The Federal Circuit has calmed some anxiety over the patentability of medical diagnostic methods under 35 U.S.C. § 101 with its decision in Prometheus Laboratories, Inc. v. Mayo Collaborative Services, holding that some method of treatment and diagnostic methods are indeed patentable subject matter. [1] That anxiety followed the Federal Circuit’s 2008 Biliski decision narrowing the scope of patentable subject matter in a case involving methods for hedging risks in commodities trading.[2] This case involving diagnostic tests for measuring levels of metabolites produced by the body after a person takes thiopurine drugs has been closely watched by the medical community. Amicus briefs were filed by Novartis Corporation, Myriad Genetics, American Intellectual Property Law Association, Biotechnology Industry Organization, Arup Laboratories and The American College of Medical Genetics.

The Prometheus patent claims cover methods of calibrating the proper dosage of thiopurine, commonly used for the treatment of Crohn’s disease and other inflammatory bowel conditions. Thiopurine compositions are pro-drugs that are broken down by the body into useful active metabolites but that also cause toxic side effects. The therapeutic goal is to maximize benefits while minimizing harmful side effects by adjusting the drug dosage to keep the metabolites at an optimum level. The methods involve (1) administering a drug that results in these metabolites and (2) determining the levels of the metabolites by sampling the patient’s blood.[3] The metabolite level is then compared to pre-determined metabolite levels that are known to be associated with either toxicity or beneficial effects in order to determine whether to increase or decrease the level of the drug.

The trial court granted summary judgment that the claims were invalid under 35 U.S.C. § 101 for failure to recite patent eligible subject matter, holding that “the patents claimed the correlations between certain thiopurine drug metabolite levels and therapeutic efficacy and toxicity.” The court found the claimed correlations to be “natural phenomena” and unpatentable “because the correlation resulted from a natural body process.” The trial court further noted that “the inventors merely observed the relationship between these naturally-produced metabolites and therapeutic efficacy and toxicity.” Finally, the trial court found that the ‘administering’ and ‘determining’ steps were merely data-gathering steps and that the use of this information to adjust dosage was a mental step.

The Federal Circuit reversed the trial court determining whether the claims were “drawn to a fundamental principle or an application of a fundamental principle” by applying the Bilski test: “A claimed process is surely patent-eligible 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.”

Disagreeing with the trial court’s conclusion that the administering and determining steps were “merely data-gathering steps,” the Federal Circuit held that the steps were transformative and central to the claimed invention because (1) there was a transformation of the human body upon administration of the drug and (2) there was transformation of the drug within the body when the drugs were metabolized. The Court concluded that method of treatment claims “are always transformative when a defined group of drugs is administered to the body to ameliorate the effects of an undesired condition.” Rejecting Mayo’s argument that the metabolism of drugs occurs “according to the process and natural law,” the Court found that drugs administered to the human body “do not pass through the body untouched without affecting it,” but “necessarily” undergo a transformation to treat the body, which is not a natural process. According to the Court, “it is virtually self-evident that a process for a chemical or physical transformation of physical objects or substances is patent-eligible subject matter.”

Additionally, the Court found that the step of “determining” the levels of metabolites “necessarily involves a transformation, for those levels cannot be determined by mere inspection.” Instead, the Court noted that “some form of manipulation . . . is necessary to extract the metabolites from a bodily sample and determine their concentration.”

The Court’s opinion also rejected the characterization by the trial court of the administering and determining steps as “insignificant extra-solution activity,” instead finding that the claimed invention was “part of treatment regimes for various diseases using thiopurine drugs.” The Court contrasted Prometheus’s claimed methods with the claims in In re Grams.[4] “In Grams, the applicant claimed a process that involved (1) performing a clinical test on individuals and (2) based on the data from that test, determining if an abnormality existed and determining possible causes of any abnormality by using an algorithm.” The Federal Circuit distinguished Grams, where “the essence of the claimed process was [a] mathematical algorithm, rather than any transformation of the tested individuals.”

The Federal Circuit also rejected the trial court’s conclusion that the mental steps found in “wherein” clauses made the claim per se patent-ineligible. The Court asserted that even if these clauses were merely a mental step and not patent-eligible, the claim as a whole was directed to more than simply the mental steps citing the following test from Bilski:

[I]t is inappropriate to determine the patent eligibility of a claim as a whole based on whether selected limitations constitute patent-eligible subject matter. After all, even though a fundamental principle itself is not patent-eligible, processes incorporating a fundamental principle may be patent-eligible. Thus, it is irrelevant that any individual step or limitation of such processes by itself would be unpatentable under § 101.

Thus, the Federal Circuit has provided some relief to those concerned about the patentability of diagnostic or method of treatment patent claims by confirming that method claims containing a transformative step based on drug administration or drug metabolization, are patent-eligible and suggesting that diagnostic method claims should be drafted to satisfy the Bilski “definitive test.”

Bilski is now on appeal at the Supreme Court, but it is unlikely that reversal of Bilski (which presumably would broaden the scope of what is patentable) would change the outcome here.