On 5 March 2025, the Wall Street Journal (WSJ) reported that Halozyme Therapeutics has offered Merck (known as MSD outside the US and Canada) an opportunity to licence patents owned by Halozyme in relation to a specific enzyme, known as Mdase. Halozyme executives reportedly claimed during a recent investor conference that MSD’s subcutaneous (SC) version of Keytruda® (pembrolizumab) infringes those patents.
WSJ reports that a spokesperson from Merck/MSD said the enzyme used in SC Keytruda® was “developed independently” from Halozyme and that Merck/MSD “strongly believe” that any Halozyme patents that attempt to cover the enzyme variant are invalid.
The WSJ report follows petitions for post-grant review filed by Merck/MSD with the US Patent Trial and Appeal Board challenging the validity of seven of Halozyme’s US patents. The petitions, which are currently pending, were filed between November 2024 and February 2025 in relation to: US 11952600, US 12018298, US 12152262, US 12123035, US 12110520, US 12054758 and US 12060590.
In November 2024, MSD revealed positive topline results from its Phase 3 trial evaluating SC pembrolizumab (MK-3475A), together with Alteogen’s berahyaluronidase alfa, administered with chemotherapy. The SC pembrolizumab demonstrated noninferior pharmacokinetics compared to intravenous (IV) Keytruda® (pembrolizumab) in combination with chemotherapy, in adults with metastatic non-small cell lung cancer (NSCLC). At the JP Morgan Healthcare Conference in San Francisco on 14 January 2025, Merck/MSD announced an expected 2025 launch for SC Keytruda®.