By Kevin Capps

On March 20, 2012, the Supreme Court issued its much-anticipated decision in Mayo Collaborative Services, DBA Mayo Medical Laboratories, et al. v. Prometheus Laboratories, Inc., with potentially far-reaching ramifications for pharmaceutical and biotechnology companies, particularly those developing diagnostic methods and assays.

At issue was the patent eligibility of certain diagnostic methods under 35 U.S.C. § 101. 35 U.S.C. § 101 provides that “[w]hoever invents or discovers any new and useful process, machine, manufacture, or composition of matter…may obtain a patent therefor, subject to the [other conditions for patentability under the Patent Act].” Given the broad language of § 101, it was long considered a relatively low barrier to patentability. However, more recent cases, particularly relating to business and computer-software-implemented methods, have curtailed and arguably defined new legal standards for patent eligibility.

Prometheus Laboratories, Inc. (“Prometheus”) was the exclusive licensee of the two patents-in-suit, which claim methods of optimizing therapeutic efficacy for the treatment of immune-mediated gastrointestinal disorders. The claims recite the steps of administering a thiopurine drug to a patient having such a disorder and determining the level of the thiopurine in the patient, along with a statement that the level of the thiopurine drug subsequently administered to the patient should be increased or decreased depending on the concentration of the drug in the patient’s system.

The Court began by noting the primary recognized exceptions to patent eligibility, namely that “laws of nature, natural phenomena, and abstract ideas are not patentable.” The Court did “recognize[], however, that too broad an interpretation of this exclusionary principle could eviscerate patent law[,…f]or all inventions at some level embody, use reflect, rest upon, or apply laws of nature, natural phenomena, or abstract ideas.”

After characterizing the “relationships between concentrations of certain metabolites in the blood and the likelihood that a dosage of a thiopurine drug will prove ineffective or cause harm” as a “law of nature,” the Court considered each of the steps recited in Prometheus’s patent claims, and concluded that the patents were invalid because “the claims inform a relevant audience about certain laws of nature; any additional steps consist of well-understood, routine, conventional activity already engaged in by the scientific community; and those steps, when viewed as a whole, add nothing significant beyond the sum of their parts taken separately.” The Court further stated that the decision is consistent with earlier Supreme Court cases, particularly Diamond v. Diehr and Parker v. Flook, because “post-solution activity that is purely conventional or obvious…cannot transform an unpatentable principle into a patentable process” (internal quotations omitted).

This case may present more questions to pharmaceutical and biotechnology companies than it resolves. While the Court concluded that Prometheus’s patent claims were not patent eligible because “any additional steps [beyond informing a relevant audience about certain laws of nature] consist of well-understood, routine, conventional activity already engaged in by the scientific community,” the Court set forth no standard for determining what further steps would be required to transform the method into patentable subject matter.

The decision is also noteworthy in that it appears to conflate the novelty and non-obviousness requirements for patentability under 35 U.S.C. §§ 102 and 103 with the issue of patent eligibility under 35 U.S.C. § 101. Indeed, the Court even “recognize[d] that, in evaluating the significance of additional steps, the §101 patent-eligibility inquiry and, say, the §102 novelty inquiry might sometimes overlap.” However, the Court did not enunciate the level of novelty and non-obviousness that a claimed diagnostic method must possess before it would be considered patent eligible under 35 U.S.C. § 101.

Finally, the Court dismissed the Federal Circuit’s rationale for upholding the validity of Prometheus’s patents because “[w]hile it takes a human action (the administration of a thiopurine drug) to trigger a manifestation of this relation in a particular person, the relation itself exists in principle apart from any human action. The relation is a consequence of the ways in which thiopurine compounds are metabolized by the body—entirely natural processes.” It remains to be seen how or whether the Court would distinguish purely therapeutic methods, particularly those that involve new uses of known compounds, since the pharmacological activities of the compounds are “a consequence of the ways in which [the drugs] are metabolized by the body—entirely natural processes.”