On August 27, 2020, the Federal Circuit issued a decision in Baxalta Inc. v. Genentech, Inc. overturning the District Court’s ruling that Genentech did not infringe the claims of US Patent No. 7,033,590 and remanded for further proceedings. The Federal Circuit’s decision was based on its finding that the District Court’s claim construction was erroneous because the statements in the patent regarding the term “antibody” were introductory not definitional. This case demonstrates the importance of providing clear definitions for each term in a patent specification and creating a clear record during prosecution.

US Patent 7,033,590 (“the ’590 patent”) discloses an antibody or antibody derivative against factor IX. The antibody aids in blood coagulation treatments for hemophiliacs. At issue was the definition of the term “antibody” and “antibody fragment.”

Antibodies are large Y-shaped protein molecules that the immune system uses to recognize various pathogens. Though the general Y-shaped structure of all antibodies is similar, the small regions at the tips of the “Y” are highly variable and allow for millions of different types of antibodies with antigen-binding sites to exist. Antibodies comprise a heavy chain and a light chain.

Baxalta alleged infringement of claims 1, 4, 17, and 19. The Court found claims 1, 4, and 19 to be illustrative and there are reproduced below.

Claim 1:

An isolated antibody or antibody fragment thereof that binds Factor IX or Factor IXa and increases the procoagulant activity of Factor IXa.

Claim 4:

The antibody or antibody fragment according to claim 1, wherein said antibody or antibody fragment is selected from the group consisting of a monoclonal antibody, a chimeric antibody, a humanized antibody, a single-chain antibody, a bispecific antibody, a diabody, and di-, oligo- or multimers thereof.

Claim 19:

The antibody or antibody fragment according to claim 4, wherein the antibody is a humanized antibody.

At the District Court level, Baxalta argued that the term “antibody” should define a molecule comprising two heavy chains and two light chains. Genentech argued a narrower definition, wherein that term refers to a molecule with two identical heavy chains and two identical light chains.

The District Court ruled in favor of Genentech. In its reasoning, the District Court relied on paragraphs in the ’590 patent stating that an antibody has two identical heavy chains and two identical light chains. Further, the Court held that during prosecution, Baxalta amended its original claims to remove broader types of antibodies, such as “chimeric antibodies,” which would not have identical heavy chains and light chains. Based on this interpretation of the term “antibody,” Genentech obtained a judgment of non-infringement.

On appeal, the Federal Circuit overturned the District Court’s claim construction. The Federal Circuit began its analysis by looking at the granted claims. The Federal Circuit looked to the plain language of the claims and held that there is nothing within claim 1 that inherently limits the antibody to identical heavy and light chains.

The Court also addressed the amendments made during patent prosecution. The Court noted that while Baxalta had amended the claims during prosecution, Baxalta’s amended claim 4 still recited “chimeric antibody” and further added the term “bispecific antibody”. By its very nature, a bispecific or chimeric antibody does not have identical heavy and light chains — thus implying that the use of the term “antibody” in claim 1 was not limited to antibodies having identical heavy chains and identical light chains. The Court recognized that the prosecution history “often lacks the clarity of the specification and thus is less useful for claim construction purposes,” as set forth in Phillips v. AWH Corp., 415 F.3d 1303. But Genentech’s attorneys were unable to explain why claim 4 had survived examination if the meaning of “antibody” excluded bispecific antibodies and instead argued for invalidation of such claims.

Finally, addressing the ’590 patent specification, the Court held that the statement that “[e]ach molecule consists of large, identical heavy chains (H chains) and two light, also identical chains (L chains),” relied upon by the District Court, was a generalized introduction to antibodies rather than a definitional statement. In support of this finding, the Court noted that the specification disclosed synthetic techniques for preparing humanized or chimeric antibodies.

This case demonstrates the importance of specifying when a term is — and is not — being defined in a patent application. Ambiguity in definitions creates the possibility of erroneous decisions and protracted litigation. This case also demonstrates the potential for dependent claims to help define the scope of independent claims. Here, the Federal Circuit found that the claim was not defined in the patent at least in part because such a finding would be contrary to the use of the term in the claims and the rest of the patent disclosure.