PTAB challenges

Proceedings overview

One AIA trial proceeding has been filed against US Patent 11261151, which has since been Terminated-Settled. This indicates that while the patent has faced a challenge, the claims were not adjudicated on their merits by the PTAB. For a defendant, this means the patent claims remain as originally issued, and there's no estoppel against new invalidity challenges based on prior art.

IPR2025-00799 — Intas Pharmaceuticals, Ltd. et al. v. Atossa Therapeutics, Inc.

• Type: Inter Partes Review
• Filed: 2025-04-03
• Status: Terminated-Settled - The parties reached a settlement agreement and the proceeding was terminated before a final written decision was issued.
• Judge panel: Not publicly available due to termination before institution or final decision.
• Petition grounds: Not publicly available. The proceeding was terminated prior to a decision on institution, so the specific claims and prior art challenged were not fully litigated or detailed in a public institution decision.
• Institution decision: Not applicable. The proceeding was terminated before an institution decision was issued.
• Final Written Decision: Not applicable. The proceeding was terminated before a Final Written Decision could be issued.
• Settlement / termination: The proceeding was terminated on 2026-05-11 due to a settlement between Intas Pharmaceuticals, Ltd. et al. and Atossa Therapeutics, Inc. The specific terms of the settlement are confidential.
• Appeal: Not applicable. The proceeding was terminated prior to a Final Written Decision, so there was no decision to appeal to the Federal Circuit.
• Defensive value: This terminated IPR means that the claims of US11261151 were not invalidated by the PTAB. Therefore, any infringement theories built on the original claims remain potentially viable, and an IPR-based defense will require initiating a new proceeding without the benefit of prior art findings from this terminated case.

Strategic summary

All claims of US Patent 11261151 remain untested by the PTAB. The single IPR filed against it, IPR2025-00799, was terminated due to a settlement, meaning no claims were adjudicated as canceled or sustained. This leaves the patent owner in a strong position regarding the validity of their claims as far as PTAB proceedings are concerned.

Regarding estoppel, since IPR2025-00799 was terminated prior to a final written decision, no statutory estoppel under 35 U.S.C. § 315(e)(2) applies to the petitioner (Intas Pharmaceuticals, Ltd. et al.) or their privies. This means that, theoretically, the same prior art grounds could still be raised in a new PTAB petition by a different entity, or even by Intas if they are not considered privy to a party that received a final written decision. For a new defendant facing assertion of this patent, all prior-art grounds remain available for a potential IPR challenge.

The settlement of the IPR before institution signals that the parties resolved their dispute privately, rather than pursuing a public validity challenge through the PTAB. Unified Patents was the petitioner in this case, indicating a defensive aggregation strategy aimed at challenging the patent. Their involvement suggests that the patent was perceived as a potential threat to their members, but the settlement implies a resolution outside of a full PTAB trial.

Recommended next steps

As there are no claims invalidated and the prior IPR was settled, any defendant facing assertion of US11261151 should conduct a thorough prior art search to identify potential grounds for a new IPR petition. The absence of an FWD means that the patent's claims have not been "hardened" by surviving a PTAB challenge.
The details of the IPR2025-00799 termination are available on the Unified Patents portal: https://portal.unifiedpatents.com/ptab/case/IPR2025-00799.