Federal Court of Canada upholds validity of Pfizer’s pneumococcal vaccine patents; Two Formulation patents held invalid

Federal Court of Canada: The Bench of Gagné, Associate CJ., upheld the validity of one pneumococcal vaccine patents pertaining to Prevnar 13 owned by Pfizer’s Wyeth LLC while held the other two patents invalid.

Finally, if the Court were to side with Wyeth on the construction of Claim 1, the Court would have to choose a cap on the number of serotypes covered by the invention or…the ambit of Wyeth’s monopoly could grow over the life of the 363 Patent as new serotypes – or their structure – are discovered.


The Merck Canada Inc. and Merck Sharp & Dohme Corp. (together Merck) had sought to  impeach three Canadian patents, one composition patent and two formulation patents, property of Wyeth LLC, pertaining to a 13-valent pneumococcal polysaccharide protein conjugate vaccine commercialized under the name Prevnar® 13. Evidently, Merck had filed a New Drug Submission to sell a 15-valent pneumococcal polysaccharide protein conjugate vaccine [V114] in Canada, apprehending that Wyeth may try to use its patents to block V114 from entering the Canadian market, Merck persuaded to challenge its validity.

Analysis by the Court

Merck argued that each of claims 1 to 6, 13, 14, 17 to 19, 22 to 30 and 36 to 38 of the 363 Patent [the Impugned Claims] were invalid. The 363 Patent was issued on June 16, 2015 which included three groups of claims: (i) Composition Claims; (ii) Use Claims; and (iii) Method/Process Claims. Claim 1 described a multivalent immunogenic composition comprising 13 distinct conjugates prepared from 13 serotypes each individually conjugated to CRM197. The Bench opined that the PSA (Person of Skill in the Art) would have understood that the 363 Patent describe the “next generation” of Wyeth’s conjugate development program and that Wyeth had managed to exceed the known limits of serotype coverage with its PCV-13 and that the 363 Patent describe a “platform” technology disclosing the details of Wyeth’s conjugation technology that were needed in order to replicate its success. The PSA would have used the platform to add other serotypes in a future vaccine, just as Merck did with its V114.

The Bench opined that both Claim 1 and the 363 Patent in its entirety indicated that Claim 1 was limited to 13 serotypes as there were sufficient bases for adding adjuvants, buffers and other excipients. However, there is no basis to go beyond 13 serotypes. Moreover, the Summary of the Invention described the invention as providing a 13-valent pneumococcal conjugate composition comprising the seven serotypes contained in Prevnar 7 (4, 6B, 9V, 14, 18C, 19F and 23F), plus six additional serotypes (1, 3, 5, 6A, 7F and 19A), which was specific and limited. There was no mention in the 363 Patent of a need, a desire, or a basis for adding any other serotype. Again, all of the 16 examples provided in the 363 Patent, which contain instructions needed by the PSA, refer only to the specific 13 serotypes recited in the claims, no others.

Hence, the Bench held that Claim 1 of the 363 Patent was limited to 13 serotypes and did not disclose any “platform” for making a vaccine with greater coverage.

Validity of 368 Patents


Analyzing the two sets of claims challenged by Merck: i) the Composition Claims; and ii) the Method/Process Claims, the Bench said that Merck had failed to meet the burden to prove that the difference between the inventive concept of the Composition Claims and the state of the art was obvious to the PSA and that the PSA would have expected that if you made the 13-valent PCV conjugated with CRM197, it would be immunogenic. Opining that conjugating is a complex endeavor and that the increasing reports on immune interference could have deterred the skilled person to pursue a 13-valent PCV all conjugated with CRM197, the Bench agreed with Wyeth that the composition of independent Claims 1 and 17 were not found in the prior art. The state of the art did not include an immunogenic composition comprising 13 individual pneumococcal conjugates (including 6A and 19A) using CRM197 as a single carrier protein. Accordingly, the composition Claims 2-5, 18 and 19, which depend directly or indirectly on Claims 1 and/or 17, by adding an adjuvant (or specific adjuvant(s)), were also not obvious at the priority date. Similarly, refuting the obviousness of the process claim, the Bench said that since the Claims 1 and 17 were neither “obvious” nor “obvious to try”, the invention disclosed in the Method/Process Claims would not have been achieved by the PSA without prolonged and arduous experimentation. Therefore, it was not “obvious to try” either.

Validity of the Formulation Patents

The 056 Patent and 111 Patent together were referred to as the Formulation Patents which were assailed by Merck for anticipation, obviousness and double patenting. Regarding the question of obviousness, the Court held that the invention as claimed would have been obvious to the PSA and the Formulation Patents were invalid for obviousness, with the exception of the serotype selection claims that were invalid for double patenting. As 7-valent claims (Claims 19 of the 056 Patent and Claim 20 of the 111 Patent) were obvious as of April 2006. Prevnar 7 had been on the market for years and was well known. Agreeing with  Merck, the Bench held that the formulations disclosed in the Formulation Patents (except for the serotype selection claims) would have been obvious to the PSA in light of the common general knowledge and the state of the art. Similarly, it would have been obvious to try to obtain stability by adding a surfactant. Therefore, there was nothing inventive about trying a surfactant to see if it would work in a polysaccharide-protein conjugate formulation and the same was an obvious solution to a well-known problem.

Double Patenting

The doctrine of double-patenting prevents a patentee from “evergreening” or from extending the monopoly given by a first patent by filing a new patent that did not disclose a new invention to the public. Noticing that the 111 Patent claimed a formulation comprising the same ingredients, the Bench said that as in 2005-2006, the use of a siliconized container means would have been obvious. Also, the 056 Patent broadly claimed a formulation containing one or more polysaccharide protein conjugates, a pH buffered saline solution with a pKa of about 3.5 to 7.5, and a surfactant. Opining that adding a surfactant to a polysaccharide protein conjugate vaccine was routine, common, and would have been obvious, the Bench held that  the claims of the Formulation Patents were all obvious variants of the invention claimed in the 363 Patent that claims a composition of 13 specific pneumococcal polysaccharides conjugated to the carrier protein CRM197 in a buffer with aluminum phosphate. The 13-valent claims (Claims 18 and 20 of the 056 Patent and Claims 19 and 21 of the 111 Patent) of the Formulation Patents were therefore held invalid for obviousness-type double patenting.


In the backdrop of above, the Bench opined that Merck had partly succeeded in meeting its burden and in establishing that Claim 1 of the 363 Patent was limited to 13 serotypes and that no particular level of immunogenicity should be read into Claim 1 of the 363 Patent. However, the Bench reached to the conclusion that Claims 1-6, 13-14, 17-19, 22-30, and 36-38 of the 363 Patent were valid, though limited to 13 serotypes. The Formulation Patents were invalid for obviousness, with the exception of the serotype selection claims that were held invalid for double patenting. As a result, Claims 1-3, 6-15, 17-24, and 29-38 of the 056 Patent as well as Claims 1-12, 17-28 of the 111 Patent were held to be invalid, void, unenforceable and of no effect.

[Merck Sharp & Dohme Corp. v. Wyeth LLC, 2021 FC 317, Decided on 30-04-2021]

Kamini Sharma, Editorial Assistant has put this report together 

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