In a significant ruling, The District Court The Hague has sided with Halozyme in its global patent dispute with MSD over the subcutaneous version of the cancer drug Keytruda. The court validated Halozyme’s European patent and issued a cross-border injunction across eight countries, barring MSD from marketing the drug.
The Dutch court dismissed MSD’s revocation action against the Dutch part of EP 2 797 622 and granted Halozyme’s counterclaims for infringement in Belgium, Denmark, France, Ireland, Italy, the Netherlands, Sweden, and Switzerland. The patent, which expires in December 2032, protects modified PH20 polypeptides with increased stability in the presence of phenolic preservatives.
Background to the Dispute
Halozyme licenses the underlying Enhanze and MDASE technologies, which enable the subcutaneous administration of drugs that were previously only available via infusion. Keytruda, with the active ingredient pembrolizumab, generated sales of approximately €25.8 billion for MSD in 2024, making it one of the world’s best-selling medicines.
The dispute centres on Keytruda SC, which contains the enzyme berahyaluronidase alfa (ALT-B4), developed by Korean company Alteogen. MSD received central EU marketing authorisation for the subcutaneous formulation and had announced plans to launch the product in Europe in early 2026.
The Dutch court found that ALT-B4 meets all features of claim 1 of EP 622, including the requirement of increased stability in the presence of phenolic preservatives. The judges rejected MSD’s argument that the comparison of stability should be assessed within the final formulation, holding instead that the test must be conducted on the modified PH20 polypeptide as such.
Infringement and Cross-Border Enforcement
The court extended its jurisdiction to cover seven countries beyond the Netherlands, applying the CJEU’s judgment in BSH vs Electrolux. The panel held that there was no reasonable and non-negligible chance that the patent would be revoked in the parallel nullity proceedings pending in Denmark, France, Sweden, and Switzerland.
The court granted a separate injunction prohibiting MSD from unlawfully facilitating infringement by its group companies through its central European marketing authorisation. The Dutch judges held that MSD, as holder of the marketing authorisation, acts contrary to societal due care if it knowingly facilitates or tolerates the marketing of Keytruda SC by its group companies in Belgium, Denmark, France, Ireland, and Italy.
Read Also: HGF Expands in France with Cabinet Marconnet Acquisition
The court further criticised MSD for breaching its duty of truthfulness under Article 21 of the Dutch Code of Civil Procedure. In its reply to the counterclaim filed in April 2026, MSD had described as “unfounded and incorrect” Halozyme’s allegation that the MSD group intended to launch Keytruda SC in European markets.
Less than a month later, MSD’s Swedish and Danish sister companies had listed Keytruda SC in the national pricing databases. The court decided not to attach further consequences to this breach, given that it had already awarded Halozyme the maximum proceeding costs for patent cases. The court ordered MSD to cease infringement within seven days of service of the judgment, subject to penalties of up to €50 million.
A team from Brinkhof represented Halozyme in the Dutch proceedings, led by partner Mark van Gardingen, who worked with partner Rien Broekstra and associates Barbara Mooij, Charlotte Tiems, and Eveline Lots. Patent attorney Atze van Stralen supported the team on technical matters, providing expertise on the patent’s validity and infringement.
Halozyme is also pursuing MSD in the US federal district court in New Jersey, alleging that Keytruda Qlex, as the product is marketed in the US, infringes 15 patents relating to Halozyme’s MDAS technology. The US case is being handled by David Nelson and Zach Summers of Quinn Emanuel Urquhart & Sullivan.
Representation and Proceedings
In Germany, the US and the UK, the biotech company relies on Quinn Emanuel Urquhart & Sullivan, with Marcus Grosch leading the German team. In the UK proceedings, a team from Osborne Clarke around Trevor Cross is also acting for Halozyme. In Italy, Halozyme is relying on Trevisan & Cuonzo, with Vittorio Cerulli Irelli and Donatella Capelli leading the case.
MSD instructed its long-standing patent counsel Hogan Lovells across all jurisdictions. Amsterdam-based partners Gertjan Kuipers and Dirk-Jan Ridderinkhof led the Dutch proceedings, with counsel Rik Zagers and associates Bram Jaarsma and Anne Schreibers providing support. In parallel proceedings, Düsseldorf-based partners Miriam Gundt and Andreas von Falck lead the German case.
The German Federal Patent Court has issued a preliminary opinion indicating that EP 622 is likely valid. The Dutch ruling forms part of a wider European dispute over Keytruda SC, with multiple proceedings ongoing across the continent.
