Safety, immunogenicity and effect on viral rebound of HTI vaccines in early treated HIV-1 infection: a randomized, placebo-controlled phase 1 trial

HIVACAT T-cell immunogen (HTI) is a novel human immunodeficiency virus (HIV) vaccine immunogen designed to elicit cellular immune responses to HIV targets associated with viral control in humans. The AELIX-002 trial was a randomized, placebo-controlled trial to evaluate as a primary objective the safety of a combination of DNA.HTI (D), MVA.HTI (M) and ChAdOx1.HTI (C) vaccines in 45 early-antiretroviral (ART)-treated individuals (44 men, 1 woman; NCT03204617). Secondary objectives included T-cell immunogenicity, the effect on viral rebound and the safety of an antiretroviral treatment interruption (ATI). Adverse events were mostly mild and transient. No related serious adverse events were observed. We show here that HTI vaccines were able to induce strong, polyfunctional and broad CD4 and CD8 T-cell responses. All participants experienced detectable viral rebound during ATI, and resumed ART when plasma HIV-1 viral load reached either >100,000 copies ml^-1, >10,000 copies ml^-1 for eight consecutive weeks, or after 24 weeks of ATI. In post-hoc analyses, HTI vaccines were associated with a prolonged time off ART in vaccinees without beneficial HLA (human leukocyte antigen) class I alleles. Plasma viral load at the end of ATI and time off ART positively correlated with vaccine-induced HTI-specific T-cell responses at ART cessation. Despite limited efficacy of the vaccines in preventing viral rebound, their ability to elicit robust T-cell responses towards HTI may be beneficial in combination cure strategies, which are currently being tested in clinical trials.

Limited Humoral and Specific T-Cell Responses After SARS-CoV-2 Vaccination in PWH With Poor Immune Reconstitution

BACKGROUND

We analyzed humoral and cellular immune responses induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) messenger RNA (mRNA) vaccines in people with human immunodeficiency virus (HIV; PWH) who had CD4+ T-cell counts <200/µL (HIV<200 group).

METHODS

This prospective cohort study included 58 PWH in the HIV<200 group, 36 with CD4+ T-cell counts >500/µL (HIV>500 group), and 33 HIV-1-negative controls (control group). Antibodies against the SARS-CoV-2 spike protein (anti-S immunoglobulin [Ig] G) and the receptor-binding domain (anti-RBD IgG) were quantified before and 4 weeks after the first and the second doses of BNT162b2 or mRNA-1273 (at week 8). Viral neutralization activity and T-cell responses were also determined.

RESULTS

At week 8, anti-S/anti-RBD IgG responses increased in all groups (P < .001). Median (interquartile range) anti-S and anti-RBD IgG levels at week 8 were 153.6 (26.4-654.9) and 171.9 (61.8-425.8) binding antibody units (BAU)/mL, respectively, in the HIV<200 group, compared with 245.6 (145-824) and 555.8 (166.4-1751) BAU/mL in the HIV>500 group and 274.7 (193.7-680.4) and 281.6 (181-831.8) BAU/mL in controls (P < .05). Neutralizing capacity and specific T-cell immune responses were absent or reduced in 33% of those in the HIV<200 group, compared with 3.7% in the HIV>500 group (P < .01).

CONCLUSIONS

One-third of PWH with CD4+ T-cell counts <200/µL show low anti-S/anti-RBD IgG levels, reduced in vitro neutralization activity against SARS-CoV-2, and no vaccine-induced T cells after receiving coronavirus disease 2019 mRNA vaccines.

HIVconsv Vaccines and Romidepsin in Early-Treated HIV-1-Infected Individuals: Safety, Immunogenicity and Effect on the Viral Reservoir (Study BCN02)

Kick&kill strategies combining drugs aiming to reactivate the viral reservoir with therapeutic vaccines to induce effective cytotoxic immune responses hold potential to achieve a functional cure for HIV-1 infection. Here, we report on an open-label, single-arm, phase I clinical trial, enrolling 15 early-treated HIV-1-infected individuals, testing the combination of the histone deacetylase inhibitor romidepsin as a latency-reversing agent and the MVA.HIVconsv vaccine. Romidepsin treatment resulted in increased histone acetylation, cell-associated HIV-1 RNA, and T-cell activation, which were associated with a marginally significant reduction of the viral reservoir. Vaccinations boosted robust and broad HIVconsv-specific T cells, which were strongly refocused toward conserved regions of the HIV-1 proteome. During a monitored ART interruption phase using plasma viral load over 2,000 copies/ml as a criterium for ART resumption, 23% of individuals showed sustained suppression of viremia up to 32 weeks without evidence for reseeding the viral reservoir. Results from this pilot study show that the combined kick&kill intervention was safe and suggest a role for this strategy in achieving an immune-driven durable viremic control.