English High Court rules in favour of Merck in patent battle

The English High Court has ruled in favour of Merck Sharp & Dohme (MSD) in a patent battle against Shionogi, over MSD's product Isentress (raltegravir).

Isentress is an HIV therapy which has been on the market since 2007.

Japan-based Shionogi had claimed that MSD had infringed European patent number 1,422,218, titled “antiviral agent”.

Shionogi developed an anti-HIV therapy called Tivicay (dolutegravir), which has been marketed by Viiv Healthcare since 2013 (a joint venture between Shionogi, GlaxoSmithKline and Pfizer). However, the '218 patent does not cover that product.

MSD 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 MSD, 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.

“All the claims of the patent, both as unconditionally proposed to be amended and as conditionally proposed to be amended, are invalid on the ground that the claimed inventions lack an inventive step,” said Mr Justice Arnold.

He added that the patent claims were also invalid because of insufficient disclosure, although the patent was not invalid on grounds of added matter.

Shionogi's unconditional and first conditional applications to amend the patent would be permissible “were it not for the fact that they do not cure the invalidity of the patent”.

But the second conditional amendment is not permissible since it would result in added matter, explained Arnold.

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