Bayer has bought itself access to Isis Pharmaceuticals’ experimental anticoagulant ISIS-FXIRx in a deal worth at at least $155 million to the latter.

The German drugmaker has paid out $100 million upfront to secure access to the first-in-class FXI inhibitor for the prevention of thrombosis, and has agreed to pay another $55 million should the drug advance past the current Phase II programme involving patients with compromised kidney function.

At this point, Bayer will assume all global clinical development as well as worldwide regulatory and commercialisation responsibilities for ISIS-FXIRx. The firm said it intends to assess the drug’s potential in patients for whom currently available anticoagulants may not be used, such as those with a high risk of bleeding due to multiple co-morbidities.

Under the deal, Isis also stands to bank to additional, undisclosed milestone payments as development of the drug progresses toward market launch, as well as tiered royalties in the low to high 20% range on gross margins of ISIS-FXIRx.