Objective: Viral rebounds inevitably follow interruption of antiretroviral treatment in HIV-1-infected individuals. The randomized ANRS 093 aimed at investigating whether a therapeutic immunization was effective in containing the long-term viral replication following discontinuation of antiretroviral drugs in patients.
Methods: Seventy HIV-1-infected patients effectively treated with antiretroviral drugs were randomized to continue treatment alone or in combination with four boosts of ALVAC 1433 and HIV-LIPO-6T vaccines followed by three cycles of subcutaneous interleukin-2. The impact of vaccination on viral replication was assessed by interrupting antiretroviral drugs first at week 40 and thereafter during follow-up until week 100. Antiretroviral drugs were re-initiated according to predefined criteria.
Results: The median cumulative time (days) off treatment was greater in the vaccine group (177) than in the control group (89) (P = 0.01). The proportion of time (mean, SE) without antivirals per-patient was 42.8% (5.1) and 26.5% (4.2) in the vaccine and control groups, respectively (P = 0.005). Viremia (median log10 copies/ml), 4 weeks following the first, second and third treatment interruption was higher in control patients (4.81, 4.44, 4.53) in comparison with vaccinated patients (4.48, 4.00, 3.66) (P = 0.42, 0.015 and 0.024, respectively). HIV-specific CD4 and CD8 T-cell responses elicited by the therapeutic immunization strongly correlated with the reduction of the time of antiviral therapy (P = 0.0027 and 0.016, respectively).
Conclusion: Our findings provide evidence that therapeutic immunization significantly impacts on HIV-1 replication. This translated into a decrease of up to 40% in the duration of exposure to antiretroviral drugs over 15 months of patients' follow-up.