Executive Summary Consistent with standing precedents, the U.S. Court of Appeals for the Federal Circuit (the court) invalidated Seagen’s US10,808,039 patent (the ’039 patent) claims directed to antibody-drug conjugates (ADCs) comprising a subgenus of tetrapeptide linkers.1The’039 patent claims generically cover Enhertu, an ADC, manufactured by Daiichi Sankyo (Daiichi), containing a tetrapeptide linker (GGFG) for treating cancer.