Lack of Drug Resistance in HIV Infection Despite PrEP: Can We Be Reassured?

The iPrEx study established the efficacy of tenofovir/FTC for preexposure prophylaxis (PrEP) among men who have sex with men, but concern persists that HIV infection could occur with suboptimal PrEP use, resulting in the development of drug-resistant virus. In a subanalysis of the iPrEx study, researchers used clinical genotype and phenotype assays, deep sequencing, a novel allele-specific polymerase chain reaction (PCR) assay, and drug-exposure measurements to investigate drug resistance in participants who seroconverted during the trial.

After randomization, 131 participants (48 in the tenofovir/FTC arm, 83 in the placebo arm) developed incident infections; none showed major tenofovir- or FTC-specific mutations identifiable by clinical ass…