In another setback for diagnostic method patents, the Federal Circuit rejected efforts by patent owner/appellant Cleveland Clinic to avoid 35 U.S.C. § 101 by restyling diagnostic method claims as “techniques” for detecting a correlation between protein levels and a disease state. Cleveland Clinic Found. v. True Health Diagnostics LLC, No. 2018-1218, 2019 WL 1452697, at *4 (Fed. Cir. Apr. 1, 2019) (“Cleveland Clinic”). The court’s unwillingness to accept the patent eligibility of diagnostic method claims – even those claims that are rephrased as a process of detection rather than the product or natural correlation per se – directly contradicts the position taken by the United States Patent and Trademark Office (USPTO) in the agency’s May 2016 Subject Matter Eligibility Guidelines (USPTO Guidelines). Cleveland Clinic, although designated as a non-precedential opinion, deepens the growing divide between administrative and judicial interpretations of 35 U.S.C. § 101 and is sure to be an unwelcome development for practitioners who have been modeling diagnostic method claims on the USPTO Guidelines since 2016.
The patents at issue, U.S. Patent No. 9,575,065 and U.S. Patent No. 9,581,597, describe diagnostic tests for determining the risk of developing cardiovascular disease (CVD) by measuring the level of a naturally occurring hemeprotein, myeloperoxidase (MPO), in a patient’s blood. Id at *1. The patents describe the breakthrough finding that “blood MPO levels strongly correlate with risk of coronary artery disease but not with traditional risk factors for coronary artery disease.” Id. at *2. But the specification and prosecution history “plainly concede” that the process steps used to measure MPO levels in the blood were “well-known in the art.” Id. at *5.
A representative claim from the ’597 patent recites:
- A method for identifying an elevated myeloperoxidase (MPO) concentration in a plasma sample from a human subject with atherosclerotic cardiovascular disease comprising:
a) contacting a sample with an anti-MPO antibody, wherein said sample is a plasma sample from a human subject having atherosclerotic cardiovascular disease;
b) spectrophotometrically detecting MPO levels in said plasma sample;
c) comparing said MPO levels in said plasma sample to a standard curve generated with known amounts of MPO to determine the MPO concentration in said sample; and
d) comparing said MPO concentration in said plasma sample from said human subject to a control MPO concentration from apparently healthy human subjects and identifying said MPO concentration in said plasma sample from said human subject as being elevated compared to said control MPO concentration.
And a representative claim from the ’065 patent recites:
- A method of detecting elevated MPO mass in a patient sample comprising:
a) obtaining a plasma sample from a human patient having atherosclerotic cardiovascular disease (CVD); and
b) detecting elevated MPO mass in said plasma sample, as compared to a control MPO mass level from the general population or apparently healthy subjects, by contacting said plasma sample with anti-MPO antibodies and detecting binding between MPO in said plasma sample and said anti-MPO antibodies.
The court determined that the claims of both patents are not patent eligible because they are directed to “the natural law that blood MPO levels correlate with atherosclerotic [cardiovascular disease].” Id. at *4. In so finding, the court was unpersuaded by Cleveland Clinic’s argument that the claims are directed to patent-eligible techniques for detecting elevated levels of MPO in the blood. According to the court, the claims merely “recite applying known methods to detect MPO levels in plasma, comparing them to standard MPO levels, and reaching a conclusion: that the patient’s blood MPO levels are elevated in comparison to a control group.” Id. at *4. The “rephrasing of the claims does not make them less directed to a natural law.” Id.
The court was equally unpersuaded by Cleveland Clinic’s argument that the claims do not recite a natural law because the phenomenon could only be observed by using certain laboratory techniques. As articulated by the court, “Inadequate measures of detection do not render a natural law any less natural.” Id. at *5.
Furthermore, the court found that the claims “contain no additional inventive concept.” Id. Even though it had never been shown that MPO was present at elevated levels in blood samples from patients with atherosclerotic CVD, the court rejected the premise that “using a known technique in a standard way to observe a natural law can confer an inventive concept.” Id.
Cleveland Clinic argued that the district court did not give appropriate deference to the USPTO Guidelines, especially patent-eligible Example 29-Claim 1, which recites:
- A method of detecting JUL-1 in a patient, said method comprising:
a. obtaining a plasma sample from a human patient; and
b. detecting whether JUL-1 is present in the plasma sample by contacting the plasma sample with an anti-JUL-1 antibody and detecting binding between JUL-1 and the antibody.
The court stated that “[w]hile we greatly respect the PTO’s expertise on all matters relating to patentability, including patent eligibility, we are not bound by its guidance.” Id. at *6. Indeed, the court found Example 29-Claim 1 to be “strikingly similar” to a claim invalidated under 35 U.S.C. § 101 in Ariosa Diagnostics, Inc. v. Sequenom, Inc., 788 F.3d 1371 (Fed. Cir. 2015). Id. The court offered the explanation that, where the techniques used to detect the protein (JUL-1) were conventionally applied, “[t]he only remaining non-conventional element of each claim is the discovery that the protein is present in the bodily sample, and the discovery of a natural law cannot by itself provide the requisite inventive concept.” Id.
Practitioners should proceed with caution when modeling claims on the USPTO Guidelines. In time, clear guidance may yet emerge from the courts and USPTO regarding the patent eligibility of all flavors of diagnostic method claims.
 “Cleveland Clinic” collectively refers to Cleveland Clinic Foundation and Cleveland HeartLab, Inc.
 Both patents claim priority from the same application and contain materially identical specifications.