September 18, 2009

Prometheus Laboratories: Federal Circuit Applies In re Bilski to Medical Treatment Claims

On September 16, 2009, a unanimous panel of the U.S. Court of Appeals for the Federal Circuit decided Prometheus Laboratories, Inc. v. Mayo Collaborative Services, Fed. Cir., No. 2008-1403, 9/16/09).

The court held that Prometheus' patent claims to a "method of optimizing therapeutic efficacy for treatment of an immune-mediated gastrointestinal disorder" constituted patent-eligible subject matter under 35 U.S.C. § 101. Prometheus is the first precedential Federal Circuit decision applying the "machine-or-transformation test" set forth in In re Bilski, 545 F.3d 943 (Fed. Cir. 2008) (en banc), cert. granted, 556 U.S. 1 (June 1, 2009) to medical process claims.

Prometheus' Claims and the District Court Decision

Prometheus sued Mayo Collaborative Services on June 15, 2004, in the U.S. District Court for the Southern District of California, alleging infringement of U.S. Patents 6,355,623 and 6,680,302. The asserted patents generally claim methods for calibrating the proper dosage of thiopurine drugs, which are used for treating both gastrointestinal and non-gastrointestinal autoimmune diseases. For example, representative claim 1 of the ‘623 patent recites:

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 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.

On March 28, 2008, the district court granted Mayo's motion for summary judgment of invalidity under 35 U.S.C. § 101. The district court reasoned that the asserted claims have three steps: (1) administer the drug to a subject; (2) determine metabolite levels; and (3) be warned that an adjustment in dosage may be required.

The district court concluded that the "administering" and "gathering" steps are merely necessary data-gathering steps and that the final "warning" step (i.e., the wherein clause) is only a mental step. The district court then concluded that the claims wholly preempt the correlations between concentrations of selected metabolites (e.g., 6-thioguanine) and therapeutic efficacy or toxicity in the patients, and thus did not claim patentable subject matter under 35 U.S.C. § 101. Notably, the district court stated that the fact that the inventors framed the claims as "treatment methods" does not render the claims patentable.

The Federal Circuit Opinion

On appeal, Prometheus argued that the claimed processes satisfy the machine-or-transformation test articulated in Bilski. Under Bilski, a claimed process is patentable under § 101 if (1) it is tied to a particular machine or apparatus, or (2) it transforms a particular article into a different state or thing. In addition, the transformation requirement cannot be satisfied solely by "insignificant extra-solution activity" or a mere "data-gathering step." At the same time, "the patent eligibility of a claim as a whole should not be based on whether selected limitations constitute patent-eligible subject matter." The Federal Circuit noted that the district court "did not have the benefit of [its] Bilski decision when deciding the § 101 issue."

The Federal Circuit agreed with Prometheus and reversed the district court's grant of summary judgment of invalidity, concluding that the "methods of treatment claimed in the patents in suit" satisfied the transformation prong of the machine-or-transformation test.

In an opinion written by Judge Lourie, and joined by Chief Judge Michel and the Honorable Ron Clark (sitting by designation), the court found that the district court erred in concluding that the disputed claims merely claim natural correlations and data-gathering steps. In doing so, the Federal Circuit indicated that the district court's reliance on the opinion of three justices dissenting from the dismissal of the grant of certiorari in Laboratory Corp. of America Holdings v. Metabolite Laboratories, Inc., 548 U.S. 124 (2006) (Breyer, J., dissenting), was misplaced because that dissent "is not controlling law and also involved different claims from the ones at issue here."

First, the court explained that the recited "administering" step is transformative: "The transformation is of the human body following administration of a drug and the various chemical and physical changes of the drug's metabolites that enable their concentrations to be determined." The court reasoned that the asserted claims are to methods of treatment, "which are always transformative when a defined group of drugs is administered to the body to ameliorate the effects of an undesired condition."

The court further explained that:

         [W]hen administering a drug such as AZA or 6-MP, the human body necessarily undergoes a transformation. The drugs do not pass through the body untouched without affecting it. In fact, the transformation that occurs, viz. the effect on the body after metabolizing the artificially administered drugs, is the entire purpose of administering the drugs. … The fact that the change of the administered drug into its metabolites relies on natural processes does not disqualify the administering step from the realm of patentability. … The transformation here, however, is the result of the physical administration of a drug to a subject to transform—i.e., treat —the subject, which is itself not a natural process.

Second, the court explained that the "determining" step is also transformative and "central to the claimed methods." According to the court, "[d]etermining the levels of 6-TG or 6-MMP in a subject necessarily involves a transformation, for those levels cannot be determined by mere inspection. Some form of manipulation, such as the high pressure liquid chromatography method specified in several of the asserted dependent claims or other modification of the substances to be measured, is necessary to extract the metabolites from a bodily sample and determine their concentration." Indeed, the court cited testimony by Prometheus' expert that "at the end of the process, the human blood sample is no longer human blood; human tissue is no longer human tissue," and stated that this "is clearly a transformation."

The court concluded that the administering and determining steps were not merely data-gathering steps, and consequently, were not insignificant extra-solution activity. Notably, the court acknowledged that the administering and determining steps gather useful data, but reasoned that the presence of those two steps in the claimed processes is not merely for the purpose of gathering data. Instead, according to the court, "the administering and determining steps are part of a treatment protocol, and they are transformative." The court then distinguished Prometheus' claims from those in In re Grams, 888 F.2d 835 (Fed. Cir. 1989), where the "essence" of the claimed process was a mathematical algorithm, rather than any transformation of the tested individuals. According to the Federal Circuit, unlike the clinical tests in Grams, the administering and determining steps in Prometheus' claimed methods are "part of treatment regimes for various diseases using thiopurine drugs."

Finally, the Federal Circuit found that the recited wherein clauses are "mental steps" and thus not patent-eligible themselves. The court explained, however, that the presence of a subsequent mental step does not, by itself, negate the transformative nature of the prior steps. According to the court, "[w]hen viewing the treatment methods as a whole, Prometheus has claimed therapeutic methods that determine the optimal dosage level for a course of treatment." The court again emphasized the disputed claims are to transformative methods of treatment, not correlations.

Impact on Patent Protection for Medical Technology

Prometheus provides helpful guidance for assessing medical method claims under the "transformation" prong of Bilski's machine-or-transformation test. Under Prometheus, for example, claims drawn to methods of medical treatment that involve a transformation of the human body, assuming the transformation is central to the "essence" of the claimed method, are patent-eligible. In particular, claims directed to methods of treatment including administering a drug to treat an undesired condition are "always transformative," and thus are patent-eligible.

The opinion, however, leaves other questions unanswered. Perhaps most notably, the patent-eligibility of purely diagnostic methods remains unclear. The Prometheus court repeatedly noted that the claims at issue were directed to methods of treatment and that the claimed determining step, while ostensibly diagnostic in nature, was "central to the purpose of the claims." Prometheus does not directly address whether a claim drawn to a method of diagnosing a condition, as opposed to treating a condition, would be patent eligible even assuming the claim recites a transformative step.

In other words, if the essence of the claim as a whole is to the diagnosis of a medical condition by identifying a correlation between patient test data and a disease, would the presence of a transformative data collection step necessarily render the claim patent eligible? In this situation, a court may find that the essence of such a claim is the correlation between patient data and a disease. As such, the transformative data collection step may be merely an extra-solution step not central to the essence of the claim. And, notably, while Prometheus emphasizes the importance of determining the "essence" of the claim to a patent-eligibility analysis, it provides little or no guidance on how to make such a determination.

Perhaps the Supreme Court's In re Bilski decision (expected in 2010) will help answer these questions with more certainty.

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