PTAB challenges

Proceedings overview

One AIA trial proceeding has been filed against US Patent 12371685. This proceeding, a Post-Grant Review (PGR), resulted in a discretionary denial of institution, meaning no claims were challenged on the merits and the patent claims remain untested by PTAB trial. This outcome provides strong defensive posture for the patent owner, as the patent has successfully resisted a PTAB challenge, making an IPR or PGR-based defense harder for potential infringers.

PGR2025-00087 — Merck Sharp & Dohme LLC v. Halozyme Inc

• Type: Post-Grant Review
• Filed: 2025-11-10
• Status: Discretionary Denial. This indicates that the PTAB declined to institute the PGR, meaning the trial on the merits of the patentability of the claims did not proceed.
• Judge panel: The panel that issued the Decision on Institution consisted of Administrative Patent Judges Deborah E. Taylor, Stacey G. White, and Kalpesh J. Brahmbhatt.
• Petition grounds: The petition challenged all claims of US 12,371,685 (claims 1-20) under 35 U.S.C. §§ 101, 102, 103, and 112. The grounds included lack of written description, obviousness, and anticipation based on various prior art references such as U.S. Patent No. 9,447,401 (Connor), U.S. Patent Application Publication No. 2018/0118830 (Wei), and a publication by Arming et al.
• Institution decision: Denied on 2026-05-10. The PTAB exercised its discretion under 35 U.S.C. § 314(a) and denied institution based on various factors, including the stage of related parallel district court litigation, the advanced stage of the district court proceedings, and the patent owner's representation that a trial was scheduled for October 2026. The panel found that judicial economy weighed against institution.
• Final Written Decision: Not applicable, as institution was denied.
• Settlement / termination: Not applicable, as the proceeding terminated at the institution decision stage.
• Appeal: Not applicable, as there was no Final Written Decision on the merits to appeal.
• Defensive value: The discretionary denial of institution means that all claims (1-20) of US12371685 remain unadjudicated at the PTAB. The denial was based on factors related to parallel litigation rather than the merits of the patentability challenges. This outcome suggests that a new PTAB challenge by the same petitioner (or its privies) on the same grounds would likely be estopped under 35 U.S.C. § 325(e)(1) because a final written decision was not reached. However, another petitioner might attempt a new PTAB challenge, although the discretionary factors considered in this denial would still be relevant.

Strategic summary

All twenty claims (claims 1-20) of US12371685 remain UNTESTED at the PTAB, as the sole PGR proceeding, PGR2025-00087, was denied institution on discretionary grounds. No claims have been canceled or sustained on the merits by the PTAB. This means the patent has not been narrowed through PTAB review.

The estoppel landscape is important here. While the petition from Merck Sharp & Dohme LLC was denied, 35 U.S.C. § 325(e)(1) states that "The petitioner in a post-grant review of a claim in a patent, or a real party in interest or privy of the petitioner, may not assert, in any other proceeding before the Office or in any civil action, or an action before the International Trade Commission, that the claim is invalid on any ground that the petitioner raised during the post-grant review." Although the petition was denied and no final written decision on the merits was issued, the grounds were raised in the petition. Thus, Merck Sharp & Dohme LLC (and its privies) are likely estopped from raising the same or reasonably could have raised grounds in future proceedings. For a different defendant currently being asserted against, the prior-art grounds raised by Merck Sharp & Dohme LLC in PGR2025-00087 are still theoretically available, unless that defendant is in privity with Merck Sharp & Dohme LLC.

The discretionary denial highlights the PTAB's increasing tendency to consider parallel district court litigation in institution decisions, particularly under Fintiv factors. The patent owner, Halozyme Inc, successfully argued against institution based on the advanced stage of district court proceedings, signaling an aggressive strategy to prosecute infringement claims in court.

Recommended next steps

For a defendant facing assertion of US12371685, the fact that PGR2025-00087 was denied institution on discretionary grounds is a critical piece of information. The patent claims remain untested by PTAB trial.

1. Review Institution Decision: Thoroughly review the PTAB's Decision Denying Institution for PGR2025-00087 to understand the specific "Fintiv" factors and reasoning applied by the panel. This decision is publicly available here and directly from the USPTO PTAB Decisions portal (search for PGR2025-00087). Understanding the PTAB's rationale will be crucial for evaluating the viability of any new PTAB challenges.
2. Evaluate Estoppel: Determine if the defendant has any privity with Merck Sharp & Dohme LLC. If not, the grounds raised in PGR2025-00087 could potentially be re-asserted in a new PTAB petition, though the Fintiv considerations would still apply.
3. District Court Status: Given the PTAB's reliance on the parallel district court litigation schedule, it is imperative to ascertain the current status of any related district court cases involving US12371685, especially the one cited as having a trial scheduled for October 2026. The outcome of such litigation could significantly impact the value and assertability of the patent.
4. Consider New PTAB Petition: While one PGR was denied institution, a defendant could explore filing their own IPR or PGR, potentially presenting different prior art or statutory challenges, or demonstrating that Fintiv factors would not weigh against institution in their specific case. However, the precedent set by PGR2025-00087 on discretionary denial must be carefully addressed in any new petition.