A Dutch court blocked Merck from manufacturing and selling injectable Keytruda’s subcutaneous formulation in eight European countries after finding Halozyme patent infringement. The ruling adds to the legal pressure around one of the best-selling formulations in the immuno-oncology landscape and could constrain commercial availability regionally. The case highlights how patent enforcement can reshape regional product strategies even after broad regulatory approvals. For companies relying on subcutaneous administration for site-of-care flexibility, such decisions can translate into operational and revenue impacts. Industry watchers will follow whether appeals or licensing arrangements mitigate supply gaps and how this interacts with ongoing formulation transitions across markets.