Safety and immunogenicity of a multivalent HIV vaccine comprising envelope protein with either DNA or NYVAC vectors (HVTN 096): a phase 1b, double-blind, placebo-controlled trial

Abstract

Background: Up to now, immunisation regimens that have been assessed for development of HIV vaccines have included purified envelope (Env) protein among the boosting components of the regimen. We postulated that co-administration of Env protein with either a DNA or NYVAC vector during priming would result in early generation of antibody responses to the Env V1/V2 region, which are important markers for effective protection against infection. We aimed to assess the safety and immunogenicity of a multivalent HIV vaccine including either DNA or NYVAC vectors alone or in combination with Env glycoprotein (gp120) followed by a co-delivered NYVAC and Env protein boost.

Methods: We did a single-centre, double-blind, placebo-controlled phase 1b trial at the Centre Hospitalier Universitaire Vaudois (Lausanne, Switzerland). We included healthy volunteers aged 18-50 years who were at low risk of HIV infection. We randomly allocated participants using computer-generated random numbers to one of four vaccination schedules or placebo (4:1), and within these schedules participants were allocated either active treatment (T1, T2, T3, and T4) or placebo (C1, C2, C3, and C4). T1 consisted of two doses of NYVAC vector followed by two doses of NYVAC vector and gp120 Env protein; T2 comprised four doses of NYVAC vector and gp120 Env protein; T3 was two doses of DNA vector followed by two doses of NYVAC vector and gp120 Env protein; and T4 was two doses of DNA vector and gp120 Env protein followed by two doses of NYVAC vector and gp120 Env protein. Placebo injections were matched to the corresponding active treatment group. Doses were administered by injection at months 0, 1, 3, and 6. Primary outcomes were safety and immunogenicity of the vaccine schedules. Immune response measures included cross-clade and epitope-specific binding antibodies, neutralising antibodies, and antibody-dependent cell-mediated cytotoxicity measured 2 weeks after the month 1, 3, and 6 vaccinations. This trial is registered with ClinicalTrials.gov, NCT01799954.

Findings: Between Aug 23, 2012, and April 18, 2013, 148 healthy adult volunteers were screened for the trial, of whom 96 participants were enrolled. 20 individuals were allocated to each active treatment group (groups T1-4; n=80) and four were assigned to each placebo group (groups C1-4; n=16). Vaccines containing the NYVAC vector (groups T1 and T2) were associated with more frequent severe reactogenicity and more adverse events than were vaccines containing the DNA vector (groups T3 and T4). The most frequent adverse events judged related to study product were lymphadenopathy (n=9) and hypoaesthesia (n=2). Two participants, one in the placebo group and one in the DNA-primed T3 group, had serious adverse events that were judged unrelated to study product. One participant in the T3 group died from cranial trauma after a motor vehicle accident. Across the active treatment groups, IgG responses 2 weeks after the 6-month dose of vaccine were 74-95%. Early administration of gp120 Env protein (groups T2 and T4) was associated with a substantially earlier and higher area under the curve for gp120 Env binding, production of anti-V1/V2 and neutralising antibodies, and better antibody-response coverage over a period of 18 months, compared with vaccination regimens that delayed administration of gp120 Env protein until the 3-month vaccination (groups T1 and T3).

Interpretation: Co-administration of gp120 Env protein components with DNA or NYVAC vectors during priming led to early and potent induction of Env V1/V2 IgG binding antibody responses. This immunisation approach should be considered for induction of preventive antibodies in future HIV vaccine efficacy trials.

Funding: National Institutes of Health, National Institute of Allergy and Infectious Diseases, and the Bill & Melinda Gates Foundation.

Figure 1

Trial profile C=control. T=treatment. BAMA=binding antibody multiplex assay. ICS=intracellular cytokine staining.

Figure 2

T-cell responses at different timepoints after vaccine administration CD4 (A) and CD8 (B) T-cell responses were measured by intracellular cytokine staining and expressed as the percentage of cells producing IL-2, IFN-γ, or both in the different treatment groups (T1–T4) and the control group (C). CD4 and CD8 T-cell responses and magnitudes of response among positive responders to any HIV PTE_g are shown 2 weeks after the month 1 (month 1·5), month 3 (month 3·5), and month 6 (month 6·5) vaccinations and 6 months after the month 6 vaccination (month 12). The proportion of positive responders for every study group is shown at the top of every panel. Horizontal lines depict median responses. Boxplots represent the distribution of responses. Circles denote positive responders. Triangles represent negative responders. T1=two doses of NYVAC vector followed by two doses of NYVAC vector and gp120 Env protein. T2=four doses of NYVAC vector and gp120 Env protein. T3=two doses of DNA vector followed by two doses of NYVAC vector and gp120 Env protein. T4=two doses of DNA vector and gp120 Env protein followed by two doses of NYVAC vector and gp120 Env protein. C=placebo groups (C1–C4), comprising matched injections. IFN=interferon. IL=interleukin. PTE_g=global potential T-cell epitope. Env=envelope.

Figure 3

Antibody responses at different timepoints after vaccine administration (A) Neutralising antibody magnitude–breadth curves are shown against a panel of six Env-pseudotyped tier 1 HIV-1 isolates (BaL.26, MN.3, SF162.LS, MW965.26, NP03.13, and TH023.6) 2 weeks after the month 1 (month 1·5), month 3 (month 3·5), and month 6 (month 6·5) vaccinations and 6 months after the month 6 vaccination (month 12). The AUC, interpretable as the geometric mean ID₅₀ titre across viruses, was used to compare groups. Individual participants are dashed lines and treatment group averages are solid lines. (B) IgG binding antibody responses and magnitudes among positive responders were measured by binding antibody multiplex assays 2 weeks after the month 1 (month 1·5), month 3 (month 3·5), and month 6 (month 6·5) vaccinations, and the durability of the antibody response was measured 6 months (month 12), 9 months (month 15), and 12 months (month 18) after the month 6 vaccination. IgG binding antibodies were measured against three vaccine-matched antigens (aggregate vaccine-matched responses) and three V1/V2 antigens. Responses to aggregate vaccine-matched antigens were judged positive if a positive response was seen to any of the vaccine-matched antigens. Errors bars show 95% CIs (upper panels) or IQRs (lower panels). (C) IgG binding magnitude AUC values are shown against aggregate vaccine-matched antigens and three V1/V2 antigens. Net MFI values are shown, and net MFI values less than 100 were truncated for MFI calculation. The AUC from months 0–18 (month 0 vaccination to 12 months after the month 6 vaccination) was calculated using the trapezoidal rule for every fully vaccinated participant. Boxplots represent the distribution of positive responders with net MFI values greater than 100. T1=two doses of NYVAC vector followed by two doses of NYVAC vector and gp120 Env protein. T2=four doses of NYVAC vector and gp120 Env protein. T3=two doses of DNA vector followed by two doses of NYVAC vector and gp120 Env protein. T4=two doses of DNA vector and gp120 Env protein followed by two doses of NYVAC vector and gp120 Env protein. C=placebo groups (C1–C4), comprising matched injections. Env=envelope. AUC=area under the curve. ID₅₀=number of virus particles needed to produce infection in 50% of people. MFI=mean fluorescence intensity.

Figure 4

Antibody-dependent cell-mediated cytotoxicity Responses (upper panels) and AUC net percentage of granzyme B activity (lower panels) are shown for three different antigens in the study groups. The AUC was the non-parametric area under the net percentage granzyme B activity versus log₁₀ (dilution) curve and was calculated using the trapezoidal rule. Circles show positive responses; negative responses are shown as triangles. Boxplots represent the distribution of positive responders only. Clade C gp120 was 96ZM651_D11gp120.avi/293F; clade AE gp120 was AE.A244_gDneg_gp120/293F; and clade B was MN_gp120gDneg/293F Monomer. As control, serum samples from the treated groups were incubated with target cells not coated with gp120. T1=two doses of NYVAC vector followed by two doses of NYVAC vector and gp120 Env protein. T2=four doses of NYVAC vector and gp120 Env protein. T3=two doses of DNA vector followed by two doses of NYVAC vector and gp120 Env protein. T4=two doses of DNA vector and gp120 Env protein followed by two doses of NYVAC vector and gp120 Env protein. C=placebo groups (C1–C4), comprising matched injections. AUC=area under the curve. Env=envelope.

Figure 5

Cross-protocol comparisons of HVTN 096, RV144, and HVTN 100 studies (A) Comparison of V1/V2 antigens common across the three protocols at peak timepoints (with study groups of HVTN 096 pooled): AE.A244 V1V2 Tags 293F (matched), gp70_B CaseA_V1_V2 (not matched), and gp70_B CaseA2 V1/V2/169K (not matched). (B) Comparison of IgG responses to gp120 antigens across the three protocols at peak timepoints (with study groups of HVTN 096 pooled): Con 6 gp12/B and Con S gp140 CFI. Boxplots show the distribution of positive responses. Circles show positive responses; negative responses are shown as triangles. The proportion of positive responders at peak timepoints (2 weeks after the month 6 vaccination) are shown at the bottom of each panel. p.rate=p value for difference in response. p.mag=p value for difference in magnitude of response. HVTN=HIV Vaccine Trials Network. MFI=mean fluorescence intensity.