Clear and Unmistakeable Evidence of a Disclaimer Found in Response to Enablement Rejection

Kumiko Ide | April 24, 2013

Biogen Idec, Inc., et al. v. GlaxoSmithKline LLC, et al.

April 16, 2013

Panel: Dyk, Plager, Reyna.  Opinion by Reyna.  Dissent by Plager.

Summary

During prosecution of the patent, applicants responded to the examiner’s enablement rejection, wherein they failed to challenge the examiner’s understanding of the crucial terms, and limited their invention to what the examiner believed their specification enabled.  The CAFC affirmed the district court’s narrow claim interpretation of the term “anti-CD20 antibody” based on prosecution history disclaimer.

実施可能要件を満たしていないとして発せられた拒絶通知に対して、出願人は、審査官の理解に対して反論することなく、明細書により実施可能であると審査官が判断したものに発明を限定するような主張を行った。よって、「anti-CD20 antibody」という用語について、狭いクレーム解釈を容認した地裁の判断は誤りでなかったとCAFCは判示した。

Details

Biogen obtained U.S. Patent No. 7,682,612 (“the ’612 patent”), which covered a method for treating patients with Chronic Lymphocytic Leukemia (CLL), involving administering the anti-CD20 antibody.

During prosecution of the ’612 patent, the examiner rejected all of the claims because the specification did not provide enablement commensurate with the scope of the claimed invention.  The examiner contended that the scope of the claimed invention included “any and all anti-CD20 antibodies, no matter the specificity or affinity for the specific epitope on the circulating tumor cells.”  While the examiner acknowledged the specification enabling for RITUXAN®, RITUXIMAB®, and 2B8-MX-DTPA, she found the specification not enabling of all other anti-CD20 antibodies, which may have different structural and functional properties.

In response, the applicants stated as follows:

even though antibodies directed to the same antigen might have different affinities and functional characteristics, one of skill in the art could readily identify an antibody that binds to CD20 with similar affinity and specificity as does RITUXAN® using techniques that are well known in the art. . . . With that knowledge in hand, the skilled artisan could readily produce anti-CD20 antibodies using similar techniques, and screen such antibodies for those having an affinity and functional activity similar to RITUXAN®.

Based on the response submitted by the applicants, the examiner withdrew her enablement rejection.

GSK developed an anti-CD20 antibody called ARZERRA®, which differed from RITUXAN® in that it (1) attaches to the second small loop of the CD20 antigen’s protein chain, (2) is fully human antibody as opposed to chimeric, and (3) has greater affinity for the CD20 antigen.

Biogen sued GSK for infringement of the ’612 patent, and GSK counterclaimed, alleging noninfringement, invalidity, and unenforceability of those claims.

The district court held a Markman hearing, and construed the term “anti-CD20 antibody” to be “rituximab and antibodies that bind to the same epitope of the CD20 antigen with similar affinity and specificity as rituximab,” which was proposed by GSK based on the prosecution history disclaimer.  Based on this construction, Biogen stipulated to noninfringement and appealed.

The CAFC agreed with the district court’s construction of the term “anti-CD20 antibody.”  During prosecution, the examiner acknowledged the specification enabling for RITUXAN®, RITUXIMAB®, and 2B8-MX-DTPA, but found the specification not enabling of all other anti-CD20 antibodies, which may have different structural and functional properties.  In response, the applicants stated the specification enabling for anti-CD20 antibodies with similar affinity and specificity as RITUXAN®.  Applicants did not challenge the examiner’s understanding of the crucial terms.  Based on this response, the CAFC found disclaimer of antibodies that do not have similar affinity and specificity as RITUXAN® clear and unmistakable.

Biogen argued that first, there is a difference between claim 1’s broad coverage of all anti-CD20 antibodies, with dependent claims, which list specific types of antibodies.  The CAFC rejected this argument, stating that prosecution history disclaimer can overcome the presumption of claim differentiation.  Second, Biogen argued that ’612 patent incorporated U.S. Patent No. 5,736,137 by reference, and therefore, this referenced patent’s definition of “anti-CD20 antibody” should control.  The ’137 patent defines “anti-CD20 antibody,” but the CAFC held that the definition stated in the referenced document does not necessarily reflect how a person of ordinary skill in the art would understand the term within the context of the ’612 patent.

Therefore, the CAFC affirmed the district court’s narrow claim interpretation of the term “anti-CD20 antibody” based on prosecution history disclaimer.

Dissent

Judge Plager dissented, finding no evidence of a clear and unmistakable disclaimer in the prosecution history. Instead, he found applicants’ response to be “at worst a non-response to the examiner’s concern.”  The prosecution history did not contain statements by the applicants that antibodies that bind to the same epitope on CD20 with similar affinity and specificity as RITUXAN® must be used.  Instead, applicants repeatedly stated that the invention was based on the discovery that anti-CD20 antibodies could treat CLL, and the claimed methods were not limited to the use of any particular anti-CD20 antibody.

Takeaway

  • Any statement made during prosecution of a patent may be used to limit the scope of the claims.
  • If applicants disagree with the examiner’s understanding, be sure to challenge his/her understanding in their response.

Full Opinion

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