US Patent Office invalidates Seagen patent in dispute with Daiichi Sankyo

Japanese drugmaker Daiichi Sankyo (TYO: 4568) yesterday announced that the US Patent and Trademark Office (US PTO) rendered a Final Written Decision invalidating all claims of Seagen’s US patent 10,808,039 (the ’039 patent) that were challenged by Daiichi Sankyo in a post-grant review proceeding (PGR).

Seagen, which is ow a subsidiary of US pharma giant Pfizer (NYSE: PFE), argues that the linker and other ADC technology used in Daiichi’s HER2-directed antibody-drug conjugate (ADC) Enhertu (trastuzumab deruxtecan) are only "improvements" to technology licensed by the Japanese drugmaker, but which Seagen says it still owns.

“We are pleased that the US PTO invalidated all challenged claims of the ’039 patent,” said Naoto Tsukaguchi, corporate officer and general counsel, Daiichi Sankyo.