The therapeutic HIV Env C5/gp41 vaccine candidate Vacc-C5 induces specific T cell regulation in a phase I/II clinical study.
Levels of non-neutralising antibodies (AB) to the C5 domain of HIV Env gp120 are inversely related to progression of HIV infection. In this phase I/II clinical study we investigated safety of Vacc-C5, a peptide-based therapeutic vaccine candidate corresponding to C5/gp41732-744as well as the effects on pre-existing AB levels to C5/gp41732-744, immune activation and T cell responses including exploratory assessments of Vacc-C5-induced T cell regulation. Our hypothesis was that exposure of the C5 peptide motif may have detrimental effects due to several of its HLA-like features and that enhancement of non-neutralising anti-C5 AB by vaccination could reduce C5 exposure and thereby chronic immune activation.



Thirty-six HIV patients on effective antiretroviral therapy were randomised to one of three dose levels of Vacc-C5 administered intramuscularly with Alhydrogel or intradermally with GM-CSF as adjuvant through initial immunisation and two booster periods over 26 weeks. Vacc-C5-specific AB were measured by ELISA and T cell responses by both IFN-γ ELISPOT and proliferative assays analysed by flow cytometry. Immune regulation was assessed by functional blockade of the two inhibitory cytokines IL-10 and TGF-β in parallel cultures. Non-parametric statistical tests were applied.



Vacc-C5 was found safe and well tolerated in all patients. Only marginal changes in humoral and cellular responses were induced, without any effect on immune activation. Overall, anti-Vacc-C5 AB levels seemed to decrease compared to pre-existing levels. Whereas Vacc-C5-specific CD8+T cell proliferative responses increased after the first booster period (p = 0.020; CD4+, p = 0.057), they were reduced after the second. In contrast, Vacc-C5-induced T cell regulation increased after completed vaccination (p ≤ 0.027) and was lower at baseline in the few AB responders identified (p = 0.027).



The therapeutic HIV vaccine candidate Vacc-C5 safely induced only marginal immune responses, whereas Vacc-C5-induced T cell regulation markedly increased. Our data support further attention on immune regulation during therapeutic HIV vaccination studies.



NCT01627678 .
Department of Infectious Diseases, Oslo University Hospital, Oslo, Norway.|K.G. Jebsen Inflammation Research Center, University of Oslo, Oslo, Norway.
Kristin
K
Brekke
Bionor Pharma, Oslo, Norway.
Maja
M
Sommerfelt
Bionor Pharma, Oslo, Norway.
Mats
M
Ökvist
Department of Infectious Diseases, Oslo University Hospital, Oslo, Norway.|University of Oslo, Oslo, Norway.|K.G. Jebsen Inflammation Research Center, University of Oslo, Oslo, Norway.
Anne Margarita
AM
Dyrhol-Riise
Department of Infectious Diseases, Oslo University Hospital, Oslo, Norway. dag.kvale@medisin.uio.no.|University of Oslo, Oslo, Norway. dag.kvale@medisin.uio.no.|K.G. Jebsen Inflammation Research Center, University of Oslo, Oslo, Norway. dag.kvale@medisin.uio.no.
Dag
D
Kvale
D016915:AIDS Vaccines / Q000008:administration & dosage / Q000009:adverse effects* / Q000276:immunology*; D016207:Cytokines / Q000097:blood / Q000276:immunology; D015658:HIV Infections / Q000188:drug therapy / Q000276:immunology / Q000517:prevention & control; D006801:Humans; D013601:T-Lymphocytes / Q000276:immunology
D016915:AIDS Vaccines; D016207:Cytokines
Antibodies; HIV; Immune activation; Immune regulation; T cell; Therapeutic vaccine