The F4/AS01B HIV-1 Vaccine Candidate Is Safe and Immunogenic, but Does Not Show Viral Efficacy in Antiretroviral Therapy-Naive, HIV-1-Infected Adults: A Randomized Controlled Trial

The impact of the investigational human immunodeficiency virus type 1 (HIV-1) F4/AS01B vaccine on HIV-1 viral load (VL) was evaluated in antiretroviral therapy (ART)-naive HIV-1 infected adults. This phase IIb, observer-blind study (NCT01218113), included ART-naive HIV-1 infected adults aged 18 to 55 years. Participants were randomized to receive 2 (F4/AS01B-2 group, N=64) or 3 (F4/ AS01B-3 group, N=62) doses of F4/AS01B or placebo (control group, N=64) at weeks 0, 4, and 28. Efficacy (HIV-1 VL, CD8⁺ T-cell count, ART initiation, and HIV-related clinical events), safety, and immunogenicity (antibody and T-cell responses) were evaluated during 48 weeks. At week 48, based on a mixed model, no statistically significant difference in HIV-1 VL change from baseline was demonstrated between F4/AS01_B-2 and control group (0.073 log10 copies/mL [97.5% confidence interval (CI):-0.088; 0.235]), or F4/AS01B-3 and control group (-0.096 log10 copies/mL [97.5% CI:-0.257; 0.065]). No differences between groups were observed in HIV-1 VL change, CD8⁺ T-cell count, ART initiation, or HIV-related clinical events at intermediate timepoints. Among F4/AS01B recipients, the most frequent solicited symptoms were pain at injection site (252/300 doses), fatigue (137/300 doses), myalgia (105/300 doses), and headache (90/300 doses). Twelve serious adverse events were reported in 6 participants; 1 was considered vaccine-related (F4/ AS01_B-2 group: Angioedema). F4/AS01B induced polyfunctional F4-specific CD8⁺ T-cells, but had no significant impact on F4-specific CD8+ T-cell and anti-F4 antibody levels. F4/AS01B had a clinically acceptable safety profile, induced F4-specific CD8⁺ T-cell responses, but did not reduce HIV-1 VL, impact CD8⁺ T-cells count, delay ART initiation, or prevent HIV-1 related clinical events.