The issued claims of the ’923 Patent are generally directed to monoclonal antibodies that bind to a human cytotoxin. At issue in this case was whether the monoclonal antibodies claimed in the ’923 Patent encompassed humanized or chimeric antibodies even though the specification described only murine monoclonal antibodies. UCB argued that the claims cannot cover humanized or chimeric antibodies even though the claim language only describes the antibodies generically as “monoclonal antibodies” due to prosecution history estoppel. Specifically, UCB argued that because Yeda attempted to add claims to chimeric and humanized versions of monoclonal antibodies and those claims were rejected by the examiner for adding new matter that was not supported in the specification, Yeda could not now assert that other more generic claims, covered chimeric or humanized antibodies. The district court agreed with UCB and construed the term “monoclonal antibody” as used in the ’923 Patent to mean “a homogenous population of a single type of antibody produced via hybridomas and not including chimeric or humanized antibodies.”
On appeal, Yeda argued that its issued claims should not have been construed to exclude chimeric or humanized antibodies because the issued claims were not amended during prosecution and had not been subject to the rejections for new matter or lack of enablement. The Federal Circuit rejected this argument and held that the prosecution history required all of the claims of the ’923 Patent to be construed as not including chimeric or humanized antibodies because Yeda yielded that claim scope in order to get its patent allowed and “the general rule is that a patent applicant cannot later obtain scope that was requested during prosecution, rejected by the Examiner, and then withdrawn by the applicant.”
UCB, Inc. v. Yeda Research & Development Co., Ltd., No. 2015-1957 (September 8, 2016).