Mayo v. Prometheus Limits Diagnostic Test Patenting

by Dechert LLP

Tuesday the Supreme Court unanimously decided Mayo Collaborative Services v. Prometheus Labs, a decision of considerable significance to the diagnostics industry.

The Court reversed the Federal Circuit Court of Appeals, which had held that patent claims to “a method of optimizing therapeutic efficacy” for treatment of a specific disorder with the steps of (a) administering a specific drug; (b) determining the level of a metabolite of the drug in the patient; wherein the dosage of the drug should be increased or decreased if the level of the drug is outside of a specified range, were patentable under the §101 utility requirement.

The Court held that such claims are unpatentable under §101 because:

[T]he claims inform a relevant audience about certain laws of nature; any additional steps consist of well-understood, routine, conventional activity already engaged in by the scientific community; and those steps, when viewed as a whole, add nothing significant beyond the sum of their parts taken separately.

566 U.S. ___ (2012) Slip Op. at 11.  Here, the law of nature would be that the optimal level of the metabolite is within the specified range.  While the Supreme Court has held many times that laws of nature are not patentable subject matter, the Federal Circuit reasoned that the claims were not merely to a natural law because the “administering” step transformed the body of the patient and the “determining” step transformed the analyte tested.  628 F.3d 1347, 1356-1357 (Fed. Cir. 2010).  The Supreme Court disagreed, finding that the “administering” step merely “helps pick out the group of individuals who are likely interested in applying a law of nature” and the “determining” step could be potentially be satisfied in the future by a technique for measuring the metabolite that involved no transformation.  Slip Op. at 19.

The Mayo decision begs several questions.  For instance, what diagnostic test patent claims remain valid in light of this ruling?  And, does this decision affect other types of biotech patent claims?

Are diagnostic test claims that are based on the correlation between an assay result and a treatment (such as susceptibility or resistance to a particular treatment correlated to a genotype or gene or protein expression) ever patentable?  Presumably a court would deem that such a correlation itself is a natural law.  Then what method steps could confer patentability to such a test?  The Court held that “well-understood, routine, conventional activity already engaged in by the scientific community” cannot be the basis for patentability, so it seems probable that a new correlation between an old treatment and an old assay would not be patentable.  Therefore, it appears that the method would have to involve either a new treatment or a new assay.  Would the treatment or assay have to be patentable individually to support patentability of a method using the assay to choose the treatment?  Perhaps the Supreme Court was trying to leave some additional scope where the method steps are individually conventional but when “viewed as a whole” add something “significant beyond the sum of their parts.”  This could very likely be the nexus for future disputes in this area.

What about new methods of treatment involving old drugs?  In dicta, Court seems to exempt these from its ruling because they involve “particular applications” of natural laws:

For here, as we have said, the steps add nothing of significance to the natural laws themselves.  Unlike, say, a typical patent on a new drug or a new way of using an existing drug, the patent claims do not confine their reach to particular applications of those laws.

Slip Op. at 18.  One wonders, however, is there really a meaningful difference between a new correlation between an assay result and a treatment on the one hand and a new correlation between a disease state and a treatment on the other?  Isn't identifying a new class of patients who would be aided by administration of an old drug merely “inform[ing] a relevant audience about certain laws of nature”?  It seems inevitable that some party accused of infringing a patent claim to a new method of treatment using an old drug will challenge this distinction.


DISCLAIMER: Because of the generality of this update, the information provided herein may not be applicable in all situations and should not be acted upon without specific legal advice based on particular situations.

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