As part of the agreement, Seragon will receive an upfront cash payment of $725m from Genentech and additional contingent payments of up to $1bn based on achievement of certain predetermined milestones.
The transaction, which is subject to customary closing conditions, is expected to be completed in the third quarter of 2014.
Upon completion of the acquisition, Seragon’s portfolio of investigational next-generation oral selective estrogen receptor degraders (SERDs) for the potential treatment of hormone receptor-positive breast cancer will be integrated into Genentech Research and Early Development.
Genentech executive vice president and head of Research and Early Development Richard Scheller said this year, breast cancer will claim the lives of nearly 40,000 women in the US, and up to half of these women will have a disease that is driven by the estrogen receptor.
"We believe these investigational oral SERDs could one day redefine the standard of care for hormone receptor-positive breast cancer," Scheller said.
Seragon has developed the next-generation SERDs to both block estradiol action at the estrogen receptor and also eliminate the estrogen receptor from the cell altogether.