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3 June 2024

Protection of diagnostic methods in Europe

The European Patent Convention (EPC) includes a provision excluding the patent protection of diagnostic methods practised on the human or animal body. In our previous article, we explored how this exclusion was interpreted by the Enlarged Board of Appeal of the European Patent Office (EPO) in decision G1/04. We concluded that it is often still possible to protect methods involved in the diagnosis of medical conditions providing that sufficient care is taken when drafting the European patent application.

This follow-up article looks at how the principles of G1/04 have subsequently been applied in three interesting decisions of the Boards of Appeal of the EPO.

Overview

Art. 53(c) EPC states that “European patents shall not be granted in respect of… methods for treatment of the human or animal body by surgery or therapy and diagnostic methods practised on the human or animal body”. The exclusion is intended to prevent situations wherein a medical or veterinary professional does not perform a diagnostic method because he or she is concerned that the method would infringe upon patent rights.

In our previous article we looked at how this exclusion was interpreted narrowly by the Enlarged Board of Appeal in G1/04. This important decision outlines the conditions that must be met for a claimed method to be excluded as an unpatentable diagnostic method. In particular, for a claimed method to contravene Art. 53(c) EPC, the claimed method has to include features relating to:

  1. the diagnosis for curative purposes stricto sensu representing the deductive medical or veterinary decision phase as a purely intellectual exercise;
  2. the preceding steps which are constitutive for making that diagnosis; and,
  3. the specific interactions with the human or animal body which occur when carrying those out among these preceding steps which are of a technical nature.

The Enlarged Board held that the method steps to be carried out when making a diagnosis as part of the medical treatment of humans or veterinary treatment of animals for curative purposes include the following phases:

(i) the examination phase involving the collection of data;

(ii) the comparison of these data with standard values;

(iii) the finding of any significant deviation, i.e. a symptom, during the comparison; and,

(iv) the attribution of the deviation to a particular clinical picture, i.e. the deductive medical or veterinary decision phase.

In essence, according to G1/04 a method is only excluded from patentability if it includes all of the necessary steps to obtain and analyse data and reach a diagnostic conclusion. Furthermore, a claimed method will fall outside the scope of the exclusion if at least one of the examination, comparison and deviation phases (i) to (iii) includes a step that is of a technical nature and is not practised on the human or animal body.

T1920/21

This decision from earlier this year concerns a patent application for a breath test to diagnose Helicobacter pylori infection. The Examining Division had refused the application on the grounds that the claims related to a diagnostic method contravening Art. 53(c) EPC, and the applicant appealed.

Claim 1 under appeal read:

1. A method for diagnosing a Helicobacter pylori infection in a patient treated with proton-pump-inhibitors (PPIs) comprising the steps of administering to the patient a mixture of citric acid, malic acid, tartaric acid in amount of 5 to 7 g, collecting a first breath sample, administering to the patient 13C-labelled urea, wherein the amount of 13C-labelled urea corresponds to 10 to 100 mg 99% 13C-urea waiting for a time of 10 to 60 minutes, thereafter collecting a second breath sample from the patient, measuring the content of 13C in the CO2 of the first and second sample and determination of a 13C/12C ratio by spectroscopy in the respective samples characterized in that a difference ∆δ of the 13C/12C ratio of the first breath sample and 13C/12C ratio of the second breath sample is calculated and the value of the difference in the range of 2 per mille to 2.9 per mille is used as a cut-off to indicate the presence of a H. pylori infection in the patient, wherein the method requires only a 1 day stop of PPI intake.”

The applicant argued in the appeal that collecting a breath sample is not practised on the human or animal body because it is not invasive. The Board of Appeal disagreed, pointing out that G1/04 makes it clear that the criterion “practised on the human or animal body” is satisfied if the performance of a step implies any interaction with the human or animal body, i.e. necessitating the presence of the body (regardless of whether or not the step is invasive or non-invasive, and also regardless of whether or not there is physical contact with the body or the step is practised at a certain distance to it). The Board noted that the two technical steps recited in claim 1 relating to breath collection necessarily require the presence of the patient  and therefore are practised on the human body.

The applicant also argued that the claimed step of measuring the content of 13C in the CO2 of the first and second samples and determining a 13C/12C ratio by spectroscopy in the respective samples is a technical step that is not practised on the human or animal body. In contrast, the Examining Division had objected that the step of the physical detection of the isotopes cannot be isolated from the steps of collecting the breath samples from the patient (which are practised on the human body, as outlined above). The Board agreed with the applicant, finding that claim 1 does not include any requirement that the measurement of the two samples must be made in the presence of the patient. The Board noted that it would be common general knowledge to the skilled person that gas isotope ratio mass spectroscopy or infrared spectrometer devices could be used to take such a measurement, and that such devices analyse the collected breath samples without any interaction with the patient or necessitating his or her presence. Therefore, since claim 1 recites at least one step of a technical nature that is not practised on the human or animal body, it was found that the method is not excluded from patentability under Art. 53(c) EPC.

T0529/19

In T0529/19, the Board of Appeal had to decide whether the diagnostic method exclusion of Art. 53(c) applied to a method of determining skin health. The patent application describes that the native fluorescence of human/mouse skin varies with ageing and UV exposure, and that skin autofluorescence spectroscopy can be used to evaluate skin health and the effects of ageing on skin health.

Claim 1 under appeal read:

  1. “A method of determining skin health of an area of skin, said method comprising the steps of

(i) exposing said area of skin to a first exposure radiation to induce said area of skin to emit a first fluorescent emission, wherein said first exposure radiation comprises primarily of wavelengths of from about 290 nm to about 300 nm;

(ii) measuring the intensity of said first fluorescent emission having a wavelength of from about 320 nm to about 350 nm;

(iii) exposing said area of skin to a second exposure radiation to induce said area of skin to emit a second fluorescent emission, wherein said second exposure radiation comprises primarily of wavelengths of from about 330 nm to about 420 nm;

(iv) measuring the intensity of said second fluorescent emission having a wavelength of from about 380 nm to about 470 nm;

(v) calculating a ratio of said intensity measured in step (ii) to said intensity measured in step (iv); and

(vi) comparing said ratio to a control ratio.

In the method of claim 1, the area of skin is exposed to a first and second radiation and the ratio of the resultant measured first and second fluorescence emissions are calculated and compared to a control ratio so as to determine the skin health of the area of skin. Unlike T1920/21 discussed above, it was not contested that the claimed method included the examination phase (i), comparison phase (ii), and deviation phase (iii) set out G1/04 and that, where technical in nature, these phases were performed on the human or animal body. However, the applicant disagreed with the finding of the Examining Division that the decision phase (iv) of G 1/04 was derivable from the wording “[a] method of determining skin health” in the preamble of claim 1, and appealed on the basis that the claimed method does not in fact include the attribution of the deviation (the comparison of the calculated ratio to a control ratio) to a particular clinical picture (the deductive medical or veterinary decision phase).

The Board agreed with the applicant because claim 1 does not specify what the determined “skin health” encompasses and therefore agreed that there was no attribution of the deviation to a particular clinical picture. The Board noted that the deviation could refer to the quotient between the compared ratios or some other parameter related to skin health, which may at most be an intermediate finding of diagnostic value.

The Board noted that whilst the claim preamble suggests that an assessment of skin health is made, the claims and description do not indicate that the assessment would actually include the attribution to a particular clinical picture. The description specifies that diabetes has an impact on the obtained values, but the claimed method does not attribute any finding on skin health to the presence or absence of diabetes. The description instead emphasises that the calculated ratio is related to the effects of ageing, and the Board held that establishing that skin ageing is greater than expected for an individual would be, at most, an intermediate finding of diagnostic value and does not represent the attribution to a particular clinical picture. The claimed method was therefore found to not be excluded from patentability under Art. 53(c) EPC.

T1232/15

In T1232/15, the Board considered an application relating to the use of adhesive strips to form a tactile aid enabling line-by-line scanning of areas of skin. The tactile aid helps a blind person to orientate themselves when scanning the surface areas of the skin to check for signs of breast cancer.

The preamble of claim 1 under appeal read:

1. Use of several adhesive and haptic strips (1a, 1b, 1c, 1d, 1e) to form an aid for blind people to enable the line-by-line scanning of skin areas comprising the breasts (7) of a female human body when carrying out a clinical breast examination…

The Examining Division objected that claim 1 defined an unpatentable method of diagnosis in contravention of Art. 53(c) EPC, and the applicant appealed. The Board of Appeal held that the steps of the method of claim 1 serve only to prepare a diagnostic procedure to be carried out by a blind person to detect breast cancer. The claims do not contain any steps that concern phase (iv) of G1/04, namely the diagnosis strictu sensu (which in the present case is the diagnosis of breast cancer based on lumps felt by palpation). Furthermore, the preceding steps for making the diagnosis are also not claimed, namely: (i) the examination phase with the collection of data (i.e. carrying out palpation); (ii) the comparison of these data with the normal values ​​(i.e. comparison with palpation on healthy patients); and, (iii) the detection of a significant deviation in this comparison. Therefore, claim 1 was not excluded as an unpatentable diagnostic method.

This case illustrates one of the core points raised in our earlier article: that it is often possible to avoid the exclusion by drafting the patent application in such a manner that the diagnostic step itself is omitted from the claim. However, great care should be taken to ensure that the diagnostic step is not nevertheless presented as being essential to the method or is otherwise deemed to be implicit from the remaining steps of the claim. Therefore, we always recommend providing a teaching in the application that highlights that one or more of such steps is not essential to the performance of the method, if possible. In the present case, the claim was directed to a method of preparing the body for a diagnostic procedure. If the claim had instead recited the steps for making the diagnosis (e.g. carrying out a palpation, comparing the palpation, deriving a deviation from that of healthy subjects and making a diagnosis), or if these steps were deemed essential/implicit to the claim, then the claim would likely have fallen foul of the Art. 53(c) EPC exclusion.

Conclusion

Each of the above decisions relates to a medical method that, at first glance, would appear to be excluded as an unpatentable diagnostic method. However, as we have seen, the exclusion is in fact applied narrowly and each of these patent applications claimed the invention in such a way that the exclusion did not in fact apply.

The key to success is therefore to keep the exclusion in mind at the outset when drafting patent applications, for example, claiming at least one technical method step that is not practiced on the human/animal body or using wording that omits at least one of phases (i) to (iv) required for a diagnosis (and ensuring that these phases are not presented as being essential/implicit). Doing this at the drafting stage is important because opportunities to amend a European patent application after filing are relatively limited due to the strict added subject matter provisions applied by the EPO. Furthermore, it is worth noting that the exclusion is limited to diagnostic methods and does not apply to product claims. For example, a claim to a breath analysis device, a skin testing device, or a kit of adhesive test strips would likely not fall within the scope of the exclusion.

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