Introduction

Sustained suppression of HIV replication necessitates adequate adherence to antiretroviral (ARV) therapy, with historical guidelines often citing near-perfect adherence (≥95%) as crucial for successful oral ARV treatment.

Aim

To analyze the effect of varying adherence on virologic outcomes for Phase 3 studies conducted for B/F/TAF and DTG + 2 NRTIs

Patient Profile

Treatment-naïve or virologically suppressed adults

Methods

• This a retrospective analysis, pooled data from Phase 3 studies conducted for B/F/TAF, totaling more than 2600 participants
• Participants with at least one post-baseline HIV-1 RNA measurement and evaluable adherence data were included in this analysis
• Adherence was calculated by pill count from returned pill bottles
• Virologic outcome was assessed by last on-treatment HIV-1 RNA.

Results

• Across all studies, most participants (78%) exhibited high adherence to treatment 
• After 48 weeks, median adherence was 78% for the B/F/TAF group and 80% for the DTG + 2 NRTI group in low-adherence participants.
• Through 96 weeks, the high adherence rate remained high for both treatment arms.
• Adherence and Virologic Suppression
  • Through 48 wks, virologic suppression was high in all adherence categories in the B/F/TAF grp. In contrast, the DTG + 2 NRTI grp showed significantly lower suppression with low adherence
• Comparative Virologic Suppression (Low Adherence)
  • At 144 weeks, virologic suppression was statistically higher in the B/F/TAF grp (97%) compared to the DTG + 2 NRTI grp (82%) among participants with low adherence, with a difference of 15.6% (P = 0.03)

• Virologic outcomes by Snapshot algorithm and missing= excluded approach
  • At wk 144, the incidence of viraemia was significantly lower in the B/F/TAF group with low adherence compared to the DTG + 2 NRTI group (-13.3% difference; P = 0.04).
  • In the DTG + 2 NRTI group, viraemia was significantly higher for participants with low adherence (P = 0.02), while the B/F/TAF group showed similarly low viraemia levels across all adherence categories.
  • The B/F/TAF group showed consistently high virologic suppression rates (97-100%) across all adherence levels at Weeks 48, 96, and 144.
  • In the DTG + 2 NRTI group, virologic suppression was significantly lower among participants with low adherence compared to those with high adherence in Week 48, with a difference of 6.5% (P < 0.0001).
  • This significant difference in virologic suppression persisted in Week 144, with a difference of 4.1% (P = 0.007) between participants with low and high adherence in the DTG + 2 NRTI group
• Two participants (<95% adherence) in the DTG + 2 NRTI grp receiving DTG & abacavir/lamivudine developed M184V
• There was no treatment-emergent resistance to B/F/TAF

Conclusion

• Suboptimal adherence (<85%) to DTG + 2 NRTIs led to lower virologic suppression, while B/F/TAF maintained high VS levels.
• B/F/TAF exhibited superior efficacy compared to DTG + 2 NRTIs in achieving and maintaining virologic suppression with suboptimal adherence

Reference

J Antimicrob Chemother 2025; 80:281–291