Thursday, June 3, 2021

Can the Scope of the Claim Grow Over Time?

Merck Sharp & Dohme v Wyeth 2021 FC 317 Gagné ACJ

2,604,363 / 2,650,056 / 2,803,111 / pneumococcal polysaccharide protein conjugate vaccine / PREVNAR 13

Wyeth’s 363 patent relates to a pneumococcal polysaccharide protein conjugate vaccine that is effective against 13 serotypes. The 056 and 111 patents are related formulation patents. Merck was concerned that Wyeth would use its patents to block the Merck V114 vaccine, which is effective against 15 serotypes [5], and accordingly brought this impeachment action. A key issue was therefore whether the 363 patent, in particular Claim 1, was limited to 13 serotypes [49]. This turned on what strikes me as a tricky issue of claim construction.

As I understand it, capsular polysaccharides are the major components on the surface of bacteria. Different serotypes have different polysaccharide cell-surface antigens. A protein conjugate vaccine is a substance that is composed of a polysaccharide antigen fused (conjugated) to a protein carrier molecule. The protein carrier substantially enhances the immune response. It is desirable to have as many different serotypes as possible covered by a single vaccine, and since 2000, efforts have been underway by various parties to develop protein conjugate vaccines that are effective against multiple serotypes. The first, released by Wyeth in 2000, was effective against 7 serotypes [17]. This was subsequently bumped up to 9 by Wyeth, 11 by DSK and Aventis, then 13 by Wyeth and now 15 by Merck [18]–[21]. Wyeth’s favoured carrier is a protein known as CRM197.

Claim 1 of the 363 patent is as follows:

A multivalent immunogenic composition, comprising 13 distinct polysaccharide-protein conjugates, together with a physiologically acceptable vehicle, wherein each of the conjugates comprises a capsular polysaccharide from a different serotype of Streptococcus pneumonia conjugated to a carrier protein, and the capsular polysaccharides are prepared from serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F and 23F, wherein the carrier protein is CRM197

As you can see, the claim itself specifically lists 13 serotypes. Wyeth nonetheless argued that the claim extended to vaccines with more serotypes, on the basis that the word “comprising” means “included but not limited to” [54]. Substantively, Wyeth argued that it had invented a “platform” which could be used to add other serotypes [52].

As I understand it, Merck accepted this interpretation of the word “comprising” but argued that the claim was nonetheless limited to 13 serotypes by the “wherein” clauses [55]. Gagné ACJ accepted Merck’s construction, but without directly accepting the argument as to the limiting effect of the “wherein” clauses.

Gagné ACJ rejected Wyeth’s argument for a number of reasons. First, “In Purdue Pharma v Canada (Attorney General), 2011 FCA 132 at para 22 [Purdue Pharma] the Federal Court of Appeal held that even if the word “comprising” used in claim language could be regarded as open-ended, the inclusion of other elements requires some justification. The basis for such an inclusion must be found within the confines of the patent. No such basis existed in Purdue Pharma, and none can be found in the 363 Patent” [22]. I didn’t like that aspect of the Purdue Pharma when I blogged on it, and I still don’t like it in that context, in part because claim construction is more certain if we accept that “comprising” has a definite meaning. Moreover, “comprising” is and should be used to encompass the addition of elements that have no effect on the invention. It is therefore problematic to require that “There must be a basis for it within the confines of the patent” [Purdue Pharma 22], because elements that have no effect on the invention are unlikely to be mentioned or contemplated.

With that said, I find the point much more persuasive as Gagné ACJ used it in the context of this claim. It is really a stretch to argue that “comprising” encompasses additional serotypes, even though that is grammatically consistent with its normal meaning of “included but not limited to.” As just noted, “comprising” is normally used to encompass ancillary components, or at least unforeseen improvements. In this case, 90 other serotypes were known at the time, and 50 had a known structure [53], [60] and presumably these were in the contemplation of the drafter at the time. If the drafter had intended to claim a “platform” encompassing some of these other serotypes, that would have been very easy to do, for example by saying that the capsular polysaccharides are prepared from serotypes “including” the 13 listed.

Gagné ACJ also relied on the fact that the disclosure was specific about the 13 serotypes that were included: “There is no mention in the 363 Patent of a need, a desire, or a basis for adding any other serotype,” even though “some 90 serotypes were known at the time” [60]. Now, strictly these observations might be considered to be reading limitations from the specification into the claims, but if Wyeth had really intended to claim a platform, presumably it would have made some kind of explicit reference to the additional serotypes, even if only in broad language to the effect of “the compositions of the invention may also include other known serotypes.” So, the specification expressly stated that “The compositions of this invention may further include one or more additional antigens for use against otitis media caused by infection with other bacteria,” and went on to specify other suitable antigens by name (p16). If the drafters contemplated completely different antigens, they must have been contemplating other S pneumoniae serotypes. But there is no hint of that, apart from the consistent use of the word “comprising” in the disclosure. This again goes to the point that if the drafter had really intended to claim a platform, they would have thought of this, and it would have been very easy to do.

As noted, Gagné ACJ didn’t appear to rely on Merck’s argument that the “wherein” clauses have a limiting effect. I am inclined to agree. The real question is whether the list of 13 serotypes should be considered exhaustive, and I don’t really see how “wherein” addresses that, one way or the other. That is, if the claim stated that the capsular polysaccharides are prepared from serotypes “including” the 13 listed, we wouldn’t have any problem construing it as encompassing other serotypes, “wherein” notwithstanding.

So, while I don’t see any easy knockdown argument, I largely agree with Gagné ACJ’s analysis. My only real quibble is that Gagné ACJ also noted that if Wyeth’s construction were accepted “It would also mean that the ambit of Wyeth’s monopoly could grow over the life of the 363 Patent as new serotypes – or their structure – are discovered. This would be contrary to the fundamental principles of claims construction (Free World at para 57)” [66]. With respect to the SCC, this is not a fundamental principle of claims construction. I addressed this in my article “What does Actavis v Lilly Mean for Canadian Law? (Part II) (2019) 31 Intellectual Property Journal 267 at 289. I excerpt part here, without footnotes:

The difficulty with this logic is that it is exceedingly well established that a claim may indeed encompass after-arising technology, even if that new technology is a patentable improvement. As Bowen LJ remarked more than a century ago, in Wenham Gas Co Ltd v Champion Gas Lamp Co, “The superadding of ingenuity to a robbery does not make the operation justifiable.” This rule has since been applied in many cases, including the Supreme Court’s own decision in Grip Printing, in which the Court held that there was infringement, notwithstanding that the variants might have been improvements, in the face of the respondent’s argument that there is no infringement if the defendant uses an article that “was not known as an equivalent at the date of the patent.” The same rule was also recognized by Lord Hoffmann in Kirin-Amgen, who remarked that “[t]here is no difficulty in principle about construing general terms to include embodiments which were unknown at the time the document was written.” To my knowledge, the rule that after-arising technology may infringe has never been doubted.

The rationale is simply that it is an infringement to take the essential elements of the patented invention, and it does not matter whether other elements are added or subtracted. This is evidently true when the variants are trivial, but it is equally true when the variant is inferior, and it remains true if the variant happens to work better than the original, whether the improvement is minor, or so substantial as to merit its own patent.

Of course, that is a criticism of the SCC, not of Gagné ACJ, who is entitled to rely on SCC precedent, but nonetheless, that precedent is shaky.

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