Merck has been dealt a significant setback in Europe after the Munich Regional Court issued a preliminary injunction blocking the launch of the company’s newly approved subcutaneous formulation of Keytruda in Germany. The decision, driven by Halozyme Therapeutics’ allegations of patent infringement, prevents Merck from distributing the faster-to-administer version of its top-selling immunotherapy and adds new intensity to an already widening international dispute over hyaluronidase-enabled drug delivery technologies. According to the court’s ruling, the subcutaneous formulation would infringe a Halozyme European patent covering modified human hyaluronidases used to support the dispersion and absorption of larger-volume biologic injections. While the order immediately halts commercial rollout in Germany, patients will continue to have full access to the original intravenous version, which remains unaffected by the litigation.
The case centers on berahyaluronidase alfa, an enabling component developed by Alteogen and incorporated into Merck’s subcutaneous Keytruda to support the rapid, high-volume delivery required for a therapy traditionally administered through a thirty-minute intravenous infusion. Halozyme asserts that this component falls within the scope of its European patent EP 2 797 622, which covers the company’s MDASE platform technology. The platform, built around modified human hyaluronidases, allows biologics that would otherwise require extended infusions to be administered in a matter of minutes. Halozyme argues that Merck’s product relies on mechanisms protected by its intellectual property, a view that the Munich court appears to have initially supported in granting the preliminary injunction. Merck, in response, is pursuing its own counter-challenges, asserting that Halozyme’s patents are overly broad and invalid. Several of those actions are pending before the German Federal Patent Court, while the companies simultaneously confront one another in parallel U.S. litigation tied to the product’s American launch under the brand Keytruda Qlex.
The commercial stakes for Merck extend well beyond Germany’s borders. Subcutaneous Keytruda is viewed as a strategically important next-generation formulation capable of preserving physician and patient uptake as the flagship intravenous version approaches major patent expirations beginning in 2028. With Keytruda generating $23 billion in sales in the first nine months of the year, the therapy represents the backbone of Merck’s oncology franchise and its broader corporate growth trajectory. A subcutaneous version that offers a two-minute administration, versus the half-hour infusion required for the IV formulation, has the potential to reduce infusion center burden, improve patient scheduling flexibility, and differentiate the brand as biosimilar entrants line up for the post-2028 window. Merck has noted that the subcutaneous version could reduce “chair and treatment” time by roughly half, even while still requiring administration by a healthcare professional. The company had expected the formulation to become a powerful lifecycle-management tool, enabling it to protect market share before biosimilar erosion begins.
Halozyme, for its part, welcomed the court’s decision. Mark Snyder, the company’s chief legal officer, said the ruling validates Halozyme’s longstanding position that its MDASE platform is both innovative and enforceable under European patent law. He asserted that Halozyme is committed to vigorously defending its intellectual property, not only in Germany but in all active jurisdictions where its technology is challenged. The company expressed confidence that the injunction would survive an appeal should Merck seek to overturn it. Halozyme also highlighted the fact that its platform has been incorporated into rival immunotherapy franchises, including subcutaneous formulations of Bristol Myers Squibb’s Opdivo and Roche’s Tecentriq, underscoring the centrality of modified hyaluronidase technologies to the industry’s broader shift away from intravenous oncology treatments.
Merck has not yet issued a public statement on its next move, but the company is widely expected to appeal. An appeal would trigger a broader review of the patent claims and, potentially, the scope of Halozyme’s protections in Europe. The outcome could reshape competitive dynamics in the immuno-oncology sector, especially as multiple companies pursue subcutaneous formulations of their blockbusters to streamline care delivery and secure more durable market positions. If Halozyme ultimately prevails, the ruling could reinforce the licensing leverage it holds over subcutaneous drug-delivery technologies. It may force developers to rely more heavily on negotiated agreements to convert IV therapies into SC formulations. If Merck succeeds in overturning the injunction or invalidating Halozyme’s claims, the ruling could open the door to alternative hyaluronidase technologies and more open competition in the subcutaneous immunotherapy market.
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Beyond the patent specifics, the injunction arrives during a pivotal period for global oncology delivery models. Hospitals and cancer centers have been under sustained pressure to optimize infusion capacity, reduce treatment times, and shift appropriate therapies into more flexible settings. Subcutaneous conversions, especially in high-volume categories like PD-1 inhibitors, are seen as essential to meeting those demands. A prolonged legal dispute over Keytruda’s subcutaneous version could delay adoption of more efficient treatment regimens in Germany and potentially influence availability across other European markets depending on future rulings.
As the litigation proceeds, the German injunction represents a meaningful disruption to Merck’s immediate commercial plans, but it also marks the opening phase of a larger legal and competitive storyline that will shape the future of subcutaneous immunotherapy delivery. With proceedings active in Germany, patent-challenge actions pending before the German Federal Patent Court, and parallel disputes unfolding in the United States, the result will have implications far beyond Keytruda itself, potentially redefining how the industry approaches formulation, delivery innovation, and IP licensing in the next decade of oncology therapeutics.
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