In Partners PrEP, 5 subjects who seroconverted carried resistance mutations (mostly to FTC); 3 out of the 5 had unrecognized acute infection at the start of PrEP. These results indicate that resistance is rare but possible, and could emerge when PrEP is initiated during acute infection. On-demand PrEP theoretically presents a risk for the emergence of resistant HIV if transmission occurs during suboptimal dosing or if a patient becomes infected between on-demand administrations. The data from IPERGAY are not sufficient to address this concern, however, as the two patients who seroconverted from the TDF/FTC arm were not taking PrEP at the time.
Do you have concerns about the emergence of drug resistance in individuals or populations with the potential use of non-daily PrEP? In what ways could we best prevent the emergence of drug resistance with the use of non-daily PrEP?