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Supreme Court Curtails Medical Diagnostic Patents


March 30, 2012

On March 20, 2012, in a unanimous decision, the Supreme Court held that a method for optimizing therapeutic efficacy merely recites a law of nature and, thus, is not patentable.  In Mayo Collaborative Services v. Prometheus Laboratories, Inc. (U.S., Case No. 10-1150, slip op.), a case of particular interest to the medical diagnostics community, the Court upheld the long-standing principle that laws of nature are not patent-eligible subject matter.  Typically, processes that apply a law of nature or natural phenomenon may only overcome this prohibition by claiming other additional inventive features that are patent eligible.  In this case, the Court held that the additional features in the claims of the patents at issue (U.S. Patent Nos. 6,355,623 and 6,680,302) were well-known, conventional steps that were not patentable, either alone or in combination, and therefore did not transform the claimed process into a patentable application of a law of nature (i.e., the correlation between drug metabolite levels and drug efficacy/harmful effects).


Claim 1 of U.S. Patent No. 6,355,623 is representative of the claims at issue and 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 x 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 x 108 red blood cells indicates a need to decrease the amount of said drug subsequently administered to said subject.

The Court's analysis began with identifying the law of nature, i.e., the relationship between the levels of drug metabolite in a patient's blood and drug efficacy.  Because the body naturally metabolizes drugs, the Court stated that the relationship is a law of nature.  The Court acknowledged that the claim recites additional steps that are not laws of nature; however, the steps are themselves not patentable and cannot transform the application of the natural phenomenon into something patentable. The Court reasoned that the step of "administering" simply notifies a pre-existing audience, namely doctors who treat patients with the drug, to consider the natural laws associated with the "wherein" clauses in their treatment decisions after "determining" the drug metabolite levels in the patient's blood.  Further, the Court noted that the step of "determining" is very general, including conventional, well-known, routine activities to those in the field as well as those activities that may be discovered later.  These additional steps in the claims at issue, considered separately or in combination, do not, according to the Court, add "significantly more" to the law of nature. The key question asked by the Court was: "do the patent claims add enough to their statements of the correlations to allow the processes they describe to qualify as patent-eligible processes that apply natural laws?" (emphasis added by the Court, slip op. at 8).

The implications of the Prometheus decision will be widespread, particularly in the biotechnology, pharmaceutical, and diagnostic industries.  The United States Patent and Trademark Office ("USPTO") has issued preliminary guidance to its patent examiners based on the decision. The guidance does not change current examination guidelines but reinforces that, "to be patent eligible, a claim that includes an exception [to patentable subject matter] should include other elements or combination of elements such that, in practice, the claimed product or process amount 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."

Issued patent claims and those pending in the USPTO that are directed to medical diagnostic methods or processes that arguably apply a law of nature should be reviewed to determine if additional inventive steps or features are present.  In the future, claims should be drafted with additional patent-eligible steps or features that apply the law of nature.

In a related development, on March 26, 2012, the Supreme Court remanded the case of the Association for Molecular Pathology v. United States Patent and Trademark Office, 653 F.3d 1329 (Fed. Cir. 2010) (also known as the "Myriad" case) to the appeals court to determine the patent-eligibility of isolated DNA sequences in light of its ruling in the Prometheus case.  The biotechnology, pharmaceutical, and diagnostic communities will continue to anxiously await the final outcome of the Myriad case.