Curium US LLC filed a petition for inter partes review (IPR), listing only itself as the real party-in-interest (RPI). However, the patent owners argued that Curium US LLC’s parent companies, Curium US Holdings LLC and Curium Pharma, should have been disclosed as RPIs, as all entities share interests and direct involvement in the patented technology. The patent owners requested discretionary denial of the petition for failure to properly identify all RPIs under 35 U.S.C. § 312(a)(2).

In response, Curium US LLC maintained that they were the sole RPI but submitted an updated mandatory notice naming the parent companies as RPIs “to moot this issue,” not as an admission. Curium US LLC contended that its supplemental notice satisfies the legal requirement to disclose all RPIs before institution of the IPR, referencing the United States Patent and Trademark Office (USPTO) Director John A. Squires' guidance and the Corning Optical case (precedential, except § II.E.1).

The Patent Trial and Appeal Board (PTAB) agreed with Curium US LLC, and declined to exercise discretion to deny IPR. However, the PTAB noted that Curium US LLC's updated RPI disclosure required the petition to be assigned a new filing date corresponding to the date of the updated notice. In this case, that new filing date is Jan. 5, 2026, the date of the submitted revised mandatory notice. Unlike other cases, the re-determined filing date did not trigger a statutory time-bar, and the proceeding may continue according to the new schedule.

Consequently, the PTAB ordered that all previously filed briefs and related documents concerning discretionary denial and preliminary responses will be expunged. All future deadlines related to the IPR will be calculated from the new Jan. 5, 2026, filing date.

Takeaway
Ensure all real parties-in-interest (RPIs) are accurately and fully disclosed at the outset of any IPR petition. Even an allegation by the patent owner can lead to significant procedural consequence — such as a resetting of filing timelines — potentially disrupting strategy and case management or even discretionary denial. Early, comprehensive RPI disclosures minimize the risk of costly delays and procedural complications.

The Curium US LLC decision has been designated Informative.