Mayo Collaborative Services v. Prometheus Laboratories, Inc.

Mayo v. Prometheus, 566 U.S. 66 (2012), was a case decided by the Supreme Court of the United States that unanimously held that claims directed to a method of giving a drug to a patient, measuring metabolites of that drug, and with a known threshold for efficacy in mind, deciding whether to increase or decrease the dosage of the drug, were not patent-eligible subject matter.

The basic idea behind the court's decision in Mayo is as follows: although a discovery of a new natural phenomenon (or a law of Nature) would satisfy the non-obviousness requirement, patent claims, that either wholly pre-empt the natural phenomenon or add no additional "inventive concept" to this discovery, do not meet patent-eligible subject matter criterion.

The decision was controversial, with proponents claiming it frees clinical pathologists to practice their medical discipline, and critics claiming that it destabilizes patent law and will stunt investment in the field of personalized medicine, preventing new products and services from emerging in that field. A 2017 study suggested that the decision has led to increased preference for trade secrecy over patenting among companies developing genetic medicine.

The case arose in a dispute between Mayo Collaborative Services and Prometheus Laboratories concerning a diagnostic test. Mayo Collaborative Services is a for-profit diagnostic testing lab offering diagnostic services that operates as a subsidiary of Mayo Foundation for Medical Education and Research, which is a nonprofit corporation affiliated with the Mayo Clinic. Mayo Collaborative Services does business as "Mayo Medical Laboratories", has 3,200 employees working in 58 laboratories and offers services worldwide.

Prometheus is a specialty pharmaceutical and diagnostics company in the fields of gastroenterology and cancer; it was bought by Nestlé in 2011. Prometheus sells diagnostic kits and also offers diagnostic services as a diagnostic testing lab.

The two US patents in the case are 6,355,623 and 6,680,302, which are owned by Hospital Sainte-Justine in Montreal. The patents concern the use of thiopurine drugs in the treatment of autoimmune diseases, such as Crohn's disease and ulcerative colitis. Different people metabolize these drugs differently, so doctors have to work with patients to find the right dose. If the dose is too high there are too many side effects, while if the dose is too low the drug does not work. When the patents were filed, the metabolites of these drugs were known, most importantly, 6-thioguanine, but the "right" level of these metabolites was not known. The scientists at Hospital Sainte-Justine identified the threshold level for effectiveness, and filed for patent protection on methods to use that threshold level to determine dosage.

The Supreme Court took claim 1 of the '623 patent as exemplary:

A method of optimizing therapeutic efficacy for treatment of an immune-mediated gastrointestinal disorder, comprising: