Personalised diagnostic method claims considered unpatentable laws of nature

Personalised diagnostic method claims considered unpatentable laws of nature

Personalised diagnostic method claims considered unpatentable laws of nature

Mayo Collaborative Services v. Prometheus Laboratories, Inc. (20 March 2012)

In a recent decision of the US Supreme Court Prometheus’ claims relating to methods of optimising the dosage of a drug were held to be invalid because they claim ‘laws of nature’ and the additional steps in the claimed methods added “nothing of significance to the natural laws themselves.”

The decision indicates that the US Federal Circuit’s “machine-or-transformation” test for assessing patent-eligibility may not be useful when the “transformation” flows from “entirely natural processes.” It appears that in order to satisfy Section 101 of the US Patents Act relating to patentability1, method claims that are based on a law of nature must recite an additional element that is not “routine” or “conventional” in the art.

Prometheus’ claims originally held patentable using “machine-or-transformation” test

The claims from Prometheus’s patents related to methods for calibrating the proper dosage of thiopurine drugs which are used for treating both gastrointestinal and non-gastrointestinal autoimmune diseases. The way in which people metabolise thiopurine compounds varies and the same dose of a thiopurine drug affects different people differently. Because of this, although scientists at the time already understood that certain thiopurine metabolites correlated with the likelihood that if a particular dose was too high it could cause harmful side effects, or too low it could cause the treatment to be ineffective, those in the field did not know the precise correlations between metabolite levels and likely harm or ineffectiveness. The methods described in the patents were designed to enable the identification of these correlations with greater precision.

The Supreme Court focused on Claim 1 as representative of the claims at issue. Claim 1 recites:

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

(a) administering a drug providing 6-thioguanine to a subject . . and

(b) determining a level of 6-thioguanine in the subject . . .

wherein the level of 6-thioguanine less than about 230 pmol per 8×108 red blood cells indicates a need to increase the amount of said drug subsequently administered to said subject and wherein the level of 6-thioguanine greater than about 400 pmol per 8×108 red blood cells indicates a need to decrease the amount of said drug subsequently administered to said subject.

It is important to note that the administration step (a) and determination step (b) were already known techniques in the art and the claim therefore relied on the ‘wherein’ clauses to provide the inventive concept.

Mayo originally purchased and used diagnostic tests based on Prometheus’s patents. However, the dispute began when Mayo decided to try to develop and market its own version of the test. Prometheus sued, and in the district court the claims were held invalid under Section 101 as unpatentable laws of nature.

In 2009, the Federal Circuit found the disputed claims patentable by applying the “machine-or-transformation” test and reversed the original district court decision. Following the “Bilski” decision where it was held that the “machine-or-transformation test”, while an important and useful clue in determining patent eligibility, was not the only way to evaluate patentability2, the case was returned to the Federal Circuit for reconsideration. On remand, the Federal Circuit again held that the process claims constituted patent-eligible subject matter because “[t]he steps recite specific treatment steps, not just the correlations themselves”.3 This second appeal to the Supreme Court followed.

Supreme Court decision finds Prometheus’ claims purely conventional and encompass ‘laws of nature’

In reaching their decision, the Court began by noting that its prior decisions in Diamond v. Diehr4 and Parker v. Flook5 concerning the patentability of natural correlations or mathematical formulae were particularly relevant to the case.

With these decisions in mind the Court stated that, “a process is not unpatentable simply because it contains a law of nature or a mathematical algorithm”. However, the Court also noted that, “to transform an unpatentable law of nature into a patent-eligible application of such a law, one must do more than simply state the law of nature while adding the words to apply it”.

The Court concluded that to transform a process that focuses upon the use of a natural law into a patent-eligible application of such a law, the process must also contain other elements or a combination of elements, sometimes referred to as an ‘inventive concept,’ sufficient to ensure that the patent in practice amounts to significantly more than a patent upon the natural law itself.

In applying this conclusion to Prometheus’ claims, the Court reasoned that while it takes human action to trigger the occurrence of the relationship between the concentration in the blood of certain thiopurine metabolites and the likelihood that the drug dosage would be ineffective or would induce harmful side-effects, “the relationship itself exists in principle apart from any human action”.

Claim analysis

  1. Step of administration – the court held that the “administering” step simply referred to the “relevant audience”, i.e. doctors treating patients. It was noted that this audience was a pre-existing audience because doctors already knew how to use thiopurine drugs to treat the recited conditions. However, the possibility of directing the claims to a new audience was discounted by the suggestion that “prohibition against patenting abstract ideas cannot be circumvented by attempting to limit the use of the formula to a particular technological environment”.
  2. Step of “determining” – greater consideration was given to the “determining step” that required doctors to determine the level of relevant metabolites in the blood. However, the Court also found this step insufficient to make the claims patent-eligible because the techniques were so well known.
  3. Wherein clauses – these describe the likely consequences of certain high or low concentrations of the metabolites. The Court found these limitations were at most a suggestion to take the relevant natural laws into account when treating a patient. The Court noted that purely conventional or obvious pre-solution activity “is normally not sufficient to transform an unpatentable law of nature into a patent-eligible application of such a law”.

Following this analysis the Court concluded that the steps involved in the claim were purely “conventional” and monopolised a law of nature.

When the claim was considered as a whole the Court also came to the conclusion that “the three steps as an ordered combination add nothing to the laws of nature that is not already present when the steps are considered separately”.

From the decision it appears that the US Court will not give much weight to “conventional” steps recited within a claim, even if they are concrete or physically transformative, i.e. steps that are well-understood, routine and considered conventional activities by those working in the field. The Court did not rule out the possibility that claims to diagnostic processes with less conventional steps would be considered patentable.

However, while noting the importance of reciting “additional features” to transform claims beyond a “law of nature”, no real guidance has been given as to what level of post-solution activity is necessary to render a claim patentable. What is clear is that transformation of a patient’s body by “administering” a drug does not satisfy the “transformation” component of the test.

It also appears that the Court considers that if a law of nature has a particular application, any claims based on that law must be narrow enough so as not to preclude others from exploiting or innovating around the law of nature on which the claim is based.

Implications of the decision extend beyond personalised medicine claims

The decision reinforces that while it remains a useful tool in determining patent eligibility of biomedical diagnostic claims the “Machine-or-transformation” test will not be the only test which is used to evaluate whether a claim is patent-eligible. It appears that significant weight will be given to the ‘law of nature’ exclusion to Section 101 which has long held that “Laws of nature, natural phenomena, and abstract ideas” are not patentable.

The decision most particularly impacts the patentability of methods of conducting personalised medicine in the US, for example, where treatment regimens for a subject are tailored based on the presence, absence or amount of one or more biomarkers that correlate with treatment efficacy.

However, in stating their position the Court noted that “all inventions at some level embody, use, reflect, rest upon, or apply laws of nature, natural phenomena, or abstract ideas”. The Court acknowledged that not all inventions are unpatentable simply because they have some relationship with a law of nature. The observation also indicates that the impact of Prometheus will not be limited to one class of invention or one field of technology.

Confirming its potential significance, almost immediately following the decision, the US Patent & Trademark Office (USPTO) distributed a short memorandum to examiners. The memorandum indicates that while examiners will in the short term continue to use the existing Bilski Guidance, they will be taking the Mayo decision into account when examining patent applications for compliance with section 101. It remains to be seen how the USPTO will apply the Mayo decision moving forward.

It is possible that the Mayo decision appears broad enough to encompass claims directed to isolated gene sequences as they exist in nature. Therefore, it also remains to be seen if the decision will have an impact on the Association for Molecular Pathology v USPTO (Myriad) case.

Lessons for Patentees

It is possible that biomedical diagnostic claims of US Patents may be prone to challenges on the basis that they claim non-patentable ‘laws of nature’, not only by examiners in the course of prosecution but also by accused infringers or potential and existing licensees of issued patents. This issue could be raised particularly where the claims relate to observation of a correlation tied to a biological process.

For the US it appears that even claims involving a machine or a transformation will have to be carefully drafted to keep the “law of nature” exclusion in mind. This consideration also extends to non-biomedical patents

For those concerned that their granted US claims are ‘similar’ to Prometheus’ claims, there are mechanisms available under US law to strengthen the validity of such claims. In relation to pending applications, it is clear that careful consideration should be given to either amend or add claims to more directly focus on specific applications of any underlying laws of nature.

It is important to bear in mind that although the decision may mean that the validity of certain patent claims is uncertain, the Supreme Court did not announce a general rule that undermines the validity of all personalised medicine patents in the US. The validity of such claims must be assessed on a fact-specific, case-by-case basis.


  1. Section 101 outlines the scope of patent-eligible subject matter and states:-
    “Whoever invents or discovers any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof, may obtain a patent therefor, subject to the conditions and requirements of this title.”
  2. Bilski v. Kappos, 561 U. S. __, __ (2010); Patents for abstract ideas are out, but not patents for business methods
  3. Prometheus Labs., Inc. v. Mayo Collaborative Services., 628 F.3d 1347, 1355 (Fed. Cir. 2010).
  4. Diamond v. Diehr, 450 U. S. 175, 185 (1981).
  5. 437 U.S. (1978).