On 19 November 2025, MSD announced that that the European Commission has approved its subcutaneous (SC) formulation of Keytruda®, to be marketed in the EU as Keytruda SC™ (pembrolizumab and berahyaluronidase alfa-pmph). The marketing authorisation covers all 33 previously approved adult indications for Keytruda® (pembrolizumab) in Europe and follows a positive recommendation from the EMA’s CHMP in September 2025.
The subcutaneous formulation was approved in the US, as Keytruda Qlex™, in September 2025 across 38 indications.
MSD was sued by Halozyme in the US on 24 April 2025 in relation to SC pembrolizumab, with Halozyme alleging that it infringes 15 patents owned by Halozyme in relation to MDASE subcutaneous delivery platform. The lawsuit followed reports in March 2025 that Halozyme had offered MSD an opportunity to licence its MDASE patents. At the time, a spokesperson from MSD said the enzyme used in SC Keytruda® was “developed independently” from Halozyme and that MSD “strongly believe” that any Halozyme patents that attempt to cover the enzyme variant are invalid.
MSD has filed petitions for post-grant review with the US Patent Trial and Appeal Board challenging the validity of 14 of Halozyme’s US patents. The petitions were filed between November 2024 and June 2025 and all 14 have been instituted. The patents at issue are: US 11952600, US 12018298, US 12152262, US 12123035, US 12110520, US 12054758, US 12060590, US 12049652, US 12104185, US 12037618, US 12091692, US 12077791, US 12195773 and US 12264345.