On 4 March 2024, Merck filed petitions for inter partes review against four Johns Hopkins University (JHU) patents relating to methods of treatment using pembrolizumab in patients whose cancers have a genetic instability called microsatellite instability-high (MSI-H). These four IPRs are IPR2024-00622 (against US10,934,356), IPR2024-00623 (against US11,325,974), IPR2024-00624 (against US11,325,975), and IPR2024-00625 (against US11,339,219). Each IPR is based on anticipation and obviousness. The petitions have not yet been instituted by the USPTO.
In November 2022 Merck filed a complaint in the United States District Court (District of Maryland) against JHU seeking declarations of breach of contract, non-infringement and promissory estoppel in relation to the same four patents. The trial has not yet been scheduled.