Skip to main content
Premium Trial:

Request an Annual Quote

Jury in Enhertu Patent Infringement Case Orders Daiichi Sankyo to Pay $41.8M in Damages

NEW YORK – A jury in the US District Court for the Eastern District of Texas has determined that Daiichi Sankyo and AstraZeneca's HER2-targeted breast and gastric cancer drug Enhertu (trastuzumab deruxtecan) infringes Seagen's US patent 10,808,039 and has ordered Daiichi Sankyo to pay $41.8 million in damages.

On April 7, the US Patent and Trademark Office initiated a post-grant review of the '039 patent at Daiichi Sankyo's request and is evaluating whether it should have granted Seagen's IP in the first place.

"Daiichi Sankyo disagrees with the jury verdict, is committed to defending its rights, and will explore options with respect to the jury verdict, including post-trial motions and an appeal," Naoto Tsukaguchi, the company's corporate officer and general counsel, said in a statement. "We are pleased that the US Patent Office has agreed to review their initial granting of the '039 patent."

Bothell, Washington-based Seagen filed a complaint against Daiichi Sankyo in October 2020, alleging that the firm is infringing its '039 patent covering a special class of protease-cleavable linkers. Seagen claimed in the complaint that it pioneered this linker technology, which is an essential component of its antibody-drug conjugates (ADCs), the first of which received US Food and Drug Administration approval in 2011.

Daiichi Sankyo's "ADC pipeline also use a protease-cleavable linker that is covered by the claims of Seagen's '039 patent," Seagen stated in its complaint, noting that although Enhertu is the first product Daiichi Sankyo launched in the US market in 2020 that uses this technology, it has other ADCs in its pipeline that might use the same technology.

"We are pleased that the jury recognized the validity of asserted claims of our patent and found that Daiichi Sankyo willfully infringed our proprietary technology without permission," Seagen CEO Clay Siegall said in a statement. "As a pioneer and leader in antibody-drug conjugate technology, protecting our intellectual property is essential to our ability to continue developing innovative therapies for cancer patients in need."

Seagen has also asked the court to order Daiichi Sankyo to pay royalties on future sales of the drug under the '039 patent, which expires in 2024.

On Dec. 23, 2020, Daiichi Sankyo petitioned the USPTO contesting the patentability of certain claims in the '039 patent and requested a post-grant review.

Enhertu, first approved in the US in 2019, is available as a treatment for patients with HER2-positive, previously treated, unresectable, metastatic breast cancer and HER2-positive, previously treated, advanced stomach cancer. Daiichi Sankyo said in a statement that it discovered the drug, which it is now jointly developing and marketing with AstraZeneca. During a recent earnings call, an AstraZeneca executive noted that Enhertu became the number one treatment for third-line HER2-positive breast cancer last year and had global in-market sales of $426 million during fiscal year 2021 (excluding Japan). 

Seagen markets Tukysa (tucatinib), which is FDA-approved in combination with Genentech's Herceptin (trastuzumab) and capecitabine for HER2-positive, previously treated, advanced, unresectable or metastatic HER2-positive breast cancer, including tumors that have spread to the brain. In 2021, revenues from Tukysa more than doubled year over year to $334 million.

According to Daiichi Sankyo, the court has yet to rule on Seagen's request for royalties or whether to award additional damages since the jury found there was willful infringement of the '039 patent.