Claim Construction Ruling in Arzerra Infringement Case

On October 17, a judge in the Southern District of California issued a significant claim construction ruling in the case of Biogen Idec and Genentech v. GlaxoSmithKline. The plaintiffs allege that defendants anti-CD20 monoclonal antibody Ofatumumab (trade name Arzerra) infringes US patent number 7,682,612. Plaintiffs market a competing anti-CD20 antibody, Rituximab (trade name Rituxan).

Based on my understanding of the case, the ruling appears to be a substantial victory for GlaxoSmithKline.

The disputed claim terms are found in claim 1 of the patent, which recites:

1. A method of treating chronic lymphocytic leukemia in a human patient, comprising administering an anti-CD20 antibody to the patient in an amount effective to treat the chronic lymphocytic leukemia, wherein the method does not include treatment with a radiolabeled anti-CD20 antibody.

The court construed the terms "anti-CD20 antibody” and “CD20 binding fragment” as “rituximab and antibodies that bind to the same epitope of the CD20 antigen with similar affinity and specificity as rituximab” and "the portion of the anti-CD20 antibody that binds to the same epitope of the CD20 antigen with similar affinity and specificity as rituximab.” This is significant, because Arzerra does not bind to the same epitope as rituximab, which appears to rule out infringement if this construction of the terms is affirmed on appeal.

The plaintiffs argued for a broader construction, such that the disputed terms would cover any antibody that binds to CD20, even antibodies that bind to different epitopes, such as Arzerra. However, the court found that the prosecution history of the patent established that during prosecution plaintiffs represented that the claims were limited to antibodies binding to the same epitope as rituximab, and the court held them to this more limited construction of the term.

The court also construed the terms "does not include treatment with a radiolabeled anti-CD20 antibody" and "radiation is not used" as "excludes the use of a radiolabeled anti-CD20 antibody or the administration of a separate radiolabeled anti-CD20 antibody," and "no form of radiation (including radiolabeled antibodies) is used," respectively. This construction is significant, because it appears to rule out infringement when Arzerra is used in conjunction with Bexxar or Zevalin, which are both radiolabeled anti-CD20 antibodies.

Thanks to Docket Navigator for making me aware of the ruling.