On Nov 25, 2016, The English High Court has ruled in favour of Merck Sharp & Dohme in a patent battle against Shionogi, over Merck’s product Isentress (raltegravir).

Japan-based Shionogi had claimed that Merck had infringed European patent number 1,422,218, titled “antiviral agent”. The patent covers Shionogi’s product Tivicay (dolutegravir), marketed by Viiv Healthcare since 2013.

Merck denied infringement and claimed that the patent should be revoked on the grounds of lack of inventive step, insufficiency and added matter. The ‘218 patent was opposed by Merck, and the European Patent Office opposition division maintained it in amended form in 2015. However, as the decision was under appeal, the amendment was suspended.

In the meantime, Shionogi made an unconditional application to amend the patent in accordance with claims maintained by the opposition division, as well as two conditional applications to amend.

On Friday, November 25, the court held that Shionogi’s patent was invalid, on the ground that it lacked inventive step and there was insufficient disclosure.

There are currently parallel proceedings going on before the courts of Germany and the Netherlands.