Extended in vivo activity of VRC01 HIV-1 prophylaxis entails initial protective efficacy and subsequent breakthrough infections.
Allan C deCamp, Michal Juraska, Li Li et al.
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In 30 seconds
The two parallel randomized antibody-mediated prevention trials assessed whether intravenous VRC01 prevented HIV-1 acquisition, with this analysis extending follow-up through the week 104 final visit. Against viruses highly sensitive to VRC01 (IC 80 < 1 microgram/milliliter), cumulative prevention efficacy was 66.3% (95% confidence interval: 32.4, 83.2%). After the final dose at week 72, HIV diagnoses and resistance were more frequent in VRC01 recipients than in placebo recipients. The findings indicate activity against sensitive viruses alongside later breakthrough infections, particularly involving viruses with reduced sensitivity.
Key findings
- Against highly VRC01-sensitive viruses (IC 80 < 1 microgram/milliliter), cumulative prevention efficacy was 66.3% (95% confidence interval: 32.4, 83.2%).
- After week 80, more diagnoses involving moderately sensitive or resistant viruses (IC 80 ≥ 5 microgram/milliliter) occurred with VRC01 than placebo (11 versus 1).
- In the post-week 80 period, HIV diagnosis and resistance to VRC01 were more frequent in the VRC01 groups than in placebo groups.
Why it matters
The results distinguish protection against antibody-sensitive viruses from protection against HIV acquisition overall. They also highlight that breakthrough infections and resistance may become more apparent as antibody concentrations wane, underscoring the challenge of relying on a single antibody to prevent infection across viruses with differing sensitivity.
What to keep in mind
The abstract reports efficacy against a defined sensitivity subgroup and follow-up through week 104; it does not provide overall efficacy estimates or further details on the analysis.