Streck Inc v. Ravgen Inc

1. Case Identification

• Case #: IPR2021-01577
• Patent #: 7,332,277
• Filed: September 28, 2021
• Petitioner(s): Streck, Inc.
• Patent Owner(s): Ravgen, Inc.
• Challenged Claims: 55-61, 68-69, 80-86, 89-92, 94, 126-130, 132-133

2. Patent Overview

• Title: Method for Detection of Genetic Disorders
• Brief Description: The ’277 patent discloses methods for detecting fetal genetic disorders by analyzing cell-free fetal DNA (cffDNA) from a maternal blood sample. The invention purports to improve accuracy by adding an agent to the sample to inhibit the lysis of maternal cells, which prevents the release of contaminating maternal DNA that could interfere with the analysis of the much rarer fetal DNA.

3. Grounds for Unpatentability

Ground 1: Obviousness over Pertl and Granger - Claims 55-61, 68-69, 80-86, 89-92, 94, 126-130, 132-133 are obvious over Pertl in view of Granger.

• Prior Art Relied Upon: Pertl (a 2000 journal article in Human Genetics) and Granger (WO 97/45729).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Pertl teaches a method of determining the sequence of cffDNA from maternal plasma using multiplex fluorescent PCR on highly polymorphic short tandem repeat (STR) markers. This method, according to Petitioner, discloses all limitations of the independent claims except for the addition of an agent specifically intended to inhibit cell lysis.
  • Motivation to Combine: Pertl cautioned that its method's sensitivity was limited because an excess of maternal "background" DNA could out-compete the rare fetal DNA sequences during PCR amplification. Petitioner asserted a person of ordinary skill in the art (POSITA) would be motivated to solve this known problem. Granger taught a direct solution, disclosing a specimen collection fluid containing a cross-linking agent (preferably formaldehyde) to prevent the lysis of blood cells and preserve sample integrity. Granger specifically noted this was crucial when analysis is delayed by transport, a common scenario for such samples. A POSITA would combine Granger’s preservation technique with Pertl’s analytical method to reduce contaminating maternal DNA, thereby improving the accuracy and sensitivity of the cffDNA analysis.
  • Expectation of Success: Granger provided detailed data showing its formaldehyde-based solution successfully stabilized blood cells and maintained peripheral blood parameters for at least seven days. Since Granger also explicitly contemplated its fluid's use for samples intended for PCR analysis, a POSITA would have had a very high expectation of success.

Ground 2: Anticipation by Chiu - Claims 55-59, 61, 68, 69, 80-86, 89, 94, and 126-130 are anticipated by Chiu.

• Prior Art Relied Upon: Chiu (a 2001 article in Clinical Chemistry).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner contended that Chiu discloses every element of the challenged claims in a single reference. Chiu describes a method of isolating and analyzing cffDNA from maternal blood samples to determine the sequence of specific genes (SRY and b-globin). Critically, Chiu’s published protocol specified collecting the blood into tubes containing ethylenediaminetetraacetic acid (EDTA). While Chiu focused on the anticoagulant properties of EDTA, Petitioner argued that its cell-lysis-inhibiting property was known in the art, citing the Lee reference. Lee (2001) explicitly teaches that anticoagulants like EDTA inhibit the lysis of white blood cells and prevent the release of their DNA, showing a dramatic difference in DNA contamination over several days between EDTA-treated and untreated samples. Thus, Chiu's disclosed use of EDTA inherently teaches the claimed "agent that inhibits lysis of cells," rendering the claims anticipated.

Ground 3: Obviousness over Chiu in view of Lee - Claims 55-59, 61, 68, 69, 80-86, 89, 94, and 126-130 are obvious over Chiu in view of Lee.

• Prior Art Relied Upon: Chiu (a 2001 article in Clinical Chemistry) and Lee (a 2001 article in Transfusion).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground builds on the teachings of Chiu and Lee. Chiu provides the primary method of analyzing cffDNA from maternal blood stabilized with the known cell lysis inhibitor, EDTA. Lee, in addition to confirming EDTA's utility, also teaches that acid citrate dextrose (ACD) is another common anticoagulant used for the same purpose of preventing cell lysis in blood samples.
  • Motivation to Combine: Lee counsels that plasma (which requires an anticoagulant) should be used over serum to monitor cell-free DNA, as the clotting process in serum generation causes white blood cell lysis and DNA release. A POSITA reading Chiu would be motivated to use an effective anticoagulant and cell lysis inhibitor. Lee presents ACD and EDTA as known, interchangeable alternatives for this purpose. Petitioner further noted that the ’277 patent itself identifies glucose (a component of ACD) as a "membrane stabilizer," which would have confirmed to a POSITA the suitability of substituting ACD for EDTA.
  • Expectation of Success: Because ACD and EDTA were well-known and interchangeable agents for stabilizing blood samples for downstream analysis, a POSITA would reasonably expect that substituting ACD for EDTA in Chiu’s protocol would predictably achieve the same result of inhibiting cell lysis.

4. Arguments Regarding Discretionary Denial

• Petitioner argued against discretionary denial under 35 U.S.C. §325(d), asserting that the petition raises new issues with prior art (Pertl, Granger, Chiu, and Lee) that was not considered during the original prosecution.
• Petitioner also contended that discretionary denial under Fintiv is inappropriate. The core arguments were that Petitioner is not a party to the parallel district court litigations involving the ’277 patent, the litigations are not advanced, and there is minimal overlap between the claims and invalidity contentions in those cases and the grounds presented in this inter partes review (IPR). The petition also distinguished its grounds from those in other IPRs filed by different parties against the same patent.

5. Relief Requested

• Petitioner requested the institution of an IPR and the cancellation of claims 55-61, 68-69, 80-86, 89-92, 94, 126-130, and 132-133 of the ’277 patent as unpatentable.