable of quantifying proteins at subfemtomolar concentrations in diluted blood samples. Voorheis, filed much earlier, taught a method for diagnosing AD and other neurological disorders by screening for tau protein in a patient's blood. Voorheis recognized the need for sensitive diagnostic tests but contemplated then-conventional methods like standard ELISA. Petitioner argued that the combination simply applied Rissin's modern, ultra-sensitive assay to the diagnostic goal outlined in Voorheis, thereby meeting all limitations of the challenged claims.
    • Motivation to Combine: Petitioner asserted that a POSITA would have been motivated to replace the older, less sensitive immunoassay methods suggested in Voorheis with the advanced, ultra-sensitive SMA taught by Rissin. Voorheis established the clinical need and diagnostic value of detecting tau in blood, while Rissin provided a significantly improved tool to do so, capable of detecting the extremely low concentrations of tau known to be present. This represents an obvious improvement of an old method by substituting a superior new technique to achieve better results for the same purpose.
    • Expectation of Success: A POSITA would have expected success because the prior art established that tau was a viable biomarker for neurological disease and that Rissin's SMA technology was thousands of times more sensitive than the conventional assays available to Voorheis. The combination was merely the application of a superior analytical tool to a known analyte for a known purpose, with a high probability of yielding more reliable and sensitive results.

4. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1 and 6-21 of the ’092 patent as unpatentable under 35 U.S.C. §103.