HONG KONG – Astellas Pharma Inc. proceeded with an exclusive option to acquire Potenza Therapeutics Inc. under a warrant purchase agreement. Tokyo-based Astellas paid Potenza an up-front fee of $164.6 million to acquire the Cambridge, Mass.-based biopharma. Upon closing, Potenza will be a wholly owned subsidiary. Shareholders of Potenza will be in for a windfall, as they are eligible for additional payments that total up to $240.1 million, depending on the progress of the various programs in clinical development.