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Supreme Court to Hear Prometheus v. Mayo; Diagnostic Methods Case Could Have Broad PGx Impact

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Originally published Jan. 21.

The US Supreme Court has agreed to hear a case that could ultimately have a broad impact on gene patenting and other intellectual property issues of interest to personalized medicine stakeholders.

The court on June 20 granted Mayo Medical Laboratories a writ of certiorari in its appeal of a lower court's decision that upheld two diagnostic method patents held by Prometheus Laboratories.

Last year, a federal appeals court upheld its earlier decision in Prometheus v. Mayo that Prometheus' contested patents, which cover methods for determining the optimal dosage of drugs to treat stomach disease, passed muster under the law (PGx Reporter 12/22/2010).

Mayo is challenging that decision before the Supreme Court, asserting that Prometheus' patents claim a natural phenomenon. "Simply put, Prometheus's patents monopolize every useful implementation of a correlation between particular types of drug treatment and the natural bodily metabolism resulting from that drug treatment," Mayo wrote in its application for a writ of certiorari to the Supreme Court on March 17.

"This correlation is unquestionably a natural phenomenon. From it, doctors may determine if a dose of a drug is too high, too low, or needs no adjustment at all," Mayo wrote. "But if Prometheus's patents are allowed to stand, doctors will no longer be free to consider this biological phenomenon in treating patients or in attempting to develop new treatments for disease. And numerous similar, overly-broad patents that restrict doctors' ability to treat patients will stand as well. This will stifle innovation, as well as raise the cost and degrade the quality of medical care throughout the United States."

Diagnostic developers and legal experts have been keeping a close watch on Prometheus since the court's handling of diagnostic method patents at issue in that case may impact another lawsuit, Association for Molecular Pathology et al. vs. the United States Patent and Trademark Office et al, which was recently heard by the Court of Appeals of the Federal Circuit.

In AMP v. USPTO, the American Civil Liberties Union and the Public Patent Foundation are challenging Myriad Genetics' BRCA gene mutation patents, taking the view that isolated gene sequences are exactly the same as DNA naturally occurring in the body. Furthermore, a New York federal district court last year invalidated Myriad's method claims, reasoning that "analyzing" and "comparing" DNA sequences were abstract mental processes; that the method claims failed to meet the "machine or transformation" test; and that obtaining DNA sequences through isolation and purification were merely "data gathering steps" (PGx Reporter 03/31/2010).

Depending on how the Supreme Court rules on the patentability of Prometheus' claims, it could set a precedent for the patentability of genetic testing methods. This in turn would affect the advancement of personalized medicine products that rely on the help of a diagnostic to identify patients that have certain gene mutations and would therefore respond to the drug.

Two patents are at issue in Prometheus — US Patent Nos. 6,355,623 and 6,680,302 — for which the company holds exclusive licenses. The patents claim methods of measuring a patient's metabolite levels to calibrate doses of a thiopurine drug to treat stomach disorders. The litigation started in 2004, when Mayo announced its intent to sell its own tests that measured the same metabolites as Prometheus' test, prompting Prometheus to sue Mayo for infringement.

A federal district court in 2008 found Prometheus' method claims were not patentable subject matter under 35 USC 101. Prometheus appealed the district court's decision to the Federal Circuit Court, which last year reversed the lower court's decision and found in favor of Prometheus that its method claims for determining metabolite levels for drug dosing met the machine-or-transformation test, and were therefore patentable.

"We conclude 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 Federal Circuit wrote in its decision at the time.

Mayo filed for certiorari with the Supreme Court, challenging the appeals court's decision. The higher court responded by vacating the appeals court's earlier decision, and instructing the lower court to revisit its decision in light of another case, Bilski v. Kappos. In Bilski, the Supreme Court decided that the machine-or-transformation test cannot be the sole determinant of patentability for inventions in the Information Age, such as medical diagnostics (PGx Reporter 06/30/2010).

Upon revisiting Prometheus, the Federal Circuit upheld its earlier decision in finding that Prometheus' method claims were valid in light of Bilski. Now, with its second certiorari appeal, Mayo has been successful in getting the Supreme Court to hear its case. While the outcome of the case is uncertain, it's likely that the Supreme Court's decision will ultimately influence AMP v. USPTO.

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