Prometheus Unbound: Patents Invalid For Claiming Natural Phenomena

2008-1403 Prometheus Labs v. Mayo Collabrative
SD/CA 04-cv-1200
Judge John Houston

Patentee Prometheus appeals from Judge John Houston's order on summary judgment finding that the patents-in-suit are invalid under § 101 for claiming unpatentable subject matter, specifically "natural phenomena."

Prometheus is the exclusive licensee of 6,355,623 and 6,680,302 directed to testing levels of certain metabolites in the blood of patients taking thiopurine drugs, including the anti-Crohn’s disease drug azathioprine (“AZA”), for treatment of autoimmune diseases.  Prometheus sells the patented test that allows doctors to monitor a patient's metabolite levels and thereby adjust medication levels to reach therapeutic goals.  After Mayo announced plans to sell a similar, competing metabolite test, Prometheus filed suit.

Generally, the patented test provides a means to measure the level of 6-thioguinine (“6-TG”) and 6-methylmercaptopurine (“6-MMP”), which indicates that an adjustment in drug dosage may be required at certain metabolite levels.  Claim 1 of the '302 is representative:

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 a level of 6-thioguanine or 6-methyl-mercaptopurine in said subject having said immune-mediated gastrointestinal disorder,

wherein a level of 6-thioguanine less than about 230 pmol per 8108 red blood cells indicates a need to increase the amount of said drug subsequently administered to said subject and

wherein a level of 6-thioguanine greater than about 400 pmol per 8108 red blood cells or a level of 6-methyl-mercaptopurine greater than about 7000 pmol per 8108 red blood cells indicates a need to decrease the amount of said drug subsequently administered to said subject.

Mayo claimed that the patents impermissibly claim natural phenomena--the correlations between thiopurine drug metabolite levels on the one hand and toxicity on the other.  The court agreed, finding the claims invalid.

While the scope of patentable subject matter under § 101 is broad, it does not include the "laws of nature, natural phenomena, and abstract ideas."  After noting that the question was one of law, the court summarized the issues:

In assessing patentability under section 101 in the context of method patents, the Supreme Court has explained that a method patent is not invalid “simply because it contains a law of nature or a mathematical algorithm.” Parker v. Flook, 437 U.S. 584, 590 (1978). But, if the claim “recites” a law of nature or a mathematical algorithm, the court must analyze whether the claim is seeking patent protection for the phenomenon “in the abstract” or whether the claim implements a natural phenomenon “in a structure or process which, when considered as a whole, is performing a function which the patent laws were designed to protect.” Diehr, 450 U.S. at 191. Thus, where the claim “wholly pre-empts” all uses of the natural phenomenon or abstract idea such that the “practical effect is a patent on the [phenomenon] itself” the claim is invalid under section 101. Benson, 409 U.S. at 71-72; see also Diehr, 450 U.S. at 187.

Reciting natural phenomenon.  According to the court, a careful reading of the claim shows that it includes only two active steps, "administering" the drug and then "determining" metabolite levels.  The bulk of the claim is directed to explaining that the metabolite levels themselves indicate a need to possible increase or decrease medications levels.  Thus, the claims recite the correlation (between metabolite levels and therapeutic efficacy)--or, as the court concluded, "what the inventors claim to have discovered is that particular concentrations of 6-TG and 6-MMP correlate with therapeutic efficacy and toxicity in patients taking AZA drugs."

The Correlations Are Natural Phenomena.  Prometheus argued that the correlations were not "natural phenomena" because they would not exist without the administration of man-made drugs.  The court rejected this argument, citing Funk Bros. (333 U.S. 127) and Lab Corp. (126 S.Ct. 2921, Breyer, J., dissenting from dismissal of certiori [see Patently-O coverage and dissent here]).  The inventors did not "invent" the correlation, but discovered it from studying patient data--the correlation is the product a a natural body process.

Wholly Pre-Empt.  The "law does not require that every conceivable use be preempted to invalidate the claim.  Rather, it is enough that the unpatentable subject matter recited in the claim has 'no substantial practical application' outside the context of the claim."  The court rejected Prometheus' argument that the correlation could still be used for research, diseases other than autoimmune or gastrointestinal and the like, finding such uses "not substantial."

The court also rejected Prometheus' argument that the Federal Circuit's recent decision in In re Comiskey saved its claims because otherwise invalid subject matter was allowable under § 101 because it was "tied" to an apparatus.  The court declined to read Comiskey so broadly, but further noted that Prometheus' claims were not "tied" to an apparatus (test equipment) but rather only incidentally implicated such equipment.

More reading:

Order on Summary Judgment

Counsel:

Prometheus: Wilson Sonsini Goodrich and Rosati (Alexandra Mahaney, Natalie Jordana Morgan, Aubrey A Haddach)
Mayo: Fish and Richardson (Michael J Kane, Jennifer K Bush, Juanita R Brooks)

Image Attribution: Prometheus Bound, copyright 2006 by Scott Eaton www.scott-eaton.com.

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