Emergent resistance in VF cases often resulted in cross-resistance to other nonnucleoside reverse transcriptase inhibitors and integrase strand transfer inhibitors. Although most cases did not meet the high-risk profile as defined by registration trials, subtype A lineages were overrepresented. Low drug levels were not elevated versus treatment successes. These data suggest that subtype-specific factors beyond A6 may influence VF risk and merit further study.
Mazzitelli et al. (Wed,) studied this question.