San Diego-based Halozyme Therapeutics (Nasdaq: HALO) said a specialized Dutch patent court in The Hague found Merck’s subcutaneous Keytruda to infringe Halozyme’s MDASE patent EP 2,797,622 and ordered Merck subsidiary MSD BV to stop manufacturing, offering, marketing, using, importing, or stocking the product in Belgium, Denmark, France, Ireland, Italy, Sweden, Switzerland, and the Netherlands. The court also rejected Merck’s arguments that the patent is invalid.
The ruling covers Keytruda SC, Merck’s subcutaneous formulation of pembrolizumab, and also bars MSD BV from facilitating infringement by affiliates through its European marketing authorization. Halozyme says the patent belongs to its MDASE portfolio, which stems from research into modified human hyaluronidases and is separate from the company’s ENHANZE licensing program.
The Dutch decision is part of a broader international patent dispute. Halozyme previously obtained a preliminary injunction in Germany in December 2025 blocking sales of Keytruda SC there, although Merck has appealed that ruling, with a hearing scheduled for November 19, 2026. Merck has also filed revocation actions against EP622 in several European jurisdictions.
In the US, Halozyme sued Merck in federal court in New Jersey in April 2025, alleging that Keytruda Qlex infringes 15 MDASE patents. Merck has challenged those patents before the US Patent and Trademark Office, and several challenged claims have already been found unpatentable in post-grant review proceedings, underscoring that the broader US dispute remains unresolved.