A specialised Dutch patent court in The Hague found that Merck infringed Halozyme’s MDASE patent EP 2,797,622 and issued an injunction against the subcutaneous version of Keytruda.
The order requires MSD BV, Merck’s entity, to stop manufacturing, offering, placing on the market, using, importing or stocking Keytruda SC in Belgium, Denmark, France, Ireland, Italy, Sweden, Switzerland and the Netherlands. It also prevents MSD from helping affiliates infringe the patent, including through its European Marketing Authorization.
The intravenous version of Keytruda remains available. It falls outside both Halozyme’s patent and the Dutch injunction.
The ruling is the latest development in Halozyme’s challenge to Merck’s subcutaneous formulation of the cancer drug. Halozyme alleged that the formulation infringed its MDASE patents, and it secured a preliminary injunction in Germany on 4 December 2025 that stopped Merck from launching Keytruda SC there.
The Dutch court rejected Merck’s arguments that the patent was invalid.
Mark Snyder, Halozyme’s Chief Legal Officer, said: “We're very pleased the Dutch court recognized the validity and infringement of Halozyme's MDASE patent EP622 and granted an injunction halting Merck's launch of Keytruda SC in multiple European markets”
Merck says the patent is invalid globally. The company also says Halozyme’s claim lacks merit and that it expects ultimately to prevail in court.
Halozyme is also pursuing a patent infringement lawsuit against Merck in US federal district court in New Jersey. In that case, it alleges that the subcutaneous Keytruda formulation, marketed in the US as QLEX, infringes 15 patents filed beginning in 2011 to protect its MDASE technology.
Halozyme said its MDASE patents are separate from its ENHANCE licensing program. It said the enforcement action against Merck would not affect licensees’ ability to use ENHANCE or the related licence fees.
Halozyme stock rose 2% following the Dutch court ruling.
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