GREAT consortium announces successful completion of a multisite African Phase I HIV-1 vaccine trial with encouraging preliminary results

OXFORD, UNITED KINGDOM – 12 JULY 2023 – The Globally Relevant AIDS Vaccine Europe-Africa Trials Partnership (GREAT) is pleased to announce the successful completion of the multisite phase I HIV-CORE 006 HIV vaccine clinical trial. This trial was made possible by six-and-a-half years of funding for the GREAT consortium from the European and Developing Countries Clinical Trials Partnership (EDCTP), which came to an end on 30 June this year.

All the components of the vaccine candidate were well tolerated by the participants with no serious adverse events reported. Preliminary analysis of the immunological trial results demonstrates the induction of high frequencies of broadly specific T cells that recognise functionally conserved regions on HIV-1 and are therefore more protective. Not all T cells are equally protective, and the T cells induced by this vaccine candidate, also called killer T cells, are underutilized in natural HIV-1 infection. Furthermore, the killer T cells the vaccine candidate induced in this trial were capable of inhibiting four major global HIV clades: A, B, C and D. Further analyses are ongoing with the first results expected to be submitted for a publication later this year.

“Over the tenure of this consortium, the study team have evaluated a highly rational, bioinformatics-assisted vaccine design to address the enormous variability of HIV-1 – one of the greatest challenges to the development of an effective vaccine against HIV/AIDS,” said Tomáš Hanke, Professor of Vaccine Immunology at the Jenner Institute, University of Oxford, the consortium coordinator and lead researcher on the trial. “The analysis so far indicates the induction of strong and multi-specific T-cell responses that recognise several vulnerable parts of proteins common to most HIV variants in each individual at the same time – targeting HIV where it hurts.”

The goal of the HIV-CORE 006 is to evaluate the safety, tolerability, and immunogenicity of a novel mosaic HIV vaccine candidate, HIVconsvX, that has been designed to target a broad range of HIV-1 variants, making it potentially applicable for HIV strains in any geographical region. While most HIV vaccine candidates to date have aimed to generate antibody or T-cell responses against more variable HIV epitopes, HIVconsvX aims to induce the immune system’s killer T cells against a group of highly conserved regions, which obliterate the virus factories in the body.

“This study represents an innovative hypothesis to harness the killer T cell arm of the immune system to prevent HIV infection from all major HIV subtypes.” said Dr. Vincent Muturi-Kioi, Senior Medical Director at IAVI. “It’s important that we have a diversity of vaccine candidates in the pipeline to make sure we have the greatest chance of success in developing an effective HIV vaccine.”

HIV-CORE 006 took place at four vaccine trial sites in Kenya, Uganda and Zambia. First vaccinations were administered at the Center for Family Health Research in Lusaka, Zambia (CFHRZ) in August 2021 with the final volunteers enrolled at the KEMRI-Wellcome Trust Research Programme in December 2021. The last follow-up visits took place at the beginning of November 2022. A total of 88 participants were enrolled in the trial, of whom 72 received the vaccine candidate and 16 received a placebo. The participant retention rate and adherence to vaccination and follow-up visits exceeded 95%.

‘’The vaccines used in this trial have demonstrated a favourable safety profile and induction of immune responses in most of the participants. These are promising results, and an important step in developing an HIV vaccine that can protect people against HIV infection in all parts of the world,’’ said Dr Paola Cicconi, Chief Investigator of the Trial and Senior Clinical Researcher at the University of Oxford’. “On behalf of the entire GREAT team, we extend our gratitude to all the participants for their huge commitment to the success of this trial.”

The GREAT team successfully completed planned capacity building activities with the four partnering clinical research centers (CRC) earlier this year. These activities focused on preparing the CRCs to participate in future HIV vaccine research and clinical trials. This included the training of personnel, procuring equipment, and updating and expanding clinical and laboratory infrastructure and establishing field-based clinical and laboratory capacity. Community and stakeholder engagement activities continue to support the dissemination of the forthcoming results.

“The GREAT consortium has leveraged international partnerships in Africa and Europe to evaluate the novel HIVconsvX vaccine candidate in countries and communities where an HIV vaccine will ultimately have the greatest public health impact,” said Dr. William Kilembe, project director, Center for Family Health Research in Zambia (CFHRZ), Zambia. “Through this trial, the consortium members have contributed to strengthening the capacity of the partnering clinical research centers to conduct robust HIV vaccine research and clinical trials. Community engagement is key to this approach, and we look forward to continuing to work with community stakeholders as the final results become available.”

The next milestone will be reporting of the primary findings later this year followed by further in-depth analyses. The candidate HIVconsvX vaccines are tested in a comprehensive developmental clinical program encompassing trials in healthy uninfected individuals for prevention of HIV, such as in HIV-CORE 006, and in people already living with HIV-1 as a potential cure.

The GREAT consortium

The HIV-CORE 006 team is led by Professor Tomáš Hanke at the Jenner Institute at Oxford University. In addition to Hanke, the trial’s Chief Investigator is Dr. Paola Cicconi at the Jenner Institute at Oxford University and the other principal investigators are Pontiano Kaleebu, M.D., Ph.D. director of MRC/UVRI and LSHTM Uganda Research Unit; Walter Jaoko, M.D., Ph.D., director of KAVI-Institute of Clinical Research (KAVI-ICR); Eduard Sanders, M.D., Ph.D., principal investigator at KEMRI-Wellcome Trust Research Programme; and William Kilembe, M.D., M.Sc., project director of the Center for Family Health Research Zambia (CFHRZ).

This project is part of the EDCTP2 programme supported by the European Union (grant number SRIA2015-1066) coordinated by Professor Tomáš Hanke. The vaccines were manufactured through funds from EDCTP, IAVI and the European AIDS Vaccine Initiative 2020 (EAVI2020).

The GREAT consortium is a collaboration with the Oxford University, IAVI, Imperial College London, KAVI-Institute of Clinical Research (KAVI-ICR) at the University of Nairobi, the Uganda Virus Research Institute-IAVI HIV Vaccine Program (UVRI-IAVI), the MRC/UVRI and LSHTM Uganda Research Unit, the Kenya Medical Research Institute-Wellcome Trust Research Programme (KWTRP), and Center for Family Health Research in Zambia CFHRZ.

The killer T-cell vaccine strategy

The trial tests a candidate T-cell vaccine strategy against HIV-1. The tested regimen consists of a prime with engineered replication-deficient simian (chimpanzee) adenovirus vector ChAdOx1 followed by a heterologous boost with two replication-deficient poxviruses called MVA. These vectors deliver unique mosaic algorithm-computed immunogens derived from the six most functionally conserved (vulnerable) regions of the HIV proteome, collectively called HIVconsvX. Two regions are from the Gag including the whole capsid protein p24 and four are derived from the Pol proteins. These regions are common to most global HIV-1 variants and are hard to change and escape. If effective, the vaccines could work across all major HIV-1 clades and be deployed as a part of a preventive package in all geographical regions.