A Randomized Placebo-Controlled Efficacy Study of a Prime Boost Therapeutic Vaccination Strategy in HIV-1-Infected Individuals: VRI02 ANRS 149 LIGHT Phase II Trial

Abstract

In this placebo-controlled phase II randomized clinical trial, 103 human immunodeficiency virus type 1 (HIV-1)-infected patients under cART (combined antiretroviral treatment) were randomized 2:1 to receive either 3 doses of DNA GTU-MultiHIV B (coding for Rev, Nef, Tat, Gag, and gp160) at week 0 (W0), W4, and W12, followed by 2 doses of LIPO-5 vaccine containing long peptides from Gag, Pol, and Nef at W20 and W24, or placebo. Analytical treatment interruption (ATI) was performed between W36 to W48. At W28, vaccinees experienced an increase in functional CD4⁺ T-cell responses (P < 0.001 for each cytokine compared to W0) measured, predominantly against Gag and Pol/Env, and an increase in HIV-specific CD8⁺ T cells producing interleukin 2 (IL-2) and tumor necrosis factor alpha (TNF-α) (P = 0.001 and 0.013, respectively), predominantly against Pol/Env and Nef. However, analysis of T-cell subsets by mass cytometry in a subpopulation showed an increase in the W28/W0 ratio for memory CD8⁺ T cells coexpressing exhaustion and senescence markers such as PD-1/TIGIT (P = 0.004) and CD27/CD57 (P = 0.044) in vaccinees compared to the placebo group. During ATI, all patients experienced viral rebound, with the maximum observed HIV RNA level at W42 (median, 4.63 log₁₀ copies [cp]/ml; interquartile range [IQR], 4.00 to 5.09), without any difference between arms. No patient resumed cART for CD4 cell count drop. Globally, the vaccine strategy was safe. However, a secondary HIV transmission during ATI was observed. These data show that the prime-boost combination of DNA and LIPO-5 vaccines elicited broad and polyfunctional T cells. The contrast between the quality of immune responses and the lack of potent viral control underscores the need for combined immunomodulatory strategies. (This study has been registered at ClinicalTrials.gov under registration no. NCT01492985.)IMPORTANCE In this placebo-controlled phase II randomized clinical trial, we evaluated the safety and immunogenicity of a therapeutic prime-boost vaccine strategy using a recombinant DNA vaccine (GTU-MultiHIV B clade) followed by a boost vaccination with a lipopeptide vaccine (HIV-LIPO-5) in HIV-infected patients on combined antiretroviral therapy. We show here that this prime-boost strategy is well tolerated, consistently with previous studies in HIV-1-infected individuals and healthy volunteers who received each vaccine component individually. Compared to the placebo group, vaccinees elicited strong and polyfunctional HIV-specific CD4⁺ and CD8⁺ T-cell responses. However, these immune responses presented some qualitative defects and were not able to control viremia following antiretroviral treatment interruption, as no difference in HIV viral rebound was observed in the vaccine and placebo groups. Several lessons were learned from these results, pointing out the urgent need to combine vaccine strategies with other immune-based interventions.

Keywords: HIV; antiretroviral therapy interruption; clinical trials; human immunodeficiency virus; therapeutic vaccine.

FIG 1

Trial design. (A) Schematics of study design. Blue arrows indicate time of DNA GTU-MultiHIV B or placebo administrations. Red arrows indicate time of HIV LIPO-5 or placebo administrations. ART, antiretroviral therapy; ATI, analytical treatment interruption; (B) Consolidated Standards of Reporting Trials (CONSORT) flow diagram for the trial. CONSORT diagram delineates the study enrollment of 103 participants who underwent randomization to the placebo or vaccine groups.

FIG 2

Functional profile of CD4⁺ and CD8⁺ T-cell responses. Production of interleukin 2 (IL-2), gamma interferon (IFN-γ), and tumor necrosis factor alpha (TNF-α) as measured by intracellular cytokine staining (ICS) using multiparametric flow cytometry after cell stimulation before (W0) and after vaccination (W28) in placebo (red) and therapeutic vaccine (blue) groups. (A) HIV-specific CD3⁺ CD4⁺ T-cell frequency; (B) HIV-specific CD3⁺ CD8⁺ T-cell frequency; (C) heatmap of P values between W28 and W0 of CD3⁺ CD4⁺ and CD3⁺ CD8⁺ marginal responses against Gag, Pol/Env, Nef, and the sum of HIV peptides (total HIV); (D) frequency of HIV-specific CD3⁺ CD4⁺ T cells producing 1, 2, or 3 cytokines in the vaccine group at W0 (light gray) and W28 (dark gray); (E) frequency of HIV-specific CD3⁺ CD8⁺ T cells producing 1, 2, or 3 cytokines in the vaccine group at W0 (light gray) and W28 (dark gray); (F) heatmap of P values between W28 and W0 of CD3⁺ CD4⁺ and CD3⁺ CD8⁺ polyfunctionality responses against Gag, Pol/Env, Nef, and total HIV peptides.

FIG 3

Mass cytometry (CyTOF) phenotyping. Ratio of memory CD8⁺ T cells at W28 compared to W0 for several subsets according to PD-1 and TIGIT (A), CD27 and CD57 (B), or HLA-DR and CD38 (C) in placebo (red) and therapeutic vaccine (blue) groups. Ratio of memory CD4⁺ T cells at W28 compared to W0 for HLA-DR and CD38 (D) in placebo (red) and therapeutic vaccine (blue) groups. P values were calculated using the Mann-Whitney test; *, P = 0.017; **, P = 0.0022.

FIG 4

Plasma HIV viral load and CD4⁺ T-cell count changes throughout the study. (A) Levels of plasma HIV RNA in the placebo (red) and therapeutic vaccine (blue) groups before and after ATI (weeks 36 to 48); (B) CD4⁺ T-cell count changes during the vaccination phase and following ATI in the placebo (red) and therapeutic vaccine (blue) groups before and after ATI (weeks 36 to 48).

FIG 5

Integrative analysis of immune response to vaccine. Principal-component analysis of ICS responses at W28. Log-transformed marginal CD4⁺ and CD8⁺ T-cell responses at W28 were included as active variables; virological markers during ATI (highest viral load, viral load slope, viral load area under the curve [AUC], and time to rebound) were included as supplementary variables. (A) Projection of variables; (B) projection of individuals represented into placebo (red) and therapeutic vaccine (blue) groups.