US FDA says Theravance/Astellas' Vibativ NDA for NP is incomplete

US drug developer Theravance says that it has received from a letter from the Food and Drug Administration indicating that the firm's response to the November 2009 Complete Response letter for the Vibativ (telavancin) New Drug Application for the treatment of nosocomial pneumonia (NP) is incomplete and that the review clock will not start until the FDA receives a complete response.

In aftermarket trading, Theravance shares lost 6% to $12.69. The stock has traded between $11.82 and $18.56 over the last year. Vibativ was approved last year as a treatment for complicated skin infections (The Pharma Letter September 14, 2009). Theravance and its marketing partner, Japan-owned Astellas Pharma, launched the drug November 5.

The FDA letter noted that, "While we acknowledge that additional mortality data and analyses have been provided to support pooling the two Phase III clinical trials (Studies 0015 and 0019), even if this is acceptable, the two pooled studies would equate to only one adequate and well-controlled trial and would not constitute substantial evidence of efficacy. The adequacy and similarity of populations across studies for the purposes of pooling has not yet been determined, and is a review issue."