To recap, in Classen, the Federal Circuit initially concluded that the claimed "method of determining whether an immunization schedule affects the incidence or severity of a chronic immune-mediated disorder in a treatment group of mammals" was not patent-eligible under § 101.  In Prometheus, however, a different panel of the Federal Circuit upheld the patent-eligibility of Prometheus's claims to a "method of optimizing therapeutic efficacy for treatment of an immune-mediated gastrointestinal disorder."  Both of these decisions were based on the Federal Circuit's application of the so-called "machine-or-transformation" test, which the Federal Circuit had recently adopted as the exclusive test for determining eligibility for patent protection under § 101. 

The Supreme Court subsequently vacated both of the Federal Circuit's initial Classen and Prometheus decisions and remanded the cases in view of the Court's Bilski decision.  In Bilski, the Supreme Court rejected the Federal Circuit's pronouncement of the machine-or-transformation test as the exclusive test for patent-eligibility under § 101.  The Court stated that its precedents "provide three exceptions to § 101's broad patent-eligibility principles: laws of nature, physical phenomena, and abstract ideas."  The Court reasoned that while the machine-or-transformation test is a "useful and important clue" in determining whether certain claimed inventions are eligible for patent protection under § 101, it is not the sole test for making this determination. 

Prometheus Developments

The claims at issue in Prometheus are directed to a "method of optimizing therapeutic efficacy for treatment of an immune-mediated gastrointestinal disorder."  The claimed method requires two active steps:  (a) administering a drug providing a certain metabolite; and (b) determining the level of the metabolite in the subject patient.  The claims also describe metabolite levels that respectively indicate a need to increase or decrease the amount of the drug subsequently administered to the patient. 

Notably, Prometheus's method claims do not expressly require a step of administering the drug after determining the level of metabolite in the patient.  Nevertheless, for reasons that are not entirely clear from its opinion, the Federal Circuit interpreted the claims as limited to "methods of treatment."  The Federal Circuit found that Prometheus's method claims recite "a patent-eligible application of naturally occurring correlations between metabolite levels and efficacy or toxicity, and thus do not wholly preempt all uses of the recited correlations." As such, according to the court, the Prometheus claims "do not preempt all uses of the natural correlations," but instead "utilize them in a series of specific steps." The court further stated that Prometheus's claimed treatment methods satisfy the machine-or-transformation test because they "transform an article into a different state or thing" and that his transformation is "central to the purpose of the claimed process."  In applying the machine-or-transformation test, the Federal Circuit reasoned that even though the Supreme Court held in Bilski that the test was not the exclusive test for patent-eligibility, the Court did state that the test was nevertheless a "useful clue" in making this determination.

In June, the Supreme Court agreed to review the Federal Circuit's second Prometheus decision.  Petitioner Mayo filed its brief on September 2, 2011.  Mayo's primary argument to the Supreme Court is that Prometheus's claims attempt to preempt all uses of a "natural phenomenon – the biological correlation between metabolite levels and health – without describing what is to be done with that phenomenon beyond considering whether a dosage adjustment may be necessary."  Mayo further argues that the "administering" and "determining" steps in Prometheus's claims are merely "data gathering" steps that cannot make an otherwise unpatentable method eligible for patent protection.  Prometheus must file its brief by October 31, 2011, and oral argument before the Supreme Court is scheduled for December 7, 2011.  A decision will likely come by mid 2012.                                                                                                                             

Classen Developments

On August 31, 2011, the Federal Circuit issued its second decision in Classen.  In a split decision, Judges Newman and Rader found that certain of Classen's claims satisfied § 101, while other claims were not eligible for patent protection. 

One representative claim at issue in Classen recites two steps: (1) "immunizing mammals in the treatment group of mammals with one or more doses of one or more immunogens, according to [an] immunization schedule"; and (2) "comparing the incidence, prevalence, frequency or severity of said chronic immune-mediated disorder or the level of a marker of such a disorder, in the treatment group, with that in the control group." 

The court found that this claim merely recites "the idea of comparing known immunization results that are, according to the patent, found in the scientific literature, but does not require using this information for immunization purposes."  The Court reasoned that this claim is directed to "the abstract principle that variation in immunization schedules may have consequences for certain diseases," which was insufficient under § 101.  In short, this claim merely attempted to claim an abstract idea and was thus not eligible for patent protection. 

A second representative claim recites a method of immunizing a mammalian subject.  This claimed method comprises two primary steps:  (a) screening a plurality of immunization schedules with respect to the risk of developing a chronic immune-mediated disorder by identifying at least two groups of mammals each having been immunized according to a different immunization schedule, and thereafter comparing the effectiveness of the immunization schedules to identify one of the immunization schedules as a lower risk schedule and the other as a higher risk schedule; and (b) immunizing the subject according to the lower risk schedule.  The court found this claim to be eligible for patent protection because, in contrast to the claims that do not satisfy § 101, it includes "the subsequent step of immunization on an optimum schedule."  The court reasoned that this further act of immunization in accordance with a lower-risk schedule moved the claims "from abstract scientific principle to specific application" and "through the coarse filter of § 101."

Notably, the Classen majority's decision appears to be based almost solely on the question of whether the representative claims are directed merely to an abstract idea.  Thus, the court did not appear to rely on the machine-or-transformation test in reaching its conclusion.  This is in stark contrast to its earlier decision in Prometheus, which appeared to rely heavily on the "transformative" nature of the "administering" and "determining" steps in Prometheus's claims. 

Judge Moore, who authored the original one-paragraph Classen opinion vacated in view of Bilski, dissented, stating that while "the precise line to be drawn between patentable subject matter and abstract idea is quite elusive," Classen's claims were "not even close." 

In addition, Chief Judge Rader, joined by Judge Newman, provided "additional views" that caution against taking a restrictive view of § 101.  According to Judge Rader, § 101 "places few, if any, limits on subject matter eligibility," and that "it is difficult to ‘invent' any category of subject matter that does not fit within the four classes" specified in § 101.  Citing public policy reasons for a broad interpretation of § 101, Judge Rader stated that the statute should be viewed as a "coarse filter" and a "threshold statement that explicitly directs attention to the ‘conditions and requirements of this title' to qualify for a patent" – i.e., the novelty, non-obviousness and adequate disclosure requirements found elsewhere in the patent laws.  Under this rationale, the Federal Circuit would be likely to uphold the patent eligibility of most method claims and rely primarily on the substantive requirements of novelty, non-obviousness and adequate description to determine the ultimate question of patentability.  And notably in this regard, Judges Rader, Newman and Moore all appear to agree that all of Classen's claims may be unlikely to satisfy these substantive requirements of patentability.

Takeaway

The latest Classen and Prometheus decisions provide at least some guidance for navigating the requirements of patent eligibility under § 101, particularly in the Classen court's rationale for upholding the patent-eligibility of some of Classen's claims but not others.  That is, Classen suggests that a specific method step requiring putting the knowledge gained from a scientific principle –e.g., the results of known immunization schedules in Classen – to "practical use" – i.e., Classen's step of "immunization in accordance with a lower-risk schedule" – will be sufficient to satisfy § 101.  This rationale also helps reconcile the Classen and Prometheus decisions, in that the Prometheus court interpreted the claims at issue as being directed to specific methods of treatment that utilize naturally occurring correlations, and not merely to methods of determining the correlation themselves. 

Thus, considering these decisions, a method will likely be patent-eligible if the claimed method accomplishes a specific result (e.g., immunization according to a lower-risk schedule or administering a drug at a therapeutically-optimal level).  On the other hand, a method will likely be ineligible for patent protection if it merely derives or obtains information about a natural phenomenon (e.g., the effectiveness of an immunization schedule). 

Medical technology companies should use caution in drafting claims to include active treatment steps, however, as this could create enforcement challenges if the person or device that performs these treatment steps is different than the person or device that performs the prior diagnostic step(s).  As usual, the best approach is to pursue a variety of claims of differing scope to cover the full breadth of the inventive methods. 

And as discussed earlier, the Supreme Court should decide Prometheus by mid-2012.  Whether this decision will further clarify patent-eligibility for medical treatment methods remains to be seen.