Supreme Court is asked to re-examine diagnostic test patents

Mayo Clinic maintains that the patents on metabolite testing violate federal law. The court reviewed the seven-year case in 2010.

By Alicia Gallegos — Posted May 16, 2011

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Mayo Clinic of Rochester, Minn., is asking the U.S. Supreme Court to re-examine whether a test that measures patients' metabolite levels to determine drug dosages should be patentable.

The seven-year court dispute, which twice has been to an appellate court and once to the high court, has generated conflicting opinions about whether the patents held by Prometheus Laboratories Inc. violate federal law.

Prometheus sued Mayo Collaborative Services and Mayo Clinic Rochester in 2004, claiming that Mayo infringed on its test patents. Prometheus' test measures metabolite levels in patients taking thiopurine drugs, then correlates those levels with the drugs' efficacy. Mayo developed its own test, which measured the same metabolites, but said its method used different levels to determine toxicity, according to court documents.

Mayo argued that Prometheus' patents were invalid because the correlations between metabolite levels and drug efficacy are derived from a natural body process. In 2008, a federal trial court agreed, ruling the patents broke laws barring the patentability of natural phenomena and abstract ideas.

In 2009, an appeals court reversed the decision, upholding the patents as valid. The Supreme Court in 2010 vacated the appellate decision in light of a similar case that changed how patent validity is measured. The case then was sent back to the lower court for reconsideration. In December 2010, the appellate court again ruled for Prometheus.

The high court has not said whether it will take up the case again.

The Prometheus patents are too broad and prevent people from freely observing natural body processes, said Jonathan Singer, an attorney for Mayo.

"People [are] discovering relationships between certain disease states and conditions in the body. The question is: Can you patent that? Can you patent that observation?" Singer said.

Singer compared Prometheus' testing methods to the correlation between alcohol and blood levels associated with intoxication. The Prometheus patents are akin to claiming ownership over the discovery of blood alcohol level and how that rate is measured, he said.

Richard P. Bress, attorney for Prometheus, said the patents describe a specific method for improving the treatment of certain diseases through a series of concrete and transformative steps. The patents require the administration of a synthetic drug and the extraction, transformation and testing of a bodily sample to determine resulting metabolite levels, he said. The results then are assessed to determine whether a change in the drug's dosage is warranted.

"Although this process -- like every other process in the natural world -- proceeds according to natural laws, it is a concrete method of improving patient treatment, not simply a naturally occurring phenomenon or an abstraction," he said.

Physicians voice concerns

Medical organizations, including the American Medical Association and the Assn. for Molecular Pathology, have raised concerns that the Prometheus patents harm the practice of medicine. Any physician measuring metabolite levels who finds an adjusted drug dosage necessary based on body correlations becomes a patent "infringer," said the associations' court brief in support of Mayo.

"If such claims to exclusive rights over the body's natural responses to illness and medical treatment are permitted to stand, the result will be a vast thicket of exclusive rights in the use of scientific data that is critical to and must be widely available for providing sound medical care," the brief said.

Prometheus' attorney argues that the opposite is true. Overturning the decision would strip protections from biotech and medicine patents, Bress said, essentially gutting the incentive necessary for researchers to invest in and develop lifesaving methods for patients.

"This is exactly the type of innovation that the patent laws were designed to encourage," he said of the Prometheus test. "The patented claims address a real-world problem: the difficulty of calibrating particular drugs used to treat the specific diseases. ... Historically, many physicians were reluctant to treat patients with these drugs, despite the potential benefits, absent a method for preventing toxic side effects while still ensuring efficacy. Prometheus' patents describe such a method."

The Mayo case is one of at least two recent patent cases that could impact medicine.

The U.S. Court of Appeals for the Federal Circuit heard arguments April 4 in a case involving the patentability of human genes. The Assn. for Molecular Pathology and others are challenging the validity of two patents held by Myriad Genetics that are linked to breast and ovarian cancer. At this article's deadline, the appellate court had not issued a decision in the case.

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