Addressing the issue of whether to grant a second inter partes review (IPR) after all of the claims had previously been adjudicated, the Patent Trial and Appeal Board (PTAB) determined that the petitioner and its foreign subsidiary were estopped from requesting or maintaining the later-filed IPR. Praxair Distribution, Inc. v. INO Therapeutics LLC, Case No. 2016-00781 (PTAB, Aug. 25, 2016) (Pollock, APJ).

INO Therapeutics is the owner of a patent that describes methods of distributing a pharmaceutical product aimed at reducing the risk or preventing the occurrence in a human patient of an adverse event associated with a medical treatment comprising inhalation of nitric oxide.

Praxair previously requested IPR of claims 1–19 of the patent, asserting that one of ordinary skill in the art would have been referred to the US Food and Drug Administration approved INOMAX® label for new warnings and precautions related to patients with left ventricular dysfunction. The PTAB agreed and determined that all claims but claim 9 were unpatentable. Applying US Court of Appeals for the Federal Circuit precedent, the PTAB determined that “providing information” to medical practitioners lacks a functional relationship to the claim elements where the methods of administering the drug can be performed irrespective of whether that knowledge is conveyed.

Praxair filed a second request for IPR because of its concern that the Federal Circuit might reverse the PTAB’s prior determination that the step of “providing . . . information” should not be given patentable weight. To bolster its argument, Praxair offered the PTAB two “recently discovered” prior art references that, according to Praxair, disclosed the provided “information.”

Under 35 USC § 315(e)(1), a petitioner may not request or maintain subsequent proceedings on a ground that it raised or reasonably could have raised during the prior proceeding. The PTAB turned to the legislative history and concluded that the phrase “reasonably could have raised” broadly encompasses “prior art which a skilled searcher conducting a diligent search reasonably could have been expected to discover.”

INO Therapeutics argued that the two articles produced by the petitioner were catalogued and accessible at dozens of libraries in the United States, including the Library of Congress and the National Library of Medicine, and that both articles are readily identified by searching Google Books using keywords from the patent specification. 

The PTAB found that the newly asserted references were not obscure texts unlikely to be discovered upon a reasonably diligent search of the relevant prior art by a skilled researcher. The PTAB did, however, note that the petitioner failed to identify the actual searcher, his or her skill level, experience in the field and searching methodology, so it had little evidence to find that Praxair conducted a diligent search.

Ultimately, the PTAB determined that because Praxair had previously challenged claims 1–19 of the patent, which resulted in a final decision, it was now estopped under § 315(e)(1) from requesting or maintaining the current proceeding with respect to any of those claims.

Practice Note: Petitioners seeking a second IPR should put forth evidence of prior art that a skilled searcher conducting a diligent search reasonably could not have been expected to discover. A mere reference to relevant subject matter, without showing that the newly asserted reference is obscure, uncatalogued and generally inaccessible, may not be sufficient to justify a second review.