Alteogen Prevails in U.S. PTAB Patent Defense as Halozyme's Invalidation Petition Is Denied

Halozyme's Invalidation Challenge Against ALT-B4 Manufacturing Technology Blocked at Initial Stage
MSD Secures First Win in Invalidation Petition... A New Phase in the Keytruda SC Patent Battle

The United States Patent Trial and Appeal Board (PTAB) has decided not to initiate a full review of the patent invalidation trial filed by Halozyme Therapeutics against Alteogen. This means that Halozyme's first direct challenge targeting Alteogen's patent was blocked at the review initiation stage. PTAB concluded that the prior art and invalidity arguments presented by Halozyme were insufficient to demonstrate a reasonable likelihood of invalidating Alteogen's patent.

Exterior view of Alteogen headquarters in Yuseong District, Daejeon. Alteogen

On May 15 (local time), PTAB issued a decision denying the institution of the invalidity proceedings requested by Halozyme. Under the U.S. system, a post-grant review can proceed to a full hearing only if the petitioner demonstrates a reasonable likelihood that at least one of the challenged claims is unpatentable. PTAB found that Halozyme did not meet even this threshold.

The patent in question is for a method of manufacturing PH20 hyaluronidase, which Alteogen registered in the United States in February. This patent covers the process of producing PH20 enzyme or its variants as recombinant proteins and is a core process technology for Alteogen's subcutaneous (SC) formulation conversion platform, ALT-B4. It is a separate patent from the substance patent that protects ALT-B4 itself. On December 10 of last year, Halozyme filed for an invalidation trial against this patent.

Halozyme argued that the temperature-shift cultivation method, the core of Alteogen's patent, was already known in the prior art and was therefore not novel. Their logic was that the process of first cultivating cells at 35-38°C and then lowering the temperature to 28-34°C to produce PH20 protein was derivable from previously published papers and patents.

Halozyme targeted all 15 claims listed in Alteogen's patent. However, PTAB determined that the combination of prior art references presented by Halozyme did not demonstrate a reasonable likelihood of invalidating any of these claims.

MSD Petition Also Invalidates Halozyme Patent ... PTAB Issues Consecutive Decisions

This latest decision is part of the ongoing patent dispute between Merck & Co. (MSD) and Halozyme over Keytruda SC. Alteogen's ALT-B4 platform has been applied to Keytruda SC, but Halozyme claims that this formulation infringes on its MDASE patent family. The MDASE patents relate to variants of hyaluronidase, a key enzyme used to convert intravenous (IV) drugs to subcutaneous injections.

MSD was the first to take action. Since November of last year, MSD has filed a total of 15 post-grant reviews (PGR) and 3 inter partes reviews (IPR) against Halozyme's MDASE patent family, launching a preemptive offensive. In response, Halozyme filed a main infringement lawsuit against MSD in the U.S. District Court for the District of New Jersey in April, alleging that Keytruda SC infringed on 15 of its MDASE patents.

Amidst these developments, on May 12, PTAB issued its first final written decision among the invalidation petitions filed by MSD, ruling one of Halozyme's patents invalid. The invalidated patent relates to a variant PH20 hyaluronidase protein, which is central to the MDASE patent family.

The basis for this invalidation was that Halozyme claimed excessively broad rights. Halozyme only provided experimental data for a single variant with one amino acid change in the PH20 enzyme but asserted rights over all variants with more than 95% similarity. PTAB determined that the claimed scope was much broader than what was actually supported by the proven technology.

According to Minyong Eom, a research fellow at Shinhan Investment Corp., the invalidated patent is the central issue among the 15 PGR and 3 IPR filings made by MSD. As the remaining patents are related to this invalidated patent, there is a high likelihood that the ongoing main infringement lawsuit will also be dismissed. The decisions on the other invalidation petitions are scheduled to be issued sequentially between June and November of this year.

The Next Turning Points: U.S. Infringement Lawsuit and European Dispute

Both of the recent PTAB decisions have been unfavorable to Halozyme. However, PTAB's refusal to initiate review does not constitute a final confirmation of the validity of Alteogen's patent. There remains a possibility that Halozyme will continue its challenge against Alteogen's patent through other avenues in the future.

The main infringement lawsuit is proceeding separately. Whether ALT-B4 actually infringed Halozyme's MDASE patents will be determined in the infringement case that Halozyme has filed against MSD in the U.S. District Court for the District of New Jersey. The dispute is also ongoing in Europe. In December of last year, the Munich Regional Court in Germany issued a preliminary injunction prohibiting the distribution and sale of Keytruda SC in Germany, based on Halozyme's European patent. MSD has filed invalidation lawsuits against the same Halozyme European patent in four countries: Germany, the United Kingdom, the Netherlands, and France.

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