A Dutch court has issued an injunction preventing Merck from manufacturing and selling a subcutaneous formulation of its cancer drug Keytruda in eight European countries. The court ruled that the drug infringes on a patent held by Halozyme Therapeutics, which specializes in drug delivery technology.
This ruling applies to Belgium, Denmark, France, Ireland, Italy, Sweden, Switzerland, and the Netherlands. The subcutaneous formulation of Keytruda, referred to as Keytruda SC in Europe, was approved by European authorities in November 2023.
Merck contended that Halozyme’s patent, which involves the modified hyaluronidase (MDASE) technology used for the subcutaneous delivery of drugs, is invalid. However, the court rejected this argument, asserting that Merck’s product does indeed infringe on Halozyme’s patent. As a result, Merck is prohibited from producing, importing, stocking, or selling this version of Keytruda in the affected countries.
This case forms part of a broader legal conflict between Halozyme and Merck, which has collaborated with South Korea’s Alteogen to develop Keytruda’s subcutaneous delivery system. Halozyme has claimed that Merck’s formulation uses an ingredient covered by its patent. The companies have been engaged in litigation across various legal forums, including the U.S. Patent Trial and Appeal Board and courts in Europe.
In addition to the Dutch ruling, a German court also issued a preliminary injunction against Merck, barring the sale of Keytruda SC in Germany, which is the largest pharmaceutical market in Europe. Merck has appealed the German ruling, with a court hearing scheduled for next month.
These legal challenges have significant implications for Merck as they prevent it from operating in three of Europe’s four largest pharmaceutical markets. In the U.K., Halozyme consented to the revocation of the disputed patent in May 2026.
Despite these setbacks, Merck’s intravenous version of Keytruda remains unaffected by the court rulings and continues to perform well in the market. In the second quarter of this year, it generated $7.9 billion in sales, compared to $463 million from the subcutaneous formulation.
As Merck transitions its product offering, the company views the subcutaneous formulation as essential for its future, especially as key patent protections for the intravenous product are set to expire in 2028. These legal setbacks hinder Merck’s ability to convert customers to the subcutaneous version, potentially complicating future competition from biosimilar products.
