Many diagnostic method inventions are based on a novel finding that the presence or concentration of a particular biomarker is indicative of the incidence, progression or severity of a particular disease. The invention lies in the correlation between the biomarker and the disease.

Prior to 2012, it was very much possible to patent this type of invention in the US. The invention would typically be claimed as a method of diagnosing the disease, wherein the method comprises the step of detecting the biomarker, or determining its concentration, in a sample from a patient.

The infamous US Supreme Court decision in Mayo Collaborative Services v. Prometheus Laboratories, Inc. (2012) – “Mayo” – changed all that. The Mayo decision implied that such correlations were “laws of nature” which were excluded from patentability (in the absence of any other steps of a non-conventional nature in the claimed method).

The decision sent a wave of concern through the medical diagnostics industry. Those concerns have been proved valid. Subsequent US decisions, such as that in Ariosa Diagnostics, Inc. v. Sequenom, Inc. (2015) (discussed here), have not only confirmed the Mayo decision, but made it even more difficult to patent diagnostic methods.

Most in the industry are dissatisfied with the current situation.  Many concerned parties have filed Amicus Briefs to urge the US Supreme Court to reconsider the Sequenom vs. Ariosa decision.

In the meantime, US Examiners are consistently objecting to diagnostic method claims for relating to patent ineligible subject-matter. Last month, the USPTO issued this guidance note, which provides some examples of the types of claims that are considered eligible and ineligble for patent protection.  Claim 2 of Example 29 of that note is an example of the type of broad diagnostic method claim based on an inventive correlation between a biomarker and a disease, which is no longer patentable in the US.

There are strategies for maximising the chances of overcoming ineligibilty objections to diagnostic method claims, but the reality is that significant limitation of claim scope is usually required.

It is therefore very disheartening to learn that the Canadian Intellectual Property Office (CIPO) has begun assessing the patentability of diagnostic method claims in a very similar way. CIPO issued guidance on the patentability of diagnostic method claims in 2015 (discussed here).  As reported below, it is now becoming clear how that guidance is being applied by Examiners during examination of Canadian patent applications, and the news is not good for patent applicants.


“The administrative notice does not have the force of law, but early office actions applying the guidance suggest that, with no basis in Canadian law, CIPO is adopting a much stricter test to determine the patentability of medical diagnostic methods… …diagnostic methods where the novelty lies in evaluating a correlation between acquired data and a disease state will likely be difficult to protect in Canada under the new administrative guidelines.”