In the case Mayo v Prometheus, (Mayo Collaborative Servs. V. Prometheus Labs., Inc., 132 S. Ct 1289 (U.S. 2012), the Supreme Court of the United States focused on the eligibility of claims to diagnostic methods.
The main claim of the challenged patent concerned a method of optimizing therapeutic efficacy for treatment of an immune-mediated disease gastrointestinal disorder comprising:
a) administering a drug providing 6-thioguanidine to a subject having said immune-mediated disease gastrointestinal disorder; and
b) determining the level of 6-thioguanidine in said subject
o a level of 6-thioguanidine in red blood cells below a first threshold indicates a need to increase the amount of said drug for a new administration and
o a level of 6-thioguanidine in red blood cells higher than a second threshold indicates a need to reduce the amount of said drug for a new administration.
According to the Supreme Court, these claims include “laws of nature, natural phenomena and abstract ideas” which are not patentable. The Court concluded that:
a) the “administering” step simply refers to doctors who treat patients and already use thiopurines to treat these autoimmune diseases,
b) the “determining” step covers any method used to calculate the levels of metabolites, all of these methods are well known in the field and
c) the “wherein” clauses simply inform the doctors of the existence of laws of nature and, in addition, they trust them to take said laws into account when treating the patient and
d) even in combination, these steps do not add anything significant that goes beyond the sum of their parts individually.
Thus, when invention resides in the discovery of a natural phenomenon, simply integrate the application of this natural phenomenon to a standard method of diagnosis consisting in removing a sample and making the necessary analysis to compare its result to the rule of the natural phenomenon is not sufficient to confer the said invention usefulness required by section 101 of the U.S. patent law.
The decision of the Court undoubtedly creates uncertainty about the patent claims to methods of diagnosis and in the area of personalized medicine. Moreover, it affects both patents already granted and the applications filed under examination for which amendments to the claims can be considered. For future applications, it will be necessary to describe methods with more practical implementation to support an acceptable claim. Following this decision, the USPTO has issued draft guidelines for patent examiners regarding the Prometheus case (see this link).