Pharmaceutical and Biotech Companies Win Important Federal Circuit Ruling that Affirms Eligibility of Patent Protection for Diagnostic Test that also Involve Treatment

by John Guynn & John Stringham

            In a recent decision, Prometheus Laboratories, Inc. v. Mayo Collaborative Services, 2008-1403 (Fed Cir. 2009)  the Federal Circuit upheld as constituting patent eligible subject matter under 35 U.S.C. § 101 a diagnostic test that also involved treatment of a patient.  The decision has important implications for pharmaceutical and biotechnology companies that sell diagnostic devices and methods. 

The case was widely watched in view of the non-decision by the Supreme Court in Laboratory Corp. of America Holdings v. Metabolite Laboratories, Inc., 548 U.S. 124 (2006) (Breyer, J., dissenting).  Unless Prometheus is eventually overruled by the Supreme Court, it at least partially removes a cloud on diagnostic treatment methods that arose as result of Justice Breyer's dissenting opinion in Metabolite.

            In the Metabolite case, the Supreme Court initially granted a petition seeking to have a case heard that involved a diagnostic method but the Court later reversed itself on the grounds that the petition had been improvidently granted.  Justice Breyer, writing in dissent of the Court's refusal to hear the Metabolite appeal, expressed in a strongly worded opinion the  view that the patent claims at issue did not constitute patent eligible subject matter, thus placing a serious cloud over claims seeking to protect such subject matter. 

In a unanimous panel decision in Prometheus the Federal Circuit stated that the dissent in Metabolite was not controlling law and also distinguished Metabolite as involving different claims than those at issue in Prometheus.  It remains to be seen, however, whether a diagnostic claim like the one in Metabolite would be upheld by either the Federal Circuit or Supreme Court as constituting patent eligible subject matter.  What follows is a comparison of the claims at issue in the Metabolite that was presented to the Supreme Court, and those at issue before the Federal Circuit in Prometheus.

            The patent at issue in Prometheus was U.S. Patent No. 6,355,623.  Claim 1 is representative of the independent claims of the ‘623 patent and reads as follows:

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.  (Emphasis added).

Applying the "transformation" test from its prior decision in Bilski, in which the Federal Circuit held that claims to processes or methods, as in the case of business method claims, are not eligible for patent protection unless they involve some kind of physical transformation, the Federal Circuit held that the claims presented in Prometheus satisfied the transformation test in two ways.  First, the administering step (step (a) noted above) was held to involve a transformation of the patient's body because of chemical and physical changes to the body by the drug's metabolites.  The fact that the change of the drug into its metabolites relies on natural processes was held to not disqualify the administering step from the realm of patentability.  The court noted that every transformation of physical matter can occur according to natural processes and natural law.

Second, and perhaps more importantly from the standpoint of the diagnostic test as claimed in the Supreme Court's  Metabolite case, the determining step (step (b) noted above) was held to also involve transformation.  The court noted that the levels of the drug and its metabolite cannot be determined by mere inspection and that some form of manipulation, such as high pressure liquid chromatography, is necessary to isolate the metabolites from a bodily sample and determine their concentration.  This, the Federal Circuit reasoned, is "transformation" under Bilski test.

The court further held that the administering and determining steps are not merely data-gathering nor insignificant post-solution activity but are central to the claims.  In reaching this conclusion, the court noted that while the administering and determining steps gather useful data, they are not merely for the purpose of gathering data.  Instead, they are part of a treatment protocol and they are transformative.

Finally, the court held that the presence of a mental step does not detract from the patentability of the claims.  While the "wherein" clauses (see the claim above) were found to be "mental steps" which, on their own, are not eligible for patent protection, the court held that their inclusion does not negate the transformative nature of the other two steps (steps (a) and (b) discussed above in the reproduced claim). 

            While by no means dispositive, the Prometheus decision provides insight into how the Federal Circuit might have ruled in Metabolite after Bilski.  As will be seen, there are important similarities and differences between the claims in Prometheus and Metabolite.  Claim 13 in Metabolite reads as follows:

A method for detecting a deficiency of cobalamin or folate in warm-blooded animals comprising the steps of:

assaying a body fluid for an elevated level of total homocysteine; and

correlating an elevated level of total homocysteine in said body fluid with a deficiency of cobalamin or folate.

            The threshold issue is whether the foregoing method involves a "transformation" that would also have satisfied the transformation test of Bilski.  Because the "determining" step in Prometheus involved manipulation of a body fluid, a similar argument could be made that the "assaying" step in Metabolite is also a transformation because it probably cannot be performed by mere inspection.  Moreover, the term "assaying" arguably implies more of a transformation than "determining".

            With regard to Metabolite, the key issue would seem to be whether the assaying step is mere data gathering or post-solution activity.  If so, then the claim in Metabolite might not have constituted patent eligible subject matter under 35 U.S.C. § 101, since mere data gathering has already been held to be ineligible § 101 subject matter, while the "correlating" step is arguably a "mental step."  Thus, left unresolved with regard to Metabolite is whether "assaying" goes beyond mere data gathering and is a physical transformation.

With these principles in mind, the following observations on Metabolite and Promethius may provide some guidance:

• A problem with the "assaying" step in Metabolite is that it is not clear that the claim describes any particular assay involving specific reagents or testing apparatus that transform matter.  It arguably covers any assay.  Such broadly recited subject matter will likely tend to increase the difficulty as qualifying a claim as constituting eligible subject matter, or at the very least may create problems with whether the claim language is adequately described in the specification.  To avoid such problems, it is preferable to recite a specific type of transformative assay or assay methodology used in the context of a particular type of machine (thus qualifying the claim under the alternative "machine" test of Bilski).

• Unlike Prometheus, the claim in Metabolite does not recite administering a drug to a patient and therefore does not involve a method of treatment.  Both the "administering" and "determining" steps were considered transformative in Promotheus.  Thus the treatment step helped to ensure patent eligibility, particularly with respect to whether the claimed process involved "mere data gathering" or "extra-solution activity" in addition to the mental steps.

• A claim in which the inventive feature or "essence of the claim" could be considered "correlating" is almost certain to be held a mental step, or merely data gathering, and thus not eligible for patent protection.