A Dendritic Cell-Based Vaccine Elicits T Cell Responses Associated with Control of HIV-1 Replication

Combination antiretroviral therapy (cART) greatly improves survival and quality of life of HIV-1-infected patients; however, cART must be continued indefinitely to prevent viral rebound and associated disease progression. Inducing HIV-1-specific immune responses with a therapeutic immunization has been proposed to control viral replication after discontinuation of cART as an alternative to cART for life. We report safety, tolerability, and immunogenicity results associated with a control of viral replication for a therapeutic vaccine using autologous monocyte-derived dendritic cells (MD-DCs) pulsed with autologous heat-inactivated whole HIV. Patients on cART with CD4(+) >450 cells/mm(3) were randomized to receive three immunizations with MD-DCs or with nonpulsed MD-DCs. Vaccination was feasible, safe, and well tolerated and shifted the virus/host balance. At weeks 12 and 24 after cART interruption, a decrease of plasma viral load setpoint >= 1 log was observed in 12 of 22 (55%) versus 1 of 11 (9%) and in 7 of 20 (35%) versus 0 of 10 (0%) patients in the DC-HIV-1 and DC-control groups, respectively. This significant decrease in plasma viral load observed in immunized recipients was associated with a consistent increase in HIV-1-specific T cell responses. These data suggest that HIV-1-specific immune responses elicited by therapeutic DC vaccines could significantly change plasma viral load setpoint after cART interruption in chronic HIV-1-infected patients treated in early stages. This proof of concept supports further investigation of new candidates and/or new optimized strategies of vaccination with the final objective of obtaining a functional cure as an alternative to cART for life.