A Phase I Double Blind, Placebo-Controlled, Randomized Study of the Safety and Immunogenicity of Electroporated HIV DNA with or without Interleukin 12 in Prime-Boost Combinations with an Ad35 HIV Vaccine in Healthy HIV-Seronegative African Adults

Abstract

Background: Strategies to enhance the immunogenicity of DNA vaccines in humans include i) co-administration of molecular adjuvants, ii) intramuscular administration followed by in vivo electroporation (IM/EP) and/or iii) boosting with a different vaccine. Combining these strategies provided protection of macaques challenged with SIV; this clinical trial was designed to mimic the vaccine regimen in the SIV study.

Methods: Seventy five healthy, HIV-seronegative adults were enrolled into a phase 1, randomized, double-blind, placebo-controlled trial. Multi-antigenic HIV (HIVMAG) plasmid DNA (pDNA) vaccine alone or co-administered with pDNA encoding human Interleukin 12 (IL-12) (GENEVAX IL-12) given by IM/EP using the TriGrid Delivery System was tested in different prime-boost regimens with recombinant Ad35 HIV vaccine given IM.

Results: All local reactions but one were mild or moderate. Systemic reactions and unsolicited adverse events including laboratory abnormalities did not differ between vaccine and placebo recipients. No serious adverse events (SAEs) were reported. T cell and antibody response rates after HIVMAG (x3) prime-Ad35 (x1) boost were independent of IL-12, while the magnitude of interferon gamma (IFN-γ) ELISPOT responses was highest after HIVMAG (x3) without IL-12. The quality and phenotype of T cell responses shown by intracellular cytokine staining (ICS) were similar between groups. Inhibition of HIV replication by autologous T cells was demonstrated after HIVMAG (x3) prime and was boosted after Ad35. HIV specific antibodies were detected only after Ad35 boost, although there was a priming effect with 3 doses of HIVMAG with or without IL-12. No anti-IL-12 antibodies were detected.

Conclusion: The vaccines were safe, well tolerated and moderately immunogenic. Repeated administration IM/EP was well accepted. An adjuvant effect of co-administered plasmid IL-12 was not detected.

Trial registration: ClinicalTrials.gov NCT01496989.

Conflict of interest statement

Competing Interests: KS, JL, BR, JG, JHC, PF and CS are or were employees or consultants of IAVI at the time of the study. IAVI has development rights for the Ad35-GRIN/Env product. No other authors have competing interests. ME and JE are employees of Profectus Biosciences which owns the rights to the HIV MAG pDNA. They both own shares in Profectus Biosciences and are listed as inventors on patents owned by Profectus Biosciences. DH is an employee of Ichor Medical Sciences Inc which owns the rights to the TriGrid Delivery System. DH owns shares in Ichor Medical Sciences Inc and is listed as an inventor on patents owned by Ichor Medical Sciences Inc. This does not alter the authors' adherence to PLOS ONE policies on sharing data and materials.

Figures

Fig 1. CONSORT Diagram.

Fig 2. Maximum Severity of Adverse Events (AE).

A. Local Solicited AE over 7 days, B. Systemic Solicited AE over 7 days, C. Unsolicited AE over 28 days.

Fig 3. Total IFN-γ ELISPOT Response Rates and Magnitude.

Responses at baseline (BL), 2 weeks after prime (Prm) and 2 weeks after boost (Bst) are shown. The y-axis shows the SFC/106 PBMC on a half-log scale. All responses are background-subtracted. Mean responses <1 were set to 1. Black dots: response below the cut-off as defined in the materials and methods to any of the 12 MAG and GRIN-Env peptide pools; red circles: response above the cut-off to any of the 12 peptide pools. For the vaccine groups, the overlaid box plot summarizes the positive responses (i.e., the median, 1st and 3rd quartiles and minimum/maximum). The x-axis shows the % responders and number of responders out of the total tested at each time point. The placebo (Pbo) responses are combined in the far right box plot.

Fig 4. HIV-specific IFN-γ ELISPOT responses in HIVMAG and Ad35-GRIN/Env immunized individuals.

At 2 weeks post final immunization in each of groups 1–5, PBMCs were collected and tested for GRIN/Env (A) and HIVMAG (B) specific IFN-γ secretion by ELISpot assay. Each stacked bar represents a response from an individual volunteer with each color representing a different peptide pool. Only individual peptide pool-specific responses that met the criteria for positivity are included.

Fig 5. CD8+ and CD4+ T-lymphocyte Responses by Intracellular Cytokine Staining and Polychromatic Flow Cytometry.

ICS was performed on a subset of samples from Groups 1–3, at baseline, visits 07/08 (2–4 weeks post HIVMAG (x3) prime) and visit 13 (2 weeks post Ad35-GRIN/Env boost). HIV-1-specific CD4+ (top panel) and CD8+ (bottom panel) T cell responses were evaluated by a 7-color ICS to assess the expression of IL-2, IFN-γ and TNF-α with peptides matched to the HIVMAG. Symbols show responses to MAG peptide pools; Env pool 1 = *, Env pool 2 = ○, Gag = ●, Nef Tat Vif = ●, Pol pool 1 = Δ, Pol pool 2 = ▲. The y-axis shows the % expressing T cells on a half-log scale.

Fig 6. VIA breadth.

VIA was assessed at baseline, 2–4 weeks post HIVMAG (x3) and at 2 weeks post Ad35-GRIN/Env boost in Groups 1–3. Each symbol represents an individual and the bar shows the mean number of viruses inhibited out of a total of 8 viruses in the panel.

Fig 7. Env Antibody Titers.

Panel A) HIV-Env subtype A (UG37) and panel B) HIV-Env subtype B (6101) specific IgG antibody titers were assessed at baseline, post prime and post boost. Black and Red arrows indicate vaccination times for Groups 1–3 and Groups 4–5, respectively.