Protection of diagnostic inventions in the USA - implications of PerkinElmer, Inc. v Intema Limited

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[authors: Adam Denley & Tom Gumley]

On 20 November 2012 the US Federal Circuit handed down a decision in PerkinElmer, Inc. v Intema Limited1 relating to the patent eligibility of diagnostic method claims. In what appears to foreshadow future decisions regarding diagnostic method claims, the Court found that the claims at issue were not directed to patent eligible subject matter as the claims were to a mental step and a law of nature and did not contain any limitation to ensure that what was claimed amounted to significantly more than a patent upon the natural law itself.

The decision

The claims at issue were directed to antenatal diagnostic testing for Down’s Syndrome which minimises the need for unnecessary invasive diagnostic tests, e.g. chorionic villus sampling, that are associated with risk of miscarriage or foetal limb defects. An abbreviated representative claim from the patent was stated in the court’s decision:

A method of determining whether a pregnant woman is at an increased risk of having a fetus with Down’s syndrome, the method comprising the steps of:

measuring the level of at least one screening marker from a first trimester of pregnancy by:

(i) assaying a sample . . . ; and/or

(ii) measuring at least one first ultrasound screening marker from an ultrasound scan . . .;

measuring the level of at least one second screening marker from a second trimester of pregnancy, the at least one second screening marker from the second trimester of pregnancy being different from the at least one first screening marker from the first trimester of pregnancy, by:

(i) assaying a sample . . .; and/or

(ii) measuring at least one second ultrasound screening marker from an ultrasound scan . . .;

and determining the risk of Down’s syndrome by comparing the measured levels of both the at least one first screening marker from the first trimester of pregnancy and the at least one second screening marker from the second trimester of pregnancy with observed relative frequency distributions of marker levels in Down’s syndrome pregnancies and in unaffected pregnancies.

Essentially the Court applied a two stage process in determining whether the claims are related to patent eligible subject matter. The first stage is to ask whether the claims recite a patent ineligible concept that is limiting on the claim (i.e. law of nature, mental process, etc). If the answer is no, then the claims are directed to patentable subject matter. However, if the answer is yes, then the next stage is to ask whether the claims contain other elements or combination of elements to ensure that the patent in practice amounts to significantly more than a patent upon the ineligible concept itself. The Court referred to the Mayo2 decision and re-iterated that a process claim would fail this second stage if the other elements were “nothing more than well-understood, routine, conventional activity previously engaged by researchers in the field”.

The Court found that the claims related to a law of nature: the relationship between screening marker levels and the risk of foetal Down’s Syndrome, and a mental process: comparing data to determine a risk level, the data being the levels of the two screening markers and the relative frequency distributions of marker levels in Down’s syndrome pregnancies and in unaffected pregnancies. The Court then looked at the claims to determine whether there were additional elements to confer patent eligibility. In the Court’s view neither the “measuring” or “determining” steps were sufficient to make the claims patent eligible and only defined “well understood” and “conventional” activity that was known to those in the field. The Court’s position was supported by statements in the patent specification that taught the “measuring” step could be performed using known methods and any markers and that statistical calculation of the risk in the “determining” step could be determined using any of the known statistical techniques. Similarly, the “assaying” step was not sufficient to save the claim.

In an analogous situation to Mayo, the Court seemed willing find that the claims would be patent eligible if there was an additional step that required a doctor who was performing the claimed method to act on the calculated risk. What the further act would need to be to confer patent eligibility was not discussed.

Implications for protection of diagnostic inventions

This decision is relevant to granted US patents, pending applications and applications in preparation as follows:

US patents: If there is the potential for the patent to be litigated then assess each claim to consider whether each meets the requirements set forth in Mayo v. Prometheus2 as follows:

  1. Is the claim a method / process claim (i.e. a claim with a series of steps)?;
  2. Does the claim recite a patent ineligible concept (i.e. law of nature, mental process, natural phenomena, abstract idea) that is a limiting feature of the claim?; and
  3. Does the claim include additional elements or steps that are sufficient to ensure that the claim amounts to significantly more that the ineligible concept itself?

If not, you may need to consider whether the claims can be amended to address invalidity, or to consider enforcement of other patents in the relevant family that provide appropriate protection from a different claim language.

US applications: With your underlying commercial objective in mind, reassess the claims and consider whether you can achieve the same commercial result with different claim language. Consider amending the claims, without adding subject matter, to include additional limitations that better define the technical aspect of a particular step of the diagnostic method / process such as:

  • the type / format of assay; 
  • the particular components of the assay, preferably novel, e.g. reagents, samples etc; and/or
  • the conditions in which the assay is carried out, e.g. temporal limitations etc.

Ultimately you are looking to limit the claims to something more than a natural principle and to something more than a well understood routine conventional activity previously engaged by scientists who work in the field.

Applications in preparation:  Diagnostic method / process claims that are not allowable in the US may be granted in other jurisdictions. So applications in preparation should be drafted with broader embodiments, potentially including those that would not meet the 3 part test mentioned above, but that otherwise meet the eligibility criteria of the relevant jurisdiction.

In preparation for a US application filing, it would seem appropriate to:

  • include detailed explanation of all experimental / technical steps of the method / process;
  • where possible, minimise statements to the effect that any known experimental assays/protocols/techniques could be used in the diagnostic method / process;
  • consider whether a step of the method / process could be performed with a technique not previously used in the relevant field; 
  • if there is a calculation step required it should be defined so that the calculation could not be performed by a human mind, e.g. the calculation must be performed by a computer programme; and
  • add versions of the diagnostic method / process that include a final step of administering a drug to treat the diagnosed disease, or that instruct a doctor or a pathologist to conduct additional diagnostic testing.

Ultimately the approach has to be based on a weighing of invalidity risk arising from a failure to meet the criteria established in Mayo against the other more common grounds of patent invalidity including obviousness and lack of enablement.

1. PerkinElmer, Inc. v. Intema Ltd., Appeal no. 2011-1577, (Fed. Cir. 2012)

2. Mayo Collaborative Services v Prometheus Labs., Inc. 132 S. Ct. 1289 (2012)