Seattle Genetics Inc. (Seagen) pulled the final thread out of a tie-up that's been unraveling for weeks by consenting to terminate the license agreement it forged in February with Immunomedics Inc. for the late-stage development, manufacturing and commercialization of IMMU-132 (sacituzumab govitecan) in multiple indications. The potential $2 billion deal called for $250 million up front and an equity investment of up to $57 million, or up to a 9.9 percent stake in Immunomedics, putting Bothell, Wash.-based Seagen in the driver's seat of the antibody-drug conjugate (ADC), which is set to begin a phase III trial in metastatic triple-negative breast cancer (mTNBC).