Patentability of diagnostic methods – has the Canadian Patent Office drawn the line?

Smart & Biggar

The importance of medical diagnostic technologies has been brought to the fore with the COVID-19 pandemic. Rarely does a day pass when the media does not report on matters of approval and availability of tests, testing protocols and capacity. As of March 6, 2021, Health Canada had approved 60 COVID-19 testing devices, and 111 applications for authorization were under evaluation. At the same time, patentability of diagnostic technologies has been as fractious an issue in Canada as it has been in the United States.

Intellectual property offices have grappled with whether a medical diagnostic constitutes a traditionally patentable concrete or physical method or instead is merely an unpatentable and intangible abstract idea, untethered to the physical world. It is a difficult problem because although a new diagnostic tool typically is embodied in a physical device or method, often the principal advance lies in the recognition of a previously unknown correlation.

Until recently, the Canadian Patent Office drew a distinction between a diagnostic method that “solves a data acquisition problem” and one that “solves a data analysis problem,” generally only the former being considered patentable. There is an attractive simplicity to the logic behind this division. An invention solving a data acquisition problem—e.g. providing a new molecular biology technique for detecting “protein X” in a biological sample—inevitably involves a new method of manipulating or transforming matter, the patentability of which has never been in dispute. But an invention instead solving a data analysis problem—e.g. being the first to relate the presence of “protein X” from a biological sample to the likelihood a subject suffers from “disease Y”—might be seen as involving merely a disembodied abstract idea.

If protein X is a known and well-characterized protein, and techniques for quantifying protein X in a sample from a subject are also known, should someone who later discovers that a level of protein X in the blood above a particular threshold indicates that the subject is at risk of developing disease Y be rewarded with a patent? The patentee has the exclusive right to make, use and sell the patented invention, and may exclude others from doing so. What would constitute infringement of the patent? Indeed, perhaps it was already routine practice to measure a subject’s protein X level using a commercially available assay. Would the patent be infringed by a physician reading a patient’s medical records, noting an elevated level of protein X, and now appreciating that the patient may be at risk of disease Y?

This is a polarizing example, and much hinges on precisely what is claimed in the hypothetical patent, but the broad issue remains. If all that is new is the discovery of the relationship between protein X and disease Y, is that the proper subject of patent protection? Indeed, if the inventor instead published a scientific article disclosing the correlation, the public could make use of the discovery with existing technologies (an assay for protein X). One might argue that granting a patent in such circumstances removes a mere scientific principle or abstract idea from the public domain.

But the discovery of the link between protein X and disease Y is of undisputable practical value in healthcare, and such innovation should be encouraged. It is consistent with the fundamental patent bargain to promote and reward such advances with time-limited exclusive rights. An analogy can be made patents for second medical uses. Patents routinely grant for new uses of known medicines, e.g. for a different therapeutic indication. The discovery that a known compound has a further therapeutic utility is as much a mere scientific principle or abstract idea as the discovery that a known molecule can be used to diagnose a disease condition. Both are valuable innovations that should be encouraged.

Notably, the Canadian Patent Office has recently broadened its interpretation of patent eligibility in the medical diagnostics field, following a decision of the Federal Court holding that the “problem-solution” approach to subject-matter eligibility discussed above is improper, albeit in the context of a computer-implemented invention for selecting and managing a securities portfolio.

Pursuant to new Examples of Patentable Subject-Matter Analysis published in November 2020, the Patent Office indicates that the following claim would fall within the definition of “invention” in section 2 of the Patent Act as being directed to a patentable “art” or “process”:

A method of diagnosing whether a human subject is at risk for developing cancer, comprising:

measuring the level of X in a biological sample from the subject; and

comparing said level to the level of a non-cancerous reference sample, wherein an increase in the level of X relative to said reference indicates the subject is at risk for cancer.

This is a broad claim, as it appears the “comparing” step might encompass a purely mental process. But the claim also includes the clearly physical “measuring” step and the Patent Office acknowledges that the two elements of the claim must cooperate in order to arrive at a diagnosis of cancer risk, such that the requirement of physicality is satisfied.

In contrast, the Patent Office indicates that the following claim would not be patentable, having no physical steps whatsoever:

A method of diagnosing whether a human subject is at risk for developing cancer, comprising:

receiving a report summarizing the level of X in a sample from the subject; and

comparing said level to the level of a non-cancerous reference sample, wherein an increase in the level of X relative to said reference indicates the subject is at risk for cancer.

Indeed, in the latter case, a physician reviewing a patient’s medical record and noting that the patient has an abnormally high level of X arguably might infringe the claim merely by recognizing that the patient may have an elevated risk of cancer. Merely thinking about something clearly should not constitute patent infringement!

In any event, the recent guidance from the Patent Office is a welcome step forward, even if it cannot provide all the answers in this difficult area. The “problem-solution” approach underpinning the Patent Office’s previous approach to analyzing medical diagnostic method claims involved deeming as “non-essential” (i.e. reading out) those claim elements that were not considered to contribute to solving the problem addressed by the invention. Any approach to examination that does not give patentable weight to all express claim limitations appears doomed from the start. If there can be no fundamental agreement as what the language of the claims means, and what claim limitations or elements will be taken into account in assessing patentability, substantive examination cannot proceed. Perhaps the Patent Office’s recent guidance will allow this impasse to be resolved, and attention turned to assessment of novelty, inventiveness, and sufficiency of disclosure. Rejecting patent applications concerning medical diagnostics on the basis that what is claimed does not constitute a “method” at all is a blunt tool for assessing patentability in this complex and important area. Diagnostic technologies are of vital importance, and the patent system must find an appropriate balance to encourage innovation in this area.

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