Sixty-three participants were enrolled in this single-arm, open-label multi-center pilot evaluating efficacy and safety of BIC/F/TAF + DRV/cobicistat as a switch regimen.  Prior to switch, participants had been taking combinations involving three or more ARV classes and three or more pills/day.  People with known or suspected INSTI resistance were excluded, as well as people with a darunavir resistance mutation score of ≥15 per the Stanford HIV Drug Resistance Database.  Median time on ART was 24.3 years, with a current median of 4 pills daily (some took as many as 10 pills/day).  Ten people switched from a regimen which included twice-daily boosted darunavir.  Proviral DNA from 39 (62%) participants revealed that 85% had resistance associated mutations at baseline; calculated GSS using DNA genotype results indicated that 95% of participants had two or more sensitive ARVs.  After 48 weeks, 95% maintained an undetectable VL.  Three people discontinued therapy due to adverse events including rash, headache and mood symptoms (anxiety), and grade 2 eGFR decrease.  The participant who experienced eGFR decrease had a history of low eGFR attributed to prior TDF use.  Pre-dose bictegravir concentrations increased by 11-31% compared with reference C_min values and were 24% higher than reference C_max.  Both treatment satisfaction and perception of adherence increased.