Keytruda SC Blocked in Eight Countries: Dutch Court Upholds Halozyme's EP 622 Patent

By Haedar

Photo: MasterTux / Pixabay

The dispute over subcutaneous pembrolizumab has reached the Netherlands. On 7 October 2026, the District Court of The Hague ruled that MSD's Keytruda SC infringes Halozyme's European patent EP 2 797 622 (EP 622), rejected MSD's challenge to the patent's validity, and ordered MSD to stop dealing in the product in eight countries: Belgium, Denmark, France, Ireland, Italy, the Netherlands, Sweden and Switzerland. The judgment is reported as ECLI:NL:RBDHA:2026:29643 (case number C/09/695432 / HA ZA 25-1075).

According to Halozyme, intravenous Keytruda is covered by neither the patent nor the order, so patients keep access to it.

The patent and the product

EP 622 claims modified PH20 polypeptides, engineered versions of the hyaluronidase enzyme, that are more stable in the presence of phenolic preservatives. Enzymes of this type allow drugs that were previously infused to be injected under the skin. JUVE Patent reports that the patent expires in December 2032.

Keytruda SC uses a different enzyme, berahyaluronidase alfa (ALT-B4), developed by the Korean company Alteogen. According to the summary of the judgment published by IE-Forum and LS&R, ALT-B4 has fifteen amino acid substitutions, five of them at positions named in claim 1 of EP 622.

MSD started the Dutch case, seeking revocation of the Dutch part of EP 622 and a declaration of non-infringement. Halozyme counterclaimed for infringement in the eight countries.

How the court read claim 1

According to the IE-Forum/LS&R summary of the judgment, the infringement dispute turned on what has to be compared. MSD submitted test results comparing finished formulations containing pembrolizumab. The court did not accept that approach. Claim 1 is a product claim with functional features, so the question is whether the modified enzyme itself is more stable in the presence of phenolic preservatives than unmodified PH20. Halozyme supported that with two studies by BionSystems, and MSD's formulation data did not answer the point.

It also held that it does not matter whether Keytruda SC contains a phenolic preservative or uses the improved stability. An enzyme with the claimed structure and property falls within the claim.

On validity, the court rejected all four grounds raised: insufficiency, added matter, lack of novelty and lack of inventive step. It found that the cited prior art gave the skilled person no reason to improve the stability of PH20 against phenolic preservatives by making substitutions at the claimed positions.

The cross-border reach

Seven of the eight countries covered are outside the Netherlands. Revocation actions against EP 622 are pending in several European countries, and JUVE Patent lists France, the UK, Denmark, Sweden and Switzerland.

MSD asked the court to stay the case until those foreign actions were decided. The court refused. Applying the Court of Justice of the European Union's judgment in BSH v Electrolux, it found no reasonable and non-negligible chance that the relevant foreign parts of the patent would be revoked. It said that the earlier Dutch approach in Roche v Primus II, under which such cases were in principle stayed, appears outdated on this point.

Instead of a stay, the court made each foreign injunction conditional. An injunction lapses if the competent national court revokes the relevant national part of EP 622, wholly or partly, at first instance or on appeal, and revives if a higher court later upholds the patent. The declaration of infringement for each foreign country lapses only on a final revocation.

The marketing authorisation point

MSD BV holds the central EU marketing authorisation for Keytruda SC. According to the published summary, the court held that holding a marketing authorisation is not, in itself, an act reserved to the patent owner. It found, however, that MSD acts unlawfully if, as holder, it knowingly facilitates or encourages infringement by other group companies, for example by letting them use its authorisation. It granted a separate injunction on that basis, limited to Belgium, Denmark, France, Ireland and Italy.

According to the reports, MSD must comply within seven days of service. The penalty is €25,000 per day or, at Halozyme's choice, per product, up to a total of €50 million. MSD was ordered to pay €284,760 in costs. The court also found that MSD had breached its duty of truthfulness under Article 21 of the Dutch Code of Civil Procedure through statements about its launch plans, but attached no further consequence to that finding.

The wider dispute

According to the reports cited below, the Netherlands is the second European jurisdiction to stop Keytruda SC. On 4 December 2025, Halozyme obtained a preliminary injunction for Germany, which MSD has appealed. In the United States, Halozyme is suing in federal court in New Jersey, alleging that the subcutaneous product sold there as Keytruda Qlex infringes 15 patents. As of the reports we relied on, Merck had not published a response to the Dutch ruling.

Points for patent owners and licensees in Asia

The first point is forum. Under BSH v Electrolux, a court in the defendant's home country can rule on infringement of foreign patents and, as this judgment shows, can grant relief for several countries at once when it sees no real risk that those patents will fall. A patent owner that sues where the defendant is based can reach markets that would otherwise need separate national actions.

The second point is claim drafting. A product claim to a modified enzyme, defined by a measurable property, reached a finished medicine whatever the role of that enzyme in the formulation. Claims built around the key component and its tested property gave the patent owner wider reach than formulation claims would have.

Asian biotech companies that supply components to multinational partners should run freedom-to-operate reviews for each European country where the partner sells, not only where the supplier itself trades.

Sources

• IE-Forum / LS&R, summary of Rb. Den Haag 7 oktober 2026, ECLI:NL:RBDHA:2026:29643 (MSD v Halozyme), in Dutch, with extracts from the operative part
• JUVE Patent, "Halozyme takes the win over MSD's cancer drug Keytruda in the Netherlands" (9 October 2026)
• Halozyme Therapeutics, "Halozyme Wins Injunction Stopping Manufacture and Sale of Merck's Keytruda SC in Multiple European Markets" (7 October 2026)