|So why did
subjects fail on MVC?
|•Most (~50-60%) subjects failed with CXCR4- or
dual/mixed-tropic virus in the MVC arms.
|•The data from the virology substudies suggest that the
most prominent reason for failure in these studies was outgrowth of
CXCR4-using viruses not detected at screening.
|•Treatment failure on MVC with CCR5-tropic virus also
occurred and resulted from phenotypic and genotypic resistance to MVC and
resistance to OBT.
|•It remains to be determined if host CCR5 genotype also
plays a role in MVC failure