By George Basharis, J.D.
District court’s narrow claim construction contradicted the plain language of dependent claims and disregarded plain meaning of a key term.
A federal district court’s constructions of the key terms "antibody" and "antibody fragments" were erroneous, the U.S. Court of Appeals for the Federal Circuit has determined, vacating a judgment of noninfringement entered in a lawsuit alleging that Genentech’s hemophilia drug Hemlibra infringed a patent for a blood clotting composition. The court’s construction was inconsistent with the plain language of dependent claims and ignored the plain meaning of the word "fragment." The district court’s construction also relied too heavily on a single written description in the patent and prosecution history (Baxalta Inc. v. Genentech, Inc., August 27, 2020, Moore, K.).
Baxalta Inc. sued Genentech, Inc. alleging that Genetech’s drug Hemlibra, which is used to treat hemophilia A patients, infringes Baxalta’s U.S. Patent No. 7,033,590 (the ’590 Patent). Hemophilia A patients have inhibitors that prevent traditional clotting factor VIII therapy. Genentech’s Hemlibra uses antibodies or antibody fragments that bind to factor IX or factor IXa to increase procoagulant activity of factor IXa to compensate for the decreased factor VIII activity in hemophilia A patients.
Antibodies are Y-shaped structures made up of two heavy chains (H chains) and two light chains (L chains). Genentech’s Hemlibra uses bispecific antibodies that have different H chains and/or different L chains. As used in the ’590 Patent, the term "antibody" could mean bispecific antibodies or structures with two identical H chains and two identical L chains. Ignoring references to bispecific antibodies in the ’590 Patent, the district court found that the term was defined by a single reference in the patent as an immunological molecule having a specific amino acid sequence comprising two identical pairs of heavy and light chains. The court found support for its construction in the prosecution history. The district court further specified that the term "antibody fragment" excluded bispecific antibodies. Based on the court’s construction, the parties stipulated to non-infringement, and Baxalta appealed.
The Federal Circuit noted that the plain language of the ’590 Patent did not limit the term "antibody" to a specific antibody consisting of two identical heavy chains and two identical light chains, as the district court had found. In fact, the court of appeals said that the patent’s dependent claims specifically mentioned bispecific antibodies, which do not consist of two identical H chains and two identical L chains. The district court focused on a contrary description that it found to define the term "antibody." However, that description was not a definition but rather a generalized introduction to antibodies. Beyond the description, the patent contained specific disclosures regarding a number of antibodies that did not comport to the district court’s narrow construction. Moreover, the prosecution history did not support the lower court’s construction because it lacked any clear statement that by substituting the phrase "antibody fragment" for "antibody derivative" at the examiner’s suggestion, as Baxalta had done to overcome an enablement rejection by the examiner, Baxalta had disclaimed antibody derivatives such as bispecific antibodies.
The district court’s construction of "antibody fragment" as a fragment of an antibody without a constant region that did not include bispecific antibodies also was rejected. Using the plain and ordinary meaning of "fragment" in light of the patent as a whole, the Federal Circuit found "antibody fragment" to include a specific amino acid sequence comprising two heavy chains and two light chains. This would include fragments of bispecific antibodies. Consequently, the Federal Circuit vacated the district court’s judgement of non-infringement.
This case is No. 19-1527.
Attorneys: Natalie A. Bennett (Morgan, Lewis & Bockius LLP) for Baxalta Inc. and Baxalta GmbH. Eric Alan Stone (Paul, Weiss, Rifkind, Wharton & Garrison LLP) for Genentech, Inc.
Companies: Baxalta Inc.; Baxalta GmbH; Genentech, Inc.; Chugai Pharmaceutical Co. Ltd.
MainStory: TopStory Patent GCNNews FedCirNews
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