Keytruda SC Barred from Sale in 8 European Countries... Alteogen Patent Risk Resurfaces

Dutch Court Finds Infringement of Halozyme Patent
Sales Banned in Nine Countries, Including Germany
MSD: "We Disagree with the Ruling"

Keytruda SC, MSD's immuno-oncology drug that uses Alteogen's technology for changing the formulation to a subcutaneous (SC) injection (marketed in the United States as Keytruda Qurex), has been barred from sale in eight European countries. The ruling came after a Dutch court found that Keytruda SC infringes a patent held by rival Halozyme. Including Germany, where sales were barred last year, the number of European countries where Keytruda SC cannot be sold has risen to nine. Patent risks that had been subsiding after a string of MSD victories in U.S. patent reviews have resurfaced in Europe.

According to Halozyme, the District Court of The Hague ruled on October 7 (local time) that MSD infringed a European patent related to Halozyme's MDASE subcutaneous injection technology. The court barred MSD BV, MSD's European marketing authorization holder, from manufacturing, selling, using, importing or holding stocks of Keytruda SC in eight countries: Belgium, Denmark, France, Ireland, Italy, Sweden, Switzerland and the Netherlands. It also prohibited MSD affiliates from selling the drug using MSD BV's European marketing authorization. The court also rejected MSD's argument that the patent was invalid. The order does not cover Keytruda in its existing intravenous (IV) formulation.

Keytruda Qlex product image. MSD

MSD said it disagrees with the ruling. According to Reuters, MSD said it strongly opposes the Dutch court issuing an injunction covering multiple countries and is considering its response. Alteogen shares closed at KRW 240,500 on October 8, down 6.42% (KRW 16,500) from the previous trading day. They fell as low as KRW 234,500 during the session.

The ruling followed a lawsuit first filed by MSD. Ahead of the launch of Keytruda SC, MSD filed a suit under the Netherlands' expedited patent proceedings seeking a declaration of non-infringement and invalidity. Halozyme filed a counterclaim seeking to bar infringement in European countries where the patent is valid. Because MSD BV is a Dutch entity, the Hague court also assessed infringement across multiple countries. Germany was excluded from the claims because sales there had already been blocked by an injunction issued by the Munich Regional Court in December 2025.

Keytruda SC is already on the market in Denmark and Sweden. In May 2026, local MSD affiliates listed Keytruda SC as an available product on the pharmaceutical price lists in both countries. Halozyme sought injunctions in July 2026 to block sales in the two countries, but the same court rejected the requests. Following this ruling on the merits, sales in both countries are also expected to be suspended.

Alteogen says the impact on its earnings will be limited. The company estimates that the eight countries covered by the order account for 6% to 8% of total Keytruda sales, and says Keytruda SC's share of sales is smaller still. Based on MSD's regional sales mix in December 2025, Hana Securities estimated that Europe accounted for about 17.6% of Keytruda sales. Keytruda SC generated $590 million in sales in the first half of 2026 (about KRW 810 billion), including $463 million in the second quarter alone. Alteogen is reportedly eligible to receive up to $1 billion in sales milestones from MSD (about KRW 1.345 trillion), followed by royalties in the 2% range. In August 2026, Alteogen said it would receive its first sales milestone payment of $25 million (about KRW 34.4 billion).

Rulings in the patent dispute between Halozyme and MSD have varied by country. Halozyme claims that Alteogen's hyaluronidase used in Keytruda SC falls within the scope of its patents and filed a patent infringement lawsuit against MSD in the U.S. District Court for the District of New Jersey in April 2025. In May 2026, the U.S. Patent Trial and Appeal Board (PTAB) issued its first decision finding a Halozyme patent invalid. In the United Kingdom, Halozyme agreed in the same month to the revocation of the patent that served as the basis for this ruling. By contrast, courts in Germany and the Netherlands found the patent valid and ruled in Halozyme's favor.

MSD is pursuing lawsuits to invalidate the patent in seven European countries. The appeal hearing concerning the German injunction is scheduled for November 19. The New Jersey lawsuit on the merits is also still pending.

This content was produced with the assistance of AI translation services.