IPR2015-00291 decided a petition filed by Daiichi Sankyo Co. Ltd. against USPN 8,168,181 owned by Alethia Biotherapeutics, Inc. The ‘181 patent issued from a continuation-in-part of the U.S. national phase of a PCT application and contains claims drawn to methods of impairing osteoclast differentiation, useful in treating various bone diseases. The Board denied the Patent Owner’s priority claim and found an attempt to antedate intervening art inadequate, leading to a holding that the ‘181 claims were unpatentable under 35 U.S.C. § 102(a). The decision illustrates the potential of intervening art not considered during prosecution and also illustrates the shifting legal view of the patentability of antibody-based technologies.

Bone metabolism involves a balance between new bone growth mediated by osteoblast cells and bone resorption or loss mediated by osteoclast cells. Too many osteoclast cells can lead to undesirable bone loss, as found in osteoporosis and other bones diseases. Reasoning that inhibition of a protein (Siglec-15) expressed in osteoclast cells might inhibit the development of osteoclasts and reduce the rate of bone destruction, the ‘181 inventors identified and characterized the Siglec-15 protein, including a determination of the sequence of the protein. A PCT application was filed that disclosed this information and described general techniques for generating and testing antibodies specifically binding and inhibiting Siglec-15. Subsequently, the CIP application maturing into the ‘181 patent was filed that added disclosure of the actual generation of specific anti-Siglec-15 antibodies. Intervening between the PCT filing date and the CIP filing date was a PCT publication of Hiruma that led to USPN 8,546,540.

In response to Petitioner’s assertion that Hiruma anticipated the claims of the ‘181 patent, the Patent Owner conceded that Hiruma, if properly available against the claims, did destroy their novelty. The Patent Owner argued that Hiruma was not available as prior art because, first, a priority claim established an effective filing date for the challenged claims that was earlier than publication of Hiruma and, second, that even if Hiruma were available against the claims, Patent Owner could antedate Hiruma.

Petitioner challenged entitlement to the priority date claimed in the ‘181 patent, asserting that the priority PCT application didn’t disclose the claimed invention in a manner that satisfied 35 U.S.C. § 112, first paragraph. Petitioner and Patent Owner argued the enablement issue, with Petitioner citing the Wands factors and arguing that undue experimentation would have been required to identify a specific anti-Siglec-15 antibody that exhibited the function of inhibiting Siglec-15’s effect on osteoclast differentiation and bone loss. The Board agreed that the priority PCT application provided no guidance or exemplification of functional anti-Siglec-15 antibodies.

Petitioner also argued lack of adequate written description to support the issued claims and Patent Owner relied on the “whole antigen characterization” theory of Noelle v. Lederman, asserting that Siglec-15, the antigen, was fully characterized in the priority PCT application and this should suffice to provide written description for a specific anti-Siglec-15 antibody having a known general antibody structure. The Board noted that the law had progressed through a series of court decisions beyond Noelle, particularly citing In re Alonso. The Board then distinguished Noelle by noting that the claim-recited antibodies had a functional requirement that distinguished them from the simple binding molecules at issue in Noelle. The Board concluded that the issued claims failed to satisfy the written description requirement. As a consequence, the priority claim fell and Hiruma became § 102(a) art against the ‘181 claims.

The Board then turned to Patent Owner’s second argument based on antedating the Hiruma reference. Both Petitioner and Patent Owner relied on witnesses to establish or deny prior conception and reasonable diligence by Patent Owner from a time prior to publication of Hiruma until constructive reduction to practice by filing the CIP application. The Board did not engage in a detailed assessment of asserted facts, reasoning instead that the Patent Owner relied on conception based on what was disclosed in the priority PCT application, which had already been determined to fall short of disclosing the invention in a manner that satisfied the enablement and written description requirements for patentability. As a result, Patent Owner could not have conceived of methods of impairing bone loss because the inventors could not have known that the methods as then understood would be useful for their intended purpose of treating bone loss disorders.

Based on its reasoning that the ‘181 claims were not entitled to the claimed priority date and were admittedly anticipated by Hiruma, which could not be antedated, the Board issued a final written decision that the ‘181 claims at issue were unpatentable.