On 10th June 2013 the Canadian Intellectual Property Office (CIPO) issued Practice Notice PN2013-04, providing guidelines to be followed in the examination of patent claims covering medical uses.

In Canada, claims directed to methods of medical treatment are considered non-patentable subject matter, outside of the scope of the Patent Act’s definition of “invention”, and are rejected during prosecution. However, certain forms of medical “use” claims – such as those directed to “use of [compound] for treatment”, “use of [compound] in the manufacture of a medicament for treatment” or “[compound] for use in treatment” – are generally considered valid if no active treatment or surgical steps are recited. The notice provides examiners with specific guidance with respect to the examination of such claims.

As an introductory point, the notice states that although medical use claims will generally be allowed, when it is determined that such claims “prevent physicians from exercising their skill and judgment in using a known compound for an established purpose”, they should be rejected as effectively covering a method of medical treatment. The notice then provides guidance for examiners in making such a determination.

Purposive claim construction
Referring to the 2011 Federal Court of Appeal decision in Canada (Attorney General) v Amazon.com, and to the recently issued Practice Notice PN2013-02, the new notice states that patentable subject matter determination must be based on a purposive construction of the claims. This may be considered a departure from past CIPO practice, which had relied on an assessment of the nature of a claim’s “contribution”.

The Supreme Court, in Free World Trust v Électro Santé Inc, established the following approach to purposive construction:

"The claims language will, on a purposive construction, show that some elements… are essential…  The identification of elements as essential or non-essential is made:

on the basis of the common knowledge of the worker skilled in the art…

as of the date the patent is published;

having regard to whether or not it was obvious to the skilled reader at the time… that a variant of a particular element would not make a difference to the way in which the invention works; or

according to the intent of the inventor, expressed or inferred from the claims, that a particular element is essential irrespective of its practical effect;

without… resort to extrinsic evidence."

By comparison, the notice sets out a purposive construction analysis emphasising identification of the “problem the inventors set out to address and the solution disclosed”. The notice instructs examiners to consider inventor statements about the background, their objectives and specific problems, needs or advantages known in the art.  The notice states that identification of the problem should be guided by the examiners’ understanding of the common general knowledge and the patent’s description.  

Patentability determined based on nature of “essential elements”
After having identified the problem and solution, the notice then instructs the examiner to determine which claim elements are “essential” to the solution. If any of the so-identified “essential elements” is considered to instruct a medical professional "how" to treat a patient, that claim should be rejected as being directed to an invalid method of medical treatment. By contrast, claim elements directed to “what” to use for treatment should not result in a finding of invalidity.

The notice lists several claim elements of particular interest to patentees in the rapidly developing field of personalised medicine as “how” elements that, if deemed essential, should result in that claim’s rejection:

  • Dosing schedules.
  • Dosage ranges.
  • Limitations to a patient sub-population.
  • Sites of administration.

Accordingly, the impact of the notice on the patentability of medical use claims that recite such limitations, if deemed essential elements, will depend on whether examiners construe such limitations as a “what” or a “how”. 

In cases where “how” elements are deemed non-essential under the notice, their “mere recitation... does not necessarily mean the claim is non-statutory”.

Although not specifically addressed by the notice, use claims directed to a series of specific dosages would appear to be allowable, as such claims arguably recite limitations directed to a number of vendible products (“what” rather than “how”). Given that there are no additional claim fees in Canada, one appropriate response to the notice may be to dissect dosage range claims, thereby claiming uses of a series of discrete dosages.

With respect to claim limitations to a patient sub-population or site of administration, the notice does not specifically address how such limitations, if worded in passive form (eg, “for administration to a site”), should be construed.  Such limitations, if appropriately worded, may be construed as directing the “what”, rather than “how”, and may thus be allowable under the notice. 

Comment
The notice represents the latest of several steps taken by CIPO in its ongoing attempt to clarify its practice relating to medical uses. This began with the reworking of Section 13.05.03 of the Manual of Patent Office Practice in 2009, which was effectively rescinded in part in 2011 by Practice Notice PN2011-04, which was in turn explicitly rescinded by the 18th March 2013 Practice Guidance Following the Amazon FCA Decision.

Whether the notice is successful in this regard will likely depend on how it is applied by examiners. In this respect, it may be appropriate to consider the following passage from the Federal Court of Appeal’s Amazon decision:

"Anyone who undertakes a purposive construction of a patent must do so on the basis of a foundation of knowledge about the relevant art… For the Commissioner [represented during prosecution by the examiner], that assistance comes in the form of submissions from the patent applicant and… staff at the patent office with… appropriate experience." (Emphasis added.)

In this spirit, if CIPO encourages examiners to solicit the assistance of patent applicants during prosecution with respect to, among other things, the critical step of purposive construction, the notice may well achieve its stated goal of ensuring “efficient, predictable and reproducible examination” of medical use claims.

This article first appeared in IAM magazine. For further information please visit www.iam-magazine.com