Jeffrey D. Hsi
Elizabeth N. Spar
Pending U.S. Supreme Court decision could further transform the standard for patentability of medical diagnostic claims.
While the status of medical methods patent claims has been in limbo in the U.S., a recent appellate court decision has provided some guidance. In the first precedential opinion applying the Bilski “machine or transformation test” to medical methods claims, the Federal Circuit held that claims to “a method of optimizing therapeutic efficacy for treatment of a disease” can constitute patentable subject matter under 35 U.S.C. §101 (Prometheus Laboratories Inc. vs. Mayo Collaborative Services).
The Prometheus patent claims at issue require: administration of a drug to a subject, determination of the level of the drug’s metabolite in the subject, and comparison of the level of the metabolite in the subject to a recited value indicative of the proper dosage.
The district court held that the claims at issue (U.S. Patent Nos. 6,355,623 and 6,680,302) to a method of optimizing therapeutic efficacy for treatment of an immune-mediated gastrointestinal disorder were invalid under 35 U.S.C. §101, i.e., were invalid as they did not pertain to patentable subject matter. The district court asserted that the claimed correlations between thiopurine drug metabolite levels and therapeutic efficacy and/or toxicity were a natural phenomenon and not patentable as the correlations were merely the result of natural bodily processes. Significantly, the district court reasoned that the steps of administering and determining were simply data-gathering steps and that the wherein clauses were nonpatentable mental steps.
Patentable Subject Matter Defined
On September 16, the Federal Circuit considered the issue on appeal and reversed the decision of the district court. The Federal Circuit held that the method of treatment claims at issue are patentable because they “transform an article into a different state of thing” and because the “transformation is central to the purpose of the claimed process.” Thus, the method claims at issue satisfy the Bilski “machine or transformation test” for patentable subject matter. The court held that the administration 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 further held that the determination step (i.e., determination of 6-TG or 6-MMP levels, which are metabolites of the drug 6-MP) is also transformative. “Determining 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 for a bodily sample and determine their concentration.”
The court concluded “that the administering and determining steps gather useful data, it is also clear that the presence of those two steps in the claimed process is not merely for the purpose of gathering data. Instead, the administering and determining steps are part of a treatment protocol, and they are transformative.”
Additionally, some claims at issue lacked an administration step. The court stated that this omission “does not diminish the patentability of the claimed methods, because the determining step, which is present in each of the asserted claims, is also transformative and central to the claimed methods.”
Finally, the court asserted that although the final “wherein” clauses are “mental steps and not patent-eligible per se, a subsequent mental step does not by itself negate the transformative nature of prior steps.”
The court’s holding (methods 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”) clarifies that medical diagnostic claims are patent eligible even if there is no explicit recitation of a chemical or physical transformation. The holding provides some guidance regarding how to draft claims to a diagnostic method, claims that recite either a step of administering a drug or a step of determining the amount of a drug or metabolite in the blood that may be considered patentable.
The holding of Prometheus provides some peace of mind to patent owners and applicants with claims directed to methods of medical diagnostics and personalized medicine wherein a method of treating disease or a method of designing a treatment for disease are based on acquiring data. The patent law world, however, continues to wait for additional guidance as the Bilski case is considered by the U.S. Supreme Court. In view of the impending U.S. Supreme Court decision in Bilski, the standard for patentability of medical diagnostic claims may itself undergo a transformation.