PTAB challenges

Proceedings overview

One AIA trial proceeding has been filed against US Patent 11703443. This proceeding, IPR2025-01319, was discretionarily denied institution by the PTAB. As a result, no claims were invalidated or sustained by the PTAB in this proceeding, leaving the patent's claims entirely untested by the PTAB. This outcome generally strengthens the patent owner's defensive posture, as the patent has faced a challenge and survived institution, indicating a potential difficulty for future petitioners to overcome the threshold for review.

IPR2025-01319 — Cytek Biosciences, Inc. v. Iris International Inc. (Current Assignee: Beckman Coulter Inc)

• Type: Inter Partes Review
• Filed: 2025-07-17
• Status: Discretionary Denial — The PTAB declined to institute the review, meaning the merits of the petition's challenges were not fully considered.
• Judge panel: Information not publicly available through direct search results for discretionary denials at this stage without accessing the full PTAB-E2E system, which is beyond this tool's capabilities.
• Petition grounds: Information regarding specific claims, prior art, and statutory bases (§ 102 / § 103 / § 112) is not publicly detailed for a discretionary denial without direct access to the petition documents or the institution decision document itself. However, PTAB records indicate the proceeding was filed, implying grounds were raised.
• Institution decision: Denied — 2026-03-27. The PTAB issued a decision of discretionary denial. This means the Board chose not to institute the inter partes review, likely based on factors such as prior art overlap with other proceedings, stage of parallel litigation, or efficient administration of justice, rather than a full merits analysis of the patentability challenges. The specific reasoning for discretionary denial is contained within the decision document.
• Final Written Decision (if issued): Not applicable. The proceeding was terminated at the institution phase by discretionary denial, so no Final Written Decision on the merits of the claims was issued.
• Settlement / termination: Terminated via discretionary denial. No settlement was reported.
• Appeal: Not applicable. As there was no Final Written Decision on the merits, there was no decision to appeal to the Federal Circuit concerning claim patentability.
• Defensive value: The discretionary denial means the challenged claims of US11703443B2 remain intact as far as this specific PTAB proceeding is concerned. This signals to potential defendants that simply filing an IPR may not be straightforward, and the PTAB may exercise its discretion to deny institution even if a petitioner meets the threshold for reasonable likelihood of unpatentability.

Strategic summary

Only one AIA trial proceeding, IPR2025-01319, has been filed against US Patent 11703443. This IPR was initiated by Cytek Biosciences, Inc. and resulted in a discretionary denial of institution by the PTAB on March 27, 2026. Consequently, no claims of US11703443 have been canceled, sustained, or otherwise adjudicated on their merits by the PTAB. All claims of US11703443 remain untested by the PTAB. The current assignee of the patent is Beckman Coulter Inc..

The estoppel landscape resulting from this discretionary denial is limited. Under 35 U.S.C. § 315(e)(1), if a final written decision issues, the petitioner or its privies are estopped from asserting in a civil action or another USPTO proceeding that a claim is invalid on any ground that the petitioner raised or reasonably could have raised during the IPR. Since IPR2025-01319 did not proceed to a Final Written Decision, the estoppel provisions of § 315(e)(1) generally do not apply to the petitioner (Cytek Biosciences, Inc.) for the specific grounds that would have been litigated had the IPR been instituted and gone to a final decision. However, the discretionary denial itself could influence future PTAB filings by Cytek Biosciences or its privies concerning this patent. For other potential defendants, all prior-art grounds remain available for challenging the patent in new IPR petitions or district court litigation, subject to the Board's discretion and the statutory requirements for institution.

The single IPR filing and its discretionary denial do not establish a clear pattern of aggressive PTAB appeals by the patent owner, nor does it indicate a concerted effort by defensive aggregators. The fact that the proceeding was denied institution suggests that the patent owner successfully argued against the merits of the petition or convinced the Board to exercise its discretion in their favor, which could be a signal of the patent's resilience against such challenges.

Recommended next steps

For a defendant facing assertion of US Patent 11703443, the discretionary denial of IPR2025-01319 means that the patent's claims have not been weakened or canceled by the PTAB. The full text of the institution decision for IPR2025-01319 would be critical to understand the specific reasons for the discretionary denial, as this could inform strategy for any future PTAB challenges. This decision can be accessed via the USPTO PTAB E2E system.

Given that there are no active PTAB proceedings and no claims have been invalidated, any infringement theory built on claims of US11703443 remains robust from a PTAB perspective. A defendant would need to consider a fresh challenge at the PTAB, potentially with different prior art or arguments, or pursue invalidity arguments in district court. The absence of successful PTAB activity suggests a high bar for such challenges, but it does not preclude them.

The patent owner, Beckman Coulter Inc., has seen this patent survive its initial PTAB challenge, which may lead to increased confidence in asserting the patent.