MSD Achieves First Invalidation of Halozyme Patent... Positive Signal for Alteogen and Keytruda SC Dispute

First Decision by US Patent Board Among 13 Cases
Momentum Weakens for Halozyme's Infringement Lawsuit Against Alteogen's ALT-B4

The United States Patent Trial and Appeal Board (PTAB) has issued its first invalidation ruling on the core 'MDASE' patent family held by Halozyme Therapeutics in its patent dispute with Merck (MSD) in the United States. As a result, Halozyme's grounds for its infringement lawsuit against Merck's "Keytruda SC"—which utilizes Alteogen's subcutaneous (SC) formulation conversion technology "ALT-B4"—have been weakened.

Product image of Keytruda SC formulation 'Keytruda Qurex' sold in the United States. Photo by Merck US

On May 12 (local time), the PTAB finalized a decision invalidating one out of the 13 Halozyme patents challenged by Merck through a post-grant review (PGR).

The MDASE patents concern variants of hyaluronidase, a key enzyme for converting intravenous (IV) drugs to subcutaneous (SC) administration. Halozyme claimed rights not only to variants with a single specific site modification in this enzyme, but also to "all proteins more than 95% similar to this variant," thus broadly extending its claimed scope of protection. In theory, this would cover up to 10 to the power of 63 possible variants.

The PTAB took issue with this aspect. The only data Halozyme provided to prove efficacy through actual experiments was for the single-site variant, and the patent specification did not sufficiently explain how variants with multiple simultaneous modifications would work. The PTAB concluded that this amounted to claiming rights beyond "the scope of technology actually possessed by the inventor," as defined by patent law.

With this decision, Alteogen and Merck have removed one of the biggest legal risks facing the Keytruda SC business. Last April, Halozyme filed a lawsuit in the U.S. District Court for the District of New Jersey, alleging that Keytruda SC infringes on 15 of its MDASE patents. Alteogen's SC formulation conversion technology, ALT-B4, is used in Keytruda SC. Since the invalidated patent was one of the 15 patents cited as grounds for infringement, Halozyme now has fewer arguments to use in the main litigation.

However, this decision does not automatically mean that ALT-B4 is considered non-infringing. The current PGR only addresses the validity of Halozyme's patents themselves, and whether ALT-B4 infringes those patents will be determined separately in the main trial at the U.S. District Court for the District of New Jersey. In addition, an inter partes review (IPR) that Halozyme filed to invalidate Alteogen's ALT-B4 manufacturing process patent is still ongoing.

Beyond the patent invalidated in this ruling, Merck has also filed additional PGRs against 12 other Halozyme patents in the same patent family. Since all of these patents stem from the same original application, the same grounds for invalidation could be applied to the remaining patents as well. Decisions on the other 12 patents are expected to be announced sequentially by early June this year.

This content was produced with the assistance of AI translation services.