Amgen will pay $425m in cash and up to $575m in performance fees for Biovex, which is testing vaccines for cancer and genital herpes.

Nasdaq-listed drugs company Amgen has agreed to buy for up to $1bn to provide an exit for the target’s investment consortium which contains Genechem Management, a venture firm originally backed by a forerunner to Shire Pharmaceuticals.

Amgen will pay $425m in cash and up to $575m in performance fees for Biovex, which is testing vaccines for cancer and genital herpes.

Venture capital firm Forbion Capital Partners, which span out from Netherlands-based bank ABN Amro in 2007, is Biovex’s largest shareholder.