In a rare move, the Patent Trial and Appeal Board (“the Board”) granted the institution of an inter partes review (“IPR”) upon a request for rehearing after initially denying its institution. IPR2017-00731 Paper No. 29. However, don’t expect such reversals to become commonplace. This case involved a panel of administrative patent judges who were not sufficiently familiar with negative limitations in a patent claim. Consequently, upon being denied institution, the petitioner needed a rehearing to educate the judges on how to correctly interpret such limitations.

Hospira, Inc. (“Petitioner”) filed a petition requesting that claims 1-14 of U.S. Patent No. 7,846,441 (“‘441 patent”), owned by Genentech, Inc. (“Patent Owner”), be reviewed as being obvious over the prior art. The ‘441 patent relates to the treatment of disorders, such as breast cancer, characterized by the overexpression of ErbB2, a transmembrane protein related to the epidermal growth factor receptor. Claim 1 recites a method of treating a cancer patient with an anti-ErbB2 antibody and a taxoid, “in the absence of an anthracycline derivative.”

Petitioner argued that claims 1-14 of the ‘441 patent were unpatentable as being obvious over Baselga 1996 and Baselga 1994. Baselga 1994 teaches that ErbB2-overexpressing tumors grown in mice resulted in 35% growth inhibition following a treatment with either the 4D5 anti-ErbB2 antibody or paclitaxel (a taxoid) alone, and a 93% growth inhibition following treatment with a combination therapy of the antibody and paclitaxel. A combination treatment of the antibody and doxorubicin (an anthracycline derivative) resulted in 70% growth inhibition.

The Board initially declined to institute an IPR. Although it acknowledged that Baselga 1994 teaches the combined treatment of an anti-ErbB2 antibody with either a taxoid or with an anthracycline, but not with both, the Board nonetheless reasoned that nothing in Baselga 1994 or Baselga 1996 suggests that a person of ordinary skill in the art would have avoided anthracyclines in pursuing a combination therapy with an anti-ErbB2 antibody and a taxoid. Without additional evidence or argument that a skilled artisan would have avoided anthracyclines, the Board concluded that Petitioner had not established a reasonable likelihood it would prevail in showing that the challenged claims would have been obvious over Baselga 1994 and Baselga 1996.

Petitioner successfully argued in its request for rehearing that the Board was erroneously led by Patent Owner to conclude that the asserted prior art was insufficient to suggest that one of ordinary skill in the art would have avoided anthracyclines. Negative limitations require the absence of something, but do not require its avoidance. A prior art reference that teaches all of the limitations of a claim, including examples having both the presence and absence of the claim’s negative limitation, is still anticipatory, despite not expressly teaching the avoidance of the negative limitation. In requiring that the prior art teach or suggest the avoidance of anthracycline derivatives, Petitioner argued that the Board had erroneously transformed the claims’ negative limitation-requiring absence-into a positive limitation requiring avoidance.

In its reversal, the Board conceded that it had erred in interpreting the limitation “in the absence of an anthracycline derivative” as requiring avoidance of anthracycline and that the Baselga 1994 reference satisfied this limitation in teaching the use of an anti-ErbB2 antibody along with the taxoid paclitaxel, while not suggesting that the anthracycline derivative doxorubicin must necessarily be included as part of a treatment regimen.

Institution decisions are not appealable. Therefore, a rehearing by the same panel of administrative patent judges is the only recourse to attack a decision to institute or not to institute. Rehearing requests rarely alter the result. As seen in this decision for Hospira, however, if it can be established that the judges failed to follow an unfamiliar applicable legal doctrine, there is an outside chance that the judges will reverse their initial decision.