It is well established that “it is the applicant, not the examiner who must give up or disclaim subject matter,” and generally remaining silent when confronted by statements made by the examiner during prosecution (e.g., reasons for allowance) is not sufficient to invoke disclaimer. However, when responding to a rejection, one should be careful to avoid inadvertently giving the appearance of adopting a characterization of the examiner that is in dispute. While disavowing statements must be “so clear as to show reasonable clarity and deliberateness,” this requirement “does not require the applicant to parrot back language used by the examiner when clearly and deliberately responding to a particular grounds for rejection. If an applicant chooses, she can challenge an examiner’s characterization in order to avoid any chance for disclaimer, but the applicants in this case did not directly challenge the examiner’s characterization.”
Background / Facts: The patents here are directed to treating patients with Chronic Lymphocytic Leukemia (CLL), a cancer in which a type of white blood cell called a B lymphocyte (“B cell”) becomes cancerous, by administering a therapeutically effective amount of an “anti-CD20 antibody,” like the patentee Biogen’s Rituxan (rituximab). During prosecution, the examiner rejected all pending claims for lack of enablement through their full scope, which could have encompassed “any and all anti-CD20 antibodies, no matter the specificity or affinity for the specific epitope on the circulating tumor cells.” In response, Biogen pointed to its disclosure of Rituxan and maintained that “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.” The examiner withdrew the enablement rejection and permitted the broad term “anti-CD20 antibody.” However, a new epitope of the CD20 antigen’s protein chain was later discovered by the accused infringer, which allowed them to use alternative anti-CD20 antibodies with properties distinctly different from Rituxan in several respects.
Issue(s): Whether the patentee’s statements in the prosecution history limit the otherwise broad term “anti-CD20 antibody” to only those antibodies “having an affinity and functional activity similar to RITUXAN.”
Holding(s): Yes. In responding to the enablement rejection, “rather than challenging the examiner’s understanding of the crucial terms, the applicants argued that the specification was enabling for anti-CD20 antibodies with similar affinity and specificity as Rituxan. Indeed, the applicants conceded that other ‘antibodies directed to the same antigen [i.e., CD20] might have different affinities and functional characteristics,’ and limited their claims to antibodies similar to Rituxan nonetheless. … While the applicants may not have repeated the examiner’s language verbatim et literatim, it is clear that they were limiting their invention to what the examiner believed they enabled: antibodies that have a similar specificity and affinity for the specific epitope to which Rituxan binds.”