USPTO hands win to Daiichi Sankyo in cancer drug dispute
The office delivered its final written decision in favour of Daiichi Sankyo in a patent clash with Pfizer-owned unit | Concerns crucial tech in Daiichi’s cancer drug | Separate dispute concerning the same patent to continue in the US Court of Appeals.
The US Patent and Trademark Office has issued a final written decision that favours Daiichi Sankyo and AstraZeneca in the patent dispute against Pfizer-owned company, Seagen, concerning essential technology in a Daiichi cancer treatment.
The decision, announced on January 17, 2024, invalidates all contested claims of one of Seagen’s patents, and stems from a post-grant review proceeding (PGR) initiated by Daiichi.
The board determined that the claims were invalidated, due to insufficient written description and the inability of a skilled individual to successfully implement and use the invention.
The challenged claims from Daiichi Sankyo were directed towards the antibody-drug conjugate (ADC) with a specific formula and characteristics.
The disputed patent owned by Seagen, US patent number 10,808,039, covers disclosed ADCs designed for targeted drug delivery, particularly in the treatment of cancer.
The patent emphasised the advantages of specific targeting, minimising adverse side effects, and improving the bioavailability of the ADCs.
Daiichi’s cancer drug is marketed under the name Enhertu.
"We are pleased that the USPTO invalidated all challenged claims of the '039 patent," said Naoto Tsukaguchi, corporate officer and general counsel at Daiichi Sankyo.
The PTAB concluded that Daiichi Sankyo successfully demonstrated the unpatentability of the ’039 patent.
Case background
Daiichi Sankyo filed a post-grant review proceeding (PGR) with the USPTO, challenging the patentability of specific claims of the '039 patent, in December 2020.
On April 7, 2022, the USPTO granted Daiichi Sankyo's request to institute the PGR, however, in July reversed this decision following a complaint from Seagen.
The USPTO then ordered the PGR panel to review the issue and decide on accepting or declining the appeal, in February 2023—the USPTO decided to proceed with the review.
The '039 patent also played a central role as the sole patent-in-suit in an infringement litigation between the two pharmaceutical giants in the US District Court for the Eastern District of Texas.
In 2020, Seagen filed a suit against Daiichi Sankyo, in the Eastern District of Texas court, alleging patent infringement of the ‘039 patent.
The court ruled in favour of Seagen, resulting in Daiichi Sankyo paying $41.82 million in damages, in April 2022.
In October 2023, the Eastern District of Texas also ordered Daiichi Sankyo to hand over an 8% royalty on all Enhertu sales from April 1, 2022 through to November 4, 2024—a decision Daiichi Sankyo is currently appealing in the US Court of Appeals for the Federal Circuit.
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