The MAYO Test: Impact on Diagnosis, Personalized Medicine and Beyond

This article was published in the April 25, 2012 edition of IP, Life Sciences and Appellate Law360

With a unanimous decision issued on March 20, 2012, in Mayo v. Prometheus Laboratories, the U.S. Supreme Court invalidated the process claims of Prometheus’ two patents as not patent-eligible based on the finding that the steps in the claimed processes apart from the natural law inherent in the definition of the invention “involve [only] well-understood, routine, conventional activity previously engaged in by researchers in the field.”

This decision reversed the Federal Circuit’s finding of patent eligibility based on the “machine or transformation” test. While acknowledging the usefulness of that test, the court refused to let it trump the “law of nature” exception to 35 USC §101.

In particular, the court found the transformative steps relied upon by the Federal Circuit to consist of well-understood, routine, conventional activity, which viewed as a whole add nothing significant beyond the sum of their parts taken separately.

Following the 2010 decision in Bilski v. Kappos, concerning “abstract ideas,” the court applied the same analysis to the long standing “law of nature” exception to patent eligibility, and further restricted the ”test for process claims reciting a law of nature, a natural phenomenon or an abstract idea.” In Mayo, the court took claim 1 of U.S. Patent No. 6,355,623 as a representative claim, and examined its patent eligibility in light of its precedents on this issue. Claim 1 of the ‘623 patent recites:

  1. A method of optimizing therapeutic efficacy for treatment of an immune-mediated gastrointestinal disorder, comprising:(a) administering a drug providing 6-thioguanine to a subject having said immune-mediated gastrointestinal disorder; and

    (b) determining the level of 6-thioguanine in said subject having said immune-mediated gastrointestinal disorder,

    wherein the level of 6-thioguanine less than about 230 pmol per 8×108 red blood cells indicates a need to increase the amount of said drug subsequently administered to said subject and

    wherein the level of 6-thioguanine greater than about 400 pmol per 8×108 red blood cells indicates a need to decrease the amount of said drug subsequently administered to said subject.

According to the court, “Prometheus’ patents set forth laws of nature — namely, relationships between concentrations of certain metabolites in the blood and the likelihood that a dosage of a thiopurine drug will prove ineffective or cause harm.”

Under the Mayo test, whether a method claim is patent-eligible depends on what in the claim constitutes a statement of a natural law and on what remains in the claim after this statement is removed. Conceding “it takes a human action (the administration of a thiopurine drug) to trigger a manifestation of this relation in a particular person,” the court stated that “the relation itself exists in principle apart from any human action,” and “[t]he relation is a consequence of the ways in which thiopurine compounds are metabolized by the body — entirely natural processes.”

In reaching its conclusion, the court focused on the steps in Prometheus’ method claims at issue, apart from what it considered a statement of a natural law (e.g., a natural relationship or correlation), and considered whether these additional steps involve an “inventive concept” or a “well-understood, routine, conventional activity.”

While silent as to what constitutes an “inventive concept,” the court rejected the analysis proposed by the Federal Circuit in its MySpace v. GraphOn decision (Fed. Cir. 2012), and advocated by the government in its amicus curiae brief. That analysis suggests determining if the claims satisfy the patentability requirement of 35 USC §§ 102, 103 and 112, before entering “the swamp of verbiage that is §101.”

The court reinforced its conclusion by going over in detail its precedents on patentable subject matter in connection with process claims involving abstract ideas, for example, Parker v. Flook, Diamond v. Diehr, Gottschalk v. Benson, and Bilski v. Kappos, and an English case, Neilson v. Harford, in which the claimed processes involved laws of nature. Without differentiating process claims involving natural laws from those involving abstract ideas, the court stated that “simply appending conventional steps, specified at a high level of generality, to laws of nature, natural phenomena, and abstract ideas cannot make those laws, phenomena, and ideas patentable.”

The Mayo analysis, based on these precedents, requires a two-step evaluation of a process claim for patent eligibility. First, remove its recitation of a law of nature, and potentially a natural phenomenon and an abstract idea as well. And second, look for an “inventive concept” in what remains. In this respect, the Mayo test appears inconsistent with the current practice, under Federal Circuit decisions, of evaluating a claim as a whole for its patent eligibility. In light of the Mayo decision, rejections and challenges of pending or issued process claims are sure to follow.

In response to the court’s decision, the U.S. Patent and Trademark Office has issued a memorandum entitled, “Preliminary Guidance on Examination Procedure to the Examining Corps.” In addition to reminding examiners of the factors in favor of and against eligibility set forth in the existing interim Bilski guidance, the preliminary guidance provides that “to be patent-eligible, a claim that includes an exception should include other elements or combination of elements such that, in practice, the claimed product or process amounts to significantly more than a law of nature, a natural phenomenon, or an abstract idea with conventional steps specified at a high level of generality appended thereto.”

How the USPTO and the courts will interpret and follow the Mayo decision remains to be seen. In the life science community particularly, claims directed to inventions in diagnostics and personalized medicine will likely face serious challenges under Mayo. Already, the Supreme Court has ordered the Federal Circuit to reconsider its decision in the highly publicized Myriad Genetics case, in view of the Mayo decision.

Applied rigorously, Mayo will be a challenge in a typical life science scenario where, upon discovery of a correlation between a biomarker and the presence of or predisposition to a disease or disorder, the correlation is often applied in diagnosis of the disease or disorder. If the biomarker and its natural function, whether or not novel or inventive, is considered a part of a natural law (i.e., the correlation), a claim directed to such a diagnostic method will likely be found not patent eligible under the Mayo test.

In view of the uncertainties surrounding the Mayo test, future patent applicants would be well advised to describe and define claim steps that cannot be characterized as a law of nature or an abstract concept and to describe and define activity that may not be characterized as a law of nature or an abstract concept, so as to differentiate it from that which is “well-understood, routine, conventional activity.”

Such descriptions and definitions may then be relied upon in a response to a rejection or challenge under § 101 to show that the elements or steps in a process claim (apart from what may be characterized as a statement of a natural law, a natural phenomenon or an abstract idea) involve an inventive, and patentable, concept.

Will these approaches be seen as what the Mayo decision characterized as “a drafting effort designed to monopolize the law of nature itself”? This too remains to be seen.

Proponents of claims subject to patent eligibility challenges may also take refuge in the Mayo decision’s reference to the non-natural law activity in Prometheus’ claims as “well-understood, routine, conventional activity” and its reference to the failure of that activity to yield more than the sum of its parts.

These references may imply a sub siliento consideration of questions ordinarily considered under §§ 102, 103 as a necessary adjunct to a § 101 analysis.

Notwithstanding the unanimity of the court in Mayo, the patentability of method claims, like those in Bilski and Mayo, will likely be a subject of argument and litigation for some time to come.

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