BioPharma, Legal

Daiichi Sankyo sues Seattle Genetics over antibody-drug conjugate technology

Seattle Genetics alleges that the Japanese drugmaker’s DS-8201 uses a linker and other technology that improve on the U.S. company’s own technology. The drug is also the subject of a $7 billion partnership with AstraZeneca.

A Japanese drugmaker is suing a U.S.-based biotech company over the latter’s claims to intellectual property dating back to a now defunct partnership between the two.

Tokyo-based Daiichi Sankyo said Monday that it had sued Seattle Genetics in the District Court of Delaware after it said Seattle Genetics laid claim to intellectual property rights related to Daiichi Sankyo’s’s antibody-drug conjugate products. The claims concern a partnership between the two companies to develop ADCs that lasted from 2008 until 2015, and in particular technology used in the drug DS-8201 (trastuzumab deruxtecan), under development for breast and other cancers.

In its own statement Monday, Seattle Genetics said that technology used in Daiichi Sankyo’s DS-8201 and other drug candidates “rightfully belongs to Seattle Genetics” under the partnering agreement the two companies entered in 2008. The biotech, based in the Seattle suburb of Bothell, Washington, said that the linker and other ADC technologies used in the drugs are improvements over its own technology. Daiichi Sankyo said Seattle Genetics’ claims were without merit.

For its part, Daiichi Sankyo has stated that DS-8201 is based on its own, proprietary technology, DXd, which also forms the backbone of another of its drug candidates, the Phase I/II DS-7300, designed to target the B7-H3 antigen in various solid tumors.

ADCs are like biological guided missiles, consisting of a monoclonal antibody targeted to a cell-surface antigen that delivers a pharmaceutical payload. Linkers are an essential component to ADCs because if improperly constructed, the pharmaceutical agent can break off prematurely, rendering the drug ineffective or causing off-target toxicity. Approved ADCs include Seattle Genetics’ only current marketed product, Adcetris (brentuximab vedotin), which works by targeting the CD30 antigen in Hodgkin’s lymphoma and certain T-cell lymphomas, and Pfizer’s Mylotarg (gemtuzumab ozogamicin) and Besponsa (inotuzumab ozogamicin), which respectively target CD33 in acute myeloid leukemia and CD22 in acute lymphoblastic leukemia. Seattle Genetics and Daiichi Sankyo developed Adcetris – originally called SGN-35 – under the former partnership.

DS-8201 is also the subject of a $7 billion partnership between Daiichi Sankyo and British drugmaker AstraZeneca announced in March. The development and commercialization agreement included an upfront payment of $1.35 billion from AstraZeneca to Daiichi Sankyo, as well as contingent payments of up to $5.55 billion, which would include $3.8 billion in regulatory milestones and $1.75 billion in sales milestones.

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