Between 28 October 2025 and 17 November 2025, the US Patent Trial and Appeal Board (PTAB) issued final decisions invalidating Johns Hopkins University’s (JHU’s) 10,934,356 (IPR2024-00622), 11,325,974 (IPR2024-00623), 11,325,975 (IPR2024-00624) and 11,643,462 (IPR2024-00648) in four inter partes review proceedings (IPRs) brought by MSD. Following invalidation of five JHU US patents in June 2025 and September 2025, this means MSD has now succeeded in all nine IPRs that it filed in relation to JHU US pembrolizumab patents in 2023-2024. JHU has filed notices of appeal to the US Court of Appeals for the Federal Circuit in relation to each of the PTAB decisions.
The nine JHU patents challenged by MSD relate to the use of pembrolizumab in treating cancer patients with high mutational burdens, such as those found in microsatellite instability high (MSI) or DNA mismatch repair deficient cancer (dMMR). In each case, the PTAB found that the patents were invalid for lack of novelty and/or obviousness based on prior art, including a record of a JHU phase 2 clinical trial of Keytruda® (pembrolizumab) in MSI/dMMR cancer.
In November 2022, MSD 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. Based on the complaint, the dispute arose out of a contract between MSD and JHU to design and conduct a clinical trial on administration regimes for Keytruda® (pembrolizumab) in cancer patients with certain genetic biomarkers. JHU filed a counter-claim on 12 April 2023, including alleging infringement of patents subject to the IPR proceedings referred to above. The US Court proceeding has been stayed pending the outcome of the IPRs. No trial date has been scheduled.