Astellas has bagged the European rights to Optimer Pharmaceuticals' new antibiotic in a deal that could be worth over $220 million to the US firm. 

The agreement, which covers certain other countries in the Middle East, Africa and the Commonwealth of Independent States, as well as Europe, involves fidaxomicin for clostridium difficile infection. The drug is an orally-administered macrocyclic antibiotic with a new mechanism and narrow spectrum of action, the firms noted, and in two Phase III trials has proved equally effective in clinical cure when compared to vancomycin, the only product approved by the US Food and Drug Administration for CDI.

Optimer notes that "most importantly, fidaxomicin was statistically superior to vancomycin in global cure and in reducing recurrences of CDI by up to 47%". Marketing applications have been filed in the USA and the European Union.

Cashwise, Astellas is paying an upfront fee of $68 million and Optimer could pocket another $156 million upon the achievement of certain regulatory and commercial milestones, double-digit royalties. The Japanese-headquartered major will be responsible for all future expenses associated with fidaxomicin in the territories covered by the pact, including the costs of the ongoing marketing authorisation application with the European Medicines Agency.

Masao Yoshida, chief executive of Astellas Pharma Europe, said the deal brings together his firm's "world-class anti-infective business capabilities, including established relationships with payers and hospitals" and Optimer's novel therapeutic. His counterpart at the latter, Pedro Lichtinger, said that if approved, fidaxomicin will provide a cost-savings opportunity for hospitals and payers, especially when used in populations at risk of recurrence".

CDI is treated with off-label use of metronidazole, as well as vancomycin, but 20%-30% of patients who initially respond experience a clinical recurrence following cessation of treatment.