“[T]he Federal Circuit held that the district court erred in its narrow construction of the term ‘antibody,’ which was inconsistent with the written description and the plain language of the claim.”
On August 27, the United States Court of Appeals for the Federal Circuit (CAFC) reversed and remanded a decision of the U.S. District Court for the District of Delaware in Baxalta Inc. v. Genentech, Inc. The CAFC reversed the district court’s claim construction of the terms “antibody” and “antibody fragment” in Baxalta’s patent claims and remanded for proceedings consistent with the correct constructions.
U.S. Patent No. 7,033,590 (the ‘590 patent), which was owned by Baxalta, relates to preparations used to treat hemophilia patients who have developed factor VIII inhibitors. Baxalta filed suit against Genentech and Chugai Pharmaceutical Co. Ltd., alleging infringement of claims 1, 4, 17, and 19 of the ‘590 patent. The district court issued a claim construction order, construing the terms “antibody” and “antibody fragment.” Following the claim construction order, the parties stipulated to non-infringement of the asserted claims and the district court entered judgment based the claim construction and stipulation. Baxalta appealed the judgment to the CAFC.
Construction of “Antibody”
The CAFC addressed the district court’s construction of the term antibody, for which the district court adopted Genentech’s construction: “an immunoglobulin molecule, having a specific amino acid sequence that only binds to the antigen that induced its synthesis or very similar antigens, consisting of two identical heavy chains (H chains) and two identical light chains (L chains).” The CAFC explained that there is nothing in the plain language of the claims to support the district court’s construction. Further, the CAFC noted that the dependent claims confirm that “antibody” is not limited to the district court’s construction. For example, the district court noted that claim 4 recites antibodies that fall outside of the district court’s construction of “antibody”. Thus, the CAFC rejected the district court’s claim construction, which would render some dependent claims invalid.
The CAFC also considered the written description in reviewing the district courts construction of the term “antibody”. Genentech argued that there is a section of the specification that supports the district court’s claim construction. However, the district court explained that the remainder of the written description and the claims do not support the district court’s construction and, therefore, it was incorrect.
In adopting its construction, the district court cited an amendment made by Baxalta during prosecution, wherein the patentee amended the claims to recite an “anti-body fragment” in place of an “antibody derivative” in order to overcome an enablement rejection. The CAFC noted that there were “no clear statements in the prosecution history regarding what scope, if any, was given up” by the amendment. Citing 3M Innovative Properties Co. v. Tredegar Corp., the CAFC explained that “in order for prosecution disclaimer to attach, the disavowal must be both clear and unmistakable.” Further, the CAFC noted that, since the parties agree that the term ‘antibody derivative’ is not a term commonly used in the art, it was possible that “the patentee was substituting a known term at the suggestion of the examiner for a less commonly used term in the art.”
Thus, the CAFC held that the district court erred in its narrow construction of the term “antibody,” which was inconsistent with the written description and the plain language of the claim. Instead, the CAFC construed “antibody” as “an immunoglobulin molecule having a specific amino acid sequence comprising two heavy chains (H chains) and two light chains (L chains).”
Construction of “Antibody Fragment”
The CAFC considered the district court’s construction of “antibody fragment,” i.e. “a fragment of an antibody which partially or completely lacks the constant region.” The district court noted that “the term ‘antibody fragment’ excludes bispecific antibodies.” The district court relied on a particular excerpt from the written description to support its claim construction but the CAFC noted that the excerpt did not define antibody fragments as necessarily “partially or completely lack[ing] the constant region.” Citing Thorner v. Sony Computer, the CAFC explained that “the standard for lexicography is exacting, requiring the patentee to ‘clearly express an intent to redefine a term.’” Noting that the written description included phrases such as “may also include,” “e.g.,” “such as,” and “etc.”, the CAFC noted that it was clear that the patentee did not intend the excerpt of the written description to define “antibody fragment.” Considering the term “according to its plain and ordinary meaning in light of the written description as a whole”, the CAFC construed “antibody fragment” to mean “a portion of an antibody” as we have defined above, that is: “a portion of an immunoglobulin molecule having a specific amino acid sequence comprising two heavy chains (H chains) and two light chains (L chains).”
The Court concluded that the district court erred in construing the terms “antibody” and “antibody fragment,” thus vacating the judgment of non-infringement and remanding for further proceedings consistent with the correct constructions of the terms.