Optimer Pharmaceuticals announced positive top-line results from the second of two Phase 3 FDA trials evaluating the safety and efficacy of fidaxomicin (OPT-80) in patients with clostridium difficile infection (CDI).
Fidaxomicin's performance over the current standard of care (vancomycin) was significant. For this study, researchers reviewed 629 patients with CDI infections. Half of the patients received fidaxomicin, and the other half received vancomycin. Researchers reported that about 88 percent of those treated with fidaxomicin and 85 percent of those treated with vancomycin were cured. Taken alone, that would not have been statistically significant, and, we discuss later, the value of the new drug would have been substantially impaired. However, significantly fewer patients taking the new antibiotic had a recurrence of infection compared to those taking vancomycin. This always had been a problem with the current standard of care.
Here’s what was critical. Back in August of 2009, an Advisory Panel unanimously backed FDA research into generics for vancomycin. It's logical to infer generics were coming, and the impact on the value of the Optimer patent was directly related to the separation the Phase 3 studies could demonstrate between respective performances of the two drugs. If fidaxomicin were deemed pretty much equal to vancomycin, the current standard of care, it would be affected by release of a generic the same as would be vancomycin. Testing statistically superior to vancomycin changes the game, rendering the one-time likely development of vancomycin generics less threatening.
Certainly Astellas Pharma Europe Ltd. sees the importance of the Phase 3 results, as they have put up $68 million in an upfront payment of cash, and a promise of up to $156M more as the drug reaches regulatory and other milestones in the assigned territory: Europe and certain other countries in the Middle East, Africa and Commonwealth of Independent States (CIS). In addition, Astellas will cover drug development and filing costs in Europe and well pay double-digit royalties (according to Zacks, they will range from the high teens to the low twenties!) on the sales of fidaxomicin in the assigned territory, if approved.