Analysis of the pharmacokinetic data from this study and other bevirimat clinical studies has revealed the bevirimat target blood levels, or threshold, above which patients are likely to respond if they lack the key Gag polymorphisms. This threshold concentration was achieved in all patients in the 203 study at liquid doses from 250mg to 400mg.
Patients who had the predictors of response and effective bevirimat target blood levels had a mean viral load reduction of 1.26 log10. The active dose range and plasma concentrations required for optimal response to bevirimat have been determined and are achievable using existing solid or liquid formulations.
The predictors of response to bevirimat were found to be specific changes to less than 1% of the amino acids on the approximately 500 position HIV Gag protein, the target for bevirimat. Patients whose virus lacks these changes were much more likely to respond to bevirimat. These specific changes in Gag, known as polymorphisms, are easily determined by a simple addition to the rapid, inexpensive genotype tests performed by practicing HIV physicians.
Additionally, company has completed a Phase IIb study of five treatment-experienced patient cohorts with doses ranging up to 400mg daily and provided preliminary analysis of the combined study results.