According to the top-line results from the phase III study announced Monday night, 88% of patients treated with OPT-80 achieved a clinical cure compared to 86% of patients treated with Vancocin. Patients were treated with OPT-80 twice daily for 10 days. Vancocin was dosed four times daily, also for 10 days. A clinical cure was defined as patients requiring no further therapy for C. diff two days after completing treatment. A key secondary endpoint of the study measured the recurrence, or relapse rate. Here, too, OPT-80 excelled, with just 15% of patients reporting a recurrence of the C. diff infection four weeks after treatment compared to a 25% recurrence rate reported for patients treated with Vancocin. Optimer's phase III study was designed to show statistically non-inferior efficacy of OPT-80 compared to Vancocin on both the primary endpoint (cure rate) and the secondary endpoint of recurrence rate. The fact that OPT-80 was numerically superior on both endpoints is a big win for the drug. Recurrence of C. diff infection in treated patients is a growing problem, so the lower recurrence rate for OPT-80 makes a strong case for using the drug as a first-line treatment. A second phase III study of OPT-80 in C. diff patients is ongoing with data expected in the second half of 2009. Optimer also said it plans to resurrect partnering discussions for OPT-80. In 2007, an experimental antibiotic from Genzyme ( GENZ) failed a closely watched phase III study. Optimer shares closed Monday at $4.60 prior to the release of the OPT-80 study results. That news sent the stock up 90% to $8.75 in the after-hours session. Know What You Own: In Tuesday's early trading, other top biotech performers include Genetic Technologies ( GENE), Targacept ( TRGT), Cytokinetics ( CYTK) and BioDelivery Sciences ( BDSI).