Prometheus labs in San Diego Credit: Prometheus

A federal court has ruled in favor of diagnostic test makers, after nearly a year of uncertainty over the patentability of medical diagnostic and treatment methods. In September the US Court of Appeals for the Federal Circuit in Prometheus Labs Incorporated v Mayo Collaborative Services, found that methods for analyzing the effect of a drug on a person can be patented. The eligibility of such patent claims had been in question since the Federal Circuit in October 2008 ruled in a case called In Re Bilski that only methods tied to a machine or those that transform something into a different state or thing are patentable. That standard, known as the 'machine-or-transformation' test, was set with business methods in mind, and appeared to exclude crucial aspects of diagnostics inventions. Diagnostics patents usually involve detecting molecules or biomarkers and correlating them with disease states―processes that might not pass this kind of machine-or-transformation test, says Stephen Albainy-Jenei, a patent attorney with Frost Brown Todd in Cincinnati, Ohio. “The In Re Bilski case really threw everything into doubt” for the pharmaceutical community, he says (Nat. Biotechnol. 27, 586–587, 2009). But the Federal Circuit took a surprising turn in its recent Prometheus decision. The patents in question, held by Prometheus Labs in San Diego, cover a diagnostic test that enables doctors to determine levels of metabolites in patients who take thiopurine drugs, and adjust dosing accordingly. The method satisfies the 'transformation' prong of the test because the human body is transformed after administration of the drug and manipulated when the sample is taken, the court said. The decision provided some comfort to diagnostic patent holders, but more changes may lie ahead, says Edward Ramage, a patent attorney with Baker Donelson in Nashville, Tennessee. Next spring the US Supreme Court will hear an appeal of In Re Bilski. “The mere fact that they've [agreed to hear] Bilski means the machine-or-transformation test probably won't stand intact,” he says.