Dutch Court Bars Merck's Keytruda SC in Eight European Countries in Halozyme Patent Win

A specialized patent court in The Hague ruled on Wednesday that Merck infringed Halozyme's MDASE patent EP 2,797,622 and rejected Merck's argument that the patent is invalid. The injunction bars MSD BV, which Halozyme describes as Merck's central European marketing authorization holder and its worldwide packaging and distribution hub, from manufacturing, offering, importing or stocking Keytruda SC in eight countries: Belgium, Denmark, France, Ireland, Italy, Sweden, Switzerland and the Netherlands. Reuters also reported the order to stop production and sale of the injectable version in those markets.

The order covers only the subcutaneous formulation, which pairs pembrolizumab with an enzyme that lets the drug be injected under the skin rather than infused. The established intravenous Keytruda is not covered by the patent or the injunction, so MRK's main oncology franchise keeps selling in these markets. What the ruling slows is Merck's effort to move European patients onto the newer injectable version. Merck said it strongly disagrees with the decision, and Fierce Pharma reported that the company vowed to fight Halozyme's patent claims.

This is the second European court win for Halozyme. A German court granted it a preliminary injunction on December 4, 2025, which stopped the Keytruda SC launch in Germany, and Halozyme is separately suing Merck in U.S. federal court in New Jersey, alleging that the subcutaneous formulation, sold in the U.S. as Keytruda Qlex, infringes 15 of its patents. Halozyme shares rose about 2% after the ruling, while Merck shares were up roughly 0.6% in Wednesday trading according to Investing.com.

What to watch: whether Merck appeals the Dutch decision, whether the two companies move toward a license or settlement, and how the U.S. case proceeds. A negotiated license would turn the dispute into potential royalty income for Halozyme, while a successful appeal could reopen the eight markets for Keytruda SC.