Daiichi Sankyo has secured a victory in its patent arbitration with Seagen, nabbing a $47 million award for attorneys’ fees and other costs, plus interest. However, a larger patent battle with Pfizer remains.
Daiichi Sankyo announced on Friday that it has won its patent arbitration dispute with Seagen, which will pay the Japanese multinational $47 million in attorneys’ fees and costs, plus interest.
Seagen and Daiichi Sankyo have for years been locked in a patent battle over technologies used in the Japanese pharma’s AstraZeneca-partnered antibody-drug conjugate (ADC) Enhertu (fam-trastuzumab deruxtecan-nxki). In August 2022, an arbitrator ruled in favor of Daiichi Sankyo finding that Seagen’s claims were invalid.
According to Daiichi Sankyo, the arbitrator awarded the company around $45.5 million in attorneys’ fees and costs, which Seagen challenged and sought to have vacated. However, a federal court denied the appeal on April 2024 and tacked on interest to Daiichi Sankyo’s award for a total of $47 million.
Pfizer, which acquired Seagen for $43 billion in March 2023, failed to appeal the ruling before a set deadline, officially handing Daiichi Sankyo the victory.
Despite Friday’s win, the larger patent battle between Pfizer and Daiicihi Sankyo may not yet be over. In January 2024, the U.S. Patent and Trademark Office ruled that Seagen’s contentious patent 10,808,039—which protects the use of auristatin peptides in ADCs via a specific linker technology—is invalid.
Seagen has also racked up legal victories in recent years. A civil action suit it filed in 2020—over the same patent infringement issue—ended in a jury victory in April 2022, awarding the company $41.82 million in damages. The District Court for the Eastern District of Texas also ruled in favor of Seagen in October 2023 with Daiichi Sankyo having to pay 8% royalty on all Enhertu sales from April 1, 2022 through November 4, 2024.
The patent dispute between Seagen and Daiichi Sankyo stretches back to 2008, when they signed a partnership that used Seagen’s ADC technology to develop therapies against solid tumors, according to Genetic Engineering & Biotechnology News. The collaboration ended in 2015.
In 2019, Seagen claimed that Daiichi Sankyo owed it a portion of the Japanese pharma’s $6.9 billion contract with AstraZeneca. Enhertu, which at the time was still under development and was the centerpiece of the AstraZeneca deal, used underlying technology that was formed between 2008 and 2015 when the companies were still partners, Seagen alleged.
In response, Daiichi Sankyo filed a Declaratory Judgement in November 2019 maintaining that Seagen’s claims were without merit.
