Introduction

The COVID-19 pandemic has highlighted the importance of medical diagnostic technologies. The media frequently reports on matters of approval, the availability of tests and testing protocols and capacity. As of 6 March 2021, Health Canada had approved 60 COVID-19 testing devices and 111 applications for authorisation were under evaluation. However, the patentability of diagnostic technologies remains a fractious issue.

IP offices have long grappled with whether a medical diagnostic constitutes a traditionally patentable concrete or physical method or instead is merely an unpatentable and intangible abstract idea. Although a new diagnostic tool is typically embodied in a physical device or method, the principal advance often lies in the recognition of a previously unknown correlation.

Previous Patent Office guidance

Until recently, the Patent Office distinguished between a diagnostic method that "solves a data acquisition problem" and one that "solves a data analysis problem", where generally only the former is considered patentable. There is an attractive simplicity to the logic behind this division. An invention which solves a data acquisition problem (eg, an invention which provides 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 disputed. However, an invention which instead solves a data analysis problem (eg, being the first to relate the presence of protein X from a biological sample to the likelihood that a subject suffers from disease Y) might arguably involve merely a disembodied abstract idea.

If protein X is a known and well-characterised protein and techniques for quantifying it in a sample from a subject are also known, should a party which 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? Patentees have the exclusive right to make, use and sell their patented invention and may exclude others from doing so. What would constitute infringement of the patent in this case? 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 developing disease Y?

This is a polarising 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? If the inventor instead published a scientific article which disclosed the correlation, the public could make use of the discovery with existing technologies (ie, an assay for protein X). Granting a patent in such circumstances arguably removes a mere scientific principle or abstract idea from the public domain.

However, 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. Patents for second medical uses are a useful analogy. Patents are routinely granted for new uses of known medicines (ie, 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.

New Patent Office guidance

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

Pursuant to the 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 of developing cancer, comprising:

  • a measure of the level of X in a biological sample from the subject; and
  • a comparison of such level to the level of a non-cancerous reference sample, wherein an increase in the level of X relative to the reference sample indicates that the subject is at risk of developing cancer.

This is a broad claim as it appears that the second step might encompass a purely mental process. However, the first step of the claim is clearly physical and the Patent Office acknowledges that the two elements of the claim must cooperate to arrive at a diagnosis of cancer risk, such that the requirement of physicality is satisfied.

However, the Patent Office indicates that the following claim would be unpatentable, as it has no physical steps whatsoever: a method of diagnosing whether a human subject is at risk of developing cancer, comprising:

  • the receipt of a report which summarises the level of X in a sample from the subject; and
  • a comparison of such level to the level of a non-cancerous reference sample, wherein an increase in the level of X relative to the reference sample indicates that the subject is at risk of developing cancer.

In this case, a physician who reviews a patient's medical record and notes that the patient has an abnormally high level of X could arguably infringe the claim merely by recognising that the patient may have an elevated risk of cancer. Simply thinking about something clearly should not constitute patent infringement.

Comment

The Patent Office's recent guidance is a welcome step forward, even if it cannot provide all of the answers in this difficult area. The problem-solution approach which underpinned the Patent Office's previous approach to analysing medical diagnostic method claims involved deeming as non-essential (ie, reading out) any 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 to what the language of the claim means and what claim limitations or elements will be considered when assessing patentability, substantive examination cannot proceed. Perhaps the Patent Office's recent guidance will enable this impasse to be resolved and attention turned instead to the 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.