US PTO grants Seagen's rehearing request in patent dispute with Daiichi Sankyo

Japanese drugmaker Daiichi Sankyo (TYO: 4568) today announced today that the US Patent and Trademark Office (PTO) has granted Seagen’s (Nasdaq: SGEN) request for rehearing of the decision to institute post-grant review, and therefore decided not to proceed with the post-grant review process in which Daiichi Sankyo was contesting the patentability of certain claims within Seagen’s US patent 10,808,039 (the ’039 patent).

In its decision, the US PTO did not decide whether or not the claims of the ’039 patent are invalid. Daiichi Sankyo’s shares were down 2.9% at 3,508 yen on the news.

In April this year, a jury in the US District Court for the Eastern District of Texas found that Daiichi Sankyo infringed Seagen’s US Patent No 10,808,039 by selling in the USA its product Enhertu (trastuzumab deruxtecan; DS-8201). Seagen was awarded damages of $41.82 million for past infringement of the patent.