PTAB invalidates Prevnar 13 patent

American pharmaceutical company  Merck & Co. has secured a victory against its rival  Pfizer in an inter partes review of a patent concerning Prevnar 13, the biggest-selling vaccine in the world.

In two separate decisions, issued yesterday, March 13, the US Patent Trial and Appeal Board (PTAB) invalidated all 45 claims of Pfizer’s patent (US number 9,492,559 B2) which covered improvements to the pneumonia vaccine.

The PTAB found that the claims of the patent, which was granted in 2015, were obvious due to prior art, including scientific articles.

The patent covered “immunogenic compositions” against certain strains, including serotype 22F, of the bacteria which causes pneumonia. Immunogenicity is the ability to provoke an immune reaction in the body.

During the course of the trial, Merck produced evidence of prior art which demonstrated methods for achieving immunogenicity against serotype 22F.

Pfizer had argued that the evidence did not demonstrate the obviousness of certain claims of the patent, including elements such as the molecular weight of the vaccine.

The PTAB, however, said that the claimed molecular weight, and other attributes, would have occurred to a person “of ordinary skill in the art”.

After reviewing the evidence, the PTAB concluded “that a preponderance of the evidence supports the obviousness of modifying the conjugate vaccine” as detailed in the patent.

The decision follows a series of inter partes reviews in 2017 which invalidated the claims of a different Pfizer patent (US number 8,562,999) concerning Prevnar 13.

Merck was represented in the most recent case by Hogan Lovells, while Pfizer was represented by White & Case.

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