PTAB challenges

Proceedings overview

Two AIA trial proceedings have been filed against US patent 11058757: IPR2026-00221, which received a discretionary denial, and IPR2026-00189, which has been instituted to trial. This gives a defendant a mixed defensive posture, as one challenge was denied, but another has advanced to trial, meaning certain claims are still under scrutiny.

IPR2026-00189 — Pfizer Inc. v. Pogona LLC

• Type: Inter Partes Review
• Filed: 2025-12-23
• Status: Trial Instituted
• Judge panel: Not publicly available yet.
• Petition grounds: Not publicly available yet.
• Institution decision: Instituted. Date and reasoning are not publicly available yet, but the status indicates trial has been instituted.
• Final Written Decision (if issued): Not yet issued.
• Settlement / termination: No information on settlement or termination.
• Appeal: Not applicable as a Final Written Decision has not been issued.
• Defensive value: This proceeding is ongoing, indicating that at least some claims of the patent are facing a validity challenge. If the claims are ultimately invalidated, it would significantly weaken the patent owner's assertion position. If the claims are upheld, it would strengthen the patent against future challenges on the same grounds.

IPR2026-00221 — Merck Sharp & Dohme LLC v. Pogona LLC

• Type: Inter Partes Review
• Filed: 2026-01-26
• Status: Discretionary Denial
• Judge panel: Not publicly available yet.
• Petition grounds: Not publicly available yet.
• Institution decision: Denied. The petition was denied discretionarily on 2026-05-19. The specific reasoning for the discretionary denial is not yet publicly available in the provided snippets.
• Final Written Decision (if issued): Not applicable as institution was denied.
• Settlement / termination: No information on settlement or termination.
• Appeal: No information on appeal to the Federal Circuit.
• Defensive value: The discretionary denial of this IPR means that the patent claims challenged by Merck Sharp & Dohme LLC in this specific proceeding have survived this particular challenge. This makes an IPR-based defense using the same or similar art somewhat harder for future challengers, particularly if the discretionary denial was based on factors beyond the merits of the art (e.g., related litigation).

Strategic summary

As of 2026-05-28, US patent 11058757 has faced two IPR challenges. IPR2026-00221, filed by Merck Sharp & Dohme LLC, resulted in a discretionary denial of institution on 2026-05-19. This means the claims challenged in that petition remain untested by the PTAB. Conversely, IPR2026-00189, filed by Pfizer Inc., has been instituted to trial. The specific claims challenged in this instituted IPR are not yet publicly known, nor are the prior art grounds. Therefore, at this stage, it cannot be definitively stated which claims of US11058757 are canceled, sustained, or remain entirely untested by the PTAB.

Regarding the estoppel landscape, for IPR2026-00221, because institution was denied, statutory estoppel under 35 U.S.C. § 315(e)(1) for instituted grounds does not apply. However, common law estoppel principles might still be argued in certain contexts. For IPR2026-00189, once a Final Written Decision is issued, Pfizer Inc. (and its privies) will be estopped from asserting in future district court or ITC actions any invalidity ground that was raised or reasonably could have been raised during the IPR. The current petitions were filed by major pharmaceutical companies (Merck Sharp & Dohme LLC and Pfizer Inc.), indicating significant interest in challenging the patent. The involvement of Unified Patents as a petitioner in IPR2026-00189 (as indicated in the previous litigation summary, although the PTAB proceedings on file list Pfizer Inc.) suggests a potential strategy of using a defensive aggregator to challenge the patent's validity.

Recommended next steps

For IPR2026-00189, which is currently in trial, monitoring upcoming trial-stage milestones, such as the oral hearing (if scheduled) and the Final Written Decision due date (which will be approximately one year from the institution date), is critical. The institution decision itself, when publicly available, should be reviewed to understand the specific claims and grounds that were advanced to trial. The USPTO PTAB E2E system should be consulted for official documents and dates related to IPR2026-00189: https://e2e.uspto.gov/ptab/.
For IPR2026-00221, the decision for discretionary denial on 2026-05-19 should be analyzed to understand the Board's reasoning, as this can inform future defensive strategies. The document can be found through the USPTO PTAB E2E system: https://e2e.uspto.gov/ptab/.