On 19 September 2025, MSD announced that Keytruda Qlex™ (pembrolizumab and berahyaluronidase alfa-pmph; MK-3475A) has been approved by the FDA for subcutaneous use in adults across 38 indications, covering most solid tumour indications for Keytruda® (pembrolizumab). MSD is planning a late September 2025 US launch for Keytruda Qlex™.
According to Business Korea, if Keytruda Qlex™ successfully penetrates the market, Alteogen, the developer of hyaluronidase technology used with the subcutaneous formulation, is expected to generate annual royalty income exceeding 1 trillion won.
The FDA had accepted MSD’s BLA for SC pembrolizumab in March 2025, with a target action date of 23 September 2025.
The good news for MSD comes a day after the European Medicines Agency (EMA) Committee for Medicinal Products for Human Use (CHMP) recommended a change to the marketing authorisation for MSD’s Keytruda®, adopting a new pharmaceutical form, solution for injection, associated with two new strengths (790 mg and 305 mg), together with subcutaneous use as a new route of administration.
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 14 petitions for post-grant review with the US Patent Trial and Appeal Board challenging the validity of US patents owned by Halozyme, a number of which are asserted in the litigation. The petitions were filed between November 2024 and June 2025. Petitions in relation to 5 patents have been instituted (US 11952600 (2 June 2025), US 12018298 (11 June 2025), US 12152262 (16 June 2025), US 12123035 (11 July 2025), US 12110520 (8 September 2025)), while others are pending.