Reconsideration leads to a reversal of course regarding a key claim limitation.
On October 26, 2017, in Hospira, Inc. v. Genentech, Inc., the Patent Trial and Appeal Board (PTAB) granted Hospira's request for rehearing and instituted inter partes review (IPR) of claims 1–14 of US Patent No. 7,846,441 (the '441 Patent). The PTAB rarely grants such requests—the grant rate has ranged from just 1.5% to 3.6% of requests over the last four years. On reconsideration, the PTAB revisited its interpretation of a key claim limitation, ultimately reversing course and siding with Hospira instead of Genentech.
The '441 Patent is directed to the treatment of disorders characterized by the overexpression of ErbB2 and covers Genentech's drug Herceptin® (trastuzumab). Hospira asserted that the patent was invalid as obvious in view of two prior art combinations. In its initial decision denying institution of the IPR, the PTAB found that Genentech successfully antedated one of the references during prosecution, knocking out one of Hospira's proposed combinations. The PTAB also addressed the limitation "in the absence of an anthracycline derivative," which is explicitly or through dependency recited in all of the challenged claims. Genentech argued that the record evidence was insufficient to suggest that a person of ordinary skill in the art would have avoided anthracyclines while pursuing the claimed therapy. The PTAB agreed and denied institution of Hospira's IPR.
In its request for rehearing, Hospira argued that the PTAB erroneously interpreted the phrase "in the absence of an anthracycline derivative" as requiring avoidance of an anthracycline derivative. Hospira argued that the limitation is negative and is satisfied by anti-ErbB2 antibody–paclitaxel combinations that do not include an anthracycline derivative. On reconsideration, the PTAB found this argument persuasive. In particular, the PTAB observed that the cited prior art suggested a therapeutic combination of an anti-ErbB2 antibody and paclitaxel, but did not suggest that doxorubicin, an anthracycline derivative, necessarily be included in the same treatment regimen. The PTAB was persuaded that this satisfied the "in the absence of an anthracycline derivative" limitation and found that Hospira established a reasonable likelihood of prevailing on its assertion that at least claim 1 was obvious in view of the prior art.
The PTAB seldom grants such requests for rehearing. In general, such requests are overwhelmingly denied (last year only 3.4% of all requests were granted in their entirety). Interestingly, approximately 65% of IPRs in which a request for rehearing was granted ultimately result in the invalidation of at least some of the claims at issue. This invalidation rate is far higher than those IPRs in which a request for rehearing was not filed, suggesting that patents are more likely to be invalidated where a request for rehearing was granted.
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