The U.S. Supreme Court granted cert. (for the second time!) in Mayo Collaborative Services v. Prometheus Labs., Inc, Supreme Court No. 10-1150, to consider whether to set limits on when inventors can patent medical diagnostic tests.

Earlier, the judgment was vacated and the case remanded to the U.S. Court of Appeals for the Federal Circuit for further consideration in light of Bilski v. Kappos, 561. The Federal Circuit, reversing the district court, upheld Prometheus’s patent claims covering a means to measure the level of 6-thioguinine (6-TG) and 6-methylmercaptopurine (6-MMP), which indicates that an adjustment in drug dosage may be required at certain metabolite levels.

The patent includes only two active steps, “administering” the drug and then “determining” metabolite levels.  The claim really just explains the correlation between metabolite levels and therapeutic efficacy and “what the inventors claim to have discovered is that particular concentrations of 6-TG and 6-MMP correlate with therapeutic efficacy and toxicity in patients taking AZA drugs.”  The district court decided as a matter of law that the asserted claims were drawn to non-statutory subject matter and as such, unpatentable.

Thankfully, cooler heads appear to have prevailed and the US Court of Appeals for the Federal Circuit has held that methods of treatment claims fall squarely within the realm of patentable subject matter. Prometheus Laboratories, Inc. v. Mayo Collaborative Services (08-1403).   The Supreme Court will review that ruling. The Court heard a case in 2006 that raised similar issues, but dismissed the case without issuing a ruling.

The question presented is:

Whether 35 U.S.C. § 101 is satisfied by a patent claim that covers observed correlations between blood test results and patient health, so that the claim effectively preempts all uses of the naturally occurring correlations, simply because well-known methods used to administer prescription drugs and test blood may involve “transformations” of body chemistry.

This will be an exciting (and tense) time for diagnostic companies after the Supreme Court, without explanation, declined to issue an opinion in Laboratory Corporation of America v. Metabolife Laboratories because the appeal was “improvidently granted.”  Justice Breyer (with Stevens and Souter) dissented.

Several medical associations have argued that patents on such diagnostic methods could impede the practice of medicine and raise the costs of medical treatment.  If that were the standard, all medical patents would be unpatentable.

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