In a decision that undoubtedly evoked a collective sigh of relief from the biotechnology community, the U.S. Court of Appeals for the Federal Circuit reversed a summary judgment of invalidity and held that methods for calibrating proper drug dosage satisfy the transformation prong of the Bilski machine-or-transformation test for patent-eligible subject matter under 35 U.S.C. section 101. Prometheus Laboratories, Inc. v. Mayo Collaborative Services, Case No. 08-1403 (Fed. Cir., Sept.16, 2009) (Lourie, J.).

Prometheus is the sole and exclusive licensee of two Mayo owned patents that claim methods for calibrating the proper dosage of thiopurine drugs, which are used for treating both gastrointestinal and non-gastrointestinal autoimmune diseases. The drugs are ultimately broken down by the body into various metabolites; the patents involve measurements of two of the metabolites, 6-methyl-mercaptopurine (6-MMP) and 6-thioguanine (6-TG). The patents claim methods that seek to optimize therapeutic efficacy while minimizing toxic side effects and typically include two separate steps: “administering” a drug that provides 6-TG to a subject and “determining” the levels of the drug’s metabolites. The measured metabolite levels are then compared to pre-determined metabolite levels, “wherein” the measured metabolite levels “indicate a need” to increase or decrease the level of drug to be administered so as to minimize toxicity and maximize efficacy of treatment.

Prometheus marketed a PROMETHEUS Thiopurine Metabolites test that used the technology covered by the patents in suit. Mayo initially purchased and used Prometheus’s test, but in 2004, Mayo announced that it intended to begin using and selling its own test. Prometheus sued Mayo for infringement and ultimately appealed to the Federal Circuit the district court grant of Mayo’s motion for summary judgment of invalidity under § 101. The district court found that the “‘administering’ and ‘determining’ steps are merely necessary data-gathering steps for any use of the correlations” and that “as construed, the final ‘wherein’ clause is only a mental step.”

On appeal, the Federal Circuit commenced its analysis by noting that the key issue is whether the claims are drawn to a fundamental principle (unpatentable) or an application of a fundamental principle (patentable). The Court noted that it articulated a “definitive test” for determining whether a process is patent-eligible under § 101 in Bilski. The Bilski machine-or-transformation test is a “two-branched inquiry,” under which a patentee may show that a process claim satisfies § 101 either by showing that his claim is tied to a particular machine, or by showing that his claim transforms an article.

Regarding transformation, the Court concluded that the methods of treatment claimed in the patents-in-suit squarely fall within the realm of patentable subject matter because they “transform an article into a different state or thing,” and this transformation is “central to the purpose of the claimed process.” The Court pointed to the transformation 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 also noted 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.” The Court further opined that even for those claims lacking an administration step, patentability is undiminished because the determining step is also transformative and central to the claimed methods, as levels of 6-TG or 6-MMP cannot be determined merely by inspection and without some form of manipulation. Having concluded that the claimed methods meet the transformation prong under Bilski, the Court did not consider whether they also meet the machine prong.