Canada’s Intellectual Property Firm

First decision under amended PMNOC Regulations: Federal Court finds Amgen’s filgrastim patent obvious

Authored byUrszula Wojtyra

UPDATE: On November 3, 2020, the Federal Court of Appeal dismissed Amgen’s appeal. See our article here.

On April 16, 2020, Justice Southcott of the Federal Court issued the first decision under the amended Patented Medicines (Notice of Compliance) Regulations (PMNOC Regulations): Amgen Inc v Pfizer Canada ULC, 2020 FC 522. In the decision, Pfizer was successful in establishing obviousness of the asserted claims of Canadian Patent No. 1,341,537 (537 patent), relating to filgrastim (Amgen’s NEUPOGEN and Pfizer’s biosimilar product NIVESTYM).

Litigation background

In 2015, under the pre-amended PMNOC Regulations, the Federal Court dismissed Amgen’s application for a prohibition order against Apotex in respect of the 537 patent (reported previously here). Relying on that decision, Pfizer had sought to dismiss the present infringement action as an abuse of process. The Federal Court dismissed the motion, which decision was upheld by the Federal Court of Appeal (as previously reported here). Justice Southcott exercised his discretion not to apply the abuse of process doctrine to specific findings as Amgen was not able to pursue an appeal of the Apotex decision.

537 patent

The 537 patent was filed in 1986 and issued in 2007. As an “Old Act” patent, the 537 patent will expire 17 years after issuance, July 31, 2024. The 537 patent relates to a granulocyte colony-stimulating factor (G-CSF) made using recombinant genetic technology.


Amgen asserted that Pfizer’s NIVESTYM would infringe claims 43 through 47. Pfizer defended and counterclaimed on the basis that the asserted claims are obvious. Pfizer also asserted that the 537 patent is invalid as (i) Amgen made wilfully misleading and untrue material allegations contrary to section 53 of the old Patent Act and (ii) the 537 patent does not sufficiently disclose the alleged invention contrary to section 38 of the old Patent Act. Pfizer also asserted that it did not infringe the patent, relying on the prior use defence.


The Court adopted the claim construction as the inventive concept of the asserted claims, including the polypeptide of the protein (claim 43), the recombinant DNA molecule for expressing the polypeptide (claim 44) and the process for making the polypeptide that had granulocyte colony-stimulating activity (claim 47). Only claim 47 required that the inventive concept had the requisite biological activity.

The Court found that, as of the priority date of August 1985, the prior art disclosed the purification of the naturally occurring G-CSF, as well as certain methods used to clone, make and test recombinant proteins. Furthermore, there would have been a motivation to clone and purify the recombinant version of G-CSF.

The Court analyzed the steps a skilled person would have undertaken to arrive at the invention, finding that a skilled person would expect potential challenges at each step, without one guaranteed solution to such challenges. Notwithstanding that success could not be predicted at each of the steps required to achieve the claimed invention, the skilled person “is not risk averse and would not be discouraged from attempting the G-CSF project by known potential problems with identifiable solutions,” and that “[a]ny potential challenges they would encounter could be addressed with skill and did not require inventiveness.” [emphasis in original]

The Court found it compelling that Pfizer’s three experts independently set out the same roadmap for what the skilled person would have taken from one of the pieces of prior art, despite being blinded to the 537 patent.

The Court concluded it was more or less self-evident to try to obtain the claimed invention, and this was not a situation with a mere possibility that something might turn up. As a result, the Court concluded that each of the asserted claims was invalid for obviousness.

Material misrepresentation and insufficiency

The 537 patent described the G-CSF as ‘pluripotent’, meaning that it stimulated growth of multiple lineages of mature blood cells from progenitor cells. However, G-CSF stimulates only the growth of granulocytes but not other cell lineages, and thus is not considered ‘pluripotent.’ Pfizer asserted that the multiple references in the 537 patent to the recombinant protein being ‘pluripotent’ were false and misleading statements, and thus the patent was invalid undersection 53 of the Patent Act. Pfizer further asserted that the 537 patent was invalid for insufficiency as it did not teach the skilled person to produce a protein that was pluripotent.

The Court dismissed both grounds of invalidity, finding that the skilled person would have understood the 537 patent’s use of the term ‘pluripotent’ referred to the naturally occurring protein that was named ‘pluripotent’ in the prior art. Therefore, there was no material misrepresentation. Furthermore, the disclosure of the 537 patent was sufficient since there was no requirement for the patent to teach a protein that stimulates growth in multiple cell lineages.

Prior user rights

Pfizer asserted it was protected from a finding of infringement by the prior use defence. Specifically, Pfizer asserted that its biosimilar NIVESTYM was manufactured from a master cell bank that was made 3 years prior to the issuance of the 537 patent. The Court held that in order for the prior use defence to assist Pfizer, it needed to have acquired the invented subject matter either before the priority date, or before January 1, 1994 when the Patent Act was amended. Furthermore, there was no common law prior use defence as there was no legislative gap. The Court therefore concluded that, had the 537 patent been valid, Pfizer would have no defence to infringement.

Amgen may appeal the judgment as of right.

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