Treatment-Emergent Bictegravir Resistance in a Treatment-Naive Individual With HIV Infection: A Case Report.

Bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) is a highly potent antiretroviral regimen with a high genetic barrier to resistance. Clinical trials have not reported treatment-emergent resistance in treatment-naive individuals. We describe a rare case of virologic failure with an emergent R263K integrase mutation in a treatment-naïve, adherent individual maintained on BIC/FTC/TAF. The patient achieved initial suppression for nearly two years before rebound viremia with R263K and D67N mutations. Following the regimen change and treatment of concurrent syphilis, viral suppression was re-established. This case highlights that emergent bictegravir resistance can occur in adherent, treatment-naïve patients, emphasizing the importance of continued resistance monitoring.