In a case on remand from the Supreme Court, the Federal Circuit has reaffirmed its previous opinion that claims directed to methods of optimizing the dosages of certain drugs for treating gastrointestinal disorders are patentable subject matter under 35 U.S.C. § 101. The decision provides insight into how the Federal Circuit interprets the Supreme Court's Bilski v. Kappos decision and shows that, while not dispositive, the "machine or transformation" test is still an important part of the Federal Circuit's § 101 jurisprudence. Prometheus Labs., Inc. v. Mayo Collaborative Services, No. 2008-1403 (Fed. Cir. Dec. 17, 2010).

Background

Prometheus Laboratories, Inc. ("Prometheus") is the owner of U.S. Patent Nos. 6,355,623 ("the '623 patent") and 6,680,302 ("the '302 patent"). The patents claim methods for determining optimal dosages for drugs that treat immune-mediated gastrointestinal disorders by measuring the level of certain toxins in a patient's bloodstream after administration of the drugs to determine whether the dosage level is so high as to be dangerous (indicating that the next dosage amount should be reduced) or so low as to be ineffective (indicating that the next dosage amount should be increased).

Claim 1 of the '623 patent is representative and reads:

  1. A method of optimizing therapeutic efficacy for treatment of an immune-mediated gastrointestinal disorder, comprising:
    1. administering a drug providing 6-thioguanine to a subject having said immune-mediated gastrointestinal disorder; and
    2. 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 8x108 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 8x108 red blood cells indicates a need to decrease the amount of said drug subsequently administered to said subject.

Claim 1 of the '302 patent is substantially the same, with the addition of determining 6-methyl-mercaptopurine ("6-MMP") levels in addition to 6-thioguanine ("6-TG") levels.

Claim 46 of the '623 patent and its dependent claims do not contain the "administering" limitation. Claim 46 reads

  1. A method of optimizing therapeutic efficacy and reducing toxicity associated with treatment of an immune-mediated gastrointestinal disorder, comprising:
    1. determining the level of 6-thioguanine or 6-methyl-mercaptopurine in a subject administered a drug selected from the group consisting of 6-mercaptopurine, azathioprine, 6-thioguanine, and 6-methylmercaptoriboside, said subject having said immune-mediated gastrointestinal disorder;

wherein the level of 6-thioguanine less than about 230 pmol per 8x108 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 8x108 red blood cells or a level of 6-methyl-mercaptopurine greater than about 7000 pmol per 8x108 red blood cells indicates a need to decrease the amount of said drug subsequently administered to said subject.

Prometheus asserted these patents against Mayo Collaborative Services ("Mayo") in the U.S. District Court for the Southern District of California. In 2008, the district court granted Mayo's motion for summary judgment that the asserted claims are invalid under § 101. The Federal Circuit reversed this judgment in 2009, applying the "machine-or-transformation test" enunciated in its prior en banc decision in Bilski. Prometheus Labs., Inc. v. Mayo Collaborative Servs., 581 F.3d 1336 (Fed. Cir. 2009) (applying In re Bilski, 545 F.3d 943 (Fed. Cir. 2008) (en banc)). However, the Supreme Court later granted certiorari to review the Federal Circuit's Bilski ruling and on June 28, 2010, issued its own decision in Bilski v. Kappos, 130 S. Ct. 3218 (2010), which held that the "machine-or-transformation test" was not the exclusive test to determine patentable subject matter under § 101. In the meantime, Prometheus had petitioned for certiorari as well. Following, its Bilski decision, the Supreme Court granted Prometheus's cert. petition, vacated the Federal Circuit's judgment in the Prometheus v. Mayo case, and remanded for further consideration in light of Bilski.

The Legal Standard After Bilski

On remand, the Federal Circuit began its analysis by reviewing the law concerning patent-eligible subject matter in light of the Supreme Court's Bilski decision. The Federal Circuit explained that 35 U.S.C. § 101 "specif[ies] four independent patent-eligible categories of inventions or discoveries-processes, machines, manufactures, and compositions of matter." However, there are "three specific exceptions to § 101's broad patent-eligibility principles: 'laws of nature, physical phenomena, and abstract ideas.'"

Claims are deemed to be drawn toward a natural phenomenon, and therefore patent-ineligible, if patenting them "would entirely preempt" the use of the natural phenomenon, the Federal Circuit explained. Moreover, "a scientific principle cannot be made patentable by limiting its use to a particular technological environment or by adding insignificant post-solution activity." Nevertheless, "an application of a law of nature or mathematical formula to a known structure or process may well be deserving of patent protection."

In determining whether claims cover a patent-ineligible law of nature or a patent-eligible application of a law of nature, the Federal Circuit stressed that the Supreme Court "did not disavow the machine-or-transformation test" but, rather, stated that the machine-or-transformation test is a "useful and important clue, an investigative tool."

Bilski Does Not Change Conclusion That Claimed Methods Are Patentable

The Federal Circuit explained that "[i]n light of the Supreme Court's decision in Bilski, patent eligibility in this case turns on whether Prometheus's asserted claims are drawn to a natural phenomenon, the patenting of which would entirely preempt its use . . ., or whether the claims are drawn only to a particular application of that phenomenon. . . ." Applying this preemption test, the Federal Circuit held that the asserted claims were patentable: "Prometheus's asserted method claims recite a patent-eligible application of naturally occurring correlations between metabolite levels and efficacy or toxicity ... [T]he claims recite specific treatment steps, not just the correlations themselves. And the steps involve a particular application of the natural correlations: the treatment of a specific disease by administering specific drugs and measuring specific metabolites. ... [T]he claims do not preempt all uses of the natural correlations; they utilize them in a series of specific steps ... comprising particular methods of treatment."

The Federal Circuit also discussed the claims' patentability under the 'machine or transformation" test, which, it pointed out, the Supreme Court had endorsed as a "useful and important clue" to patentability under § 101. Focusing on the "transformation" prong of the "machine-or-transformation" test, the court held that the "administration" limitation of some of the asserted claims constituted a "transformation ... of the human body and of its components following the administration of a specific class of drugs and the various chemical and physical changes of the drugs' metabolites that enable their concentrations to be determined," and was not drawn merely to "natural correlations and data-gathering steps." Indeed, the Federal Circuit stated the more general rule that "claims to methods of treatment ... are always transformative when one of a defined group of drugs is administered to the body to ameliorate the effects of an undesired condition."

The Federal Circuit held that the asserted claims that did not contain the "administering" step were also transformative because they contained a "determining" step, and "[d]etermining the levels of 6-TG or 6-MMP in a subject necessarily involves a transformation. Some form of manipulation, such as the high pressure liquid chromatography method specified in several of the asserted dependent claims or some other modification of the substances to be measured, is necessary to extract the metabolites from a bodily sample and determine their concentration."

The Federal Circuit disagreed with the district court's conclusion that the "administering" and "determining" steps are "merely necessary data-gathering steps for any use of the correlations," i.e., a patent-ineligible law of nature combined with "insignificant extra-solution activity." Rather, the administering and determining steps are "central to the claims" since "the drugs are administered to provide 6-TG, which is thought to be the drugs' active metabolite in the treatment of disease, to a subject ... [and] [m]easuring the levels of 6-TG and 6-MMP is what enables possible adjustments to thiopurine drug dosage to be detected for optimizing efficacy or reducing toxicity during a course of treatment." In other words, the claims are "not drawn merely to correlations between metabolite levels and toxicity or efficacy," but to "treatment regimes for various diseases using thiopurine drugs." The inclusion of "the final 'wherein' clauses [which] are mental steps and thus not patent-eligible per se ... does not detract from the patentability of [the] claimed methods as a whole," which also include the patent-eligible "administering" and "determining" steps. For these reasons, the Federal Circuit held that the asserted method claims were patent-eligible and again reversed the district court's grant of summary judgment of invalidity under § 101.

Conclusion

The Prometheus case shows that the Federal Circuit still places great weight on the "machine or transformation" test set forth in the court's en banc Bilski decision, despite the Supreme Court's subsequent ruling that it cannot be used as the exclusive test for patentability under § 101. Prometheus suggest that an analysis of patentability under § 101 should begin with a determination of whether the claimed subject matter falls into one of the three traditional exceptions to patent eligibility (laws of nature, physical phenomena, and abstract ideas). For inventions that do not fall into one of those prohibited categories, a showing that the invention satisfies the machine or transformation test is a useful and important tool for confirming that the subject matter is patent-eligible.