Halozyme wins Dutch ruling against Merck's subcutaneous Keytruda: the eight markets where Keytruda SC is now blocked

Halozyme Therapeutics (Nasdaq: HALO) said on Wednesday, October 7, 2026 that the District Court of The Hague found Merck's subcutaneous Keytruda infringes Halozyme's European patent EP 2,797,622 and ordered Merck's Dutch subsidiary, MSD BV, to stop manufacturing, offering, marketing, importing and stocking the product in eight markets: Belgium, Denmark, France, Ireland, Italy, Sweden, Switzerland and the Netherlands. The court also rejected Merck's argument that the patent is invalid. The news first reached the MoveSurge news feed at 08:30:25 ET, before the market opened; HALO was at $111.40 when a second report crossed at 09:27:33 ET, three minutes before the opening bell, and traded 0.88% higher at $112.38 fifteen minutes later. The MoveSurge reaction reading, taken ten minutes after that report, had HALO 0.37% higher at $111.81.

The order applies only to the under-the-skin version of Keytruda, which Merck sells in the US as Keytruda Qlex. Intravenous Keytruda is outside both the patent and the injunction, so patients in those countries keep access to the drug. The court also barred MSD BV from facilitating infringement by its affiliates, including by letting them use its European marketing authorization, the regulatory approval the subcutaneous product is sold under.

Merck's own shares barely moved: MRK was 0.1% higher a minute after a later report of the ruling reached the MoveSurge news feed at 09:39:19 ET.

Merck's subcutaneous Keytruda, court by court

How one Dutch case reached eight countries

A European patent is a bundle of national patents, one for each country where it is validated. Merck's subsidiary opened the Dutch case itself, asking the court to declare that it did not infringe EP 2,797,622 and to revoke the Dutch part of the patent. Halozyme answered with cross-border infringement counterclaims covering every country where the patent is in force except Germany, which has its own proceedings. Because MSD BV is the Dutch company that holds Merck's central European marketing authorization, a single Dutch judgment against it could reach Belgium, France, Italy and the other markets in the order.

The July hearing on preliminary relief went the other way. The same court refused to bar the product from Denmark and Sweden while the main case was pending, finding that a statement in Merck's pleadings was not a binding promise Halozyme could rely on. The main proceedings, heard at the end of July, have now produced the injunction Halozyme failed to get on an interim basis. EP 2,797,622 runs until December 2032.

The US patent fight runs on a different track

In the US, Merck has attacked Halozyme's patents on modified hyaluronidase, the enzyme family Halozyme calls MDASE, at the Patent Trial and Appeal Board. On May 12, 2026 the board invalidated US Patent No. 11,952,600, finding that its claims were not supported by enough description to show how to make and use the full range of enzymes they covered. Merck filed review petitions against 14 more Halozyme patents between November 2024 and November 2025; the board instituted 13 of them and denied the last on May 15, 2026, and Merck filed three further petitions in March 2026. The American and European rulings concern different patents with different claims, so the US board's decisions do not bind the European courts.