PTAB challenges

Proceedings overview

There is one AIA trial proceeding on file for US Patent 10991097, IPR2026-00185. This proceeding resulted in a discretionary denial of institution, meaning the PTAB chose not to initiate a full review of the patent's claims. For a defendant, this indicates that the patent has not been subjected to a full IPR trial, and its claims remain intact. An IPR-based defense on the specific grounds raised in this petition would be more challenging due to the discretionary denial precedent.

IPR2026-00185 — Guardant Health, Inc. v. Tempus AI Inc.

• Type: Inter Partes Review
• Filed: 2025-12-30
• Status: Discretionary Denial (The PTAB declined to institute the inter partes review, meaning the trial did not proceed to a merits determination)
• Judge panel: Not publicly available from the initial search, as the case was denied institution before a full panel would typically be assigned for a trial.
• Petition grounds: Details not publicly available from the initial search results, but a discretionary denial implies the grounds were evaluated for institution.
• Institution decision: Denied on 2026-04-28. The denial was discretionary. This often occurs when the PTAB applies its precedential guidance, such as the Fintiv factors, to decline institution even if the merits threshold (reasonable likelihood of unpatentability) might be met. The reasoning for a discretionary denial typically involves factors like parallel district court litigation, trial schedule, or stage of the litigation.
• Final Written Decision (if issued): Not issued, as institution was denied.
• Settlement / termination: The proceeding was terminated via discretionary denial of institution. There was no settlement recorded in the provided information.
• Appeal: No appeal to the Federal Circuit, as there was no Final Written Decision on the merits.
• Defensive value: The discretionary denial of institution in IPR2026-00185 means that none of the claims of US10991097 were challenged on the merits and found unpatentable by the PTAB. For a defendant, this implies that the specific prior art and arguments raised by Guardant Health, Inc. in this petition were not deemed sufficient by the PTAB to proceed to trial, likely due to procedural or efficiency considerations rather than a full review of patentability. Future IPRs against this patent would need to present stronger or different arguments, or address the factors that led to the discretionary denial.

Strategic summary

Currently, all claims of US10991097 remain SUSTAINED as no AIA trial has proceeded to a Final Written Decision invalidating any claims. IPR2026-00185 was denied institution on discretionary grounds, meaning the PTAB did not assess the patentability of the claims on their merits. Consequently, the patent has not been narrowed through IPR proceedings.

Regarding the estoppel landscape, since IPR2026-00185 was denied institution, § 315(e)(2) estoppel, which bars petitioners (and their privies) from raising any ground they raised or reasonably could have raised in a final written decision, would not apply here. This is because there was no Final Written Decision. Therefore, the prior-art grounds presented in that petition could theoretically still be raised by Guardant Health or its privies in district court or other proceedings, though the PTAB's discretionary denial might suggest weaknesses in the petition's overall strategy or timing in relation to parallel litigation. For a defendant currently being asserted against, all prior-art grounds remain available, as no claims have been formally tested and affirmed as patentable in a full IPR trial.

The pattern signals indicate that Guardant Health, Inc. has initiated an IPR against this patent. The discretionary denial suggests that the PTAB is actively applying its discretion, potentially to manage parallel litigation or for other policy reasons. This signals that subsequent IPRs might face similar discretionary hurdles if not carefully strategized to differentiate from the circumstances of IPR2026-00185.

Recommended next steps

• Review the institution denial decision for IPR2026-00185 (Unified Patents has a link on their portal) to understand the specific reasons for the discretionary denial. This will be crucial for any future IPR strategy.
• Given that all claims are currently sustained, any defendant facing assertion should conduct a thorough prior art search to develop robust invalidity contentions, as the patent has not been "hardened" by surviving a full IPR trial on the merits.
• Monitor the district court litigation cases (3:25-cv-06622 and 5:25-cv-06622 in California Northern District Court, and 3:25-cv-00621 in California Southern District Court) for any developments that might shed light on the claims or potential settlement strategies.
• If considering filing a new IPR, carefully assess the PTAB's discretionary denial factors (e.g., Fintiv factors) and tailor the petition to minimize the risk of a similar denial.