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 proceed to a full trial regarding the patent invalidation petition that Halozyme Therapeutics filed against Alteogen. This means Halozyme’s first direct challenge targeting Alteogen’s patent was blocked at the initial review stage. The PTAB determined that the prior art and invalidation logic submitted by Halozyme did not sufficiently demonstrate a likelihood of invalidating Alteogen’s patent.

Taeyeon Jeon, CEO of Alteogen, is being interviewed at the Alteogen headquarters in Yuseong-gu, Daejeon, on the 23rd of last month. Photo by Donghoon Jung

On the 15th (local time), the PTAB issued a decision rejecting Halozyme’s request to institute a trial for invalidation. Under the U.S. system, a patent trial only proceeds if the petitioner can show a reasonable likelihood that at least one of the disputed claims will be found invalid. The PTAB concluded that Halozyme did not meet even this threshold.

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

Halozyme argued that the core of Alteogen’s patent—the temperature shift culture method—was already known in prior technology and therefore not novel. Their logic was that the process of culturing cells first at 35-38°C and then lowering the temperature to 28-34°C to produce PH20 protein could be derived from already published prior papers and patents.

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

MSD’s Petition Results in Halozyme Patent Invalidation … Consecutive PTAB Decisions

This decision is part of the ongoing patent dispute between Merck (MSD) and Halozyme in the United States over Keytruda SC. Alteogen’s ALT-B4 platform is used in Keytruda SC, but Halozyme claims that this formulation infringes on its MDASE patent family. The MDASE patents relate to variants of hyaluronidase, the key enzyme used to convert intravenous (IV) drugs to subcutaneous (SC) formulations.

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 the Halozyme MDASE patent family, launching a preemptive offensive. In response, Halozyme filed a substantive infringement lawsuit against MSD in the U.S. District Court for the District of New Jersey in April, claiming that Keytruda SC infringes on 15 of its MDASE patents.

Amidst this, on May 12, the PTAB issued its first final written decision among the invalidation petitions filed by MSD, ruling one Halozyme patent invalid. The invalidated patent concerned a right to a modified PH20 hyaluronidase protein, which is central to the MDASE patent family.

The basis for invalidation was that Halozyme claimed an excessively broad scope of rights. While Halozyme only provided experimental data for a single variant with one substitution in the PH20 enzyme, it claimed rights over all variants with more than 95% similarity. The PTAB viewed this as a claim to a much broader scope than what was actually demonstrated by the technology.

Minyong Eom, a research analyst at Shinhan Investment Corp., analyzed in a report on the 14th that the invalidated patent was the core issue among the 15 PGRs and 3 IPRs filed by MSD. Since the other patents are related to the one just invalidated, there is a high likelihood that the ongoing substantive infringement lawsuit will also be dismissed. Decisions on the remaining invalidation petitions are expected to be issued sequentially between June and November this year.

Next Critical Junction: U.S. Infringement Lawsuit and European Disputes

Both recent PTAB decisions have gone against Halozyme. However, the PTAB’s denial to institute trial does not constitute a final confirmation of the validity of Alteogen’s patent. There remains the possibility that Halozyme may continue its challenge against Alteogen’s patent through other avenues in the future.

The substantive infringement lawsuits proceed separately. Whether ALT-B4 actually infringed upon Halozyme’s MDASE patents will be determined in the lawsuit Halozyme filed against MSD in the U.S. District Court for the District of New Jersey. Meanwhile, disputes continue in Europe. In December of last year, the Munich District Court in Germany issued a preliminary injunction to prohibit 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.