In a unanimous ruling the US Supreme Court has rendered invalid two patents covering a method for determining proper drug dosage. The 20 March decision sent ripples through the medical diagnostics industry, which has been closely following the case.

The patents were held by Prometheus Laboratories, a therapeutics and diagnostics company based in San Diego, California. They covered the process of administering thiopurine drugs — which are used to treat autoimmune diseases such as Crohn’s disease — to patients and then measuring the levels of certain metabolites in the blood to determine whether the patient had received a safe and effective dose.

A new landmark for patent law? Credit: Daderot

The defendant in the case, a division of the Mayo Clinic, based in Rochester, Minnesota, initially bought diagnostic tests based on the patents, but in 2004 decided that it wanted to market its its own test, which uses a similar method. Prometheus sued in June of that year, and the case has been working its way through the courts ever since.

The medical-diagnostics industry has been shaken by recent legal challenges to its patents, most notably a high profile case challening the validity of gene patents held by Myriad Genetics, a diagnostics company based in Salt Lake City, Utah (see 'US Court upholds Myriad's breast cancer gene patents'). Critics argue that some of the patents being challenged are based on natural phenomena, which are not patentable unless they have been somehow altered by humans. The Supreme Court agreed, a decision which sent the share prices of some biotechnology companies tumbling; Myriad's stock dropped by more than 5%.

The ruling is also likely to send companies and universities scrambling to determine which of their discoveries are still eligible for patenting, says William Simmons, a patent attorney at the law firm Sughrue Mion in Washington DC. “There are going to be areas of technology that are methods for treating individuals that simply cannot be patented as a result of this decision,” he says. “It has a dramatic impact on the medical community and the scientific research community.

Natural laws

In 2010, the US Court of Appeals for the Federal Circuit sided with Prometheus and upheld the patents, saying that the administration of drugs to patients and the measurement of metabolites in the blood were both steps that “transformed a particular article into a different state or thing.” But the Supreme Court disagreed. Neither step was transformative, wrote Justice Stephen Breyer, arguing instead that the patents covered a law of nature. Harking back to the archetypal ‘eureka moment’ of antiquity, Breyer wrote: “Nor could Archimedes have secured a patent for his famous principle of flotation by claiming a process consisting of simply telling boat builders to refer to that principle in order to determine whether an object will float.”

Such a position is strongly opposed by the biotechnology industry, which has said that overturning the patents could stifle innovation, particularly in the development of personalized medicine. In a statement released after the court issued its decision, Hans Sauer, deputy general counsel for intellectual property at the Biotechnology Industry Organization, a Washington DC-based lobbying group, cautioned against unintended consequences of the decision for patents on biomarker-based diagnostic methods. ”The Court's opinion fails to appropriately recognize the importance of personalized medicine,” he wrote, “and of the research and investment incentives needed to develop new individualized therapies for untreated diseases.

In contrast, Breyer argued that upholding rather than striking down the patents risked inhibiting future innovation, ”a danger that becomes acute when a patented process is no more than a general instruction to 'apply the natural law'.” 

Simmons says that the decision could lead some companies to re-evaluate their research plans. “Do they shut down personalized medicine efforts because they may not be able to get medical methods claims?” he says. “I’m not sure how one can go about determining whether any medical method would be patentable based on this decision.”

The Supreme Court has yet to decide whether it will hear the Myriad Genetics gene-patenting case. While it is hard to predict how today's decision will affect the company's chances, Simmons says, “It may not bode well for Myriad.”