Evaluation of Elvitegravir/Cobicistat/Emtricitabine/Tenofovir Alafenamide in Treatment-Naive Patients Living With Human Immunodeficiency Virus (HIV) With High Viral Load: A Retrospective Observational Study.

Introduction Data on the long-term real-world efficacy of elvitegravir/cobicistat/emtricitabine/tenofovir alafenamide (E/C/F/TAF) in people living with HIV (PLWH) presenting with high baseline viral loads remain limited. This study aimed to assess the virological and immunological efficacy of E/C/F/TAF in treatment-naive patients stratified by baseline viremia levels. Methods This retrospective, single-center, observational study evaluated 67 treatment-naive adult patients who initiated E/C/F/TAF therapy between 2017 and 2018. Patients were stratified into three baseline viral load strata: low (<100,000 copies/mL; n=41), high (100,000 to <1,000,000 copies/mL; n=15), and very high (≥1,000,000 copies/mL; n=11). Virological suppression kinetics and absolute CD4+ T cell counts were longitudinally analyzed over a 24-month follow-up period using available-case analysis. Results Overall virological suppression was achieved in 85.1% (57/67) of patients at month six. Stratified analysis at month six revealed a statistically significant difference in early suppression rates: 97.6% (40/41) in the low, 73.3% (11/15) in the high, and 54.5% (6/11) in the very high strata (p<0.001). However, this disparity progressively narrowed; by month 12, suppression rates reached 100.0% (40/40) in the low, 86.7% (13/15) in the high, and 90.9% (10/11) in the very high strata (p=0.06), maintaining statistical similarity through month 24 (p=0.16), where 100.0% of the low (40/40) and high (14/14) strata, and 90.0% (9/10) of the very high stratum achieved suppression. Only one patient (baseline viral load: 3,393,215 copies/mL) exhibited persistent low-level viremia, which gradually declined to 114 copies/mL at month 12 and 54 copies/mL at month 24. Immunologically, the mean absolute CD4+ T cell count for the entire cohort expanded significantly from 414.1±254.8 cells/µL at baseline to 730.4±308.3 cells/µL at month 24. Linear mixed-effects modeling demonstrated a significant overall increase in CD4+ counts over time (p<0.001) and a significant time-by-group interaction (p=0.013), confirming an accelerated 'catch-up' immune recovery in the very high viral load stratum by month 24. Conclusions E/C/F/TAF was associated with durable long-term virological and immunological responses in treatment-naive PLWH, including those with high baseline viremia. Although high pre-treatment viral load was associated with a transient delay in early viral suppression at month six, this did not appear to compromise longer-term treatment outcomes. These findings suggest that E/C/F/TAF may represent a useful treatment option, particularly in clinical settings where second-generation integrase inhibitors are restricted or unavailable.