Claim 1 of US Patent Number 6,355,623 is representative of the claims issue:
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 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 8.times.10.sup.8 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 8.times.10.sup.8 red blood cells indicates a need to decrease the amount of said drug subsequently administered to said subject.
In its opinion, the Federal Circuit held that the both the step of administering a drug and the step of determining the level of drug metabolite in the patient are sufficiently transformative to satisfy the transformation prong of the Bilski machine-or-transformation test. The court did not address the issue of whether the claims satisfied the machine prong of the test, since satisfaction of the transformation prong was sufficient to find all of the claims at issue patent eligible.
With respect to the administration step, the court held that administration of the drug to a patient results in “various chemical and physical changes of the drug’s metabolites that enable their concentrations to be determined” is clearly transformative. The court found that “the asserted claims are in effect claims 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,” and that "the human body necessarily undergoes a transformation" upon the administration of the drug. The court rejected Mayo’s argument that metabolism of a man-made drug is a natural phenomenon merely because it involves natural processes, pointing out that all transformations operate by natural principles.
If the Federal Circuit had stopped there, its holding would have left unresolved the question of whether a diagnostic claim that does not recite an administration step would satisfy the Bilski test. For example, many diagnostic claims simply recite a step of determining the presence of some biomarker, such as a genetic mutation or profile, or the level of a metabolite. In some cases, explicit recitation of an administration step would not be practical for the patentee. For example, if the invention is a method of identifying a genetic mutation which results in a predisposition for cancer, it would be difficult to include a step requiring administration of the drug without rendering the patent highly susceptible to circumvention.
Fortunately, the Federal Circuit went on to hold that determining the level of drug metabolites in the patient's body is also transformative, and would have been independently sufficient to render the claim patent eligible, finding that “[d]etermining the levels of [drug metabolites] in a subject necessarily involves a transformation, for those levels cannot be determined by mere inspection.” Examples of transformation include high-pressure liquid chromatography methods, methods of extracting metabolites from the human body, etc. Thus, it appears that any method of diagnosis that would inherently require some physical manipulation or transformation of a sample should satisfy the transformation prong of Bilski. This is good news for genetic diagnostic companies holding method patents that probably claim methods of identifying genetic mutations of medical significance, without being limited to any particular analytic methodologies or patient treatment steps.
Mayo had argued that the transformations involved in sample analysis are mere data gathering steps amounting to nothing more than "insignificant extra-solution activity." But the Federal Circuit rejected this argument, finding that to the contrary, the “transformation is central to the purpose of the claims, since the determining step is, like the administering step, a significant part of the claimed method treatment . . . , central to the claims rather than merely insignificant extra-solution activity.
Mayo had also argued that the “wherein” clauses at the end of the claims were merely unpatentable mental processes, but the Federal Circuit pointed out that in analyzing a claim for patent eligibility one must consider the claim as a whole. The inclusion of mental process steps in an otherwise patent eligible claim is not render the claim patent ineligible.