The FDA indicated in its letter that it cannot approve the application for oritavancin in its current form and will require Targanta to perform an additional well-controlled clinical study to demonstrate efficacy and safety in order to gain approval.
The FDA requested that a sufficient number of patients with methicillin-resistant Staphylococcus aureus (MRSA) as the cause of complicated skin and skin structure infections (cSSSI) be enrolled in the study to demonstrate the effectiveness of oritavancin in this subset of patients.
The FDA further suggested that the clinical study evaluate the effect of oritavancin on macrophage function and monitor for the potential for subsequent infections that could possibly be related to macrophage dysfunction due to the long terminal half-life of oritavancin. The FDA also requested that the clinical study collect additional information on phlebitis rates.
In its letter to Targanta, the FDA stated the company’s new drug application did not demonstrate the safety and efficacy of oritavancin for treatment of cSSSI. The FDA reasoned that ARRI, the second and larger of two Phase III clinical studies which met a 10% non-inferiority margin, provided evidence of activity of oritavancin but did not provide substantial evidence alone or in combination with ARRD, the smaller of two Phase III clinical studies, to support the efficacy and safety of oritavancin.